Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards, 17414-17888 [2022-04934]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 87, Number 59 (Monday, March 28, 2022)]
[Proposed Rules]
[Pages 17414-17888]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-04934]



[[Page 17413]]

Vol. 87

Monday,

No. 59

March 28, 2022

Part II





Environmental Protection Agency





-----------------------------------------------------------------------





40 CFR Parts 2, 59, 60, et al.





Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and 
Vehicle Standards; Proposed Rule

Federal Register / Vol. 87 , No. 59 / Monday, March 28, 2022 / 
Proposed Rules

[[Page 17414]]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 2, 59, 60, 80, 85, 86, 87, 600, 1027, 1030, 1033, 
1036, 1037, 1039, 1042, 1043, 1045, 1048, 1051, 1054, 1060, 1065, 
1066, 1068, and 1090

[EPA-HQ-OAR-2019-0055; FRL-7165-03-OAR]
RIN 2060-AU41


Control of Air Pollution From New Motor Vehicles: Heavy-Duty 
Engine and Vehicle Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA) is proposing a rule 
that would reduce air pollution from highway heavy-duty vehicles and 
engines, including ozone, particulate matter, and greenhouse gases. 
This proposal would change the heavy-duty emission control program--
including the standards, test procedures, useful life, warranty, and 
other requirements--to further reduce the air quality impacts of heavy-
duty engines across a range of operating conditions and over a longer 
period of the operational life of heavy-duty engines. Heavy-duty 
vehicles and engines are important contributors to concentrations of 
ozone and particulate matter and their resulting threat to public 
health, which includes premature death, respiratory illness (including 
childhood asthma), cardiovascular problems, and other adverse health 
impacts. This proposal would reduce emissions of nitrogen oxides and 
other pollutants. In addition, this proposal would make targeted 
updates to the existing Heavy-Duty Greenhouse Gas Emissions Phase 2 
program, proposing that further GHG reductions in the MY 2027 timeframe 
are appropriate considering lead time, costs, and other factors, 
including market shifts to zero-emission technologies in certain 
segments of the heavy-duty vehicle sector. We also propose limited 
amendments to the regulations that implement our air pollutant emission 
standards for other sectors (e.g., light-duty vehicles, marine diesel 
engines, locomotives, various types of nonroad engines, vehicles, and 
equipment).

DATES: Comments: Written comments must be received on or before May 13, 
2022. Under the Paperwork Reduction Act (PRA), comments on the 
information collection provisions are best assured of consideration if 
the Office of Management and Budget (OMB) receives a copy of your 
comments on or before April 27, 2022.
    Public Hearing: EPA plans to hold a virtual public hearing on April 
12, 2022. An additional session may be held on April 13, 2022. Please 
refer to Participation in Virtual Public Hearing in the SUPPLEMENTARY 
INFORMATION section for additional information on the public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0055, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/ 
(our preferred method). Follow the online instructions for submitting 
comments.
     Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2019-0055 in the subject line of the message.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, OAR, Docket EPA-HQ-OAR-2019-0055, Mail Code 28221T, 1200 
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand Delivery or Courier (by scheduled appointment only): 
EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution 
Avenue NW, Washington, DC 20004. The Docket Center's hours of 
operations are 8:30 a.m.-4:30 p.m., Monday-Friday (except Federal 
Holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov/, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the ``Public Participation'' 
heading of the SUPPLEMENTARY INFORMATION section of this document. Out 
of an abundance of caution for members of the public and our staff, the 
EPA Docket Center and Reading Room are open to the public by 
appointment only to reduce the risk of transmitting COVID-19. Our 
Docket Center staff also continues to provide remote customer service 
via email, phone, and webform. Hand deliveries and couriers may be 
received by scheduled appointment only. For further information on EPA 
Docket Center services and the current status, please visit us online 
at https://www.epa.gov/dockets.
    Public Hearing. EPA plans to hold a virtual public hearing for this 
rulemaking. Please refer to Participation in Virtual Public Hearing in 
the SUPPLEMENTARY INFORMATION section for additional information.

FOR FURTHER INFORMATION CONTACT: Brian Nelson, Assessment and Standards 
Division, Office of Transportation and Air Quality, Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
telephone number: (734) 214-4278; email address: [email protected].

SUPPLEMENTARY INFORMATION: 

A. Public Participation

Written Comments

    Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2019-
0055, at https://www.regulations.gov (our preferred method), or the 
other methods identified in the ADDRESSES section. Once submitted, 
comments cannot be edited or removed from the docket. The EPA may 
publish any comment received to its public docket. Do not submit 
electronically any information you consider to be Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Multimedia submissions (audio, video, etc.) must be 
accompanied by a written comment. The written comment is considered the 
official comment and should include discussion of all points you wish 
to make. The EPA will generally not consider comments or comment 
contents located outside of the primary submission (i.e., on the web, 
cloud, or other file sharing system). For additional submission 
methods, the full EPA public comment policy, information about CBI or 
multimedia submissions, and general guidance on making effective 
comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Due to public health concerns related to COVID-19, the EPA Docket 
Center and Reading Room are open to the public by appointment only. Our 
Docket Center staff also continues to provide remote customer service 
via email, phone, and webform. Hand deliveries or couriers will be 
received by scheduled appointment only. For further information and 
updates on EPA Docket Center services, please visit us online at 
https://www.epa.gov/dockets.
    The EPA continues to carefully and continuously monitor information 
from the Centers for Disease Control and Prevention (CDC), local area 
health departments, and our Federal partners so that we can respond 
rapidly as conditions change regarding COVID-19.

Participation in Virtual Public Hearing

    Please note that because of current CDC recommendations, as well as 
state and local orders for social distancing to

[[Page 17415]]

limit the spread of COVID-19, EPA cannot hold in-person public meetings 
at this time.
    The EPA plans to hold a virtual public hearing on April 12, 2022. 
An additional session may be held on April 13, 2022. This hearing will 
be held using Zoom. In order to attend the virtual public hearing, all 
attendees (including those who will not be presenting verbal testimony) 
must register in advance. EPA will begin registering speakers for the 
hearing upon publication of this document in the Federal Register. To 
register, please use the registration link that will be available on 
the EPA rule web page once registration begins: https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-and-related-materials-control-air-1. A separate registration form must be submitted 
for each person attending the hearing.
    The last day to register to speak at the hearing will be five 
working days before the first public hearing date. The EPA will post a 
general agenda for the hearing with the order of speakers at: https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-and-related-materials-control-air-1. This agenda will be available no 
later than two working days before the first public hearing date.
    In order to allow everyone to be heard, EPA is limiting verbal 
testimony to three minutes per person. Speakers will not be able to 
share graphics via the virtual public hearing. Speakers will be able to 
request an approximate speaking time as part of the registration 
process, with preferences considered on a first-come, first-served 
basis. EPA also recommends submitting the text of oral comments as 
written comments to the rulemaking docket.
    EPA will make every effort to follow the schedule as closely as 
possible on the day of the hearing; however, please plan for the 
hearings to run either ahead of schedule or behind schedule.
    The EPA may ask clarifying questions during the oral presentations, 
but will not respond to the presentations at that time. Written 
statements and supporting information submitted during the comment 
period will be considered with the same weight as oral comments and 
supporting information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will 
be posted online at: https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-and-related-materials-control-air-1. 
While the EPA expects the hearing to go forward as described here, 
please monitor our website or contact Tuana Phillips, (202)-565-0074, 
[email protected] to determine if there are any updates. The EPA 
does not intend to publish a document in the Federal Register 
announcing updates.
    If you require the services of a translator or special 
accommodations such as audio description, please identify these needs 
when you register for the hearing or by contacting Tuana Phillips at 
(202)-565-0074, [email protected]. EPA may not be able to arrange 
accommodations without advance notice.

B. General Information

Does this action apply to me?

    This action relates to companies that manufacture, sell, or import 
into the United States new heavy-duty highway engines. Additional 
amendments apply for gasoline refueling facilities and for 
manufacturers of all sizes and types of motor vehicles, stationary 
engines, aircraft and aircraft engines, and various types of nonroad 
engines, vehicles, and equipment. Regulated categories and entities 
include the following:

------------------------------------------------------------------------
          NAICS codes \a\                        NAICS title
------------------------------------------------------------------------
326199............................  All Other Plastics Product
                                     Manufacturing.
332431............................  Metal Can Manufacturing.
335312............................  Motor and Generator Manufacturing.
336111............................  Automobile Manufacturing.
336112............................  Light Truck and Utility Vehicle
                                     Manufacturing.
336120............................  Heavy Duty Truck Manufacturing.
336211............................  Motor Vehicle Body Manufacturing.
336212............................  Truck Trailer Manufacturing.
336213............................  Motor Home Manufacturing.
336411............................  Manufacturers of new aircraft.
336412............................  Manufacturers of new aircraft
                                     engines.
333618............................  Other Engine Equipment
                                     Manufacturing.
336999............................  All Other Transportation Equipment
                                     Manufacturing.
423110............................  Automotive and Other Motor Vehicle
                                     Merchant Wholesalers.
447110............................  Gasoline Stations with Convenience
                                     Stores.
447190............................  Other Gasoline Stations.
454310............................  Fuel dealers.
811111............................  General Automotive Repair.
811112............................  Automotive Exhaust System Repair.
811198............................  All Other Automotive Repair and
                                     Maintenance.
------------------------------------------------------------------------
\a\ NAICS Association. NAICS & SIC Identification Tools. Available
  online: https://www.naics.com/search.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated. To determine whether 
your entity is regulated by this action, you should carefully examine 
the applicability criteria found in Sections XII and XIII of this 
preamble. If you have questions regarding the applicability of this 
action to a particular entity, consult the person listed in the FOR 
FURTHER INFORMATION CONTACT section.

What action is the agency taking?

    The Environmental Protection Agency (EPA) is proposing a rule that 
would reduce air pollution from highway heavy-duty vehicles and 
engines. This proposal would change the heavy-duty emission control 
program--including the standards, test procedures, regulatory useful 
life, emission-related warranty, and other requirements--to further 
reduce the air quality impacts of heavy-duty engines across a range of 
operating conditions and over a longer period of the operational life 
of heavy-duty engines. Heavy-duty vehicles and engines are important 
contributors to concentrations of ozone and particulate matter and 
their resulting threat to public health, which includes premature 
death, respiratory illness (including childhood asthma), cardiovascular 
problems, and other adverse health impacts. This proposal would reduce 
emissions of nitrogen oxides and other pollutants. In addition, this 
proposal would make targeted updates to the existing Heavy-Duty 
Greenhouse Gas Emissions Phase 2 program, proposing that further GHG 
reductions in the MY 2027 timeframe are appropriate considering lead 
time, costs, and other factors, including market shifts to zero-
emission technologies in certain segments of the heavy-duty vehicle 
sector.

What is the agency's authority for taking this action?

    Section 202(a)(1) of the Clean Air Act requires the EPA to set 
emission standards for air pollutants from new motor vehicles or new 
motor vehicle engines, which the Administrator has found cause or 
contribute to air pollution that may endanger public health or welfare. 
See Sections I.A.4, I.F, and XIV of this preamble for more information 
on the agency's authority for this action.

What are the incremental costs and benefits of this action?

    We compare total monetized health benefits to total costs 
associated with the proposed Options 1 and 2 in Section IX. Our results 
show that annual benefits of the proposed Option 1 would be larger than 
the annual costs in 2045, a year when the program would be fully 
implemented and when most of the regulated fleet would have turned 
over,

[[Page 17416]]

with annual net benefits of $9 and $31 billion assuming a 3 percent 
discount rate, and net benefits of $8 and $28 billion assuming a 7 
percent discount rate.\1\ Annual benefits would also be larger than 
annual costs in 2045 for the proposed Option 2, although net benefits 
would be lower than from the proposed Option 1 (net benefits of 
proposed Option 2 would be $6 and $23 billion at a 3 percent discount 
rate, and net benefits of $5 and 21 billion at a 7 percent discount 
rate). See Section VIII for more details on the net benefit estimates. 
For both the proposed Options 1 and 2, benefits also outweigh the costs 
when expressed in present value terms and as equalized annual values.
---------------------------------------------------------------------------

    \1\ The range of benefits and net benefits reflects a 
combination of assumed PM2.5 and ozone mortality risk 
estimates and selected discount rate.
---------------------------------------------------------------------------

Did EPA conduct a peer review before issuing this action?

    This regulatory action was supported by influential scientific 
information. Therefore, EPA conducted peer reviews in accordance with 
OMB's Final Information Quality Bulletin for Peer Review. Specifically, 
we conducted peer reviews on five analyses: (1) Analysis of Heavy-Duty 
Vehicle Sales Impacts Due to New Regulation (Sales Impacts), (2) 
Exhaust Emission Rates for Heavy-Duty Onroad Vehicles in MOVES_CTI NPRM 
(Emission Rates), (3) Population and Activity of Onroad Vehicles in 
MOVES_CTI NPRM (Population and Activity), (4) Cost teardowns of Heavy-
Duty Valvetrain (Valvetrain costs), and (5) Cost teardown of Emission 
Aftertreatment Systems (Aftertreatment Costs). These peer reviews were 
all letter reviews conducted by a contractor. The peer review reports 
for each analysis are located in the docket for this action and at 
EPA's Science Inventory (https://cfpub.epa.gov/si/).

Table of Contents

ES. Executive Summary
    A. Purpose of the Regulatory Action
    B. Overview of the Regulatory Action
    C. Summary of the Major Provisions in the Regulatory Action
    D. Projected Emission Reductions, Air Quality Improvements, 
Costs, and Benefits
    E. Summary of Specific Requests for Comments
I. Introduction
    A. Brief Overview of the Heavy-Duty Truck Industry
    B. History of Emission Standards for Heavy-Duty Engines and 
Vehicles
    C. Petitions to EPA for Additional NOX Emissions 
Control
    D. California Heavy-Duty Highway Low NOX Program 
Development
    E. Advance Notice of Proposed Rulemaking
    F. EPA Statutory Authority for the Proposal
    G. Basis of the Proposed Standards
II. Need for Additional Emissions Control
    A. Background on Pollutants Impacted by This Proposal
    B. Health Effects Associated With Exposure to Pollutants 
Impacted by This Proposal
    C. Environmental Effects Associated With Exposure to Pollutants 
Impacted by This Proposal
III. Proposed Test Procedures and Standards
    A. Overview
    B. Summary of Compression-Ignition Exhaust Emission Standards 
and Duty Cycle Test Procedures
    C. Summary of Compression-Ignition Off-Cycle Standards and In-
Use Test Procedures
    D. Summary of Spark-Ignition Heavy-Duty Engine Exhaust Emission 
Standards and Test Procedures
    E. Summary of Spark-Ignition Heavy-Duty Vehicle Refueling 
Emission Standards and Test Procedures
IV. Compliance Provisions and Flexibilities
    A. Regulatory Useful Life
    B. Ensuring Long-Term In-Use Emissions Performance
    C. Onboard Diagnostics
    D. Inducements
    E. Certification Updates
    F. Durability Testing
    G. Averaging, Banking, and Trading
    H. Early Adoption Incentives
    I. Compliance Options for Generating NOX Emission 
Credits From Electric Vehicles
    J. Fuel Quality
    K. Other Flexibilities Under Consideration
V. Program Costs
    A. Technology Package Costs
    B. Operating Costs
    C. Program Costs
VI. Estimated Emission Reductions From the Proposal and Alternatives
    A. Emission Inventory Methodology
    B. Estimated Emission Reductions From the Proposed Criteria 
Pollutant Program
    C. Estimated Emission Reductions From the Alternatives Analyzed
    D. Evaluating Emission Impacts of Electric Vehicles in the 
Proposed Emission Inventory Baseline
VII. Air Quality Impacts of the Proposed Rule
    A. Ozone
    B. Particulate Matter
    C. Nitrogen Dioxide
    D. Carbon Monoxide
    E. Air Toxics
    F. Visibility
    G. Nitrogen Deposition
    H. Demographic Analysis of Air Quality
VIII. Benefits of the Program
IX. Comparison of Benefits and Costs
    A. Methods
    B. Results
X. Economic Impact Analysis
    A. Impact on Vehicle Sales, Mode Shift, and Fleet Turnover
    B. Employment Impacts
XI. Targeted Updates to the HD GHG Phase 2 Heavy-Duty Greenhouse Gas 
Emissions Program
    A. Background on Heavy-Duty Greenhouse Gas Emission Standards
    B. What has changed since we finalized the HD GHG Phase 2 rule?
    C. Proposed Changes to HD GHG Phase 2 CO2 Standards 
for Targeted Subcategories
    D. HD GHG Phase 2 Advanced Technology Credits for CO2 
Emissions
    E. Emissions and Cost Impacts of Proposed Revised MY 2027 
CO2 Emission Standards
    F. Summary of Proposed Changes to HD GHG Phase 2
XII. Other Amendments
    A. General Compliance Provisions (40 CFR Part 1068) and Other 
Cross-Sector Issues
    B. Heavy-Duty Highway Engine and Vehicle Emission Standards (40 
CFR Parts 1036 and 1037)
    C. Fuel Dispensing Rates for Heavy-Duty Vehicles (40 CFR Parts 
80 and 1090)
    D. Refueling Interface for Motor Vehicles (40 CFR Parts 80 and 
1090)
    E. Light-Duty Motor Vehicles (40 CFR Parts 85, 86, and 600)
    F. Large Nonroad Spark-Ignition Engines (40 CFR Part 1048)
    G. Small Nonroad Spark-Ignition Engines (40 CFR Part 1054)
    H. Recreational Vehicles and Nonroad Evaporative Emissions (40 
CFR Parts 1051 and 1060)
    I. Marine Diesel Engines (40 CFR Parts 1042 and 1043)
    J. Locomotives (40 CFR Part 1033)
    K. Stationary Compression-Ignition Engines (40 CFR Part 60, 
Subpart IIII)
    L. Heavy-Duty Compression-Ignition Engines (40 CFR Part 86)
XIII. Executive Orders Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA) and 
1 CFR Part 51
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations.
XIV. Statutory Provisions and Legal Authority

Executive Summary

A. Purpose of the Regulatory Action

    The Environmental Protection Agency (EPA) is proposing a 
multipollutant rule to further reduce air pollution from heavy-duty 
engines and vehicles across the United States, including ozone and 
particulate matter (PM). In addition, as part of this rulemaking we are 
proposing

[[Page 17417]]

targeted updates to the existing Heavy-Duty Greenhouse Gas Emissions 
Phase 2 program (HD GHG Phase 2). This proposed rulemaking builds on 
and improves the existing emission control program for on-highway 
heavy-duty engines and vehicles. This proposal is pursuant to EPA's 
authority under the Clean Air Act to regulate air pollutants emitted 
from mobile sources. The proposal is also consistent with Executive 
Order (E.O.) 14037, which directed EPA to consider setting new oxides 
of nitrogen (NOX) emission standards and updating the 
existing GHG emissions standards for heavy-duty engines and 
vehicles.2 3 In this proposed action, EPA is co-proposing 
two regulatory options for new NOX standards: Proposed 
Option 1 and proposed Option 2. As discussed in Section B.1 of this 
Executive Summary and throughout this preamble, we request comment on 
the options presented, as well as the full range of options between 
them.
---------------------------------------------------------------------------

    \2\ President Joseph Biden. Executive Order on Strengthening 
American Leadership in Clean Cars and Trucks. 86 FR 43583, August 
10, 2021.
    \3\ Oxides of nitrogen (NOX) refers to nitric oxide 
(NO) and nitrogen dioxide (NO2).
---------------------------------------------------------------------------

    Heavy-duty (HD) engines operating across the U.S. emit 
NOX and other pollutants that contribute to ambient levels 
of ozone, PM, and NOX. These pollutants are linked to 
premature death, respiratory illness (including childhood asthma), 
cardiovascular problems, and other adverse health impacts. Data show 
that heavy-duty engines are important contributors to concentrations of 
ozone and PM2.5 and their resulting threat to public 
health.\4\ \5\
---------------------------------------------------------------------------

    \4\ Zawacki et al, 2018. Mobile source contributions to ambient 
ozone and particulate matter in 2025. Atmospheric Environment, Vol 
188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
    \5\ Davidson et al, 2020. The recent and future health burden of 
the U.S. mobile sector apportioned by source. Environmental Research 
Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
---------------------------------------------------------------------------

    The proposed rulemaking would change key provisions of the heavy-
duty emission control program--including the standards, test 
procedures, regulatory useful life, emission-related warranty, and 
other requirements; the two regulatory options (proposed Options 1 and 
2) would result in different numeric levels of the standards and 
lengths of useful life and warranty periods. The proposed Options 1 and 
2 and the range between them provide the numeric values for these key 
provisions that we focus on for this proposal. Together, the key 
provisions in the proposal would further reduce the air quality impacts 
of heavy-duty engines across a range of operating conditions and over a 
longer period of the operational life of heavy-duty engines (see 
Section I.B for an overview of the proposed program). The requirements 
in the proposed Option 1 and the proposed Option 2 would lower 
emissions of NOX and other air pollutants (PM, hydrocarbons 
(HC), air toxics, and carbon monoxide (CO)) beginning as early as model 
year (MY) 2027. The emission reductions from both the proposed Option 1 
and the proposed Option 2 would increase over time as more new, cleaner 
vehicles enter the fleet.
    We estimate that if finalized as proposed, the proposed Option 1 
would reduce NOX emissions from heavy-duty vehicles in 2040 
by more than 50 percent; by 2045, a year by which most of the regulated 
fleet would have turned over, heavy-duty NOX emissions would 
be more than 60 percent lower than they would have been without this 
action. Our estimates show proposed Option 2 would reduce heavy-duty 
NOX emissions in 2045 by 47 percent (see Section I.D for 
more information on our projected emission reductions from proposed 
Option 1 or 2). These emission reductions would result in air quality 
improvements in ozone and PM2.5; we estimate that in 2045, 
the proposed Option 1 would result in total annual monetized ozone- and 
PM2.5-related benefits of $12 and $33 billion at a 3 percent 
discount rate, and $10 and $30 billion at a 7 percent discount rate. In 
the same calendar year, proposed Option 2 would result in total annual 
monetized ozone- and PM2.5-related benefits of $9 and $26 
billion at a 3 percent discount rate, and $8 and $23 billion at a 7 
percent discount (see Section VIII for discussion on quantified and 
monetized health impacts). Given the analysis we present in this 
proposal, we currently believe that Option 1 may be a more appropriate 
level of stringency as it would result in a greater level of achievable 
emission reduction for the model years proposed, which is consistent 
with EPA's statutory authority under Clean Air Act section 202(a)(3). 
These emission reductions would result in widespread decreases in 
ambient concentrations of pollutants such as ozone and 
PM2.5. These widespread projected air quality improvements 
would play an important role in addressing concerns from states, local 
communities, and Tribal governments about the contributions of heavy-
duty engines to air quality challenges they face such as meeting their 
obligations to attain or continue to meet National Ambient Air Quality 
Standards (NAAQS), and to reduce other human health and environmental 
impacts of air pollution.
    In addition to further reducing emissions of NOX and 
other ozone and PM2.5 precursors, as part of this rulemaking 
we are proposing targeted updates to the existing Heavy-Duty Greenhouse 
Gas Emissions Phase 2 program (HD GHG Phase 2).\6\ The proposed updates 
would apply to certain CO2 standards for MYs 2027 and later 
trucks that are appropriate considering lead time, costs, and other 
factors, including market shifts to zero-emission technologies in 
certain segments of the heavy-duty vehicle sector. The proposed updates 
are intended to balance further incentivizing zero and near-zero 
emissions vehicle development with ensuring that the standards achieve 
an appropriate fleet-wide level of CO2 emissions reductions.
---------------------------------------------------------------------------

    \6\ 81 FR at 73478 (October 25, 2016).
---------------------------------------------------------------------------

1. Industry Overview
    Heavy-duty highway vehicles (also referred to as ``trucks'' in this 
preamble) range from vocational vehicles that support local and 
regional construction, refuse collection, and delivery work to long-
haul tractor-trailers that move freight cross-country. This diverse 
array of vehicles is categorized into weight classes based on gross 
vehicle weight ratings (GVWR) that span Class 2b trucks and vans 
greater than 8,500 lbs GVWR through Class 8 long-haul tractors and 
other commercial vehicles that exceed 33,000 lbs GVWR.\7\ These 
vehicles are primarily powered by diesel-fueled, compression-ignition 
(CI) engines, although gasoline-fueled, spark-ignition (SI) engines are 
common in the lighter weight classes, and

[[Page 17418]]

smaller numbers of alternative fuel engines (e.g., liquified petroleum 
gas, compressed natural gas) are found in the heavy-duty fleet. 
Vehicles powered by electricity, either in the form of battery electric 
vehicles (BEVs) or fuel cell electric vehicles (FCEVs) are also 
increasingly entering the heavy-duty fleet. The operational 
characteristics of some commercial applications (e.g., delivery 
vehicles) can be similar across several vehicle weight classes, 
allowing a single engine, or electric power source in the case of BEVs 
and FCEVs, to be installed in a variety of vehicles. For instance, 
engine specifications needed for a Class 4 parcel delivery vehicle may 
be similar to the needs of a Class 5 mixed freight delivery vehicle or 
a Class 6 beverage truck. Performance differences needed to operate 
across this range of vehicles can be achieved through adjustments to 
chassis-based systems (e.g., transmission, cooling system) external to 
the engine.
---------------------------------------------------------------------------

    \7\ This proposed rulemaking includes revised criteria pollutant 
standards for engine-certified Class 2b through 8 heavy-duty engines 
and vehicles; this proposal also includes revised GHG standards for 
Class 4 through 8 vehicles. Class 2b and 3 vehicles with GVWR 
between 8,500 and 14,000 pounds are primarily commercial pickup 
trucks and vans and are sometimes referred to as ``medium-duty 
vehicles''. The majority of Class 2b and 3 vehicles are chassis-
certified vehicles, and EPA intends to include them in a future 
combined light-duty and medium-duty rulemaking action, consistent 
with E.O, 14037, Section 2a. Heavy-duty engines and vehicles are 
also used in nonroad applications, such as construction equipment; 
nonroad heavy-duty engines and vehicles are not the focus of this 
proposal. See Section I for more discussion on the spectrum of 
heavy-duty vehicles and how they relate to the proposed rule. As 
outlined in Section C of this Executive Summary and detailed in 
Section XII, this proposal also includes limited amendments to 
regulations that implement our air pollutant emission standards for 
other industry sectors, including light-duty vehicles, light-duty 
trucks, marine diesel engines, locomotives, and various types of 
nonroad engines, vehicles, and equipment.
---------------------------------------------------------------------------

2. The Need for Additional Emission Control of NOX and Other 
Pollutants From Heavy-Duty Engines
    Across the U.S., NOX emissions from heavy-duty engines 
are important contributors to concentrations of ozone and 
PM2.5 and their resulting health effects.8 9 
Heavy-duty engines will continue to be one of the largest contributors 
to mobile source NOX emissions nationwide in the future, 
representing 32 percent of the mobile source NOX emissions 
in calendar year 2045.\10\ Furthermore, it is estimated that heavy-duty 
engines would represent 89 percent of the onroad NOX 
inventory in calendar year 2045.\11\ Reducing NOX emissions 
is a critical part of many areas' strategies to attain and maintain the 
ozone and PM NAAQS; many state and local agencies anticipate challenges 
in attaining the NAAQS, maintaining the NAAQS in the future, and/or 
preventing nonattainment (see Section II). Some nonattainment areas 
have already been ``bumped up'' to higher classifications because of 
challenges in attaining the NAAQS.\12\
---------------------------------------------------------------------------

    \8\ Zawacki et al, 2018. Mobile source contributions to ambient 
ozone and particulate matter in 2025. Atmospheric Environment, Vol 
188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
    \9\ Davidson et al, 2020. The recent and future health burden of 
the U.S. mobile sector apportioned by source. Environmental Research 
Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
    \10\ U.S. Environmental Protection Agency (2021). 2016v1 
Platform. https://www.epa.gov/air-emissions-modeling/2016v1-platform.
    \11\ Han, Jaehoon. Memorandum to the Docket EPA-HQ-OAR-2019-
0055: ``MOVES Modeling-Related Data Files (MOVES Code, Input 
Databases and Runspecs) for the Proposed Heavy-Duty 2027 
Standards''. February 2022.
    \12\ For example, in September 2019 several 2008 ozone 
nonattainment areas were reclassified from moderate to serious, 
including Dallas, Chicago, Connecticut, New York/New Jersey and 
Houston, and in January 2020, Denver. The 2008 NAAQS for ozone is an 
8-hour standard with a level of 0.075 ppm, which the 2015 ozone 
NAAQS lowered to 0.070 ppm.
---------------------------------------------------------------------------

    In addition, emissions from heavy-duty engines can significantly 
affect individuals living near truck freight routes. Based on a study 
EPA conducted of people living near truck routes, an estimated 72 
million people live within 200 meters of a truck freight route (see 
discussion in Section II.B.7). Relative to the rest of the population, 
people of color and those with lower incomes are more likely to live 
near truck routes (see Sections II.B and VII.H for additional 
discussion on our analysis of environmental justice impacts of this 
proposal). This population includes children, and in addition, 
childcare facilities and schools can be in close proximity to freight 
routes.\13\
---------------------------------------------------------------------------

    \13\ Kingsley, S., Eliot, M., Carlson, L. et al. Proximity of US 
schools to major roadways: a nationwide assessment. J Expo Sci 
Environ Epidemiol 24, 253-259 (2014). https://doi.org/10.1038/jes.2014.5.
---------------------------------------------------------------------------

    Clean Air Act section 202(a)(3)(A) requires EPA to set emission 
standards for NOX, PM, HC, and CO that reflect the greatest 
degree of emission reduction achievable through the application of 
technology that will be available for the model year to which such 
standards apply. Although heavy-duty engines have become much cleaner 
over the last decade, catalysts and other technologies have evolved 
such that harmful air pollutants can be reduced even further.
    Heavy-duty emissions that affect local and regional populations are 
attributable to several engine operating modes and processes. 
Specifically, the operating modes and processes projected to contribute 
the most to the heavy-duty NOX emission inventory in 2045 
are medium-to-high load (36 percent), low-load (28 percent), and aging 
(24 percent) (i.e., deterioration and mal-maintenance of the engine's 
emission control system) (see Section VI for more information on 
projected inventory contributions from each operating mode or process). 
These data suggest that medium- and high-load operating conditions 
continue to merit concern, while also showing that opportunities for 
significant additional emission reductions and related air quality 
improvements can be achieved through provisions that encourage emission 
control under low-load operation and throughout an engine's operational 
life. Our approach for provisions that address these aspects of the 
emission inventory is outlined below and described in more detail in 
sections that follow.
    As described in Section III, the standards in proposed Options 1 
and 2 would reduce emissions during a broader range of operating 
conditions that span nearly all in-use operation. The standards in 
proposed Options 1 and 2 are based on technology improvements which 
have become available over the 20 years since the last major rule was 
promulgated to address emissions of NOX, PM, HC, and CO 
(hereafter referred to as ``criteria pollutants'') and toxic pollutants 
from heavy-duty engines. As further detailed in Section III, available 
data indicate that emission levels demonstrated for certification are 
not achieved under the broad range of real-world operating 
conditions.14 15 16 17 In fact, less than ten percent of the 
data collected during a typical test while the vehicle is operated on 
the road is subject to EPA's in-use, on-the-road emission 
standards.\18\ These testing data further show that NOX 
emissions from heavy-duty diesel vehicles are high during many periods 
of vehicle operation that are not subject to current on-the-road 
emission standards. For example, ``low-load'' engine conditions occur 
when a vehicle operates in stop-and-go traffic or is idling; these low-
load conditions can result in exhaust temperature decreases that then 
lead to the diesel engine's selective catalytic reduction (SCR)-based 
emission control system becoming less effective or ceasing to function. 
Test data collected as part of EPA's manufacturer-run in-use testing 
program indicate that this low-load operation could account for more 
than half of the NOX emissions from a

[[Page 17419]]

vehicle during a typical workday.\19\ Similarly, heavy-duty SI engines 
also operate in conditions where their catalyst technology becomes less 
effective, resulting in higher levels of air pollutants; however, 
unlike CI engines, it is sustained medium-to-high load operation where 
emission levels are less certain.
---------------------------------------------------------------------------

    \14\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of 
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel 
Engines Using Portable Emissions Measurement System (PEMS).'' 29th 
CRC Real World Emissions Workshop, March 10-13, 2019.
    \15\ Sandhu, Gurdas, et al. ``Identifying Areas of High 
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
    \16\ Sandhu, Gurdas, et al. ``In-Use Emission Rates for MY 2010+ 
Heavy-Duty Diesel Vehicles''. 27th CRC Real-World Emissions 
Workshop, March 26-29, 2017.
    \17\ As noted in Section C of this Executive Summary and 
discussed in Section III, testing engines and vehicles while they 
are operating over the road without a defined duty cycle is referred 
to as ``off-cycle'' testing; as detailed in Section III, we are 
proposing new off-cycle test procedures and standards as part of 
this rulemaking.
    \18\ Heavy-duty CI engines are currently subject to off-cycle 
standards that are not limited to specific test cycles, but we use 
the term ``on-the-road'' here for readability.
    \19\ Sandhu, Gurdas, et al. ``Identifying Areas of High 
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
---------------------------------------------------------------------------

    As noted in this Section A.2 of the Executive Summary, 
deterioration and mal-maintenance of the engine's emission control 
system is also projected to result in NOX emissions that 
would represent a substantial part of the HD inventory in 2045. To 
address this problem, as part of our comprehensive approach, both 
proposed Options 1 and 2 include longer regulatory useful life and 
emission-related warranty requirements that would maintain emission 
control through more of the operational life of heavy-duty vehicles 
(see Section IV for more discussion on the proposed useful life and 
warranty requirements).
    Reducing NOX emissions from heavy-duty vehicles would 
address health and environmental issues raised by state, local, and 
Tribal agencies in their comments on the Advance Notice of Proposed 
Rule (ANPR).\20\ In addition to concerns about meeting the ozone and 
PM2.5 NAAQS, they expressed concerns about environmental 
justice, regional haze, and damage to terrestrial and aquatic 
ecosystems. They mentioned the impacts of NOX emissions on 
numerous locations, such as the Chesapeake Bay, Narragansett Bay, Long 
Island Sound, Joshua Tree National Park and the surrounding Mojave 
Desert, the Adirondacks, and other areas. Tribes and agencies commented 
that NOX deposition into lakes is harmful to fish and other 
aquatic life forms on which they depend for subsistence livelihoods. 
They also commented that regional haze and increased rates of 
weathering caused by pollution are of particular concern and can damage 
culturally significant archeological sites.
---------------------------------------------------------------------------

    \20\ The Agency published an ANPR on January 21, 2020 to present 
EPA's early thinking on this rulemaking and solicit feedback from 
stakeholders to inform this proposal (85 FR 3306).
---------------------------------------------------------------------------

3. The Historic Opportunity for Clean Air Provided by Zero-Emission 
Vehicles
    We are at the early stages of a significant transition in the 
history of the heavy-duty on-highway sector--a shift to zero-emission 
vehicle (ZEV) technologies. This change is underway and presents an 
opportunity for significant reductions in heavy-duty vehicle emissions. 
Major trucking fleets, manufacturers and U.S. states have announced 
plans to transition the heavy-duty fleet to zero-emissions technology, 
and over just the past few years we have seen the early introduction of 
zero-emission technology into a number of heavy-duty vehicle market 
segments.
    Executive Order 14037 identifies three potential regulatory actions 
for EPA to consider: (1) This proposed rule for heavy-duty vehicles for 
new criteria pollutant standards and strengthening of the Model Year 
2027 GHG standards; (2) a separate rulemaking to establish more 
stringent criteria and GHG emission standards for medium-duty vehicles 
for Model Year 2027 and later (in combination with light-duty 
vehicles); and (3) a third rulemaking to establish new GHG standards 
for heavy-duty vehicles for Model Year 2030 and later. This strategy 
will establish the EPA regulatory path for the future of the heavy-duty 
vehicle sector, and in each of these actions EPA will consider the 
critical role of ZEVs in enabling stringent emission standards.
    In addition to the proposed standards and requirements for 
NOX and other air pollutant emissions, we are also proposing 
targeted revisions to the already stringent HD GHG Phase 2 rulemaking, 
which EPA finalized in 2016.\21\ The HD GHG Phase 2 program includes 
GHG emission standards tailored to certain regulatory vehicle 
categories in addition to heavy-duty engines including: Combination 
tractors; vocational vehicles; and heavy-duty pickup trucks and vans. 
The HD GHG Phase 2 program includes progressively more stringent 
CO2 emission standards for HD engines and vehicles; these 
standards phase in starting in MY 2021 through MY 2027. The program 
built upon the GHG Phase 1 program promulgated in 2011, which set the 
first-ever GHG emission standards for heavy-duty engines and 
trucks.\22\
---------------------------------------------------------------------------

    \21\ 81 FR 73478 (October 25, 2016). Note that the HD GHG Phase 
2 program also includes coordinated fuel efficiency standards 
established by the U.S. Department of Transportation through the 
National Highway Traffic Safety Administration, and those standards 
were established in a joint rulemaking process with EPA.
    \22\ 76 FR 57106, September 15, 2011.
---------------------------------------------------------------------------

    When the HD GHG Phase 2 rule was promulgated in 2016, we 
established the Phase 2 GHG standards and advanced technology 
incentives on the premise that electrification of the heavy-duty market 
was unlikely to occur in the timeframe of the program. However, several 
factors have arisen since the adoption of Phase 2 that have changed our 
outlook for heavy-duty electric vehicles. First, the heavy-duty market 
has evolved such that in 2021, there are a number of manufacturers 
producing fully electric heavy-duty vehicles in a number of 
applications. Second, the State of California has adopted an Advanced 
Clean Trucks program that includes a manufacturer sales requirement for 
zero-emission truck sales, specifically that ``manufacturers who 
certify Class 2b-8 chassis or complete vehicles with combustion engines 
would be required to sell zero-emission trucks as an increasing 
percentage of their annual California sales from 2024 to 2035.'' \23\ 
Finally, other states have signed a Memorandum of Understanding 
establishing goals to increase the heavy-duty electric vehicle 
market.\24\ We are proposing that further GHG reductions in the MY 2027 
timeframe are appropriate considering lead time, costs, and other 
factors, including these developments to zero-emission technologies in 
certain segments of the heavy-duty vehicle sector. We discuss the 
impacts of these factors on the heavy-duty market in Section XI. As 
outlined in Section I.B and detailed in Section XI, we are proposing to 
increase the stringency of the existing MY 2027 standards for many of 
the vocational vehicle and tractor subcategories, specifically those 
where we project early introduction of ZEVs. We are also considering 
whether it would be appropriate in the final rule to increase the 
stringency of the standards even more than what we propose for MYs 
2027-2029, including the potential for progressively more stringent 
CO2 standards across these three model years. Progressively 
strengthening the stringency of the standards for model years 2028 and 
2029 could help smooth the transition to ambitious greenhouse gas 
standards for the heavy-duty sector starting as soon as model year 
2030. We believe there is information and data that could support 
higher projected penetrations of HD ZEVs in the MY 2027 to 2029 
timeframe and we request comment and additional supporting information 
and data on higher penetration rates, which could serve as the basis 
for the increase in the stringency of the CO2 standards for 
specific Phase 2 vehicle subcategories. For example, what information 
and data are available that

[[Page 17420]]

would support HD ZEV penetration rates of 5 percent or 10 percent (or 
higher) in this timeframe, and in what HD vehicle applications and 
categories. We are also requesting comment on an aspect of the HD GHG 
Phase 2 advanced technology incentive program.
---------------------------------------------------------------------------

    \23\ CARB. ``Notice of Decision: Advanced Clean Truck 
Regulation.'' June 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/nod.pdf.
    \24\ Fifteen states and one district sign Multi-State MOU. 
https://www.nescaum.org/documents/multistate-truck-zev-governors-mou-20200714.pdf.
---------------------------------------------------------------------------

    EPA has heard from a number of stakeholders urging EPA to put in 
place policies to rapidly advance ZEVs in this current rulemaking, and 
to establish standards requiring 100 percent of all new heavy-duty 
vehicles be zero-emission no later than 2035. The stakeholders state 
that accelerating ZEV technologies in the heavy-duty market is 
necessary to prioritize environmental justice in communities that are 
impacted by freight transportation and already overburdened by 
pollution.\25\ One policy EPA has been asked to consider is the 
establishment of a ZEV sales mandate (i.e., a nationwide requirement 
for manufacturers to produce a portion of their new vehicle fleet as 
ZEVs). EPA is not proposing in this action to establish a heavy-duty 
ZEV mandate. EPA in this action is considering how the development and 
deployment of ZEVs can further the goals of environmental protection 
and best be reflected in the establishment of EPA's standards and 
regulatory program for MY 2027 and later heavy-duty vehicles. As 
discussed earlier in this section, EPA will also be considering the 
important role of ZEV technologies in the upcoming light-duty and 
medium-duty vehicle proposal for MY 2027 and later, and in the heavy-
duty vehicle proposal for MY 2030 and later. EPA requests comment under 
this proposal on how the Agency can best consider the potential for ZEV 
technologies to significantly reduce air pollution from the heavy-duty 
vehicle sector (including but not limited to the topic of whether and 
how to consider including specific sales requirements for HD ZEVs).
---------------------------------------------------------------------------

    \25\ Letter to EPA Administrator Michael Regan from the Moving 
Forward Network. October 26, 2021.
---------------------------------------------------------------------------

4. Statutory Authority for This Action
    As discussed in Section I, EPA is proposing revisions to emission 
standards and other requirements applicable to emissions of 
NOX, PM, HC, CO, and GHG from new heavy-duty engines and 
vehicles under our broad statutory authority to regulate air pollutants 
emitted from mobile sources, consistent with our history of using a 
multi-pollutant approach to regulating criteria pollutants and GHG 
emissions from heavy-duty engines and vehicles. Section 202(a)(1) of 
the Clean Air Act (CAA) requires the EPA to ``by regulation prescribe 
(and from time to time revise) . . . standards applicable to the 
emission of any air pollutant from any class or classes of new motor 
vehicles or new motor vehicle engines . . . , which in his judgment 
cause, or contribute to, air pollution which may reasonably be 
anticipated to endanger public health or welfare''. Standards under CAA 
section 202(a) take effect ``after such period as the Administrator 
finds necessary to permit the development and application of the 
requisite technology, giving appropriate consideration to the cost of 
compliance within such period.'' Thus, in establishing or revising CAA 
section 202(a) standards designed to reduce air pollution that 
endangers public health and welfare, EPA also must consider issues of 
technological feasibility, compliance cost, and lead time. EPA may 
consider other factors such as safety. There are currently heavy-duty 
engine and vehicle standards for emissions of NOX, PM, HC, 
CO, and GHGs.
    Under CAA section 202(a)(3)(A), standards for emissions of 
NOX, PM, HC, and CO emissions from heavy-duty vehicles and 
engines are to ``reflect the greatest degree of emission reduction 
achievable through the application of technology which the 
Administrator determines will be available for the model year to which 
such standards apply, giving appropriate consideration to cost, energy, 
and safety factors associated with the application of such 
technology.'' \26\ Section 202(a)(3)(C) requires that these standards 
apply for no less than 3 model years and apply no earlier than 4 years 
after promulgation.
---------------------------------------------------------------------------

    \26\ Section 202(a)(3)(A) and (C) apply only to regulations 
applicable to emissions of these four pollutants and do not apply to 
regulations applicable to GHGs.
---------------------------------------------------------------------------

    Emission standards set under CAA section 202(a) apply to vehicles 
and engines ``for their useful life.'' CAA section 202(d) directs EPA 
to prescribe regulations under which the useful life of vehicles and 
engines shall be determined, and for heavy-duty vehicles and engines 
establishes minimum values of 10 years or 100,000 miles, whichever 
occurs first, unless EPA determines that greater values are 
appropriate. CAA section 207(a) further requires manufacturers to 
provide an emissions warranty, and EPA set the current warranty periods 
for heavy-duty engines in 1983.\27\
---------------------------------------------------------------------------

    \27\ 48 FR 52170, November 16, 1983.
---------------------------------------------------------------------------

    As outlined in this executive summary, the proposed program would 
reduce heavy-duty emissions through several major provisions pursuant 
to the CAA authority described in this section. Sections I.F and XIV of 
this preamble further discuss our statutory authority for this 
proposal; Section I.G further describes the basis of our proposed 
NOX, PM, HC, CO, and GHG emission standards and other 
requirements. Section XIII describes how this proposal is also 
consistent with E.O. 14037, ``Strengthening American Leadership in 
Clean Cars and Trucks'' (August 5, 2021), which directs EPA to consider 
taking action to establish new NOX standards for heavy-duty 
engines and vehicles beginning with model year 2027.

B. Overview of the Regulatory Action

    Our approach to further reduce air pollution from highway heavy-
duty engines and vehicles through the proposed program features several 
key provisions. We co-propose options to address criteria pollutant 
emissions from heavy-duty engines. In addition, this proposal would 
make targeted updates to the existing Heavy-Duty Greenhouse Gas 
Emissions Phase 2 program, proposing that further GHG reductions in the 
MY 2027 timeframe are appropriate considering lead time, costs, and 
other factors, including market shifts to zero-emission technologies in 
certain segments of the heavy-duty vehicle sector. We also propose 
limited amendments to the regulations that implement our air pollutant 
emission standards for other sectors (e.g., light-duty vehicles, marine 
diesel engines, locomotives, various types of nonroad engines, 
vehicles, and equipment). Our proposed provisions are briefly described 
in this Section I.B and summarized in Section I.C. We describe the 
proposed Options 1 and 2 in detail in the Sections III, IV, and XI. We 
discuss our analyses of estimated emission reductions, air quality 
improvements, costs, and monetized benefits of the proposed program in 
Section I.D below, and these are detailed in Sections V through X.
1. Overview of Criteria Pollutant Program
    The proposed provisions to reduce criteria pollutant emissions can 
be thought of in three broad categories: (1) Controlling emissions 
under a broader range of engine operating conditions, (2) maintaining 
emission control over a greater portion of an engine's operational 
life,\28\ and (3) providing manufacturers with flexibilities to meet

[[Page 17421]]

the proposed standards while clarifying our regulations. Specifically, 
provisions in the first category would include updated test procedures 
and revised emission standards, while those in the second category 
would include lengthened regulatory useful life and emission warranty 
periods, as well as several other updates to encourage proper 
maintenance and repair. These provisions would apply to heavy-duty 
engines used in Class 2b through 8 vehicles.\29\ Provisions in the 
third category would provide opportunities to generate NOX 
emission credits that provide manufacturers with flexibilities to meet 
the proposed standards and encourage the introduction of new emission 
control technologies earlier than required. This category also includes 
our proposal to modernize our current regulatory text, including 
clarifications and updates for hybrid electric, battery-electric, and 
fuel cell electric heavy-duty vehicles.
---------------------------------------------------------------------------

    \28\ As further discussed in Section IV.A, we use ``operational 
life'' to refer to when engines are in use on the road.
    \29\ EPA plans to consider new standards for chassis-certified 
Class 2b and 3 vehicles (GVWR between 8,500 and 14,000 pounds) as 
part of a future combined light-duty and medium-duty rulemaking 
action, consistent with E.O. 14037. We are not proposing changes to 
the standards or test procedures for chassis-certified heavy-duty 
vehicles. Instead, this proposal focuses on engine-certified 
products.
---------------------------------------------------------------------------

    Our discussion below focuses on the revised emission standards and 
useful life and warranty periods contained in two regulatory options 
that we are proposing: The proposed Option 1 and the proposed Option 2. 
Although we refer to the two regulatory options as the proposed Option 
1 and the proposed Option 2, we are giving full consideration to both 
options, as well as the full range of options between them. Both the 
proposed Option 1 and the proposed Option 2 would begin in MY 2027, but 
the proposed Option 1 would have a second step in MY 2031. Overall, 
proposed Option 2 is less stringent than the MY 2031 standards in the 
proposed Option l because the proposed Option 2 has higher numeric 
NOX emission standards and shorter useful life periods. As 
discussed in Section D of this Executive Summary and Section VI, we 
project proposed Option 1 would result in greater emission reductions 
than proposed Option 2; Section I.G summarizes the basis of our 
proposed Options 1 and 2 with details on our feasibility analysis for 
each option presented in Section III. In addition to the proposed 
Options 1 and 2, we present an alternative (the Alternative) that we 
also considered. The Alternative is more stringent than either the 
proposed Option 1 MY 2031 standards or the proposed Option 2 because 
the Alternative has shorter lead time, lower numeric NOX 
emission standards and longer useful life periods. We note that we 
currently are unable to conclude that the Alternative is feasible in 
the MY 2027 timeframe over the useful life periods in the Alternative 
in light of deterioration in the emission control technologies that we 
have evaluated to date, and we expect that we would need additional 
supporting data or other information in order to determine that the 
Alternative is feasible in the MY 2027 timeframe to consider adopting 
it in the final rule.
    The proposed Option 1 and proposed Option 2 generally represent the 
range of regulatory options, including the standards and test 
procedures, regulatory useful life and emission-related warranty 
periods and implementation schedules that we are currently considering 
in this rulemaking, depending in part on any additional comments and 
other information we receive on the feasibility, costs, and other 
impacts of the proposed Options 1 and 2. We request comment on all 
aspects of the proposed Options 1 and 2, or other alternatives roughly 
within the range of options covered by the proposed Options 1 and 2, 
including the revised emission standards and useful life and warranty 
periods, one and two-step approaches, model years of implementation and 
other provisions described in this proposal. Based on currently 
available information, in order to consider adopting the Alternative in 
the final rule, we believe we would need additional supporting data or 
other information to be able to conclude that the Alternative is 
feasible in the MY 2027 timeframe. We request comment, including 
relevant data and other information, related to the feasibility of the 
implementation model year, numeric levels of the emission standards, 
and useful life and warranty periods included in the Alternative, or 
other alternatives outside the range of options covered by the proposed 
Options 1 and 2.
    We will continue learning about the capability and durability of 
engine and aftertreatment technologies through our ongoing technology 
evaluations, as well as any information provided in public comments on 
this proposal. Section III describes our plans for expanding on the 
analyses developed for this proposal.
2. Overview of Targeted Revisions to the HD GHG Phase 2 Program
    In addition to the proposed criteria pollutant program provisions, 
we are proposing to increase the stringency of the existing GHG 
standards for MY 2027 trucks and requesting comment on updates to the 
advanced technology incentive program for electric vehicles. We propose 
updates to select MY 2027 GHG standards after consideration of the 
market shifts to zero-emission technologies in certain segments of the 
heavy-duty vehicle sector. These proposed GHG provisions are based on 
our evaluation of the heavy-duty EV market for the MY 2024 through 2027 
timeframe. While the HD Phase 2 GHG standards were developed in 2016 
based on the premise that electrification of the heavy-duty market 
beyond low volume demonstration projects was unlikely to occur in the 
timeframe of the program, our current evaluation shows that there are a 
number of manufacturers producing fully electric heavy-duty vehicles in 
several applications in 2021--and this number is expected to grow in 
the near term. These developments along with considerations of lead 
time, costs and other factors have demonstrated that further GHG 
reductions in the MY 2027 timeframe are appropriate. We expect school 
buses, transit buses, delivery trucks (such as box trucks or step 
vans), and short haul tractors to have the highest EV sales of all 
heavy-duty vehicle types between now and 2030.\30\ We have given 
careful consideration to an approach that would result in targeted 
updates to reflect the emerging HD EV market without fundamentally 
changing the HD GHG Phase 2 program as a whole. Thus, we are proposing 
targeted updates to the HD Phase 2 GHG standards to account for the 
current electrification of the market by making changes to only those 
standards that are impacted by these four types of electric vehicles. 
We believe this proposal considered the feasibility of technologies, 
cost, lead time, emissions impact, and other relevant factors, and 
therefore these standards are appropriate under CAA section 202(a). We 
also are seeking comment on changes to the advanced technology credit 
program since the current level of HD GHG Phase 2 incentives for 
electrification may no longer be appropriate for certain segments of 
the HD EV market considering the projected rise in electrification. We 
provide an overview of this approach in this Section I.C and detail our 
proposal in Section XI.
---------------------------------------------------------------------------

    \30\ See Section XI.B for more on the growing EV market for 
these four vehicle types.

---------------------------------------------------------------------------

[[Page 17422]]

C. Summary of the Major Provisions in the Regulatory Action

1. Controlling Criteria Pollutant Emissions Under a Broader Range of 
Engine Operating Conditions
    In the first broad category of provisions to reduce criteria 
pollutant emissions in this rulemaking, we are proposing to reduce 
emissions from heavy-duty engines under a range of operating conditions 
through revisions to our emissions standards and test procedures. These 
revisions would apply to both laboratory-based standards and test 
procedures for both heavy-duty CI and SI engines, as well as the 
standards and test procedures for heavy-duty CI engines on the road in 
the real world.\31\
---------------------------------------------------------------------------

    \31\ Duty cycle test procedures measure emissions while the 
engine is operating over precisely defined duty cycles in an 
emissions testing laboratory and provide very repeatable emission 
measurements. ``Off-cycle'' test procedures measure emissions while 
the engine is not operating on a specified duty-cycle; this testing 
can be conducted while the engine is being driven on the road (e.g., 
on a package delivery route), or in an emission testing laboratory. 
We may also refer to off-cycle test procedures in this preamble as 
``on the road'' testing for simplicity. Both duty cycle and off-
cycle testing are conducted pre-production (e.g., for certification) 
or post-production to verify that the engine meets applicable duty 
cycle or off-cycle emission standards throughout useful life (See 
Section III.A and IV.K for more discussion).
---------------------------------------------------------------------------

i. Proposed Laboratory Standards and Test Procedures
    For heavy-duty CI engines, we are proposing new standards for 
laboratory-based tests using the current duty cycles, the transient 
Federal Test Procedure (FTP) and the steady-state Supplemental Emission 
Test (SET) procedure. These existing test procedures require CI engine 
manufacturers to demonstrate the effectiveness of emission controls 
when the engine is transitioning from low-to-high loads or operating 
under sustained high load, but do not provide for demonstrating 
emission control under sustained low-load operations. We are proposing 
that laboratory demonstrations for heavy-duty CI engines would also 
include a new low-load cycle (LLC) test procedure to demonstrate that 
emission controls are meeting proposed LLC standards when the engine is 
operating under low-load and idle conditions. The proposed addition of 
the LLC would help ensure lower NOX emissions in urban areas 
and other locations where heavy-duty vehicles operate in stop-and-go 
traffic or other low-load conditions.
    For heavy-duty SI engines, we are proposing new standards for their 
laboratory demonstrations using the current FTP duty cycle, and updates 
to the current engine mapping procedure to ensure the engines achieve 
the highest torque level possible during testing. We are proposing to 
add the SET procedure to the heavy-duty SI laboratory demonstrations; 
it is currently only required for heavy-duty CI engines. Heavy-duty SI 
engines are increasingly used in larger heavy-duty vehicles, which 
makes it more likely for these engines to be used in higher-load 
operations covered by the SET. We are further proposing a new refueling 
emission standard for incomplete vehicles above 14,000 lb GVWR starting 
in MY 2027.\32\ The proposed refueling standard is based on the current 
refueling standard that applies to complete heavy-duty gasoline-fueled 
vehicles. Consistent with the current evaporative emission standards 
that apply for these same vehicles, we are proposing that manufacturers 
could use an engineering analysis to demonstrate that they meet our 
proposed refueling standard.
---------------------------------------------------------------------------

    \32\ Some vehicle manufactures sell their engines or 
``incomplete vehicles'' (i.e., chassis that include their engines, 
the frame, and a transmission) to body builders who design and 
assemble the final vehicle.
---------------------------------------------------------------------------

    Our proposed Option 1 and proposed Option 2 NOX emission 
standards for all defined duty cycles for heavy-duty CI and SI engines 
are detailed in Table 1. As shown, the proposed Option 1 NOX 
standards would be implemented in two steps beginning with MY 2027 and 
becoming more stringent in MY 2031. The proposed Option 2 
NOX emission standards would be implemented with a single 
step in MY 2027. As noted in Section B.1 of this Executive Summary, 
overall, we consider proposed Option 2 to be less stringent than the 
standards in the proposed Option 1 because proposed Option 2 has higher 
numeric NOX emission standards with similar useful life 
periods as the proposed Option 1 in MY 2027, and shorter length of 
useful life periods than the proposed Option 1 in MY 2031. In contrast, 
the Alternative is more stringent than proposed Option 1's MY 2031 
standards (see Section III), and we currently do not have information 
to support the conclusion that the combination of shorter lead time, 
lower numeric levels of the standards and longer useful life periods in 
the Alternative is feasible in the MY 2027 timeframe based on the 
emission control technologies we have evaluated to date. See Section 
III for more discussion on feasibility. Consistent with our current 
approach for criteria pollutants, the standards in proposed Options 1 
and 2, presented in Table 1, are numerically identical for SI and CI 
engines.\33\
---------------------------------------------------------------------------

    \33\ See Section III for our proposed and alternative PM, HC, 
and CO standards.

   Table 1--Proposed Options 1 and 2 NOX Emission Standards for Heavy-Duty CI and SI Engines on Specific Duty
                                                     Cycles
                                   [Milligrams/horsepower-hour (mg/hp-hr)] \a\
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1                           Proposed
                                 ----------------------------------------------------------------    Option 2
                                    Model years             Model years 2031 and later           ---------------
                                     2027-2030   ------------------------------------------------   Model years
                                 ----------------                                                 2027 and later
           Duty cycle                             Spark ignition     Heavy HDE    Heavy HDE from ---------------
                                                    HDE, light        through       IUL to full   Spark ignition
                                  All HD engines     HDE, and      intermediate     useful life     HDE, light
                                                    medium HDE      useful life        (FUL)        HDE, medium
                                                                       (IUL)                      HDE, heavy HDE
----------------------------------------------------------------------------------------------------------------
FTP (transient mid/high load                  35              20              20              40              50
 conditions)....................
SET (steady-state conditions)...              35              20              20              40              50
LLC (low-load conditions).......              90              50              50             100             100
----------------------------------------------------------------------------------------------------------------
\a\ The current FTP and SET standard for all HD engines is 0.20 g/hp-hr or 200 mg/hp-hr; we are proposing the
  LLC test procedure and therefore there is not a current standard for the LLC.


[[Page 17423]]

ii. Proposed On-the-Road Standards and Test Procedures
    In addition to demonstrating emission control over defined duty 
cycles in a laboratory, heavy-duty CI engines must be able to 
demonstrate emission control over an undefined duty cycle while engines 
are in use on the road in the real world. Both proposed Options 1 and 2 
include updates to the procedure for ``off-cycle'' testing, such that 
data collected during a wider range of operating conditions would be 
valid, and therefore subject to emission standards.\34\
---------------------------------------------------------------------------

    \34\ As discussed in Section III, ``off-cycle'' testing measures 
emissions while the engine is not operating on a specified duty-
cycle; this testing can be conducted while the engine is being 
driven on the road (e.g., on a package delivery route), or in an 
emission testing laboratory.
---------------------------------------------------------------------------

    Similar to the current approach, emission measurements collected 
during off-cycle testing would be collected on a second-by-second 
basis. We are proposing the emissions data would be grouped into 300-
second windows of operation. Each 300-second window would then be 
binned based on the type of operation that the engine performs during 
that 300-second period. Specifically, the average power of the engine 
during each 300-second window would determine whether the emissions 
during that window are binned as idle (Bin 1), low-load (Bin 2), or 
medium-to-high load (Bin 3).\35\
---------------------------------------------------------------------------

    \35\ Due to the challenges of measuring engine power directly on 
in-use vehicles, we are proposing to use the CO2 emission 
rate (grams per second) as a surrogate for engine power; further, we 
propose to normalize CO2 emission rates relative to the 
nominal maximum CO2 rate of the engine (e.g., when an 
engine with a maximum CO2 emission rate of 50 g/sec emits 
at a rate of 10 g/sec, its normalized CO2 emission rate 
is 20 percent).
---------------------------------------------------------------------------

    Our proposed 3-bin approach would cover a wide range of operations 
that occur in the real world--significantly more in-use operation than 
today's requirements. Bin 1 would include extended idle and other very 
low-load operations, where engine exhaust temperatures may drop below 
the optimal temperature where SCR-based aftertreatment works best. Bin 
2 would include a large fraction of urban driving conditions, during 
which engine exhaust temperatures are generally moderate. Bin 3 would 
include higher-power operations, such as on-highway driving that 
typically results in higher exhaust temperatures and high catalyst 
efficiencies.\36\ Given the different operational profiles of each of 
these three bins, we are proposing a separate standard for each bin. 
The proposed structure follows that of our current not-to-exceed (NTE) 
off-cycle standards, while covering a much broader range of engine 
operation.
---------------------------------------------------------------------------

    \36\ Because the proposed approach considers time-averaged 
power, any of the bins could include some idle operation and any of 
the bins could include some high-power operation.
---------------------------------------------------------------------------

    Table 2 presents our proposed Option 1 and Option 2 off-cycle 
standards for NOX emissions from heavy-duty CI engines. The 
proposed Option 2 off-cycle NOX standards are higher (less 
stringent) and have a shorter useful life than the proposed Option 1 
standards in MY 2031. For the Alternative, our assessment of currently 
available data indicates that the off-cycle standard for the medium/
high load bin (Bin 3) would not be feasible in the MY 2027 timeframe, 
and additional or different technology would be necessary to meet the 
Alternative off-cycle standards. See Section III for details on the 
off-cycle standards for other pollutants in the proposed Options 1 and 
2 and the Alternative.

               Table 2--Proposed Options 1 and 2 Off-Cycle NOX Standards for Heavy-Duty CI Engines
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1                           Proposed
                                 ----------------------------------------------------------------    Option 2
                                    Model years             Model years 2031 and later           ---------------
          Operation bin              2027-2030   ------------------------------------------------   Model years
                                 ----------------                                                 2027 and later
                                                  Light HDE, and     Heavy HDE    Heavy HDE from ---------------
                                  All HD engines    medium HDE      through IUL     IUL to FUL    All HD engines
----------------------------------------------------------------------------------------------------------------
idle (g/hr).....................              10             7.5             7.5             7.5              15
low load (mg/hp-hr).............             180              75             7.5             150             150
medium/high load (mg/hp-hr).....              70              30              30              60              75
----------------------------------------------------------------------------------------------------------------

    In addition to the proposed standards for the defined duty cycle 
and off-cycle test procedures, the proposed Options 1 and 2 include 
several other provisions for controlling emissions from specific 
operations in CI or SI engines. First, we are proposing to allow CI 
engine manufacturers to voluntarily certify to the California Air 
Resources Board (CARB) clean idle standards by adding to EPA 
regulations an idle test procedure that is based on an existing CARB 
procedure.\37\ We are also proposing to require a closed crankcase 
ventilation system for all highway CI engines to prevent crankcase 
emissions from being emitted directly to the atmosphere. See Section 
III.B for more discussion on both the proposed idle and crankcase 
provisions. For heavy-duty SI, we are proposing refueling emission 
standards for incomplete vehicles above 14,000 lb GVWR (see Section 
III.E for more discussion).
---------------------------------------------------------------------------

    \37\ 13 CCR 1956.8 (a)(6)(C)--Optional NOX idling 
emission standard.
---------------------------------------------------------------------------

2. Maintaining Criteria Pollutant Emission Control Over a Greater 
Portion of an Engine's Operational Life
    Reducing emissions under a broad range of engine operating 
conditions is one category of our proposed program provisions. 
Maintaining emission control over a greater portion of an engine's 
operational life is the second broad category of proposed provisions. 
The major elements in this category include proposals to (1) extend the 
regulatory useful life of heavy-duty engines, (2) provide an 
opportunity for manufacturers to use rapidly aged parts necessary to 
demonstrate emission performance over the regulatory useful life, (3) 
lengthen emission warranty periods, and 4) increase the likelihood that 
emission controls will be maintained properly through more of the 
service life of heavy-duty engines. Our proposals for each of these 
elements is outlined below and detailed in Section IV; unless 
explicitly stated otherwise, proposals for each of these elements would 
apply under both proposed Options 1 and 2, as well as the full range of 
options in between them.
i. Proposed Useful Life Periods
    EPA is proposing to increase the regulatory useful life mileage 
values for new heavy-duty engines to better reflect real-world usage, 
extend the emissions durability requirement for heavy-duty engines, and 
ensure certified emission performance is maintained throughout

[[Page 17424]]

more of an engine's operational life. For proposed Option 1, Increases 
to useful life values for heavy-duty engines would apply in two steps, 
as discussed in Section IV.A. For the first step for CI engines, MY 
2027 through 2030, we are proposing useful life mileage values that are 
approximately a midpoint between the current useful life mileages and 
our proposed CI engines MY 2031 and later mileages. For the second 
step, we are proposing useful life mileage values for MY 2031 and later 
CI engines that cover a majority of the estimated operational life 
mileages, but less than the first out-of-frame rebuild for these 
engines. The proposed Option 1 first step for SI engines in MY 2027 
through 2030 would better align with the current useful life mileages 
for GHG emission standards applicable to these engines. The proposed 
Option 1 second step useful life mileage for SI engines for MY 2031 and 
later is based on the published engine service life for heavy-duty 
gasoline engines in the market today.
    The useful life mileages in the proposed Option 2 are shorter than 
those in the proposed Option 1; we are giving full consideration to the 
useful life periods of proposed Options 1 and 2, and the range between 
the useful life periods in the proposed Options. Our proposed Option 1 
and Option 2 useful life periods for heavy-duty CI and SI engines are 
presented in Table 3. See Section IV for the useful periods of the 
Alternative.\38\
---------------------------------------------------------------------------

    \38\ As noted in this Section C of the Executive Summary, we are 
proposing refueling standards for HD SI engines that are certified 
as incomplete vehicles that are equivalent to the standards in 
effect for complete heavy-duty vehicles. We propose to apply the 
existing useful life periods for the complete vehicle refueling 
standards (15 years or 150,000 miles; see 40 CFR 1037.103(f) and 
86.1805-16(d) for ``MDPV'' and ``HDV'') to the HD SI engines 
certified as incomplete vehicles. See preamble Section IV.A for more 
details.

                   Table 3--Proposed Options 1 and 2 Useful Life Periods for Heavy-Duty CI and SI Engines Criteria Pollutant Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Spark-ignition HDE                         Compression-ignition
                                                                 ---------------------------------------------------------------------------------------
                           Model year                                                         Light HDE            Medium HDE           Heavy HDE b c
                                                                    Miles      Years   -----------------------------------------------------------------
                                                                                          Miles      Years      Miles      Years      Miles      Years
--------------------------------------------------------------------------------------------------------------------------------------------------------
Current \a\.....................................................    110,000         10    110,000         10    185,000         10    435,000         10
Proposed Option 1: 2027-2030....................................    155,000         12    190,000         12    270,000         11    600,000         11
Proposed Option 1 \d\: 2031 and later...........................    200,000         15    270,000         15    350,000         12    800,000         12
Proposed Option 2: 2027 and later...............................    150,000         10    250,000         10    325,000         10    650,000         10
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Spark-ignition HDE and Light HDE for GHG emission standards is 15 years or 150,000 miles. See 40 CFR 1036.108(d).
\b\ We are also proposing to increase the hours-based useful life criterion from the current 22,000 hours for Heavy HDE to 32,000 hours for model years
  2027-2030 and 40,000 hours for model years 2031 and later.
\c\ The Heavy HDE class includes certain SI engines (e.g., natural gas-fueled engines) intended for use in Class 8 vehicles.
\d\ For MY 2031 and later Heavy HDE, the proposed Option 1 would include intermediate useful life periods of 435,000 miles, 10 years, or 22,000 hours,
  whichever comes first. See Section III for a discussion of the proposed Option 1 standards we propose to apply for the intermediate and full useful
  life periods.

ii. Proposed Durability Demonstration Updates
    The proposed longer useful life periods outlined in Table 3 would 
require manufacturers to extend their durability demonstrations, which 
show that the engines will meet applicable emission standards 
throughout their regulatory useful life. EPA regulations require 
manufacturers to include durability demonstration data as part of an 
application for certification of an engine family. Manufacturers 
typically complete this demonstration by following regulatory 
procedures to calculate a deterioration factor (DF).
    To address the need for accurate and efficient emission durability 
demonstration methods, EPA worked with manufacturers and CARB to 
address this concern through guidance for MY 2020 and later 
engines.\39\ In Section IV.F, we propose three methods for determining 
DFs, consistent with the recent guidance, including a new option to 
bench-age the aftertreatment system to limit the burden of generating a 
DF over the proposed lengthened useful life periods. We also propose to 
codify in the EPA regulations three DF verification options available 
to manufacturers in recent guidance. The proposed verification options 
would confirm the accuracy of the DF values submitted by manufacturers 
for certification. We also introduce a test program to evaluate a 
rapid-aging protocol for diesel catalysts that we may consider as an 
option for CI engine manufacturers to use in their durability 
demonstration.
---------------------------------------------------------------------------

    \39\ U.S. EPA. ``Guidance on Deterioration Factor Validation 
Methods for Heavy-Duty Diesel Highway Engines and Nonroad Diesel 
Engines equipped with SCR.'' CD-2020-19 (HD Highway and Nonroad). 
November 17, 2020.
---------------------------------------------------------------------------

iii. Proposed Emissions Warranty Periods
    EPA's current emission-related warranty periods range from 22 
percent to 54 percent of regulatory useful life. As EPA is proposing to 
lengthen the useful life periods in this rulemaking, we are also 
proposing to lengthen the emission warranty periods and increase the 
fraction of useful life miles covered under warranty. These proposed 
revised warranty periods are expected to result in better engine 
maintenance and less tampering, helping to maintain the benefits of the 
emission controls. In addition, longer regulatory warranty periods may 
lead engine manufacturers to simplify repair processes and make them 
more aware of system defects that would be tracked and reported to EPA 
over a longer period.
    In Section IV.B, we provide detailed discussion and request comment 
on these four ways that longer emission warranty periods may enhance 
long-term performance of emission-related devices and systems. We also 
discuss other impacts of lengthening regulatory emission warranty 
periods and other approaches that vary coverage and may similarly 
ensure long-term in-use emission performance.
    EPA is proposing to lengthen the emissions warranty periods for all 
primary intended service classes to cover a larger portion of the 
operational lives of new heavy-duty engines. Our proposed Option 1 
warranty mileages for MY 2031 are approximately 80 percent of the 
proposed useful life mileages. The proposed Option 1 MY 2027 through 
2030 mileages are

[[Page 17425]]

approximately midpoints between the current and proposed Option 1 MY 
2031 and later mileages. The proposed Option 2 set of emission warranty 
periods would match CARB's Step 1 warranty periods that will already be 
in effect beginning in model year 2022 for engines sold in 
California.\40\ We believe the proposed Option 2 mileages represent an 
appropriate lower end of the range we are considering for the revised 
regulatory emission warranty periods. Our proposed Option 1 and 
proposed Option 2 emission warranty periods are presented in Table 
4.\41\ See Section IV.B for updates in proposed Options 1 and 2 to our 
years-based warranty periods and add hours-based warranty periods for 
all engine classes to cover low average annual mileage applications. We 
also considered an alternative set of warranty periods that are 
presented in Section IV.B.
---------------------------------------------------------------------------

    \40\ For SI engines, the Alternative 1 warranty mileage matches 
the current useful life, consistent with the approach for Light HDE 
Alternative 1 warranty.
    \41\ In addition to exhaust standards, we are proposing 
refueling standards for HD SI engines that are certified as 
incomplete vehicles. The onboard refueling vapor recovery systems 
necessary to meet the proposed refueling standards will likely build 
on existing evaporative emissions systems, and we propose to apply 
the existing warranty periods for evaporative emission control 
systems to the ORVR systems (5 years or 50,000 miles). See Preamble 
IV.B.1.

            Table 4--Proposed Options 1 and 2 Emission-Related Warranty Periods for Heavy-Duty CI and SI Engines Criteria Pollutant Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Spark-ignition HDE                         Compression-ignition
                                                        ----------------------------------------------------------------------------------------
                       Model year                                                    Light HDE            Medium HDE             Heavy HDE        Years
                                                           Miles      Hours   ------------------------------------------------------------------
                                                                                 Miles      Hours      Miles      Hours      Miles      Hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
Current................................................     50,000         NA     50,000         NA    100,000         NA    100,000         NA        5
Proposed Option 1: 2027-2030...........................    110,000      6,000    150,000      7,000    220,000     11,000    450,000     22,000        7
Proposed Option 1: 2031 and later......................    160,000      8,000    210,000     10,000    280,000     14,000    600,000     30,000       10
Proposed Option 2: 2027 and later......................    110,000         NA    110,000         NA    150,000         NA    350,000         NA        5
--------------------------------------------------------------------------------------------------------------------------------------------------------

iv. Proposed Provisions To Ensure Long-Term Emissions Performance
    In the ANPR, we introduced several ideas for an enhanced, 
comprehensive strategy to increase the likelihood that emission 
controls will be maintained properly through more of the operational 
life of heavy-duty engines, including beyond their useful life periods. 
Our proposed updates to maintenance provisions include defining the 
type of maintenance manufacturers may choose to recommend to owners in 
maintenance instructions, updating minimum maintenance intervals for 
certain critical emission-related components, and outlining specific 
requirements for maintenance instructions provided in the owner's 
manual.
    We are proposing changes to the owner's manual and emissions label 
requirements to ensure access to certain maintenance information and 
improve serviceability. We expect this additional maintenance 
information to improve factors that contribute to mal-maintenance, 
which would result in better service experiences for independent repair 
technicians, specialized repair technicians, owners who repair their 
own equipment, and possibly vehicle inspection and maintenance 
technicians. We also believe that improving owner experiences with 
operating and maintaining heavy-duty engines can reduce the likelihood 
of tampering.
v. Proposed Inducement Provisions
    ANPR commenters indicated that engine derates or ``inducements'' 
are a significant source of operator frustration.\42\ EPA currently has 
guidance on potential options manufacturers might utilize to meet 
existing requirements through an inducement strategy for their SCR-
based aftertreatment system.\43\ We are proposing to codify inducement 
provisions after considering manufacturer designs and operator 
experiences with SCR-based aftertreatment systems. In Section IV.D, we 
present the key principles we followed in developing the proposed 
inducement provisions, which includes a focus on conditions that are 
within an operator's control, a multi-step derate schedule, and a 
backup check to override false inducements. We also include a detailed 
set of requests for comment highlighting the wide range of adjustments 
we are currently considering.
---------------------------------------------------------------------------

    \42\ Engine derating is an aftertreatment design strategy that 
reduces engine performance to induce operators to maintain 
appropriate levels of high-quality diesel emission fluid (DEF) in 
their SCR-based aftertreatment systems. Throughout this preamble we 
refer to engine derates that derive from DEF-related triggers as 
``inducements.''
    \43\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055. 
``Inducement-Related Guidance Documents, and Workshop 
Presentation.'' October 1, 2021.
---------------------------------------------------------------------------

vi. Proposed Onboard Diagnostics Provisions
    Onboard diagnostics (OBD) refer to systems of electronic 
controllers and sensors required by current regulation to detect 
malfunctions of engines and emission controls. EPA's existing OBD 
program, promulgated in 2009, allows manufacturers to demonstrate how 
the OBD system they have designed to comply with California OBD 
requirements also complies with the intent of the EPA OBD 
requirements.\44\ Although EPA maintains separate OBD regulations, all 
manufacturers currently seek OBD approval from CARB for OBD systems in 
engine families applying for 50-state certification, and then use this 
approval to demonstrate compliance with EPA requirements.
---------------------------------------------------------------------------

    \44\ See 40 CFR 86.010-18(a)(5).
---------------------------------------------------------------------------

    In Section IV.C, we are proposing to update our OBD regulations 
both to better address newer diagnostic methods and available 
technologies, and to streamline provisions where possible. We propose 
to incorporate by reference the existing CARB OBD regulations updated 
in 2019 as the starting point for our updated OBD regulations.\45\ We 
are proposing to exclude or revise certain CARB provisions that we 
believe are not appropriate for a federal program and are proposing to 
include additional elements to improve the usefulness of

[[Page 17426]]

OBD systems for users (see Section IV.C for details).
---------------------------------------------------------------------------

    \45\ CARB Final Rulemaking to Consider Technical Status and 
Prosed Revisions to On-Board Diagnostic System Requirements for 
Heavy-Engines, Passenger Cars, Light-Duty Trucks, Medium Duty 
Vehicles and Engines was approved and became effective on July 31, 
2013. California Code of Regulations sections 1968.2 and 1971.1 
available at: https://ww3.arb.ca.gov/regact/2012/hdobd12/hdobd12.htm.
---------------------------------------------------------------------------

    EPA is specifically proposing additional OBD elements to improve 
the robustness and usefulness of OBD systems. These additional elements 
include emission system health monitors, an expanded list of publicly 
available OBD parameters, additional freeze frame data parameters, and 
enabling certain self-testing capabilities for owners. These proposed 
changes would benefit the environment by helping to reduce 
malfunctioning emission systems in-use through access to additional 
data that may be useful for service technicians, state and local 
inspection and maintenance operations, and owners.
3. Other Proposed Compliance Provisions and Flexibilities
    In addition to the key program provisions, we are also proposing 
several provisions to provide manufacturers with flexibility to meet 
the proposed standards and encourage the introduction of new emission 
control technologies earlier than required; these provisions would 
apply under both proposed Options 1 and 2, as well as the full range of 
options in between them. These provisions include our proposal to 
migrate and update the compliance provisions of 40 CFR part 86, subpart 
A, to 40 CFR part 1036; continue averaging, banking, and trading (ABT) 
of credits generated against our heavy-duty engine criteria pollutant 
standards; provide incentives for early adoption of technologies to 
meet the standards; allow manufacturers to generate NOX 
emission credits for hybrid electric, battery electric, and fuel cell 
electric vehicles (HEVs, BEVs, and FCEVs); and make limited amendments 
to regulations that implement our air pollutant emission standards for 
other industry sectors, including light-duty vehicles, light-duty 
trucks, marine diesel engines, locomotives, and various types of 
nonroad engines, vehicles, and equipment.
i. Proposed Migration From 40 CFR Part 86, Subpart A
    Heavy-duty criteria pollutant regulations were originally codified 
into 40 CFR part 86, subpart A, in the 1980s. We believe this 
rulemaking provides an opportunity to clarify (and otherwise improve) 
the wording of our existing heavy-duty criteria pollutant regulations 
in plain language and migrate them to 40 CFR part 1036.\46\ Part 1036, 
which was created for the Phase 1 GHG program, provides a consistent, 
updated format for our regulations, with improved organization. In 
general, this migration is not intended to change the compliance 
program previously specified in part 86, except as specifically 
proposed in this rulemaking. See our summary of the proposed migration 
in Section III.A, and additional details in our memorandum to the 
docket.\47\ The proposed provisions of part 1036 would generally apply 
for model years 2027 and later, unless noted, and manufacturers would 
continue to use part 86 in the interim.
---------------------------------------------------------------------------

    \46\ We are proposing to migrate some provisions to parts 1065 
and 1068 to apply broadly to other sectors. Additionally, some 
current vehicle provisions in part 1037 refer to part 86 and we are 
proposing to update those references in part 1037 as needed.
    \47\ Stout, Alan; Brakora, Jessica. Memorandum to docket EPA-HQ-
OAR-2019-0055. ``Technical Issues Related to Migrating Heavy-Duty 
Highway Engine Certification Requirements from 40 CFR part 86, 
subpart A, to 40 CFR part 1036''. October 1, 2021.
---------------------------------------------------------------------------

ii. Proposed Opportunities for NOX Emission Credits
    We are proposing targeted revisions to the current emissions ABT 
provisions to account for specific aspects of the broader proposed 
program. We are also proposing an early adoption incentive program that 
would recognize the environmental benefits of lower-emitting vehicles 
entering the fleet ahead of required compliance dates for the proposed 
standards. Through this optional program, manufacturers who demonstrate 
early compliance with the proposed MY 2027 or MY 2031 standards would 
apply a multiplier to emission credits generated under the proposed ABT 
program (see Section IV.H for details). We are also proposing to offer 
NOX emission credits for HEVs, BEVs and FCEVs based on the 
near-zero or zero-tailpipe emissions performance of these technologies, 
for HEVs or BEVs and FCEVs, respectively, and after consideration of 
ANPR comments. We are choosing not to propose emission credit 
multipliers for HEVs, BEVs, and FCEVs. We believe that the potential 
loss of emission reductions that could result from providing credit 
multipliers is not justified in light of the current extent of 
technology development and implementation. Manufacturers choosing to 
generate NOX emission credits from BEVs or FCEVs would need 
to conduct testing and meet durability requirements discussed in 
Section IV.
iii. Other Amendments
    EPA has promulgated emission standards for highway and nonroad 
engines, vehicles, and equipment. Section XII of this proposed rule 
describes several amendments to correct, clarify, and streamline a wide 
range of regulatory provisions for many of those different types of 
engines, vehicles, and equipment. Section XII.A includes technical 
amendments to compliance provisions that apply broadly across EPA's 
emission control programs to multiple industry sectors, including 
light-duty vehicles, light-duty trucks, marine diesel engines, 
locomotives, and various other types of nonroad engines, vehicles, and 
equipment. Some of those amendments are for broadly applicable testing 
and compliance provisions in 40 CFR parts 1065, 1066, and 1068. Other 
cross-sector issues involve making the same or similar changes in 
multiple standard-setting parts for individual industry sectors. The 
rest of Section XII describes proposed amendments that apply uniquely 
for individual industry sectors.
    We are proposing amendments in two areas of note for the general 
compliance provisions in 40 CFR part 1068. First, we are proposing to 
take a comprehensive approach for making confidentiality determinations 
related to compliance information that companies submit to EPA. We are 
proposing to apply these provisions for all highway, nonroad, and 
stationary engine, vehicle, and equipment programs, as well as aircraft 
and portable fuel containers.
    Second, we are proposing provisions that include clarifying text to 
establish what qualifies as an adjustable parameter and to identify the 
practically adjustable range for those adjustable parameters. The 
proposed adjustable-parameter amendments also include specific 
provisions related to electronic controls that aim to deter tampering.
4. Targeted Revisions to the HD GHG Phase 2 Program
    As noted at the start of this Section I.B, we have developed a 
proposed approach to make targeted updates that take into consideration 
the growing HD electric vehicle market without fundamentally changing 
the HD GHG Phase 2 program as a whole. These developments along with 
considerations of lead time, costs and other factors have demonstrated 
that further GHG reductions in the MY 2027 timeframe are appropriate. 
Specifically, we propose to adjust the HD GHG Phase 2 vehicle GHG 
emission standards by sales-weighting the projected heavy-duty EV 
production levels of school buses, transit buses, commercial delivery 
trucks, and short-haul tractors and by lowering the applicable emission 
standards in MY 2027 accordingly. We project these four vehicle types 
will have the highest EV sales of all heavy-

[[Page 17427]]

duty vehicle types between now and 2030. Because these four EV vehicle 
types do not correspond directly with the specific subcategories for 
standards that we developed in HD GHG Phase 2 (subcategories 
differentiated by vehicle weight, use, fuel type, etc.), we use EPA 
certification data to determine which subcategories of standards would 
be impacted by EV production in MY 2027. By sales-weighing the 
projected production levels of the four EV vehicle types in 2027, our 
proposed approach adjusts 17 of the 33 MY 2027 Phase 2 vocational 
vehicle and tractor standards and does not change any MY 2021 or MY 
2024 standards or any of the Class 2b/3 pickup truck and van standards. 
We request comment on the proposed approach to determine the threshold.
    In addition to these proposed standard adjustments, we are 
requesting comment on options to update the advanced technology 
incentive program for electric and plug-in hybrid vehicles beginning in 
MY 2024. These changes may be appropriate to reflect that such levels 
of incentives for electrification may no longer be appropriate for 
certain segments of the HD EV market. We are trying to balance 
providing additional incentives for the continued development of zero 
and near-zero emission vehicles without inadvertently undermining the 
GHG emission reductions from the HD GHG Phase 2 program with 
inappropriate incentives.

D. Projected Emission Reductions, Air Quality Improvements, Costs, and 
Benefits

    Our analysis of the estimated emission reductions, air quality 
improvements, costs, and monetized benefits of the proposed criteria 
pollutant program is outlined below and detailed in Sections V through 
X. While the discussion below generally focuses on our analysis of the 
proposed Option 1, we also discuss the proposed Option 2; additional 
information on analyses of proposed Options 1 and 2 is included in the 
sections that follow. As discussed in Section III, we currently lack 
information to show that the Alternative is feasible in the MY 2027 
timeframe based on the emission control technologies that we have 
evaluated to date, and therefore we are not presenting an analysis of 
the costs or benefits of the Alternative. We expect that we would need 
additional data supporting the feasibility of the Alternative to 
further consider it in the development of the final rule.
    The proposed provisions in Options 1 and 2, which are described in 
detail in Sections III and IV, are expected to reduce emissions from 
highway heavy-duty engines in several ways. We project the proposed 
emission standards for heavy-duty CI engines would reduce tailpipe 
emissions of NOX; the combination of the proposed low-load 
test cycle and off-cycle test procedure for CI engines would help to 
ensure that the reductions in tailpipe emissions are achieved in-use, 
not only under high-speed, on-highway conditions, but also under low-
load and idle conditions. We also project reduced tailpipe emissions of 
NOX, CO, PM, VOCs, associated air toxics, and methane from 
the proposed emission standards for heavy-duty SI engines, particularly 
under cold-start and high-load operating conditions. The longer 
emission warranty and regulatory useful life requirements for heavy-
duty CI and SI engines in the proposed Options 1 and 2 would help 
maintain the expected emission reductions for all pollutants, including 
primary exhaust PM2.5, throughout the useful life of the 
engine. The onboard refueling vapor recovery requirements for heavy-
duty SI engines in the proposed Options 1 and 2 would reduce VOCs and 
associated air toxics. Table 5 summarizes the projected reductions in 
heavy-duty emission from the proposed Options 1 and 2 in 2045 and shows 
the significant reductions in NOX emissions from the 
proposal. In general, we estimate that Option 2 would result in lower 
emission reductions because of the less stringent emission standards 
combined with shorter useful life and warranty periods than the 
proposed Option 1 in MY 2031. Section VI and draft Regulatory Impact 
Analysis (RIA) Chapter 5 provide more information on our projected 
emission reductions for proposed Options 1 and 2, as well as the 
Alternative.

   Table 5--Projected Heavy--Duty Emission Reductions in 2045 From the
                   Proposed Options 1 and 2 Standards
------------------------------------------------------------------------
                                                  Percent reduction in
                                                   highway heavy-duty
                                                        emissions
                   Pollutant                   -------------------------
                                                  Proposed     Proposed
                                                  Option 1     Option 2
------------------------------------------------------------------------
NOX...........................................           61           47
Primary PM2.5.................................           26           24
VOC...........................................           21           20
CO............................................           17           16
------------------------------------------------------------------------

    The proposed criteria pollutant program in proposed Options 1 and 2 
would also reduce emissions of other pollutants. For instance, the 
proposed Option 1 would result in a 27 percent reduction in benzene and 
a 0.7 percent reduction in methane from highway heavy-duty engines in 
2045. Leading up to 2045, emission reductions are expected to increase 
over time as the fleet turns over to new, compliant engines.
    Reductions in emissions of NOX, VOC, PM2.5, 
and CO from the proposed rule are projected to lead to decreases in 
ambient concentrations of ozone, PM2.5, NO2, and 
CO. The proposed Option 1 standards would significantly decrease ozone 
concentrations across the country, with a population-weighted average 
decrease of over 2 ppb in 2045.\48\ Ambient PM2.5, 
NO2 and CO concentrations are also predicted to improve in 
2045 as a result of the proposed Option 1 program. The emission 
reductions provided by the proposed standards would be important in 
helping areas attain the NAAQS and prevent future nonattainment. In 
addition, the proposed Option 1 standards are expected to result in 
improvements in nitrogen deposition and visibility, but they are 
predicted to have relatively little impact on ambient concentrations of 
air toxics.
---------------------------------------------------------------------------

    \48\ Due to resource constraints, we only conducted air quality 
modeling for the proposed Option 1.
---------------------------------------------------------------------------

    We also used our air quality data from modeling Option 1 to conduct 
a demographic analysis of human exposure to future air quality in 
scenarios with and without the proposed criteria pollutant standards in 
place. To compare demographic trends, we sorted 2045 baseline air 
quality concentrations from highest to lowest concentration and created 
two groups: Areas within the contiguous U.S. with the worst air quality 
and the rest of the country. We found that in the 2045 baseline, the 
number of people of color living within areas with the worst air 
quality is nearly double that of non-Hispanic Whites. We also found 
that the largest predicted improvements in both ozone and 
PM2.5 are estimated to occur in areas with the worst 
baseline air quality, where larger numbers of people of color are 
projected to reside. More details on our air quality modeling and 
demographic analyses are included in Section VII and draft RIA Chapter 
6.
    Our estimates of reductions in heavy-duty engine emissions, and 
associated air quality impacts, are based on manufacturers adding 
emissions-reduction technologies in response to the proposed Options 1 
or 2 criteria pollutant standards, along with making emission control 
components more durable in response to the longer regulatory useful 
life periods in the proposed Options 1 or 2. We also estimate costs to 
both truck owners and manufacturers attributable to the longer emission 
warranty for both the proposed Options 1 and 2. We estimate costs of

[[Page 17428]]

the proposed Options 1 and 2 to both manufacturers and truck owners in 
our program cost analysis in Section V and draft RIA Chapter 7.
    Our evaluation of costs to manufacturers includes direct costs 
(i.e., cost of materials, labor costs) and indirect manufacturing costs 
(e.g., warranty, research and development). The direct manufacturing 
costs include individual technology costs for emission-related engine 
components and for exhaust aftertreatment systems. Importantly, our 
analysis of direct manufacturing costs includes the costs of the 
existing emission control technologies because we expect the emissions 
warranty and regulatory useful life provisions in the proposed Options 
1 and 2 to have some impact on not only the new technology added to 
comply with the proposed standards, but also on any existing emission 
control components. The cost estimates thus reflect the portion of 
baseline case engine hardware and aftertreatment systems for which new 
costs would be incurred due to the proposed warranty and useful life 
provisions, even absent any changes in the level of emission standards. 
The indirect manufacturing costs in our analysis include warranty 
costs, research and development costs, profits and other indirect 
costs. We combine direct and indirect manufacturing costs to calculate 
total technology costs, which we then add to operating costs in our 
calculation of program costs.
    As part of our evaluation of operating costs, we estimate costs 
truck owners incur to repair emission control system components. Our 
repair cost estimates are based on industry data showing the amount 
spent annually by truck owners on different types of repairs, and our 
estimate of the percentage of those repairs that are related to 
emission control components. Our analysis of this data shows that 
extending the useful life and emission warranty periods would lower 
emission repair costs during several years of operation for several 
vehicle types. More discussion on our emission repair costs estimates 
of the proposed Options 1 and 2 criteria pollutant standards is 
included in Section V, with additional details presented in draft RIA 
Chapter 7.
    We combined our estimates of emission repair costs with other 
operating costs (i.e., urea/DEF, fuel consumption) and technology costs 
to calculate total program costs. Our analysis of proposed Option 1 
shows that total costs for the criteria pollutant program relative to 
the baseline (or no action scenario) range from $1.8 billion in 2027 to 
$2.3 billion in 2045 (2017 dollars, undiscounted, see Table V-16). We 
estimate that proposed Option 2 would result in higher costs than the 
proposed Option 1 in 2045. We expect that the same emission control 
technologies would be needed to meet both the proposed Option 1 and 2 
standards, which would result in the same direct technology costs in 
both cases. The higher projected costs of the proposed Option 2 
relative to the proposed Option 1 result from our expectation that the 
shorter useful life and emission warranty periods of the proposed 
Option 2 compared to proposed Option 1 in MY 2031 and later would lead 
to higher emission control system repair costs for proposed Option 2 
than the proposed Option 1 (i.e., shorter emissions warranty periods 
result in higher emission repair costs in proposed Option 2) (see 
Section V for details). Overall, the analysis shows that the costs of 
proposed Option 1 are less than the costs of proposed Option 2. The 
present value of program costs for proposed Options 1 and 2, and 
additional details are presented in Section V.
    Section VIII presents our analysis of the human health benefits 
associated with the proposed Options 1 and 2. We estimate that in 2045, 
the proposed Option 1 would result in total annual monetized ozone- and 
PM2.5-related benefits of $12 and $33 billion at a 3 percent 
discount rate, and $10 and $30 billion at a 7 percent discount 
rate.\49\ In the same calendar year, proposed Option 2 would result in 
total annual monetized ozone- and PM2.5-related benefits of 
$9 and $26 billion at a 3 percent discount rate, and $8 and $23 billion 
at a 7 percent discount. These benefits only reflect those associated 
with reductions in NOX emissions (a precursor to both ozone 
and secondarily-formed PM2.5) and directly-emitted 
PM2.5 from highway heavy-duty engines. There are additional 
human health and environmental benefits associated with reductions in 
exposure to ambient concentrations of PM2.5, ozone, and NO2 
that EPA has not quantified due to data, resource, or methodological 
limitations. There would also be benefits associated with reductions in 
air toxic pollutant emissions that result from the proposed program, 
but we did not attempt to monetize those impacts due to methodological 
limitations. The estimated benefits of the proposed Options 1 and 2 
would be larger if we were able to monetize all unquantified benefits 
at this time. More detailed information about the benefits analysis 
conducted for the proposal, including the present value of program 
benefits for Options 1 and 2, is included in Section VIII and draft RIA 
Chapter 8.
---------------------------------------------------------------------------

    \49\ 2045 is a snapshot year chosen to approximate the annual 
health benefits that occur in a year in which the proposed program 
would be fully implemented and when most of the regulated fleet 
would have turned over.
---------------------------------------------------------------------------

    We compare total monetized health benefits to total costs 
associated with the proposed Options 1 and 2 in Section IX. Table 6 
shows that annual benefits of the proposed Option 1 would be larger 
than the annual costs in 2045, with annual net benefits of $9 and $31 
billion assuming a 3 percent discount rate, and net benefits of $8 and 
$28 billion assuming a 7 percent discount rate.\50\ Annual benefits 
would also be larger than annual costs in 2045 for the proposed Option 
2, although net benefits would be slightly lower than from the proposed 
Option 1 (net benefits of proposed Option 2 would be $6 and $23 billion 
at a 3 percent discount rate, and net benefits of $5 and 21 billion at 
a 7 percent discount rate). For both the proposed Options 1 and 2, 
benefits also outweigh the costs when expressed in present value terms 
and as equalized annual values.
---------------------------------------------------------------------------

    \50\ The range of benefits and net benefits reflects a 
combination of assumed PM2.5 and ozone mortality risk 
estimates and selected discount rate.

              Table 6--2045 Costs, Benefits and Net Benefits of the Proposed Option 1 and Option 2
                                              [Billions, 2017$] a b
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1               Proposed Option 2
                                                 ---------------------------------------------------------------
                                                    3% discount     7% discount     3% discount     7% discount
----------------------------------------------------------------------------------------------------------------
2045:
    Benefits....................................         $12-$33         $10-$30        $9.1-$26        $8.2-$23
    Costs.......................................             2.3             2.3             2.9             2.9

[[Page 17429]]

 
    Net Benefits................................          9.2-31          8.1-28          6.2-23          5.3-21
----------------------------------------------------------------------------------------------------------------
\a\ All benefits estimates are rounded to two significant figures; numbers may not sum due to independent
  rounding. The range of benefits (and net benefits) in this table are two separate estimates and do not
  represent lower- and upper-bound estimates, though they do reflect a grouping of estimates that yield more and
  less conservative benefits totals. The costs and benefits in 2045 are presented in annual terms and are not
  discounted. However, all benefits in the table reflect a 3 percent and 7 percent discount rate used to account
  for cessation lag in the valuation of avoided premature deaths associated with long-term exposure.
\b\ The benefits associated with the standards presented here do not include the full complement of health,
  environmental, and climate-related benefits that, if quantified and monetized, would increase the total
  monetized benefits.

    Section X examines the potential impacts of the proposed standards 
on heavy-duty vehicles (sales, mode shift, fleet turnover) and 
employment in the heavy-duty industry. The proposed standards may 
impact vehicle sales due to both changes in purchase price and longer 
emission warranty mileage requirements; these effects may show up as 
increased purchases of more new vehicles than usual before the proposed 
standards come into effect, in anticipation of higher prices after the 
proposed standards (``pre-buy''). The proposed standards may also 
reduce sales after the proposed standards would be in place (``low-
buy''). In this proposal, we suggest an approach to quantify potential 
impacts on vehicle sales due to new emission standards; we also provide 
an example of how the results could be applied to the final regulatory 
analysis for this rule in draft RIA Chapter 10.1. Our example results 
for proposed Option 1 suggest pre- and low-buy for Class 8 trucks may 
range from zero to approximately two percent increase in sales over a 
period of up to 8 months before the 2031 standards begin (pre-buy), and 
a decrease in sales from zero to approximately two percent over a 
period of up to 12 months after the 2031 standards begin (low-buy). We 
have provided the example results as information for commenters to 
consider and provide input to EPA on this type of approach for 
quantifying how emissions regulations may impact heavy-duty vehicle 
sales fleet turnover. Based on input we receive, we may consider using 
this type of analysis in the final rule to inform both the potential 
impacts on vehicle sales, and the related impacts on employment in the 
heavy-duty industry. We expect little mode shift due to the proposed 
standards because of the large difference in cost of moving goods via 
trucks versus other modes of transport (e.g., planes or barges).
    Employment impacts of the proposed standards depend on the effects 
of the standards on sales, the share of labor in the costs of the 
standards, and changes in labor intensity due to the standards. We 
quantify the effects of costs on employment, and we discuss the effects 
due to sales and labor intensity qualitatively. This partial 
quantification of employment impacts estimates that increased costs of 
vehicles and parts would, by itself and holding labor intensity 
constant, be expected to increase employment by 400 to 2,200 job-years 
in 2027, and 300 to 1,800 job-years in 2032 under proposed Option 
1.\51\ Employment would be expected to increase by 400 to 2,200 job 
years, and 300 to 1,500 job years in 2027 and 2032 respectively under 
proposed Option 2. See Section X for further detail on limitations and 
assumptions of this analysis.
---------------------------------------------------------------------------

    \51\ Where a job-year is, for example, one year of full-time 
work for one person, or one year of half-time work for two people.
---------------------------------------------------------------------------

    Finally, the projected cost and GHG emission impacts of the 
proposed changes to the HD GHG Phase 2 program are described in Section 
XI.E.

E. Summary of Specific Requests for Comments

    We are requesting comment on all aspects of this proposed 
rulemaking. In addition, as detailed in the sections that follow, we 
are specifically requesting comments from stakeholders on a variety of 
key topics throughout this proposed to inform the final rulemaking 
process. In this section we highlight topics on which we believe it 
would be especially beneficial to receive comments from stakeholders, 
or which may be of most interest to stakeholders.
    Section III presents extensive information and analyses, including 
two options for the proposed criteria pollutant standards, to provide 
notice that EPA will be considering a range of numeric emission 
standard values and implementation dates in the final rule. We are 
requesting comment on the proposed Options 1 and 2, as well as the 
Alternative, standards for each duty cycle, as well as the one- and 
two-step approaches in proposed Options 1 and 2, respectively, and the 
implementation dates of MYs 2027 and 2031. In addition, we are 
requesting input on several aspects of the proposed new LLC duty cycle 
for heavy-duty CI engines and applying the SET duty cycle to heavy-duty 
SI engines (see Section III). We are also requesting comment on several 
aspects of the proposed off-cycle standards for heavy-duty CI engines, 
including the levels of the standards in proposed Options 1 and 2 and 
the specific operating range covered by each bin, and whether off-cycle 
standards and in-use testing should also apply for SI engines. For SI 
engines, we request comment on our proposed refueling HC emission 
standard for incomplete vehicles above 14,000 lb GVWR, including 
requests for comment and data to inform test procedure updates we 
should consider to measure HC emissions from these larger fuel systems 
and vehicles. We are also requesting comment on whether EPA should 
finalize interim standards for testing used to verify that the engine 
meets the standards through useful life (i.e., in-use testing that 
occurs after the vehicle enters commerce). Typically, EPA sets the same 
standards for in-use testing and certification testing but, in some 
cases, we have provided higher in-use standards to give manufacturers 
time to gain experience with the new technology needed to meet the 
standards.\52\ As outlined in this Executive Summary and discussed in 
Sections III and IV, we are proposing to significantly lower 
NOX emission standards and to significantly increase the 
regulatory useful life for heavy-duty on highway engines, which would 
require manufactures to develop and produce additional engine and 
aftertreatment technology. Due to the combination of lower (more 
stringent) numeric standards and longer useful periods included in our 
proposal, we are requesting comment on whether

[[Page 17430]]

EPA should finalize in-use standards that are 40 to 100 percent higher 
than the proposed Option 1 standards for MY 2027 to MY 2033 engines.
---------------------------------------------------------------------------

    \52\ See 81 FR 23414 (April 28, 2014).
---------------------------------------------------------------------------

    In Section IV we detail our requests for comment on a number of 
topics related to our proposed lengthened useful life and warranty 
periods, as well as other compliance provisions and flexibilities. For 
instance, we are requesting stakeholder input on our proposed useful 
life and warranty periods, as well as the range of options covered by 
the proposed Options 1 and 2, or other alternatives outside of that 
range. In addition to the proposed warranty periods, we request comment 
on other approaches to warranty, such as graduated warranty phases, 
that may similarly ensure long-term in-use emission performance with a 
smaller impact on the purchase price. We further request comment on our 
proposed provisions to increase the likelihood that emission controls 
will be maintained properly through more of the service life of heavy-
duty engines (e.g., revise inducement strategies, improve 
serviceability). In addition, we are interested in stakeholder input on 
our proposed approaches for the durability demonstration that 
manufacturers are required to include their application for 
certification (see Section IV.F for details). We are also interested in 
stakeholder input on our proposed requirements for manufacturers 
choosing to generate NOX emission credits from BEVs or 
FCEVs, as well as whether EPA should consider for this final rule, or 
other future rules, restrictions for NOX emission credits in 
the longer term (e.g., beyond MY 2031) (See Section IV.I for details).
    Throughout Sections III and IV, we discuss areas where our proposal 
differs from the California Air Resources Board (CARB) Heavy-Duty 
Omnibus Rulemaking, and request comment on our proposal, including 
whether it is appropriate to harmonize the federal and CARB regulatory 
programs more in light of the authority and requirements of CAA section 
202, and the benefits or challenges if EPA were to finalize particular 
aspects of its program that are or are not fully aligned with the 
Omnibus.
    There are also several topics that we are requesting comment on 
that relate to the analyses that support our proposal. For instance, we 
are interested in stakeholder input on our approach for estimating 
emission reductions from lengthening useful life and warranty periods 
(see Section VI for details). We are also interested in comments on our 
estimate of repair costs for emission control system components (see 
Section V for details). We request comment on the method we outline to 
estimate potential impacts of a proposed regulation on heavy-duty 
vehicle sales; we also request comment on approaches to estimate 
employment impacts attributable to the proposed rule (see Section X for 
details).
    We are also interested in input from environmental justice 
stakeholders and underserved and overburdened communities, including 
children's health stakeholders, regarding the need for revised 
standards and how heavy-duty vehicles affect communities (see Section 
II); the air quality improvements we project from this proposal and how 
they are distributed (see Section VII); and ways the proposal could be 
improved to advance environmental protection for all people, including 
people of color, low-income communities, and those who live near 
highways or in heavily trafficked areas with frequent truck congestion 
and idling, such as ports.
    In Section XI, we request comment in a number of areas related to 
the proposed updates to the HD GHG Phase 2 program for certain heavy-
duty vehicles that are shifting to zero-emission vehicles. We are 
considering whether it would be appropriate in the final rule to 
increase the stringency of the standards even more than what we 
propose. Therefore, we request information on heavy-duty electric 
vehicle sales projections, including for what HD vehicle types, to help 
inform our HD electric vehicle sales projections in the MY 2024 through 
MY 2029 timeframe. We also are considering whether to establish more 
stringent standards beyond MY 2027, specifically in MY 2028 and MY 2029 
using the methodology described in Section XI.C.1. We request comment 
on appropriate stringency and supporting data for each of those model 
years.
    We are also interested in stakeholder input that supports changes 
to the advanced technology credit multiplier approach under 
consideration. In addition, we request comment under this proposal on 
how EPA can best consider the potential for ZEV technology to 
significantly reduce air pollution from the heavy-duty vehicle sector, 
including whether and how to consider including specific sales 
requirements for HD ZEVs.
    For these and all requests for comment detailed throughout the 
proposal, stakeholders are encouraged to provide their rationale and 
any available data that supports to their perspectives.

I. Introduction

A. Brief Overview of the Heavy-Duty Truck Industry

    Heavy-duty highway vehicles (also referred to as ``trucks'' in this 
preamble) range from commercial pickup trucks to vocational vehicles 
that support local and regional transportation, construction, refuse 
collection, and delivery work, to line-haul tractor-trailers that move 
freight cross-country. This diverse array of vehicles is categorized 
into weight classes based on gross vehicle weight ratings (GVWR). These 
weight classes span Class 2b pickup trucks and vans from 8,500 to 
10,000 lbs GVWR through Class 8 line-haul tractors and other commercial 
vehicles that exceed 33,000 lbs GVWR.53 54
---------------------------------------------------------------------------

    \53\ This proposed rulemaking includes revised criteria 
pollutants standards for engine-certified Class 2b through 8 heavy-
duty engines and vehicles; this proposal also includes revised GHG 
standards for Class 4 through 8 vehicles. Class 2b and 3 vehicles 
with GVWR between 8,500 and 14,000 pounds are primarily commercial 
pickup trucks and vans and are sometimes referred to as ``medium-
duty vehicles''. The majority of Class 2b and 3 vehicles are 
chassis-certified vehicles and will be included in a future combined 
light-duty and medium-duty rulemaking action, consistent with E.O. 
14037, Section 2a. Heavy-duty engines and vehicles are also used in 
nonroad applications, such as construction equipment; nonroad heavy-
duty engines and vehicles are not the focus of this proposal. See 
Section I for more discussion on the spectrum of heavy-duty vehicles 
and how they relate to the proposed rule. See Sections I.B and III 
for more discussion on the spectrum of heavy-duty vehicles and how 
they relate to the proposed rule.
    \54\ The focus of this proposal is on highway heavy-duty engines 
and vehicles. However, we are also proposing limited amendments to 
regulations that implement our air pollutant emission standards for 
other sectors, including light-duty vehicles, light-duty trucks, 
marine diesel engines, locomotives, and various types of nonroad 
engines, vehicles, and equipment (see Section XII).
---------------------------------------------------------------------------

    Heavy-duty highway vehicles are primarily powered by diesel-fueled, 
compression-ignition (CI) engines. However, gasoline-fueled, spark-
ignition (SI) engines are common in the lighter weight classes, and 
smaller numbers of alternative fuel engines (e.g., liquified petroleum 
gas, compressed natural gas) are found in the heavy-duty fleet. 
Vehicles powered by electricity, either in the form of battery electric 
vehicles (BEVs) or fuel cell electric vehicles (FCEVs) are also 
increasingly entering the heavy-duty fleet. The operational 
characteristics of some commercial applications (e.g., delivery 
vehicles) can be similar across several vehicle weight classes, 
allowing a single engine, or electric power source in the case of BEVs 
and FCEVs, to be installed in a variety of vehicles. For instance, 
engine specifications needed for a Class 4 parcel delivery vehicle may 
be similar

[[Page 17431]]

to the needs of a Class 5 mixed freight delivery vehicle or a Class 6 
beverage truck. Any performance differences needed to operate across 
this range of vehicles can be achieved through adjustments to chassis-
based systems (i.e., transmission, cooling system) external to the 
engine.
    The industry that designs and manufactures these heavy-duty 
vehicles is composed of three primary segments: Vehicle manufacturers, 
engine manufacturers and other major component manufacturers, and 
secondary manufacturers (i.e., body builders). Some vehicle 
manufacturers are vertically integrated, designing, developing, and 
testing their engines in-house for use in their vehicles, while others 
purchase some or all of their engines from independent engine 
suppliers. Today, only one major independent engine manufacturer 
supports the heavy-duty truck industry, though some vehicle 
manufactures sell their engines or ``incomplete vehicles'' (i.e., 
chassis that include their engines, the frame, and a transmission) to 
body builders who design and assemble the final vehicle. Each of these 
subindustries is often supported by common suppliers for subsystems 
such as transmissions, axles, engine controls, and emission controls.
    In addition to the manufacturers and suppliers responsible for 
producing highway heavy-duty vehicles, an extended network of 
dealerships, repair and service facilities, and rebuilding facilities 
contribute to the sale, maintenance, and extended life of these 
vehicles and engines. Heavy-duty vehicle dealerships offer customers a 
place to order vehicles from a specific manufacturer and include 
service facilities for those vehicles and engines. Dealership service 
technicians are trained to perform regular maintenance and make 
repairs, which generally include repairs under warranty and in response 
to manufacturer recalls. Some trucking fleets, businesses, and large 
municipalities benefit from hiring their own technicians to service 
their vehicles in their own facilities. Many refueling centers along 
major trucking routes have also expanded their facilities to include 
roadside assistance and service stations to diagnose and repair common 
problems.
    Heavy-duty CI engines installed in the larger weight classes of 
vehicles are designed to be rebuilt. Dealerships and other service 
facilities are generally equipped to replace common components, such as 
pistons and bearings that wear over time. However, large-scale (i.e., 
``out-of-frame'') engine overhauls that replace most of the engine 
components require a more sophisticated process that only a limited 
number of facilities provide. Some heavy-duty engine manufacturers have 
established their own rebuilding facilities as a separate branch of 
their operations and others work with independent rebuilding factories 
that are affiliated with multiple engine manufacturers. Rebuilding 
allows owners to extend the life of their engines at a lower cost than 
purchasing a replacement vehicle, which has made the practice common 
for some heavy-duty engines.
    The end-users for highway heavy-duty vehicles are as diverse as the 
applications for which these vehicles are purchased. Smaller weight 
class heavy-duty vehicles are commonly purchased by delivery services, 
contractors, and municipalities. The middle weight class vehicles tend 
to be commercial vehicles for businesses and municipal work that 
transport people and goods locally and regionally or provide services 
such as utilities. Vehicles in the heaviest weight classes are 
generally purchased by businesses with high load demands, such as 
construction, towing or refuse collection, or freight delivery fleets 
and owner-operators with both load and speed demands for regional and 
long-haul goods movement. The competitive nature of the businesses and 
owner-operators that purchase and operate highway heavy-duty vehicles 
means that any time the vehicle is unable to operate due to maintenance 
or repair (i.e., downtime) can lead to a loss in income. This need for 
reliability drives much of the truck and engine manufacturers' 
innovation and research to meet the needs of their customers.

B. History of Emission Standards for Heavy-Duty Engines and Vehicles

    Emission standards for heavy-duty highway engines in the U.S. were 
first issued by the Department of Health, Education, and Welfare in the 
1960s. These standards and the corresponding certification and testing 
procedures were codified at 45 CFR part 1201. In 1972, shortly after 
EPA was created as a federal agency and given responsibility for 
regulating heavy-duty engines, EPA published new standards and updated 
procedures while migrating the regulations to 40 CFR part 85 as part of 
the effort to consolidate all EPA regulations in a single location.\55\ 
EPA created 40 CFR part 86 in 1976 to reorganize emission standards and 
certification requirements for light-duty vehicles and heavy-duty 
highway engines. In 1985, EPA promulgated new standards for heavy-duty 
highway engines, codifying the standards in 40 CFR part 86, subpart A. 
Since then, EPA has promulgated several rules for highway heavy-duty 
engines and vehicles to set new and more stringent emission standards 
for criteria pollutants and precursors,\56\ to set requirements for 
controlling evaporative and refueling emissions,\57\ to establish 
emission control programs for greenhouse gases (GHGs), and to add or 
revise certification procedures.\58\
---------------------------------------------------------------------------

    \55\ See Section I.G for additional discussion on EPA's 
Statutory Authority relevant to this proposal.
    \56\ For example, oxides of nitrogen (NOX), 
hydrocarbons (HC), particulate matter (PM) and carbon monoxide (CO).
    \57\ See Section III.E for more discussion on controlling 
evaporative and refueling emissions from light- and heavy-duty 
vehicles.
    \58\ U.S. Environmental Protection Agency. ``EPA Emission 
Standards for Heavy-Duty Highway Engines and Vehicles,'' Available 
online: https://www.epa.gov/emission-standards-reference-guide/epa-emission-standards-heavy-duty-highway-engines-and-vehicles. (last 
accessed June 25, 2021).
---------------------------------------------------------------------------

    EPA's criteria pollutant regulatory programs for the heavy-duty 
highway industry apply to engines.\59\ Our regulations require that 
engine manufacturers identify the ``primary intended service class'' 
for each engine by considering the vehicles for which they design and 
market their engines. Heavy-duty CI engines are specified as light 
heavy-duty engine (Light HDE), medium heavy-duty engine (Medium HDE), 
or heavy heavy-duty engine (Heavy HDE) based largely on the weight 
class of the vehicles in which the engines are expected to be installed 
and the potential for rebuild. SI heavy-duty engines are generally 
specified as a single spark-ignition HDE service class unless they are 
designed or intended for use in the largest heavy-duty vehicles, and 
therefore considered heavy HDEs.\60\ EPA sets emission standards and 
other regulatory provisions, including regulatory useful life and 
emissions warranty periods, that are targeted for the operational 
characteristics of each primary intended service class.
---------------------------------------------------------------------------

    \59\ EPA's regulations address heavy-duty engines and vehicles 
separately from light-duty vehicles. Vehicles with GVWR above 8,500 
pounds (Class 2b and above) are classified in the regulations as 
heavy-duty. For criteria pollutants EPA's standards generally apply 
to the engine rather than the vehicle for heavy-duty. However, most 
of the Class 2b and 3 pickup trucks and vans (vehicles with a GVWR 
between 8,500 and 14,000 pounds) are chassis-certified heavy-duty 
vehicles and covered by standards in EPA's Tier 3 program (79 FR 
23414, April 28, 2014; 80 FR 0978, February 19, 2015). As noted in 
Section III, there are a small number of Class 2b and 3 engines 
(e.g., trucks with dual rear wheels that are sold with a cab and 
chassis only), which are the subject of this proposed rulemaking.
    \60\ See 40 CFR 1036.140(a)(3).
---------------------------------------------------------------------------

    In the 1990s, EPA issued increasingly stringent standards for 
NOX, CO, HC,

[[Page 17432]]

and PM. These exhaust standards were derived from engine-based emission 
control strategies and manufacturers generally certified their engines' 
emission performance over defined duty cycles on an engine dynamometer 
(i.e., ``engine certification''). In 1997, EPA finalized standards for 
heavy-duty highway diesels (62 FR 54693, October 21, 1997), effective 
beginning with the 2004 model year, including a combined non-methane 
hydrocarbon (NMHC) and NOX standard that represented a 
reduction of NOX emissions by 50 percent. These 
NOX reductions also resulted in significant reductions in 
secondary nitrate PM.
    In early 2001, EPA finalized the 2007 Heavy-Duty Engine and Vehicle 
Rule (66 FR 5002, January 18, 2001) to continue addressing 
NOX and PM emissions from both diesel and gasoline-fueled 
highway heavy-duty engines. This rule established a comprehensive 
national program that regulated a heavy-duty engine and its fuel as a 
single system, with emission standards taking effect beginning with 
model year (MY) 2007 and fully phasing in by MY 2010 (EPA 2010 
standards). Prior to 2007, emission standards were based on controlling 
the emissions formed during the combustion process (i.e., engine-out 
emissions), and there was no further control of emissions between the 
engine and the truck's tailpipe. But with promulgation of the 2007 
final rule, emission standards were, for the first time, based on the 
use of technologies to capture, convert, and reduce harmful engine-out 
emissions, resulting in tailpipe emissions that were cleaner than 
engine-out emissions. By and large, the industry met these new 
standards through the use of exhaust aftertreatment technologies, 
namely, diesel oxidation catalysts, particulate filters, and high-
efficiency catalytic exhaust emission control devices. Consistent with 
previous criteria pollutant regulatory programs, the program also 
offered flexibility to manufacturers through the use of various 
emission credits averaging, banking, and trading (ABT) programs.
    To ensure proper functioning of these aftertreatment technologies, 
which could be damaged by sulfur, EPA also reduced the allowable level 
of sulfur in highway diesel fuel by 97 percent by mid-2006. Together, 
the use of exhaust aftertreatment technologies and lower-sulfur fuel 
resulted in diesel-fueled trucks that emitted PM and NOX 
tailpipe emissions at levels 90 percent and 95 percent below emission 
levels from then-current highway heavy-duty engines, respectively. The 
PM standard for new highway heavy-duty engines was set at 0.01 grams 
(10 milligrams, or 10 mg) per horsepower-hour (mg/hp-hr) by MY 2007 and 
the NOX and NMHC standards of 200 mg/hp-hr and 140 mg/hp-hr, 
respectively, were set to phase in between model years 2007 and 
2010.\61\ In finalizing that rule, EPA estimated that the emission 
reductions would achieve significant health and environmental impacts, 
and that the total monetized PM2.5 and ozone-related 
benefits of the program would exceed $70 billion, versus program costs 
of $4 billion (1999$).
---------------------------------------------------------------------------

    \61\ Heavy-duty engine emission standards are defined in work 
specific units (i.e., milligrams per horsepower-hour) because the 
standards cover a large range of engine ratings, and thus time 
specific standards would not provide equal stringency across all 
engines.
---------------------------------------------------------------------------

    In 2005, EPA finalized a manufacturer-run, in-use testing program 
that uses portable emission measurement systems to measure HC, CO, 
NOX, and PM emissions from the exhaust of in-use heavy-duty 
diesel trucks (70 FR 34594, June 14, 2005). The fully enforceable 
program began in 2007. This effort was a significant advancement in 
helping to ensure that the benefits of more stringent emission 
standards are realized under real-world driving conditions.
    In 2009, as advanced emissions control systems were being 
introduced to meet the MY 2007/2010 standards, EPA promulgated a final 
rule to require that these advanced emissions control systems be 
monitored for malfunctions via an onboard diagnostic (OBD) system (74 
FR 8310, February 24, 2009). The rule, which has been fully phased in, 
required engine manufacturers to install OBD systems that monitor the 
functioning of emission control components on new engines and alert the 
vehicle operator to any detected need for emission-related repair. It 
also required that manufacturers make available to the service and 
repair industry information necessary to perform repair and maintenance 
service on OBD systems and other emission related engine components. In 
addition, EPA published a series of documents that provided guidance to 
manufacturers on potential methods and measures to ensure that trucks 
equipped with Selective Catalytic Reduction (SCR) technology would be 
refilled with the specified quantity and quality of a urea-water 
mixture (also known as diesel exhaust fluid, or DEF) necessary for the 
proper functioning of this NOX-reducing technology. These 
guidance documents describe potential approaches that included 
progressive levels of alerts and warnings communicated to the driver of 
the truck, which would allow adequate time to refill the DEF tank, but 
ultimately, if DEF is not added, or if it is determined to be of 
insufficient quality, a vehicle speed-limiting ``inducement'' would be 
triggered, requiring the DEF tank to be refilled or the system to be 
repaired.
    Also in 2009, EPA and Department of Transportation's National 
Highway Traffic Safety Administration (NHTSA) began working on a joint 
regulatory program to reduce GHG emissions and fuel consumption from 
heavy-duty vehicles and engines.\62\ By utilizing regulatory approaches 
recommended by the National Academy of Sciences, the first phase 
(``Phase 1'') of the GHG and fuel efficiency program was finalized in 
2011 (76 FR 57106, September 15, 2011).\63\ The Phase 1 program, 
spanning implementation from MY 2014 to 2018, included separate 
standards for highway heavy-duty vehicles and heavy-duty engines. The 
program offered flexibility allowing manufacturers to attain these 
standards through a mix of technologies and the option to participate 
in an emissions credit ABT program. In the Phase 1 rulemaking EPA also 
revised the heavy-duty vehicle and engine regulations to make them 
consistent with the light-duty vehicle approach, such that all criteria 
pollutant and GHG standards would apply regardless of fuel type, 
including all-electric vehicles (EVs).
---------------------------------------------------------------------------

    \62\ Greenhouse gas emissions from heavy-duty engines are 
primarily carbon dioxide (CO2), but also include methane 
(CH4) and nitrous oxide (N2O). Because 
CO2 is formed from the combustion of fuel, it is directly 
related to fuel consumption.
    \63\ National Research Council; Transportation Research Board. 
The National Academies' Committee to Assess Fuel Economy 
Technologies for Medium- and Heavy-Duty Vehicles; ``Technologies and 
Approaches to Reducing the Fuel Consumption of Medium- and Heavy-
Duty Vehicles.'' 2010. Available online: https://www.nap.edu/catalog/12845/technologies-and-approaches-to-reducing-the-fuel-consumption-of-medium-and-heavy-duty-vehicles.
---------------------------------------------------------------------------

    In 2016, EPA and NHTSA finalized the Heavy-Duty Phase 2 GHG and 
fuel efficiency program (``HD GHG Phase 2'') (81 FR 73478, October 25, 
2016). HD GHG Phase 2 includes technology-advancing performance-based 
standards for highway heavy-duty vehicles and heavy-duty engines that 
will phase in over the long term, with initial standards for most 
vehicles and engines commencing in MY 2021, increasing in stringency in 
MY 2024, and culminating in MY 2027 standards. HD GHG Phase 2 built 
upon the Phase 1 program and set standards based not only on currently 
available technologies, but also on technologies that were still under 
development or not yet widely deployed. To ensure adequate time for

[[Page 17433]]

technology development, HD GHG Phase 2 provided up to 10 years lead 
time to allow for the development and phase-in of these control 
technologies. EPA recently finalized technical amendments to the HD GHG 
Phase 2 rulemaking (``HD Technical Amendments'') that included changes 
to the test procedures for heavy-duty engines and vehicles to improve 
accuracy and reduce testing burden.\64\
---------------------------------------------------------------------------

    \64\ 86 FR 34308, June 29, 2021.
---------------------------------------------------------------------------

C. Petitions to EPA for Additional NOX Emissions Control

    In the summer of 2016 more than 20 organizations, including state 
and local air agencies from across the country, petitioned EPA to 
develop more stringent NOX emission standards for on-road 
heavy-duty engines.\65\ Among the reasons stated by the petitioners for 
such an EPA rulemaking was the need for NOX emission 
reductions to reduce adverse health and welfare impacts and to help 
areas attain the NAAQS. EPA subsequently met with a wide range of 
stakeholders in listening sessions, during which certain themes were 
consistent across those stakeholders.\66\ For example, it became clear 
that there is broad support for federal action in collaboration with 
the California Air Resources Board (CARB). So-called ``50-state'' 
standards would enable technology suppliers and manufacturers to 
efficiently produce a single set of reliable and compliant products. 
There was also broad acknowledgement of the value of aligning 
implementation of new NOX standards with existing MY 2021, 
2024, and 2027 milestones for HD Phase 2 GHG and fuel efficiency 
standards. Stakeholders thought that such alignment would ensure that 
the GHG and fuel consumption reductions achieved under HD GHG Phase 2 
are maintained and allow the regulated industry to implement GHG- and 
NOX-reducing technologies into their products at the same 
time.\67\
---------------------------------------------------------------------------

    \65\ Brakora, Jessica. ``Petitions to EPA for Revised 
NOX Standards for Heavy-Duty Engines'' Memorandum to 
Docket EPA-HQ-OAR-2019-0055. December 4, 2019.
    \66\ Stakeholders included: Emissions control technology 
suppliers; engine and vehicle manufacturers; a labor union that 
represents heavy-duty engine, parts, and vehicle manufacturing 
workers; a heavy-duty trucking fleet trade association; an owner-
operator driver association; a truck dealers trade association; 
environmental, non-governmental organizations; states and regional 
air quality districts; Tribal interests; California Air Resources 
Board (CARB); and the petitioners.
    \67\ U.S. EPA. 2016. Memorandum in Response to Petition for 
Rulemaking to Adopt Ultra-Low NOX Standards for On-
Highway Heavy-Duty Trucks and Engines. Available at https://19january2017snapshot.epa.gov/sites/production/files/2016-12/documents/nox-memorandum-nox-petition-response-2016-12-20.pdf.
---------------------------------------------------------------------------

    EPA responded to the petitions on December 20, 2016, noting that an 
opportunity exists to develop a new, harmonized national NOX 
reduction strategy for heavy-duty highway engines.\68\ EPA emphasized 
the importance of scientific and technological information when 
determining the appropriate level and form of a future low 
NOX standard and highlighted the following potential 
components of the action:
---------------------------------------------------------------------------

    \68\ U.S. EPA. 2016. Memorandum in Response to Petition for 
Rulemaking to Adopt Ultra-Low NOX Standards for On-
Highway Heavy-Duty Trucks and Engines. Available at https://19january2017snapshot.epa.gov/sites/production/files/2016-12/documents/nox-memorandum-nox-petition-response-2016-12-20.pdf.

 Lower NOX emission standards
 Improvements to test procedures and test cycles to ensure 
emission reductions occur in the real world, not only over the 
currently applicable certification test cycles
 Updated certification and in-use testing protocols
 Longer periods of mandatory emission-related component 
warranties
 Consideration of longer regulatory useful life, reflecting 
actual in-use activity
 Consideration of rebuilding
 Incentives to encourage the transition to current- and next-
generation cleaner technologies as soon as possible

    As outlined in the Executive Summary and detailed in the sections 
that follow, this proposed rulemaking considered these components.

D. California Heavy-Duty Highway Low NOX Program Development

    In this section, we present a summary of recent efforts by the 
state of California to establish new, lower emission standards for 
highway heavy-duty engines and vehicles.\69\ For the past several 
decades, EPA and the California Air Resources Board (CARB) have worked 
together to reduce air pollutants from highway heavy-duty engines and 
vehicles by establishing harmonized emission standards for new engines 
and vehicles. For much of this time, EPA has taken the lead in 
establishing emission standards through notice and comment rulemaking, 
after which CARB would adopt the same standards and test procedures. 
For example, EPA promulgated the current heavy-duty engine 
NOX and PM standards in a 2001 final rule, and CARB 
subsequently adopted the same emission standards. EPA and CARB often 
cooperate during the implementation of highway heavy-duty standards. 
Thus, for many years, the regulated industry has been able to design a 
single product line of engines and vehicles that can be certified to 
both EPA and CARB emission standards (which have been the same) and 
sold in all 50 states.
---------------------------------------------------------------------------

    \69\ California has long had the unique ability among states to 
adopt its own separate new motor vehicle and engine standards per 
Section 209 of the Clean Air Act. Although CAA section 209(a) 
expressly preempts states from adopting and enforcing standards 
relating to the control of emissions from new motor vehicles or new 
motor vehicle engines (such as state controls for new heavy-duty 
engines and vehicles), CAA section 209(b) directs EPA to waive this 
preemption for California under certain conditions. Even with 
California's ability under the CAA to establish its own emission 
standards, EPA and the California Air Resources Board have worked 
closely together over the past several decades to largely harmonize 
new heavy-duty vehicle and engine criteria pollutant standard 
programs.
---------------------------------------------------------------------------

    Given the significant ozone and PM air quality challenges in the 
state of California, CARB has taken several steps since the EPA 2010 
standards were implemented to encourage or establish standards and 
requirements that go beyond EPA requirements, to further reduce 
NOX emissions from heavy-duty vehicles and engines in its 
state. CARB's optional (voluntary) low NOX program, which 
started in 2013, was created to encourage heavy-duty engine 
manufacturers to introduce technologies that emit NOX at 
levels below the current EPA 2010 standards. Under this optional 
program, manufacturers can certify engines to one of three levels of 
stringency that are 50, 75, and 90 percent below the existing EPA 2010 
standards with the lowest optional standard being 20 milligrams 
NOX per horsepower-hour (mg/hp-h).\70\ To date, only natural 
gas and liquefied petroleum gas engines have been certified to these 
optional standards.\71\
---------------------------------------------------------------------------

    \70\ California Code of Regulations, Title 13, section 1956.8.
    \71\ California Air Resources Board. ``Optional Low 
NOX Certified Heavy-Duty Engines''. February 2020. 
Available online: https://ww3.arb.ca.gov/msprog/onroad/optionnox/optional_low_nox_certified_hd_engines.pdf.
---------------------------------------------------------------------------

    In May 2016, CARB published its Mobile Source Strategy that 
outlined its approach to reduce in-state emissions from mobile sources 
and meet its air quality targets.\72\ In November 2016, CARB held its 
first Public Workshop on its plans to update its heavy-duty engine and 
vehicle programs.\73\ CARB's 2016 Workshop kicked off a technology

[[Page 17434]]

demonstration program (the CARB ``Low NOX Demonstration 
Program''), and announced plans to update emission standards, 
laboratory-based and in-use test procedures, emissions warranty, 
durability demonstration requirements, and regulatory useful life 
provisions. The initiatives introduced in its 2016 Workshop have since 
become components of CARB's Heavy-Duty ``Omnibus'' Rulemaking.\74\
---------------------------------------------------------------------------

    \72\ California Air Resources Board. ``Mobile Source Strategy''. 
May 2016. Available online: https://ww3.arb.ca.gov/planning/sip/2016sip/2016mobsrc.pdf.
    \73\ California Air Resources Board. ``Heavy-Duty Low 
NOX: Meetings & Workshops''. Available online: https://ww2.arb.ca.gov/our-work/programs/heavy-duty-low-nox/heavy-duty-low-nox-meetings-workshops.
    \74\ California Air Resources Board. Heavy-Duty Engine and 
Vehicle Omnibus Regulation and Associated Amendments. Available 
online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
---------------------------------------------------------------------------

    CARB's goal for its Low NOX Demonstration Program was to 
investigate the feasibility of reducing NOX emissions to 
levels significantly below today's EPA 2010 standards. Southwest 
Research Institute (SwRI) was contracted to perform the work, which was 
split into three ``Stages.'' \75\ In Stage 1 and 1b, SwRI demonstrated 
an engine technology package capable of achieving a 90 percent 
NOX emissions reduction on today's regulatory test cycles to 
a useful life of 435,000 miles using an accelerated aging process.\76\ 
In Stage 2, SwRI developed and evaluated a new low load-focused engine 
test cycle. In Stage 3, SwRI evaluated a new engine platform and 
different technology package to ensure both criteria and GHG emission 
performance. EPA has been closely observing CARB's Low NOX 
Demonstration Program as a member of the Low NOX Advisory 
Group for the technology development work, which includes 
representatives from heavy-duty engine and aftertreatment industries, 
as well as from federal, state, and local governmental agencies.\77\
---------------------------------------------------------------------------

    \75\ Southwest Research Institute. ``Update on Heavy-Duty Low 
NOX Demonstration Programs at SwRI''. September 26, 2019. 
Available online: https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190926/guest/swri_hd_low_nox_demo_programs.pdf.
    \76\ Southwest Research Institute. ``Evaluating Technologies and 
Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty Vehicles: 
Final Report''. April 2017. Available online: https://ww3.arb.ca.gov/research/apr/past/13-312.pdf.
    \77\ California Air Resources Board. ``Evaluating Technologies 
and Methods to Lower Nitrogen Oxide Emissions from Heavy-Duty 
Vehicles''. May 10, 2017. Available online: https://ww3.arb.ca.gov/research/veh-emissions/low-nox/low-nox.htm.
---------------------------------------------------------------------------

    CARB has published several updates related to its Omnibus 
Rulemaking. In June 2018, CARB approved its ``Step 1'' update to 
California's emission control system warranty regulations.\78\ Starting 
in MY 2022, the existing 100,000-mile warranty for all diesel engines 
will increase to 110,000 miles for engines certified as light heavy-
duty, 150,000 miles for medium heavy-duty engines, and 350,000 miles 
for heavy heavy-duty engines. In November 2018, CARB approved revisions 
to the OBD requirements that include implementation of real emissions 
assessment logging (REAL) for heavy-duty engines and other 
vehicles.\79\ In April 2019, CARB published a ``Staff White Paper'' to 
present its staff's assessment of the technologies they believed were 
feasible for medium and heavy heavy-duty diesel engines in the 2022-
2026 timeframe.\80\
---------------------------------------------------------------------------

    \78\ California Air Resources Board. ``HD Warranty 2018'' June 
28, 2018. Available online: https://ww2.arb.ca.gov/rulemaking/2018/hd-warranty-2018.
    \79\ California Air Resources Board. ``Heavy-Duty OBD 
Regulations and Rulemaking''. Available online: https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
    \80\ California Air Resources Board. ``California Air Resources 
Board Staff Current Assessment of the Technical Feasibility of Lower 
NOX Standards and Associated Test Procedures for 2022 and 
Subsequent Model Year Medium-Duty and Heavy-Duty Diesel Engines''. 
April 18, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/white_paper_04182019a.pdf.
---------------------------------------------------------------------------

    In August 2020, the CARB governing board approved the staff 
proposal for the Omnibus rule and directed staff to initiate the 
process of finalizing the provisions.81 82 The final Omnibus 
rule was approved by the California Office of Administrative Law in 
December 2021. The final rule includes updates to CARB engine 
standards, duty-cycle test procedures, and heavy-duty off-cycle testing 
program that would take effect in MY 2024, with additional updates to 
warranty, durability, and useful life requirements and further 
reductions in standards in MYs 2027 and 2031.\83\
---------------------------------------------------------------------------

    \81\ California Air Resources Board. ``Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments''. June 23, 2020. Available online at: https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf.
    \82\ California Air Resources Board. Heavy-Duty Engine and 
Vehicle Omnibus Regulation and Associated Amendments. Available 
online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \83\ Throughout this proposal we use ``Omnibus'' to refer to the 
engine standards, duty-cycle test procedures, heavy-duty off-cycle 
testing program, useful life and warranty requirements included in 
the final Omnibus.
---------------------------------------------------------------------------

    As described in Sections I.F and I.G, with details in Sections III 
and IV, EPA is proposing new NOX, PM, HC, and CO emission 
standards for heavy-duty engines that reflect the greatest degree of 
emission reduction achievable through the application of technology 
that we have determined would be available for the model years to which 
the proposed standards would apply. In doing so we have given 
appropriate consideration to additional factors, namely lead time, 
cost, energy, and safety (see Sections I.F and I.G for more 
discussion). Throughout the rulemaking process we will continue to 
evaluate what standards are appropriate given the factors that we are 
directed to consider under CAA section 202(a)(3). As noted at the start 
of this Section I.D, EPA and CARB have historically worked together to 
establish harmonized emission standards for new heavy-duty engines and 
vehicles. We have received comments from different stakeholder groups 
who have expressed perspectives on the alignment between the EPA and 
CARB Omnibus standards they would like EPA to consider during the 
rulemaking. For instance, in response to an Advance Notice of Proposed 
Rulemaking (ANPR) for this rule, many stakeholders encouraged EPA to 
develop a national program harmonized to the greatest extent possible 
(see Section I.E).\84\ Following the ANPR, various stakeholders have 
provided EPA with additional perspectives on the Omnibus rule and on 
the extent to which EPA should align with the California program. For 
example, organizations such as the National Association of Clean Air 
Agencies,\85\ the National Tribal Air Association,\86\ as well as 
multiple vehicle supplier trade associations \87\ have written letters 
to EPA in support of strong federal standards that reflect both the 
stringency and timeline of CARB's standards. In contrast, some engine 
manufacturers have raised concerns about EPA harmonizing its national 
program with California's rule because of their concerns with that 
program's overall stringency, costs, and focus on near-term 
NOX reductions over long-term CO2 emission 
reductions. EPA has considered these harmonization comments in light of 
the authority and requirements of CAA sections 202 and

[[Page 17435]]

207 in developing the proposed standards, regulatory useful life 
periods, and emissions warranty periods and intends to continue to take 
into consideration potential harmonization with the CARB Omnibus 
program, as appropriate and consistent with CAA sections 202 and 207, 
during the rulemaking. As described in Sections III and IV, a notable 
difference between the proposed EPA program and the Omnibus rule is 
that the first step of the Omnibus rule takes effect in MY 2024, 
whereas the first step of the proposed EPA program is in MY 2027. EPA's 
statutory authority requires a four-year lead time for any heavy-duty 
engine or vehicle standard promulgated or revised under CAA section 
202(a)(3) (see Section I.F). In Sections III and IV, we discuss areas 
where our proposal aligns with or differs from the Omnibus rule and 
request comment on issues related to harmonization between the federal 
and CARB regulatory programs, including benefits or challenges if EPA 
were to finalize particular aspects of its program that are not fully 
aligned with the Omnibus rule.\88\
---------------------------------------------------------------------------

    \84\ The Agency published an ANPR on January 21, 2020 to present 
EPA's early thinking on this rulemaking and solicit feedback from 
stakeholders to inform this proposal (85 FR 3306).
    \85\ Letter to EPA Administrator Michael Regan from the National 
Association of Clean Air Agencies. Re: The urgent need for federal 
regulatory action to adopt more stringent NOX standards 
for heavy-duty engines and vehicles, beginning immediately with 
highway heavy-duty trucks. August 26, 2021.
    \86\ Letter to EPA Administrator Andrew Wheeler from the 
National Tribal Air Association. Re: EPA's Advance Notice of 
Proposed Rulemaking for Control of Air Pollution from New Motor 
Vehicles: Heavy-Duty Engine Standards Docket ID EPA-HQ-OAR-2019-
0055. February 20, 2020.
    \87\ Letter to EPA Administrator Michael Regan from the Motor & 
Equipment Manufacturers Association, Manufacturers of Emission 
Controls Association, Advanced Engine Systems Institute, and 
Alliance for Vehicle Efficiency. Re: Completion of EPA's Heavy-duty 
Low-NOX Rulemaking. June 24, 2021.
    \88\ Draft RIA Chapter 5, Appendix 6 includes tables that 
present the main elements (i.e., numeric level of standards, useful 
life, emission warranty) of CARB Omnibus requirements and EPA 
proposal.
---------------------------------------------------------------------------

    As discussed in the draft RIA, we analyzed the emission inventory 
and air quality impacts for the proposed criteria pollutant standards 
before the Omnibus Rule was finalized. We may incorporate the Omnibus 
rule into our emission inventory and other analyses as appropriate for 
the final rulemaking (FRM).89 90 We also may incorporate the 
CARB Advanced Clean Truck (ACT) Regulation into our final rule 
analyses. As further discussed in Sections IV, VI, and XI, the CARB ACT 
Regulation requires a minimum percentage of each manufacturer's heavy-
duty vehicle sales in the state of California to be zero tailpipe 
emission technologies starting in MY 2024.91 92
---------------------------------------------------------------------------

    \89\ See Section VI and draft RIA Chapter 5 for more information 
on our emission inventory modeling for the proposal and plans to 
incorporate other updates in our modeling for the final rule.
    \90\ EPA has received waiver requests under CAA section 209(b) 
from California for the Omnibus or ACT rules; EPA is currently 
reviewing the waiver requests for the CA Omnibus and ACT rules and 
may consider including these rules in our analyses for the final 
rule. See Section III.B for discussion on our proposed approach to a 
voluntary standard based on one aspect of the Omnibus requirements.
    \91\ CARB. ``Notice of Decision: Advanced Clean Truck 
Regulation.'' June 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/nod.pdf.
    \92\ Buysse and Sharpe. (July 20, 2020) ``California's Advanced 
Clean Trucks regulation: Sales requirements for zero-emission heavy-
duty trucks'', available online at: https://theicct.org/publications/california-hdv-ev-update-jul2020 (last accessed August 
11, 2021).
---------------------------------------------------------------------------

E. Advance Notice of Proposed Rulemaking

    The ANPR provided background for the provisions proposed in this 
rulemaking to address criteria pollutant emissions from heavy-duty 
engines, including technologies we are evaluating, test programs we 
have initiated, and compliance programs under consideration, as well as 
requests for comments and data. The ANPR did not include discussion on 
the potential stringency of standards, potential costs of the 
standards, or a quantitative assessment of societal impacts (e.g., air 
quality, economic, environmental health); these topics are presented in 
this proposal.\93\
---------------------------------------------------------------------------

    \93\ The ANPR also did not include the proposed, targeted 
revisions to the HD GHG Phase 2 program that are included in this 
rulemaking (see Section I.G for a summary of these proposed 
provisions and Section XI for details).
---------------------------------------------------------------------------

    EPA received over 300 comments on the ANPR from a wide range of 
stakeholders, including: Government organizations (state, local, and 
Tribal), environmental groups, trade associations, heavy-duty engine 
manufacturers, independent owner-operators, suppliers, individual 
fleets, and individual private citizens. We provide a brief overview of 
the perspectives included in these comments in this subsection, with 
more specific discussion of comments included in subsequent sections of 
the proposal as relevant to individual comments or groups of comments.
    Comments from government organizations, including multiple state 
and local air agencies, emphasized that reductions in NOX 
emissions from heavy-duty engines are necessary for attainment and 
maintenance of the NAAQS. States commented that they cannot control 
heavy-duty engine emissions since they cross state borders and 
controlling emissions from other sources would be economically 
burdensome. Commenters stated that areas in nonattainment of the NAAQS 
are having difficulty attaining, and some areas currently in attainment 
are close to or exceeding the NAAQS. As further discussed in Section 
II, commenters noted environmental justice and other public health 
concerns, along with regional haze and ecosystem concerns. These 
commenters requested stringent emission controls on heavy-duty engines 
in as short a timeframe as possible (including early incentives) and 
expressed widespread interest in ensuring control over the lifetime of 
the engine, including addressing emissions from tampering and idling.
    Several environmental groups submitted comments that were similar 
to several of the state and local agency comments; environmental groups 
supported stringent emission controls and maintaining that level of 
emission control for longer durations by lengthening useful life and 
emission warranty periods. These commenters further supported 
improvements to the in-use testing program for heavy-duty diesel 
engines, and anti-tampering measures for all heavy-duty engines.
    Comments from the Truck and Engine Manufacturers Association (EMA), 
a trade association for heavy-duty engine and truck manufacturers 
emphasized broad support for a 50-state program and encouraged EPA to 
conduct a thorough analysis of the costs and benefits of proposed 
NOX emission standards. To emphasize their cost concerns, 
EMA provided an industry-sponsored assessment of the cost to comply 
with potential requirements discussed in the April 2019 CARB Staff 
Whitepaper.\94\
---------------------------------------------------------------------------

    \94\ California Air Resources Board. ``California Air Resources 
Board Staff Current Assessment of the Technical Feasibility of Lower 
NOX Standards and Associated Test Procedures for 2022 and 
Subsequent Model Year Medium-Duty and Heavy-Duty Diesel Engines''. 
April 18, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/white_paper_04182019a.pdf.
---------------------------------------------------------------------------

    Several truck owners, truck operators, fleets, and dealerships also 
expressed general support for a national, harmonized low-NOX 
program. Many commenters included their experiences with expensive 
towing costs and downtime from emission system failures; they stated 
that although the reliability of emission system controls has improved 
since the 2010 timeframe, it remains an ongoing concern. ANPR 
commenters also indicated that engine derates or ``inducements'' are a 
significant source of operator frustration.\95\ In addition, commenters 
urged EPA to conduct a thorough cost assessment, and noted that if the 
initial purchase price, or operational costs for new trucks is too 
high, then it may incentivize owners to keep older trucks on the road. 
These commenters expressed varying views on lengthening emission 
warranty requirements, with some urging a careful consideration of the 
impacts of longer warranty requirements, while others expressed

[[Page 17436]]

support for longer warranty requirements.
---------------------------------------------------------------------------

    \95\ Engine derating is a control strategy that reduces engine 
performance to protect the engine or induce an operator behavior, 
such as maintaining appropriate levels of high-quality diesel 
emission fluid (DEF) in their SCR-based aftertreatment systems. 
Throughout this preamble we refer to engine derates that derive from 
aftertreatment-related triggers as ``inducements''.
---------------------------------------------------------------------------

    Suppliers, supplier trade groups, and labor groups were all 
generally supportive of more stringent NOX emission 
standards. They also generally stated strong support for a 50-state, 
harmonized EPA-CARB program. They also emphasized the importance of 
providing industry with regulatory certainty. They noted that EPA must 
balance emission reductions with technology costs, feasibility, lead-
time, and avoid market disruptions. Several suppliers and trade groups 
provided detailed technical information on low NOX 
technology. They also expressed support for longer useful life and 
warranty requirements but cautioned EPA to carefully design longer 
emissions warranty requirements and to consider a phase-in approach. 
Several suppliers and trade groups also supported incentives for the 
early introduction of low-NOX technology.
    All of the ANPR comments are part of the docket for the proposal 
and have informed our thinking in developing the proposed provisions to 
address criteria pollutant emissions from heavy-duty engines.

F. EPA Statutory Authority for the Proposal

    This section briefly summarizes the statutory authority for the 
proposed rule. Title II of the Clean Air Act provides for comprehensive 
regulation of mobile sources, authorizing EPA to regulate emissions of 
air pollutants from all mobile source categories. Specific Title II 
authorities for this proposal include: CAA sections 202, 203, 206, 207, 
208, 213, 216, and 301 (42 U.S.C. 7521, 7522, 7525, 7541, 7542, 7547, 
7550, and 7601). We discuss some key aspects of these sections in 
relation to this proposed action immediately below (see also Section 
XIV of this preamble), as well as in each of the relevant sections 
later in this proposal. Regarding the confidentiality determinations 
EPA is proposing to make through this notice and comment rulemaking for 
much of the information collected by EPA for certification and 
compliance under Title II, see Section XII.A. for discussion of 
relevant statutory authority.
    Statutory authority for the proposed NOX, PM, HC, CO, 
and GHG emission standards in this action comes from CAA section 202(a) 
which states that ``the Administrator shall by regulation prescribe 
(and from time to time revise) . . . standards applicable to the 
emission of any air pollutant from any class or classes of new . . . 
motor vehicle engines, which in his judgment cause, or contribute to, 
air pollution which may reasonably be anticipated to endanger public 
health or welfare.'' Standards under CAA section 202(a) take effect 
``after such period as the Administrator finds necessary to permit the 
development and application of the requisite technology, giving 
appropriate consideration to the cost of compliance within such 
period.'' Thus, in establishing or revising CAA section 202(a) 
standards designed to reduce air pollution that endangers public health 
and welfare, EPA also must consider issues of technological 
feasibility, compliance cost, and lead time. EPA may consider other 
factors and in previous engine and vehicle standards rulemakings has 
considered the impacts of potential standards on the heavy-duty 
industry, fuel savings, oil conservation, energy security and other 
energy impacts, as well as other relevant considerations such as 
safety.
1. Statutory Authority for Proposed Criteria Pollutant Program
    Section 202(a)(3) further addresses EPA authority to establish 
standards for emissions of NOX, PM, HC, and CO from heavy-
duty engines and vehicles. Section 202(a)(3)(A) requires that such 
standards ``reflect the greatest degree of emission reduction 
achievable through the application of technology which the 
Administrator determines will be available for the model year to which 
such standards apply, giving appropriate consideration to cost, energy, 
and safety factors associated with the application of such 
technology.'' Section 202(a)(3)(B) allows EPA to take into account air 
quality information in revising such standards. Section 202(a)(3)(C) 
provides that standards shall apply for a period of no less than three 
model years beginning no earlier than the model year commencing four 
years after promulgation. CAA section 202(a)(3)(A) is a technology-
forcing provision and reflects Congress' intent that standards be based 
on projections of future advances in pollution control capability, 
considering costs and other statutory factors.96 97 CAA 
section 202(a)(3) neither requires that EPA consider all the statutory 
factors equally nor mandates a specific method of cost-analysis; rather 
EPA has discretion in determining the appropriate consideration to give 
such factors.\98\
---------------------------------------------------------------------------

    \96\ See National Petrochemical & Refiners Association v. EPA, 
287 F.3d 1130, 1136 (D.C. Cir. 2002) (explaining that EPA is 
authorized to adopt ``technology-forcing'' regulations under CAA 
section 202(a)(3)); NRDC v. Thomas, 805 F.2d 410, 428 n.30 (D.C. 
Cir. 1986) (explaining that such statutory language that ``seek[s] 
to promote technological advances while also accounting for cost 
does not detract from their categorization as technology-forcing 
standards''); see also Husqvarna AB v. EPA, 254 F.3d 195 (D.C. Cir. 
2001) (explaining that CAA sections 202 and 213 have similar 
language and are technology-forcing standards).
    \97\ In this context, the term ``technology-forcing'' has a 
specific legal meaning and is used to distinguish standards that may 
require manufacturers to develop new technologies (or significantly 
improve existing technologies) from standards that can be met using 
off-the-shelf technology alone. Technology-forcing standards such as 
those in this proposed rule do not require manufacturers to use 
specific technologies.
    \98\ See, e.g., Sierra Club v. EPA, 325 F.3d 374, 378 (D.C. Cir. 
2003) (explaining that similar technology-forcing language in CAA 
section 202(1)(2) ``does not resolve how the Administrator should 
weigh all [the statutory] factors in the process of finding the 
`greatest emission reduction achievable' ''); Husqvarna AB v. EPA, 
254 F.3d 195, 200 (D.C. Cir. 2001) (explaining that under CAA 
section 213's similar technology-forcing authority that ``EPA did 
not deviate from its statutory mandate or frustrate congressional 
will by placing primary significance on the `greatest degree of 
emission reduction achievable' '' or by considering cost and other 
statutory factors as important but secondary).
---------------------------------------------------------------------------

    Section II, and Chapter 4 of the draft RIA, describe EPA's analysis 
of information regarding heavy-duty engines' contribution to air 
pollution and how that pollution adversely impacts public health and 
welfare. Section I.G, with more detail in Section III and Chapter 4 of 
the draft RIA, discusses our feasibility analysis of the standards and 
useful life periods for both proposed Options. Our evaluation shows 
that the standards and useful life periods in both steps of proposed 
Option 1 are feasible and would result in the greatest emission 
reductions achievable for the model years to which they are proposed to 
apply, pursuant to CAA section 202(a)(3), giving appropriate 
consideration to costs, lead time, and other factors. Our analysis 
further shows that the standards and useful life periods in proposed 
Option 2 are feasible in the 2027 model year, but would result in lower 
levels of emission reductions compared to proposed Option 1. As 
explained further in Section III and Chapter 3 of the draft RIA, we 
expect that additional data from EPA's ongoing work to demonstrate the 
performance of emission control technologies, as well as information 
received in public comments, will allow us to refine our assessments 
and consideration of the feasibility of the combination of the 
standards and useful life periods, particularly for the largest CI 
engines (HHDEs), in proposed Options 1 and 2, after consideration of 
lead time, costs, and other factors. Therefore, we are co-proposing 
Options 1 and 2 standards and useful life periods, and the range of 
options in between them, as the options that may

[[Page 17437]]

potentially be appropriate to finalize pursuant to CAA section 
202(a)(3) once EPA has considered that additional data and other 
information. We considered costs and lead time in designing the 
proposed program options, including in our analysis of how 
manufacturers would adopt advanced emission control technologies to 
meet the proposed standards for the applicable model years. For 
example, the first step of proposed Option 1 allows manufacturers to 
minimize costs by implementing a single redesign of heavy-duty engines 
for MY 2027, which is when both the final step of the HD GHG Phase 2 
standards and the first step of the proposed Option 1 standards would 
start to apply. The second step of proposed Option 1 (MY 2031) would 
provide manufacturers the time needed to ensure that emission control 
components are durable enough for the proposed second step of revised 
standards and longer useful life periods.99 100
---------------------------------------------------------------------------

    \99\ The second step of the proposed Option 1 standards in MY 
2031 provides four years of stability following the first step of 
the program.
    \100\ See Section III for details on our proposed test cycles 
and standards, and Section IV for our proposed compliance 
provisions.
---------------------------------------------------------------------------

    As described in Section III, we are proposing new test cycles for 
both pre-production and post-certification testing. Manufacturers 
demonstrate compliance over specified duty cycle test procedures during 
pre-production testing, which is conducted by EPA or the manufacturer. 
These data and other information submitted by the manufacturer as part 
of their certification application are the basis on which EPA issues 
certificates of conformity pursuant to CAA section 206. Under CAA 
section 203, sales of new vehicles are prohibited unless the vehicle is 
covered by a certificate of conformity. Compliance with standards is 
required not only at certification but throughout the useful life 
period of the engine and vehicle, based on post-certification testing. 
Post-certification testing can include both specific duty cycle test 
procedures and off-cycle test procedures that are conducted with 
undefined duty cycles either on the road or in the laboratory (see 
Sections III.A and IV.K for more discussion on for testing at various 
stages in the life of an engine).
    As described in Section IV, we are proposing to lengthen regulatory 
useful life and emission warranty periods to better reflect the 
mileages and time periods over which heavy-duty engines are driven 
today. CAA section 202(d) directs EPA to prescribe regulations under 
which the useful life of vehicles and engines are determined and 
establishes minimum values of 10 years or 100,000 miles, whichever 
occurs first, unless EPA determines that a period of greater duration 
or mileage is appropriate. EPA may apply adjustment factors to assure 
compliance with requirements in use throughout useful life (CAA section 
206(a)). CAA section 207(a) requires manufacturers to provide an 
emissions warranty, which EPA last updated in its regulations for 
heavy-duty engines in 1983 (see 40 CFR 86.085-2).\101\
---------------------------------------------------------------------------

    \101\ 48 FR 52170, November 16, 1983.
---------------------------------------------------------------------------

2. Statutory Authority for Targeted Revisions to the Heavy-Duty GHG 
Phase 2 Program
    In addition, as discussed in Section XI, EPA is proposing a limited 
set of revisions to MY 2027 Phase 2 GHG emissions standards under its 
CAA section 202(a) authority described in this section (Section I.F). 
We have developed an approach to propose targeted updates to HD GHG 
Phase 2 standards that take into consideration the growing HD electric 
vehicle market without fundamentally changing the HD GHG Phase 2 
program as a whole. In addition, we are requesting comment on potential 
changes to the advanced technology incentive program for electric 
vehicles beginning in MY 2024.

G. Basis of the Proposed Standards

    Our approach to further reduce air pollution from highway heavy-
duty engines and vehicles through the proposed program features several 
key provisions. The primary provisions address criteria pollutant 
emissions from heavy-duty engines. In addition, this proposal would 
make targeted updates to the existing Heavy-Duty Greenhouse Gas 
Emissions Phase 2 program, proposing that further GHG reductions in the 
MY 2027 timeframe are appropriate considering lead time, costs, and 
other factors, including market shifts to zero-emission technologies in 
certain segments of the heavy-duty vehicle sector.
1. Basis of the Proposed Criteria Pollutant Standards
    Heavy-duty engines across the U.S. emit NOX, PM, VOCs, 
and CO that contribute to ambient levels of ozone, PM, NOX, 
and CO; these pollutants are linked to premature death, respiratory 
illness (including childhood asthma), cardiovascular problems, and 
other adverse health impacts. In addition, these pollutants reduce 
visibility and negatively impact ecosystems. Data show that 
NOX emissions from heavy-duty engines are important 
contributors to concentrations of ozone and PM2.5 and their 
resulting threat to public health.102 103 As discussed in 
Section II, we estimate that heavy-duty engines will continue to be one 
of the largest contributors to mobile source NOX emissions 
nationwide in the future, representing 32 percent of the mobile source 
and 89 percent of the onroad NOX emission inventories in 
calendar year 2045.104 105 For the reasons summarized here 
and explained further in those sections, EPA concludes that revised 
standards are warranted to address the emissions of these pollutants 
and their contribution to national air pollution.
---------------------------------------------------------------------------

    \102\ Zawacki et al, 2018. Mobile source contributions to 
ambient ozone and particulate matter in 2025. Atmospheric 
Environment, Vol 188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
    \103\ Davidson et al, 2020. The recent and future health burden 
of the U.S. mobile sector apportioned by source. Environmental 
Research Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
    \104\ U.S. Environmental Protection Agency (2021). 2016v1 
Platform. https://www.epa.gov/air-emissions-modeling/2016v1-platform.
    \105\ Han, Jaehoon. Memorandum to the Docket EPA-HQ-OAR-2019-
0055: ``MOVES Modeling-Related Data Files (MOVES Code, Input 
Databases and Runspecs) for the Proposed Heavy-Duty 2027 
Standards''. February 2022.
---------------------------------------------------------------------------

    As required by CAA section 202(a)(3), EPA is proposing new 
NOX, PM, HC, and CO emission standards for heavy-duty 
engines that reflect the greatest degree of emission reduction 
achievable through the application of technology that we have 
determined would be available for the model years to which the proposed 
standards would apply. In doing so we have given appropriate 
consideration to additional factors, namely lead time, cost, energy, 
and safety. Our technical assessments are primarily based on results 
from diesel engine demonstration testing conducted by CARB at Southwest 
Research Institute,\106\ heavy-duty gasoline and diesel engines testing 
conducted at EPA's National Vehicle and Fuel Emissions Laboratory 
(NVFEL), heavy-duty engine certification data submitted to EPA by 
manufacturers, ANPR comments, and other data submitted by industry 
stakeholders or studies conducted by EPA, as more specifically 
identified in the sections that follow. We expect that additional data 
from EPA's ongoing work to demonstrate the performance of emission 
control technologies will allow us to refine our assessments and 
consideration of the feasibility of the combination of

[[Page 17438]]

standards and useful life periods in proposed Options 1 and 2, after 
consideration of lead time, costs, and other factors. Therefore, we are 
co-proposing Options 1 and 2 to illustrate a broader range of potential 
options. We also present an alternative (the Alternative) that we 
considered in the development of this proposal but for which we 
currently lack information to conclude would be feasible throughout the 
useful periods included in this alternative and in the model year in 
which the standards would begin. As outlined in this section and 
detailed in Sections III and IV, we solicit comment on the proposed 
Options 1 and 2, the Alternative presented, or other alternatives 
within and outside the range of options.
---------------------------------------------------------------------------

    \106\ See Section III.B and draft RIA Chapter 3.1 for more 
details and discussion on data from diesel engine demonstration 
testing.
---------------------------------------------------------------------------

    As noted in the Executive Summary and discussed in Section III, the 
proposed Options 1 and 2 standards and the Alternative would each begin 
to apply in MY 2027. We selected this model year for two reasons. 
First, as explained in Section I.F, the CAA requires EPA to provide at 
least four years of lead time from the promulgation of a final rule. We 
expect to finalize this rulemaking in 2022, such that MY 2027 would be 
the earliest model year the new requirements could apply. Second, the 
timing of the final stage of the HD GHG Phase 2 program in MY 2027 
leads us to believe that MY 2027 is the appropriate time for the 
proposed standards to begin since this would allow manufacturers to 
design a single engine platform that complies with both HD GHG Phase 2 
and the criteria pollutant requirements. We expect that a single engine 
design for both rulemakings would minimize costs and improve 
reliability of the emission control components by integrating design 
changes for both rules (see Section III.A for more discussion on MY 
2027 as the first implementation year for the proposed program).
    The MY 2031 standards in proposed Option 1 would begin four model 
years after the MY 2027 standards in proposed Option 1, which is an 
additional year beyond the CAA requirement for at least three years of 
stability.\107\ Both steps of the proposed Option 1 standards reflect 
the greatest degree of emission reductions achievable in each model 
year when combined with the proposed longer useful life periods, new 
test cycles, and other compliance provisions that start in each model 
year. We expect that the changes to useful life in proposed Options 1 
and 2 would improve component durability, but additional increases in 
useful life, such as those associated with the proposed MY 2031 
standards in proposed Option 1, may take manufacturers more time to 
develop (see Section IV for more discussion). Therefore, proposed 
Option 1 includes a two-step approach to allow additional lead time for 
manufacturers to develop emission control components durable enough for 
the proposed longer useful life periods. In Section III.A we request 
comment on the two-step approach in proposed Option 1.
---------------------------------------------------------------------------

    \107\ The two alternative sets of standards that we present 
would each be implemented in a single step beginning in MY 2027.
---------------------------------------------------------------------------

    In Sections III and IV, we present the details of the two-step 
proposed Option 1 (MYs 2027 and 2031) and the proposed Option 2 that 
would occur in a single step (MY 2027). We also present details of the 
Alternative, which would also occur in a single step (MY 2027). 
Overall, proposed Option 2 is less stringent than the MY 2031 standards 
in proposed Option 1 due to higher numeric levels of the NOX 
emission standards and shorter useful life periods in proposed Option 
2. For our proposed Options 1 and 2 standards, we project that the 
emission control technologies used in MY 2027 would build on those used 
in light- and heavy-duty engines today. For heavy-duty CI engines, 
under both the proposed Option 1 MY 2031 standards and the proposed 
Option 2 standards, we project the use of the valvetrain engine 
technology combined with updates to the SCR system configuration that 
builds on what is used in current light-duty trucks and heavy-duty 
engines. For heavy-duty SI engines, the technologies we are evaluating 
that would achieve the standards in the proposed Options 1 and 2 
largely build on the three-way catalyst-based emission control 
strategies used in heavy-duty SI chassis certified engine products.
    The Alternative we considered includes lower (more stringent) 
numeric NOX emission levels for Heavy HDEs, and lower HC 
emission levels for all CI and SI engine classes, combined with longer 
useful life periods and shorter lead time compared to the MY 2031 
standards in proposed Option 1. The test data we currently have from 
our engine demonstration program is not sufficient to conclude that the 
Alternative standards would be feasible in the MY2027 timeframe; we 
would need additional data before we could project that the Alternative 
is feasible for the MY 2027 timeframe.
    We continue to believe it is appropriate for SI and CI engines to 
have numerically identical standards for the criteria pollutants. As 
described in Section III, the proposed standards for each pollutant are 
primarily based on the engine type (CI and SI) for which the particular 
emission standard is most challenging to achieve. The NOX 
standards in proposed Options 1 and 2 are based primarily on emission 
test data from CI engine demonstration work, while the HC and CO 
standards in the proposed Options 1 and 2 are based on the SI engine 
demonstration program. Currently available engine demonstration test 
data show that the heavy-duty CI engine technologies we are evaluating 
can achieve a 75 to 90 percent reduction from current NOX 
standards. These data indicate that the NOX standards for MY 
2027 in proposed Options 1 and 2 are achievable for a useful life 
period of 600,000 miles, which encompasses the proposed Option 2 useful 
life periods for Light HDE and Medium HDEs. Our evaluation of the 
current data suggests that the proposed Option 2 standards would also 
be feasible out to the proposed Option 2 Heavy HDE useful life; we are 
continuing to collect data to confirm our extrapolation of data out to 
the longer HDE useful life mileage. As discussed in Section IV.A, 
useful life mileages for proposed Option 2 are higher than the MY 2027 
useful life values in proposed Option 1, but lower than the MY 2031 
useful life values in proposed Option 1. The useful life mileages 
included in the proposed Options 1 and 2 are based on the operational 
life of engines in the field today. Data show that heavy-duty engines 
are operating in the real world well beyond the useful life periods in 
our existing regulations, and thus we are proposing longer useful life 
periods to ensure that emission control systems are durable for an 
appropriate portion of their use in the real world (see Section IV for 
details). For the Alternative, data suggest that to meet the 
combination of numeric levels of the Alternative NOX 
emission standards and useful life periods for Light HDEs and Medium 
HDEs, it may be appropriate for EPA to consider providing manufacturers 
with additional lead time, beyond the MY 2027 implementation date of 
the Alternative. For Heavy HDEs, our evaluation of current data 
suggests that wholly different emission control technologies than we 
have evaluated to date (i.e., not based on CDA and a dual SCR) would be 
needed to meet the Alternative NOX standards for Heavy HDEs; 
we request comment on this conclusion and on the availability, or 
potential development and timeline, of such additional technologies.
    Our demonstration test data do show that CI engines can achieve the 
PM, HC, and CO standards in proposed Options

[[Page 17439]]

1 and 2, each of which would result in at least a 50 percent reduction 
from current emission standards for PM, HC, and CO. The HC and CO 
standards in the proposed Options 1 and 2, are based on SI engine 
demonstration data with a catalyst aged beyond the useful life of those 
scenarios. Available data indicate that the combination of 
NOX, HC, and CO emission levels over the longer useful life 
period reflected in the SI standards of the Alternative would be very 
challenging to meet in the MY 2027 timeframe. In contrast, we believe 
the additional lead time provided by the second step of the MY 2031 
standards in proposed Option 1, combined with the higher numeric 
standard for HC and the shorter useful life mileage, results in the MY 
2031 standards in proposed Option 1 being both feasible and technology 
forcing.
    We are also proposing to require onboard refueling vapor recovery 
(ORVR) for incomplete vehicles over 14,000 lb GVWR fueled by gasoline 
and other volatile fuels. Currently, hydrocarbon vapors from those 
vehicles are uncontrolled during refueling events, despite technology 
to control these emissions being widely adopted in vehicles in lower 
weight classes for almost 20 years. Recent data show this lack of 
emission control technology can result in refueling emissions that are 
more than 10 times current light-duty refueling standards (see Section 
III.D.2 for more discussion). We included ORVR in the analysis of both 
proposed Options 1 and 2, as well as the Alternative.
    Our PM standards are based on certification test data that show the 
proposed 50 percent reduction in the current PM standard is achievable 
in CI and SI heavy-duty engines being certified today; the same 
reduction in PM standard is included in both proposed Options 1 and 2, 
as well as the Alternative. We believe lowering the PM standard to a 
level currently achievable through the use of emission control 
technology used in new engines being sold today is appropriate. EPA is 
not aware of any technology that is feasible to adopt in the 2027 
timeframe that would reduce PM emissions further, and variability in PM 
measurement starts to increase at PM levels lower than the proposed 
standard. Nevertheless, we request comment on if there are technologies 
that EPA could consider that would enable a PM standard lower than 5 
mg/hp-hr.
    The proposed Options 1 and 2 generally represent the range of 
options, including the NOX, HC, and CO standards, useful 
life periods and lead time that we are currently considering in this 
rule; we expect we may receive additional information through public 
comments or data we continue to collect on the feasibility, costs, and 
other impacts of the proposed Options 1 and 2.\108\ In order to 
consider adopting the Alternative in the final rule, we would need 
additional information to be able to conclude that the Alternative is 
feasible in the MY 2027 timeframe. We request comment on all aspects of 
the proposal, including the revised emission standards and useful life 
and warranty periods, one and two-step approaches, model years of 
implementation in proposed Options 1 and 2, or other alternatives 
roughly within the range of options covered by the proposed Options 1 
and 2, as well as other provisions described in this proposal. We also 
request comment, including relevant data and other information, related 
to the feasibility of the implementation model year, numeric levels of 
the emission standards, and useful life and warranty periods included 
in the Alternative, or other alternatives outside the range of options 
covered by the proposed Options 1 and 2.
---------------------------------------------------------------------------

    \108\ The numeric level of the standards for PM are consistent 
across the proposal and both alternatives since they are intended to 
ensure that the level of PM emissions from current engines does not 
increase as manufacturers make adjustments to further control 
NOX, CO2 or other pollutants. See Section 
III.B.2 for more discussion.
---------------------------------------------------------------------------

    As described in Section III, we are proposing new laboratory test 
duty cycles and standards in response to data that show a current lack 
of emission control under low-load conditions in CI heavy-duty engines, 
and under high-load in SI heavy-duty engines. As noted in Section VI, 
we project that without the proposed provisions, low- and high-load 
engine operations would account for 28 and 36 percent, respectively, of 
the heavy-duty NOX emission inventory in 2045.
    Proposed Option 1 includes requirements for lowering the numeric 
level of the standard and lengthening useful life in two steps. 
Consistent with our approach for useful life, proposed Option 1 would 
lengthen emission warranty mileages in two steps, such that the 
proposed MY 2031 warranty would cover an appropriate portion of the 
proposed MY 2031 regulatory useful life (see Section IV.B for more 
discussion). The proposed Option 2 would lengthen emission warranty 
mileages in a single step, consistent with the proposed single step 
increase in useful life in proposed Option 2. While warranty periods do 
not directly impact the stringency of the proposed standards, we expect 
the proposed lengthened warranty periods would improve air quality and 
we included them in our inventory and cost analyses of the proposed 
Option 1 and Option 2 standards.
    We are also proposing additional compliance provisions that would 
begin in MY 2027, such as targeted provisions to help ensure that 
owners can efficiently maintain emissions performance over the 
operational life of the engine. We are proposing provisions to enhance 
communication with operators, including updated diagnostic 
requirements, a revised inducement policy for SCR-based aftertreatment 
systems, and improved access to service information (see Section IV.B 
for more discussion). We believe these proposed provisions could 
decrease the likelihood that owners tamper with (i.e., remove or 
otherwise disable) emission control systems.
    The emission reductions from the proposed program would increase 
over time as more new, cleaner vehicles enter the fleet. For example, 
by 2040 the proposed Option 1 would reduce heavy-duty NOX 
emissions by more than 55 percent, compared to projected 2040 emissions 
without the proposed rule. The proposed Option 2 would reduce heavy-
duty NOX emissions by 44 percent in 2040 (see Section VI for 
details on projected emission reductions from proposed Option 1 or 2). 
These emission reductions would lower ambient concentrations of 
pollutants such as ozone and PM2.5. Our analysis shows that 
the proposed Option 1 would provide more emission reductions than 
proposed Option 2, and less reductions than the Alternative. Our air 
quality modeling analysis of Option 1's projected emission reductions 
shows widespread reductions in ambient concentrations of air pollutants 
in 2045, which is a year by which most of the regulated fleet would 
have turned over.\109\ Our analysis shows that these emission 
reductions would result in significant improvements in ozone 
concentrations; ambient PM2.5, NO2 and CO 
concentrations would also improve in 2045 (see Section VII for 
details). Based on our air quality analysis of PM2.5 and 
ozone, we estimate that in 2045, the proposed Option 1 would result in 
total annual monetized health benefits of $12 and $33 billion at a 3 
percent discount rate and $10 and $30 billion at a 7 percent discount 
rate (2017 dollars). We estimate that in 2045, the proposed Option 2 
would result in total annual

[[Page 17440]]

monetized health benefits of $9 and $26 billion at a 3 percent discount 
rate and $8 and $23 billion at a 7 percent discount rate (2017 dollars) 
(see Section VIII for details).
---------------------------------------------------------------------------

    \109\ Due to resource constraints, we only conducted air quality 
modeling for the proposed Option 1.
---------------------------------------------------------------------------

    In addition to projected health benefits, we considered several 
other factors in developing the proposed standards, including cost, 
energy, and safety. Our cost analysis, presented in Section V, accounts 
for costs to manufacturers and to truck owners. Costs to manufacturers 
include direct manufacturing costs (i.e., new hardware/technology) and 
indirect costs (e.g., emission warranty, R&D), while costs to truck 
owners include operating costs (e.g., fuel, diesel exhaust fluid, 
emission control system repairs). Our analysis shows that direct 
manufacturing costs are the same for proposed Options 1 and 2; however, 
indirect costs result in total costs to manufacturers (i.e., total 
technology costs) under the proposed Option 1 being slightly higher 
than under the proposed Option 2. The operating costs associated with 
the proposed Option 1 are estimated to be lower than those of proposed 
Option 2. The lower operating costs in proposed Option 1 (largely from 
lower repair costs) offset the higher technology costs (due to higher 
warranty and R&D driven indirect costs) in proposed Option 1, which 
results in a lower total cost of proposed Option 1 relative to proposed 
Option 2 when costs are summed for 2027 through 2045. For the 
Alternative, we have not determined the incremental direct 
manufacturing costs of the technology needed to meet the standards, and 
we would need additional data before we could project that the 
Alternative is feasible for the MY 2027 timeframe.
    Section IX compares the benefits and costs of the proposed Options 
1 and 2. Our analysis shows that while proposed Option 2 provides 
higher emission reductions in the early years of the program, it has 
lower net benefits than proposed Option 1 when considering the time 
period of 2027 through 2045; this is a result of both higher costs and 
lower emission reductions relative to proposed Option 1 in the later 
years of the program. As noted throughout this section and discussed in 
Sections III and IV, we do not currently have information to project 
that the Alternative standards as currently formulated are feasible in 
the MY 2027 timeframe with the emission control technologies we 
evaluated to date, and thus we are not presenting an analysis of the 
costs or benefits of the Alternative.
    Our current evaluation of available data shows that the standards 
and useful life periods in both steps of proposed Option 1 are feasible 
and that each step would result in the greatest degree of emission 
reduction achievable for the model years to which they are proposed to 
apply, pursuant to CAA section 202(a)(3), giving appropriate 
consideration to cost, lead time, and other factors. Our analysis 
further shows that the standards and useful life periods in proposed 
Option 2 are feasible in the 2027 model year, but would result in lower 
levels of emission reductions compared to proposed Option 1. Given the 
analysis we present in this proposal, we currently believe that 
proposed Option 1 may be a more appropriate level of stringency as it 
would result in a greater level of achievable emission reduction for 
the model years proposed, which is consistent with EPA's statutory 
authority under Clean Air Act section 202(a)(3). However, as further 
discussed in Section III and draft RIA Chapter 3, we expect that 
additional data from EPA's ongoing work to demonstrate the performance 
of emission control technologies, as well as information received in 
public comments, will allow us to refine our assessments and 
consideration of the feasibility of the combination of the standards 
and useful life periods, particularly for the largest CI engines 
(HHDEs), in proposed Options 1 and 2, after consideration of lead time, 
costs, and other factors. Therefore, we are co-proposing Options 1 and 
2 standards and useful life periods, and the range of options in 
between them, as the options that may potentially be appropriate to 
finalize pursuant to CAA section 202(a)(3) once EPA has considered that 
additional data and other information.
    Our analysis further shows that the proposed Option 1 and 2 
standards would have no negative impacts on energy; as discussed in 
Section III, our evaluation of test engine data shows no change in 
energy consumption (i.e., fuel) relative to a baseline engine. 
Similarly, we anticipate no negative impacts on safety due to the 
proposed program.
2. Basis of the Targeted Revisions to the HD GHG Phase 2 Program
    In addition to the proposed criteria pollutant program provisions, 
we are proposing targeted updates to certain CO2 standards 
for MY 2027 trucks, and we are requesting comment on updates to the 
advanced technology incentive program for electric vehicles. The 
transportation sector is the largest U.S. source of GHG emissions, 
representing 29 percent of total GHG emissions.\110\ Within the 
transportation sector, heavy-duty vehicles are the second largest 
contributor, at 23 percent.\111\ GHG emissions have significant impacts 
on public health and welfare as evidenced by the well-documented 
scientific record and as set forth in EPA's Endangerment and Cause or 
Contribute Findings under CAA section 202(a).\112\ Therefore, continued 
emission reductions in the heavy-duty vehicle sector are appropriate.
---------------------------------------------------------------------------

    \110\ Inventory of U.S. Greenhouse Gas Emissions and Sinks: 
1990-2019 (EPA-430-R-21-005, published April 2021).
    \111\ Ibid.
    \112\ 74 FR 66496, December 15, 2009; 81 FR 54422, August 15, 
2016.
---------------------------------------------------------------------------

    We are at the early stages of a significant transition in the 
history of the heavy-duty on-highway sector--a shift to zero-emission 
vehicle technologies. This change is underway and presents an 
opportunity for significant reductions in heavy-duty GHG emissions. 
Major trucking fleets, manufacturers and U.S. states have announced 
plans to shift the heavy-duty fleet toward zero-emissions technology 
beyond levels we accounted for in setting the existing HD GHG Phase 2 
standards, as detailed in Section XI. Specifically, we set the existing 
Phase 2 standards at levels that would require all conventional 
vehicles to install varying combinations of emission-control 
technologies (the degree and types of technology can differ, with some 
vehicles that have less being offset by others with more, which would 
lead to CO2 emissions reductions). As discussed in Section 
XI, the rise in electrification beyond what we had anticipated when 
finalizing the HD GHG Phase 2 program (e.g., the California Advanced 
Clean Trucks rulemaking) would enable manufacturers to produce some 
conventional vehicles without installing any of the GHG emission-
reducing technologies that we projected in the HD GHG Phase 2 
rulemaking, absent the changes we are proposing in this 
document.113 114
---------------------------------------------------------------------------

    \113\ CARB. ``Notice of Decision: Advanced Clean Truck 
Regulation.'' June 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/nod.pdf.
    For more information on this proposed rulemaking in California 
see: https://ww2.arb.ca.gov/rulemaking/2019/advancedcleantrucks?utm_medium=email&utm_source=govdelivery.
    \114\ EPA is currently reviewing a waiver request under CAA 
section 209(b) from California for the ACT rule.
---------------------------------------------------------------------------

    To address this issue, EPA is proposing under its authority in CAA 
section 202(a) to revise GHG emissions standards for a subset of MY 
2027 heavy-duty vehicles. Specifically, we

[[Page 17441]]

propose to adjust HD Phase 2 vehicle GHG emission standards by sales-
weighting the projected EV production levels of school buses, transit 
buses, delivery trucks, and short-haul tractors and by lowering the 
applicable GHG emission standards in MY 2027 accordingly. Our proposed 
approach adjusts 17 of the 33 MY 2027 Phase 2 vocational vehicle and 
tractor standards and does not change any MY 2021 or MY 2024 standards 
or any of the Class 2b/3 pickup truck and van standards. In addition, 
we are requesting comment on potential changes to the advanced 
technology incentive program for electric vehicles beginning in MY 
2024.
    Under CAA section 202(a), emission standards take effect ``after 
such period as the Administrator finds necessary to permit the 
development and application of the requisite technology, giving 
appropriate consideration to the cost of compliance within such 
period.'' Thus, in establishing or revising CAA section 202(a) 
standards, EPA must consider issues of technological feasibility, 
compliance cost, and lead time. The proposed revised standards are 
based on the same technology packages used to derive the current HD GHG 
Phase 2 standards, which we applied to the subset of the vehicles that 
would otherwise not require GHG-reducing technologies due to the higher 
projection of HD electric vehicles in MY 2027 and beyond and the 
incentive program. The HD GHG Phase 2 standards were based on adoption 
rates for technologies in technology packages that EPA regards as 
appropriate under CAA section 202(a) for the reasons given in the HD 
GHG Phase 2 rulemaking in Section III.D.1 for tractors and Section 
V.C.1 for vocational vehicles.\115\ We continue to believe these 
technologies can be adopted at the estimated technology adoption rates 
for these proposed revised standards within the lead time that would be 
provided. The fleet-wide average cost per tractor projected to meet the 
proposed revised MY 2027 standards is approximately $10,200 to $10,500. 
The fleet-wide average cost per vocational vehicle to meet the proposed 
revised MY 2027 standards ranges between $1,500 and $5,700. These 
increased costs would be recovered in the form of fuel savings during 
the first two years of ownership for tractors and first four years for 
vocational vehicles, which we still consider to be reasonable.\116\ In 
addition, manufacturers would retain leeway to develop alternative 
compliance paths, increasing the likelihood of the proposed revised 
standards' successful implementation. The targeted adjustments to the 
select standards we are proposing would result in modest CO2 
emissions reductions and climate-related benefits associated with these 
emission reductions. As described in more detail in Section XI, we 
believe this proposal considered feasibility, cost, lead time, 
emissions impact, and other relevant factors, and therefore these 
standards are appropriate under CAA section 202(a).
---------------------------------------------------------------------------

    \115\ 81 FR 73585 through 73613; 81 FR 73693 through 73719.
    \116\ 81 FR 73904.
---------------------------------------------------------------------------

    In addition to these proposed standard adjustments, we are 
requesting comment on options to update the advanced technology 
incentive program for electric and plug-in hybrid vehicles beginning in 
MY 2024. These changes may be appropriate to reflect that such levels 
of incentives for electrification may no longer be appropriate for 
certain segments of the HD EV market. We are interested in trying to 
balance providing incentivizes for the continued development of zero 
and near-zero emission vehicles without inadvertently undermining the 
GHG emission reductions expected from the existing HD GHG Phase 2 
program with inappropriate incentives.

II. Need for Additional Emissions Control

    This proposal would reduce emissions from heavy-duty engines that 
contribute to ambient levels of ozone, PM, NOX and CO, which 
are all pollutants for which EPA has established health-based NAAQS. 
These pollutants are linked to premature death, respiratory illness 
(including childhood asthma), cardiovascular problems, and other 
adverse health impacts. Many groups are at greater risk than healthy 
people from these pollutants, including people with heart or lung 
disease, outdoor workers, older adults and children. These pollutants 
also reduce visibility and negatively impact ecosystems. This proposal 
would also reduce emissions of air toxics from heavy-duty engines. A 
more detailed discussion of the health and environmental effects 
associated with the pollutants affected by this proposed rule is 
included in Sections II.B and II.C and Chapter 4 of the draft RIA.
    As further described in Sections II.B.7 and II.B.8, populations who 
live, work, or go to school near high-traffic roadways experience 
higher rates of numerous adverse health effects, compared to 
populations far away from major roads. In addition, there is 
substantial evidence that people who live or attend school near major 
roadways are more likely to be people of color, Hispanic ethnicity, 
and/or low socioeconomic status.
    Across the U.S., NOX emissions from heavy-duty engines 
are important contributors to concentrations of ozone and 
PM2.5 and their resulting threat to public 
health.117 118 The emissions modeling done for the proposed 
rule \119\ (see Chapter 5 of the draft RIA) indicates that heavy-duty 
engines will continue to be one of the largest contributors to mobile 
source NOX emissions nationwide in the future, representing 
32 percent of the mobile source NOX in calendar year 
2045.\120\ Furthermore, it is estimated that heavy-duty engines will 
represent 89 percent of the onroad NOX inventory in calendar 
year 2045.\121\ The emission reductions that would occur from the 
proposed rule are projected to reduce air pollution that is (and is 
projected to continue to be) at levels that endanger public health and 
welfare.
---------------------------------------------------------------------------

    \117\ Zawacki et al., 2018. Mobile source contributions to 
ambient ozone and particulate matter in 2025. Atmospheric 
Environment, Vol 188, pg 129-141. Available online: https://doi.org/10.1016/j.atmosenv.2018.04.057.
    \118\ Davidson et al., 2020. The recent and future health burden 
of the U.S. mobile sector apportioned by source. Environmental 
Research Letters. Available online: https://doi.org/10.1088/1748-9326/ab83a8.
    \119\ Sectors other than onroad were projected from 2016v1 
Emissions Modeling Platform, https://views.cira.colostate.edu/wiki/wiki/10202.
    \120\ U.S. Environmental Protection Agency (2021). 2016v1 
Platform. https://www.epa.gov/air-emissions-modeling/2016v1-platform.
    \121\ Han, Jaehoon. Memorandum to the Docket EPA-HQ-OAR-2019-
0055: ``MOVES Modeling-Related Data Files (MOVES Code, Input 
Databases and Runspecs) for the Proposed Heavy-Duty 2027 
Standards''. February 2022.
---------------------------------------------------------------------------

    Many state and local agencies across the country have asked the EPA 
to further reduce NOX emissions, specifically from heavy-
duty engines, because such reductions will be a critical part of many 
areas' strategies to attain and maintain the ozone and PM NAAQS. These 
state and local agencies anticipate challenges in attaining the NAAQS, 
maintaining the NAAQS in the future, and/or preventing nonattainment. 
Some nonattainment areas have already been ``bumped up'' to higher 
classifications because of challenges in attaining the NAAQS; others 
say they are struggling to avoid nonattainment.\122\ Many state and 
local agencies commented on the ANPR that heavy-duty vehicles are one 
of their largest sources of NOX emissions. They

[[Page 17442]]

commented that without action to reduce emissions from heavy-duty 
vehicles, they would have to adopt other potentially more burdensome 
and costly measures to reduce emissions from other sources under their 
state or local authority, such as local businesses. More information on 
the projected emission reductions and air quality impacts that would 
result from this proposed rule is provided in Sections VI and VII.
---------------------------------------------------------------------------

    \122\ For example, in September 2019 several 2008 ozone 
nonattainment areas were reclassified from moderate to serious, 
including Dallas, Chicago, Connecticut, New York/New Jersey and 
Houston, and in January 2020, Denver. The 2008 NAAQS for ozone is an 
8-hour standard with a level of 0.075 ppm, which the 2015 ozone 
NAAQS lowered to 0.070 ppm.
---------------------------------------------------------------------------

    In their comments on the ANPR, environmental groups as well as 
state, local, and Tribal agencies supported additional NOX 
reductions from heavy-duty vehicles to address concerns about 
environmental justice and ensuring that all communities benefit from 
improvements in air quality. Commenters also supported additional 
NOX reductions from heavy-duty vehicles in order to address 
concerns about regional haze, and damage to terrestrial and aquatic 
ecosystems. They mentioned the impacts of NOX emissions on 
numerous locations, such as the Chesapeake Bay, Narragansett Bay, Long 
Island Sound, Joshua Tree National Park and the surrounding Mojave 
Desert, the Adirondacks, and other areas. Tribes and agencies commented 
that NOX deposition into lakes is harmful to fish and other 
aquatic life forms on which they depend for subsistence livelihoods. 
They also commented that regional haze and increased rates of 
weathering caused by pollution are of particular concern and can damage 
culturally significant archeological sites.

A. Background on Pollutants Impacted by This Proposal

1. Ozone
    Ground-level ozone pollution forms in areas with high 
concentrations of ambient NOX and VOCs when solar radiation 
is strong. Major U.S. sources of NOX are highway and nonroad 
motor vehicles, engines, power plants and other industrial sources, 
with natural sources, such as soil, vegetation, and lightning, serving 
as smaller sources. Vegetation is the dominant source of VOCs in the 
U.S. Volatile consumer and commercial products, such as propellants and 
solvents, highway and nonroad vehicles, engines, fires, and industrial 
sources also contribute to the atmospheric burden of VOCs at ground-
level.
    The processes underlying ozone formation, transport, and 
accumulation are complex. Ground-level ozone is produced and destroyed 
by an interwoven network of free radical reactions involving the 
hydroxyl radical (OH), NO, NO2, and complex reaction 
intermediates derived from VOCs. Many of these reactions are sensitive 
to temperature and available sunlight. High ozone events most often 
occur when ambient temperatures and sunlight intensities remain high 
for several days under stagnant conditions. Ozone and its precursors 
can also be transported hundreds of miles downwind which can lead to 
elevated ozone levels in areas with otherwise low VOC or NOX 
emissions. As an air mass moves and is exposed to changing ambient 
concentrations of NOX and VOCs, the ozone photochemical 
regime (relative sensitivity of ozone formation to NOX and 
VOC emissions) can change.
    When ambient VOC concentrations are high, comparatively small 
amounts of NOX catalyze rapid ozone formation. Without 
available NOX, ground-level ozone production is severely 
limited, and VOC reductions would have little impact on ozone 
concentrations. Photochemistry under these conditions is said to be 
``NOX-limited.'' When NOX levels are sufficiently 
high, faster NO2 oxidation consumes more radicals, dampening 
ozone production. Under these ``VOC-limited'' conditions (also referred 
to as '' NOX-saturated'' conditions), VOC reductions are 
effective in reducing ozone, and NOX can react directly with 
ozone resulting in suppressed ozone concentrations near NOX 
emission sources. Under these NOX-saturated conditions, 
NOX reductions can actually increase local ozone under 
certain circumstances, but overall ozone production (considering 
downwind formation) decreases and even in VOC-limited areas, 
NOX reductions are not expected to increase ozone levels if 
the NOX reductions are sufficiently large--large enough to 
become NOX-limited.
    The primary NAAQS for ozone, established in 2015 and retained in 
2020, is an 8-hour standard with a level of 0.07 ppm.\123\ EPA recently 
announced that it will reconsider the previous administration's 
decision to retain the ozone NAAQS.\124\ The EPA is also implementing 
the previous 8-hour ozone primary standard, set in 2008, at a level of 
0.075 ppm. As of May 31, 2021, there were 34 ozone nonattainment areas 
for the 2008 ozone NAAQS, composed of 151 full or partial counties, 
with a population of more than 99 million, and 50 ozone nonattainment 
areas for the 2015 ozone NAAQS, composed of 205 full or partial 
counties, with a population of more than 122 million. In total, there 
are currently, as of May 31, 2021, 57 ozone nonattainment areas with a 
population of more than 122 million people.\125\
---------------------------------------------------------------------------

    \123\ https://www.epa.gov/ground-level-ozone-pollution/ozone-national-ambient-air-quality-standards-naaqs.
    \124\ https://www.epa.gov/ground-level-ozone-pollution/epa-reconsider-previous-administrations-decision-retain-2015-ozone.
    \125\ The population total is calculated by summing, without 
double counting, the 2008 and 2015 ozone nonattainment populations 
contained in the Criteria Pollutant Nonattainment Summary report 
(https://www.epa.gov/green-book/green-book-data-download).
---------------------------------------------------------------------------

    States with ozone nonattainment areas are required to take action 
to bring those areas into attainment. The attainment date assigned to 
an ozone nonattainment area is based on the area's classification. The 
attainment dates for areas designated nonattainment for the 2008 8-hour 
ozone NAAQS are in the 2015 to 2032 timeframe, depending on the 
severity of the problem in each area. Attainment dates for areas 
designated nonattainment for the 2015 ozone NAAQS will be in the 2021 
to 2038 timeframe, again depending on the severity of the problem in 
each area.\126\ The proposed rule would begin to take effect in MY 2027 
and would assist areas with attaining the NAAQS and may relieve areas 
with already stringent local regulations from some of the burden 
associated with adopting additional local controls.\127\ The proposed 
rule could also provide assistance to counties with ambient 
concentrations near the level of the NAAQS who are working to ensure 
long-term attainment or maintenance of the NAAQS.
---------------------------------------------------------------------------

    \126\ https://www.epa.gov/ground-level-ozone-pollution/ozone-naaqs-timelines.
    \127\ While not quantified in the air quality modeling analysis 
for this proposed rule, the Early Adoption Incentives under the 
proposed program could encourage manufacturers to introduce new 
emission control technologies prior to the 2027 model year, which 
may help to accelerate some benefits of the proposed program (See 
Preamble Section IV.H for more details on the proposed Early 
Adoption Incentives).
---------------------------------------------------------------------------

2. Particulate Matter
    Particulate matter (PM) is a complex mixture of solid particles and 
liquid droplets distributed among numerous atmospheric gases which 
interact with solid and liquid phases. Particles in the atmosphere 
range in size from less than 0.01 to more than 10 micrometers ([mu]m) 
in diameter.\128\ Atmospheric particles can be grouped into several 
classes according to their aerodynamic diameter and physical sizes. 
Generally, the three broad classes of particles include ultrafine 
particles (UFPs, generally

[[Page 17443]]

considered as particles with a diameter less than or equal to 0.1 [mu]m 
[typically based on physical size, thermal diffusivity or electrical 
mobility]), ``fine'' particles (PM2.5; particles with a 
nominal mean aerodynamic diameter less than or equal to 2.5 [mu]m), and 
``thoracic'' particles (PM10; particles with a nominal mean 
aerodynamic diameter less than or equal to 10 [mu]m). Particles that 
fall within the size range between PM2.5 and 
PM10, are referred to as ``thoracic coarse particles'' 
(PM10-2.5, particles with a nominal mean aerodynamic 
diameter greater than 2.5 [mu]m and less than or equal to 10 [mu]m). 
EPA currently has NAAQS for PM2.5 and PM10.\129\
---------------------------------------------------------------------------

    \128\ U.S. EPA. Policy Assessment (PA) for the Review of the 
National Ambient Air Quality Standards for Particulate Matter (Final 
Report, 2020). U.S. Environmental Protection Agency, Washington, DC, 
EPA/452/R-20/002, 2020.
    \129\ Regulatory definitions of PM size fractions, and 
information on reference and equivalent methods for measuring PM in 
ambient air, are provided in 40 CFR parts 50, 53, and 58. With 
regard to NAAQS which provide protection against health and welfare 
effects, the 24-hour PM10 standard provides protection 
against effects associated with short-term exposure to thoracic 
coarse particles (i.e., PM10-2.5).
---------------------------------------------------------------------------

    Most particles are found in the lower troposphere, where they can 
have residence times ranging from a few hours to weeks. Particles are 
removed from the atmosphere by wet deposition, such as when they are 
carried by rain or snow, or by dry deposition, when particles settle 
out of suspension due to gravity. Atmospheric lifetimes are generally 
longest for PM2.5, which often remains in the atmosphere for 
days to weeks before being removed by wet or dry deposition.\130\ In 
contrast, atmospheric lifetimes for UFP and PM10-2.5 are 
shorter. Within hours, UFP can undergo coagulation and condensation 
that lead to formation of larger particles in the accumulation mode, or 
can be removed from the atmosphere by evaporation, deposition, or 
reactions with other atmospheric components. PM10-2.5 are 
also generally removed from the atmosphere within hours, through wet or 
dry deposition.\131\
---------------------------------------------------------------------------

    \130\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019. Table 2-
1.
    \131\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019. Table 2-
1.
---------------------------------------------------------------------------

    Particulate matter consists of both primary and secondary 
particles. Primary particles are emitted directly from sources, such as 
combustion-related activities (e.g., industrial activities, motor 
vehicle operation, biomass burning), while secondary particles are 
formed through atmospheric chemical reactions of gaseous precursors 
(e.g., sulfur oxides (SOX), nitrogen oxides (NOX) 
and volatile organic compounds (VOCs)). From 2000 to 2017, national 
annual average ambient PM2.5 concentrations have declined by 
over 40 percent,\132\ largely reflecting reductions in emissions of 
precursor gases.
---------------------------------------------------------------------------

    \132\ See https://www.epa.gov/air-trends/particulate-matter-pm25-trends and https://www.epa.gov/air-trends/particulate-matter-pm25-trends#pmnat for more information.
---------------------------------------------------------------------------

    There are two primary NAAQS for PM2.5: An annual 
standard (12.0 micrograms per cubic meter ([mu]g/m3)) and a 24-hour 
standard (35 [mu]g/m3), and there are two secondary NAAQS for 
PM2.5: An annual standard (15.0 [mu]g/m3) and a 24-hour 
standard (35 [mu]g/m3). The initial PM2.5 standards were set 
in 1997 and revisions to the standards were finalized in 2006 and in 
December 2012 and then retained in 2020. On June 10, 2021, EPA 
announced that it will reconsider the previous administration's 
decision to retain the PM NAAQS.\133\
---------------------------------------------------------------------------

    \133\ https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm.
---------------------------------------------------------------------------

    There are many areas of the country that are currently in 
nonattainment for the annual and 24-hour primary PM2.5 
NAAQS. As of May 31, 2021, more than 19 million people lived in the 4 
areas that are designated as nonattainment for the 1997 
PM2.5 NAAQS. Also, as of May 31, 2021, more than 31 million 
people lived in the 14 areas that are designated as nonattainment for 
the 2006 PM2.5 NAAQS and more than 20 million people lived 
in the 6 areas designated as nonattainment for the 2012 
PM2.5 NAAQS. In total, there are currently 17 
PM2.5 nonattainment areas with a population of more than 32 
million people.\134\ The proposed rule would take effect in MY 2027 and 
would assist areas with attaining the NAAQS and may relieve areas with 
already stringent local regulations from some of the burden associated 
with adopting additional local controls.\135\ The proposed rule would 
also assist counties with ambient concentrations near the level of the 
NAAQS who are working to ensure long-term attainment or maintenance of 
the PM2.5 NAAQS.
---------------------------------------------------------------------------

    \134\ The population total is calculated by summing, without 
double counting, the 1997, 2006 and 2012 PM2.5 
nonattainment populations contained in the Criteria Pollutant 
Nonattainment Summary report (https://www.epa.gov/green-book/green-book-data-download).
    \135\ While not quantified in the air quality modeling analysis 
for this proposed rule, the Early Adoption Incentives under the 
proposed program could encourage manufacturers to introduce new 
emission control technologies prior to the 2027 model year, which 
may help to accelerate some benefits of the proposed program (See 
Preamble Section IV.H for more details on the proposed Early 
Adoption Incentives).
---------------------------------------------------------------------------

3. Nitrogen Oxides
    Oxides of nitrogen (NOX) refers to nitric oxide (NO) and 
nitrogen dioxide (NO2). Most NO2 is formed in the 
air through the oxidation of nitric oxide (NO) emitted when fuel is 
burned at a high temperature. NOX is a criteria pollutant, 
regulated for its adverse effects on public health and the environment, 
and highway vehicles are an important contributor to NOX 
emissions. NOX, along with VOCs, are the two major 
precursors of ozone and NOX is also a major contributor to 
secondary PM2.5 formation. There are two primary NAAQS for 
NO2: An annual standard (53 ppb) and a 1-hour standard (100 
ppb).\136\ In 2010, EPA established requirements for monitoring 
NO2 near roadways expected to have the highest 
concentrations within large cities. Monitoring within this near-roadway 
network began in 2014, with additional sites deployed in the following 
years. At present, there are no nonattainment areas for NO2.
---------------------------------------------------------------------------

    \136\ The statistical form of the 1-hour NAAQS for 
NO2 is the 3-year average of the yearly distribution of 
1-hour daily maximum concentrations.
---------------------------------------------------------------------------

4. Carbon Monoxide
    Carbon monoxide (CO) is a colorless, odorless gas emitted from 
combustion processes. Nationally, particularly in urban areas, the 
majority of CO emissions to ambient air come from mobile sources.\137\ 
There are two primary NAAQS for CO: An 8-hour standard (9 ppm) and a 1-
hour standard (35 ppm). There are currently no CO nonattainment areas; 
as of September 27, 2010, all CO nonattainment areas have been 
redesignated to attainment. The past designations were based on the 
existing community-wide monitoring network. EPA made an addition to the 
ambient air monitoring requirements for CO during the 2011 NAAQS 
review. Those new requirements called for CO monitors to be operated 
near roads in Core Based Statistical Areas (CBSAs) of 1 million or more 
persons, in addition to the existing community-based network (76 FR 
54294, August 31, 2011).
---------------------------------------------------------------------------

    \137\ U.S. EPA, (2010). Integrated Science Assessment for Carbon 
Monoxide (Final Report). U.S. Environmental Protection Agency, 
Washington, DC, EPA/600/R-09/019F, 2010. https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=218686. See Section 2.1.
---------------------------------------------------------------------------

5. Diesel Exhaust
    Diesel exhaust is a complex mixture composed of particulate matter, 
carbon dioxide, oxygen, nitrogen, water vapor, carbon monoxide, 
nitrogen compounds, sulfur compounds and numerous low-molecular-weight 
hydrocarbons. A number of these gaseous hydrocarbon components are 
individually known to be toxic, including aldehydes, benzene

[[Page 17444]]

and 1,3-butadiene. The diesel particulate matter present in diesel 
exhaust consists mostly of fine particles (<2.5 [mu]m), of which a 
significant fraction is ultrafine particles (<0.1 [mu]m). These 
particles have a large surface area which makes them an excellent 
medium for adsorbing organics and their small size makes them highly 
respirable. Many of the organic compounds present in the gases and on 
the particles, such as polycyclic organic matter, are individually 
known to have mutagenic and carcinogenic properties.
    Diesel exhaust varies significantly in chemical composition and 
particle sizes between different engine types (heavy-duty, light-duty), 
engine operating conditions (idle, acceleration, deceleration), and 
fuel formulations (high/low sulfur fuel). Also, there are emissions 
differences between on-road and nonroad engines because the nonroad 
engines are generally of older technology. After being emitted in the 
engine exhaust, diesel exhaust undergoes dilution as well as chemical 
and physical changes in the atmosphere. The lifetime of the components 
present in diesel exhaust ranges from seconds to days.
    Because diesel particulate matter (DPM) is part of overall ambient 
PM, varies considerably in composition, and lacks distinct chemical 
markers that enable it to be easily distinguished from overall primary 
PM, we do not have direct measurements of DPM in the ambient air.\138\ 
DPM concentrations are estimated using ambient air quality modeling 
based on DPM emission inventories. DPM emission inventories are 
computed as the exhaust PM emissions from mobile sources combusting 
diesel or residual oil fuel. DPM concentrations were estimated as part 
of the 2014 National Air Toxics Assessment (NATA).\139\ Areas with high 
concentrations are clustered in the Northeast, Great Lake States, 
California, and the Gulf Coast States, with the highest impacts 
occurring in major urban cores, and are also distributed throughout the 
rest of the U.S. Approximately half of average ambient DPM in the U.S. 
can be attributed to heavy-duty diesel engines, with the remainder 
attributable to nonroad engines.
---------------------------------------------------------------------------

    \138\ DPM in exhaust from a high-load, high-speed engine (e.g., 
heavy-duty truck engines) without aftertreatment such as a diesel 
particle filter (DPM) is mostly made of ``soot,'' consisting of 
elemental/black carbon (EC/BC), some organic material, and trace 
elements. At low loads, DPM in high-speed engine exhaust is mostly 
made of organic carbon (OC), with considerably less EC/BC. Low-speed 
diesel engines' (e.g., large marine engines) exhaust PM is comprised 
of more sulfate and less EC/BC, with OC contributing as well.
    \139\ U.S. EPA (2018) Technical Support Document EPA's 2014 
National Air Toxics Assessment. https://www.epa.gov/national-air-toxics-assessment/2014-nata-assessment-results.
---------------------------------------------------------------------------

6. Air Toxics
    The most recent available data indicate that the majority of 
Americans continue to be exposed to ambient concentrations of air 
toxics at levels which have the potential to cause adverse health 
effects.\140\ The levels of air toxics to which people are exposed vary 
depending on where people live and work and the kinds of activities in 
which they engage, as discussed in detail in EPA's 2007 Mobile Source 
Air Toxics Rule.\141\ According to the National Air Toxic Assessment 
(NATA) for 2014, mobile sources were responsible for over 40 percent of 
outdoor anthropogenic toxic emissions and were the largest contributor 
to national average cancer and noncancer risk from directly emitted 
pollutants.142 143 Mobile sources are also significant 
contributors to precursor emissions which react to form air 
toxics.\144\ Formaldehyde is the largest contributor to cancer risk of 
all 71 pollutants quantitatively assessed in the 2014 NATA. Mobile 
sources were responsible for more than 25 percent of primary 
anthropogenic emissions of this pollutant in 2014 and are significant 
contributors to formaldehyde precursor emissions. Benzene is also a 
large contributor to cancer risk, and mobile sources account for almost 
70 percent of ambient exposure.
---------------------------------------------------------------------------

    \140\ U.S. EPA (2018) Technical Support Document EPA's 2014 
National Air Toxics Assessment. https://www.epa.gov/national-air-toxics-assessment/2014-nata-assessment-results.
    \141\ U.S. Environmental Protection Agency (2007). Control of 
Hazardous Air Pollutants from Mobile Sources; Final Rule. 72 FR 
8434, February 26, 2007.
    \142\ U.S. EPA. (2018) 2014 NATA: Assessment Results. https://www.epa.gov/national-air-toxics-assessment/2014-nata-assessment-results.
    \143\ NATA also includes estimates of risk attributable to 
background concentrations, which includes contributions from long-
range transport, persistent air toxics, and natural sources; as well 
as secondary concentrations, where toxics are formed via secondary 
formation. Mobile sources substantially contribute to long-range 
transport and secondarily formed air toxics.
    \144\ Rich Cook, Sharon Phillips, Madeleine Strum, Alison Eyth & 
James Thurman (2020): Contribution of mobile sources to secondary 
formation of carbonyl compounds, Journal of the Air & Waste 
Management Association, DOI: 10.1080/10962247.2020.1813839.
---------------------------------------------------------------------------

B. Health Effects Associated With Exposure to Pollutants Impacted by 
This Proposal

    Heavy duty engines emit pollutants that contribute to ambient 
concentrations of ozone, PM, NO2, CO, and air toxics. A 
discussion of the health effects associated with exposure to these 
pollutants, and a discussion on environmental justice, is included in 
this section of the preamble. Additionally, children are recognized to 
have increased vulnerability and susceptibility related to air 
pollution and other environmental exposures; this is discussed further 
in Section XIII of the Preamble. Information on emission reductions and 
air quality impacts from this proposed rule are included in Section VI 
and VII of this preamble.
1. Ozone
    This section provides a summary of the health effects associated 
with exposure to ambient concentrations of ozone.\145\ The information 
in this section is based on the information and conclusions in the 
April 2020 Integrated Science Assessment for Ozone (Ozone ISA).\146\ 
The Ozone ISA concludes that human exposures to ambient concentrations 
of ozone are associated with a number of adverse health effects and 
characterizes the weight of evidence for these health effects.\147\ The 
discussion below highlights the Ozone ISA's conclusions pertaining to 
health effects associated with both short-term and long-term periods of 
exposure to ozone.
---------------------------------------------------------------------------

    \145\ Human exposure to ozone varies over time due to changes in 
ambient ozone concentration and because people move between 
locations which have notably different ozone concentrations. Also, 
the amount of ozone delivered to the lung is influenced not only by 
the ambient concentrations but also by the breathing route and rate.
    \146\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone 
and Related Photochemical Oxidants (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012, 
2020.
    \147\ The ISA evaluates evidence and draws conclusions on the 
causal relationship between relevant pollutant exposures and health 
effects, assigning one of five ``weight of evidence'' 
determinations: Causal relationship, likely to be a causal 
relationship, suggestive of a causal relationship, inadequate to 
infer a causal relationship, and not likely to be a causal 
relationship. For more information on these levels of evidence, 
please refer to Table II in the Preamble of the ISA.
---------------------------------------------------------------------------

    For short-term exposure to ozone, the Ozone ISA concludes that 
respiratory effects, including lung function decrements, pulmonary 
inflammation, exacerbation of asthma, respiratory-related hospital 
admissions, and mortality, are causally associated with ozone exposure. 
It also concludes that metabolic effects, including metabolic syndrome 
(i.e., changes in insulin or glucose levels, cholesterol levels, 
obesity and blood pressure) and complications due to diabetes are 
likely to be causally associated with short-term exposure to ozone and 
that evidence is suggestive of a causal relationship between 
cardiovascular

[[Page 17445]]

effects, central nervous system effects and total mortality and short-
term exposure to ozone.
    For long-term exposure to ozone, the Ozone ISA concludes that 
respiratory effects, including new onset asthma, pulmonary inflammation 
and injury, are likely to be causally related with ozone exposure. The 
Ozone ISA characterizes the evidence as suggestive of a causal 
relationship for associations between long-term ozone exposure and 
cardiovascular effects, metabolic effects, reproductive and 
developmental effects, central nervous system effects and total 
mortality. The evidence is inadequate to infer a causal relationship 
between chronic ozone exposure and increased risk of cancer.
    Finally, interindividual variation in human responses to ozone 
exposure can result in some groups being at increased risk for 
detrimental effects in response to exposure. In addition, some groups 
are at increased risk of exposure due to their activities, such as 
outdoor workers and children. The Ozone ISA identified several groups 
that are at increased risk for ozone-related health effects. These 
groups are people with asthma, children and older adults, individuals 
with reduced intake of certain nutrients (i.e., Vitamins C and E), 
outdoor workers, and individuals having certain genetic variants 
related to oxidative metabolism or inflammation. Ozone exposure during 
childhood can have lasting effects through adulthood. Such effects 
include altered function of the respiratory and immune systems. 
Children absorb higher doses (normalized to lung surface area) of 
ambient ozone, compared to adults, due to their increased time spent 
outdoors, higher ventilation rates relative to body size, and a 
tendency to breathe a greater fraction of air through the mouth. 
Children also have a higher asthma prevalence compared to adults. 
Recent epidemiologic studies provide generally consistent evidence that 
long-term ozone exposure is associated with the development of asthma 
in children. Studies comparing age groups reported higher magnitude 
associations for short-term ozone exposure and respiratory hospital 
admissions and emergency room visits among children than for adults. 
Panel studies also provide support for experimental studies with 
consistent associations between short-term ozone exposure and lung 
function and pulmonary inflammation in healthy children. Additional 
children's vulnerability and susceptibility factors are listed in 
Section XIII of the Preamble.
2. Particulate Matter
    Scientific evidence spanning animal toxicological, controlled human 
exposure, and epidemiologic studies shows that exposure to ambient PM 
is associated with a broad range of health effects. These health 
effects are discussed in detail in the Integrated Science Assessment 
for Particulate Matter (PM ISA), which was finalized in December 
2019.\148\ The PM ISA characterizes the causal nature of relationships 
between PM exposure and broad health categories (e.g., cardiovascular 
effects, respiratory effects, etc.) using a weight-of-evidence 
approach.\149\ Within this characterization, the PM ISA summarizes the 
health effects evidence for short- and long-term exposures to 
PM2.5, PM10-2.5, and ultrafine particles, and 
concludes that human exposures to ambient PM2.5 are 
associated with a number of adverse health effects. The discussion 
below highlights the PM ISA's conclusions pertaining to the health 
effects evidence for both short- and long-term PM exposures. Further 
discussion of PM-related health effects can also be found in the 2020 
Policy Assessment for the review of the PM NAAQS.\150\
---------------------------------------------------------------------------

    \148\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
    \149\ The causal framework draws upon the assessment and 
integration of evidence from across scientific disciplines, spanning 
atmospheric chemistry, exposure, dosimetry and health effects 
studies (i.e., epidemiologic, controlled human exposure, and animal 
toxicological studies), and assess the related uncertainties and 
limitations that ultimately influence our understanding of the 
evidence. This framework employs a five-level hierarchy that 
classifies the overall weight-of-evidence with respect to the causal 
nature of relationships between criteria pollutant exposures and 
health and welfare effects using the following categorizations: 
Causal relationship; likely to be causal relationship; suggestive 
of, but not sufficient to infer, a causal relationship; inadequate 
to infer the presence or absence of a causal relationship; and not 
likely to be a causal relationship (U.S. EPA. (2019). Integrated 
Science Assessment for Particulate Matter (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R-19/188, 
Section P. 3.2.3).
    \150\ U.S. EPA. Policy Assessment (PA) for the Review of the 
National Ambient Air Quality Standards for Particulate Matter (Final 
Report, 2020). U.S. Environmental Protection Agency, Washington, DC, 
EPA/452/R-20/002, 2020.
---------------------------------------------------------------------------

    EPA has concluded that recent evidence in combination with evidence 
evaluated in the 2009 PM ISA supports a ``causal relationship'' between 
both long- and short-term exposures to PM2.5 and mortality 
and cardiovascular effects and a ``likely to be causal relationship'' 
between long- and short-term PM2.5 exposures and respiratory 
effects.\151\ Additionally, recent experimental and epidemiologic 
studies provide evidence supporting a ``likely to be causal 
relationship'' between long-term PM2.5 exposure and nervous 
system effects, and long-term PM2.5 exposure and cancer. In 
addition, EPA noted that there was more limited and uncertain evidence 
for long-term PM2.5 exposure and reproductive and 
developmental effects (i.e., male/female reproduction and fertility; 
pregnancy and birth outcomes), long- and short-term exposures and 
metabolic effects, and short-term exposure and nervous system effects 
resulting in the ISA concluding ``suggestive of, but not sufficient to 
infer, a causal relationship.''
---------------------------------------------------------------------------

    \151\ U.S. EPA. (2009). Integrated Science Assessment for 
Particulate Matter (Final Report). U.S. Environmental Protection 
Agency, Washington, DC, EPA/600/R-08/139F.
---------------------------------------------------------------------------

    As discussed extensively in the 2019 PM ISA, recent studies 
continue to support and extend the evidence base linking short- and 
long-term PM2.5 exposures and mortality.\152\ For short-term 
PM2.5 exposure, recent multi-city studies, in combination 
with single- and multi-city studies evaluated in the 2009 PM ISA, 
provide evidence of consistent, positive associations across studies 
conducted in different geographic locations, populations with different 
demographic characteristics, and studies using different exposure 
assignment techniques. Additionally, the consistent and coherent 
evidence across scientific disciplines for cardiovascular morbidity, 
particularly ischemic events and heart failure, and to a lesser degree 
for respiratory morbidity, with the strongest evidence for 
exacerbations of chronic obstructive pulmonary disease (COPD) and 
asthma, provide biological plausibility for cause-specific mortality 
and ultimately total mortality.
---------------------------------------------------------------------------

    \152\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
---------------------------------------------------------------------------

    In addition to reanalyses and extensions of the American Cancer 
Society (ACS) and Harvard Six Cities (HSC) cohorts, multiple new cohort 
studies conducted in the U.S. and Canada consisting of people employed 
in a specific job (e.g., teacher, nurse), and that apply different 
exposure assignment techniques provide evidence of positive 
associations between long-term PM2.5 exposure and mortality. 
Biological plausibility for mortality due to long-term PM2.5 
exposure is provided by the coherence of effects across scientific 
disciplines for cardiovascular morbidity, particularly for coronary 
heart disease (CHD), stroke and atherosclerosis, and for respiratory 
morbidity, particularly for the

[[Page 17446]]

development of COPD. Additionally, recent studies provide evidence 
indicating that as long-term PM2.5 concentrations decrease 
there is an increase in life expectancy.
    A large body of recent studies examining both short- and long-term 
PM2.5 exposure and cardiovascular effects supports and 
extends the evidence base evaluated in the 2009 PM ISA. Some of the 
strongest evidence from both experimental and epidemiologic studies 
examining short-term PM2.5 exposures are for ischemic heart 
disease (IHD) and heart failure. The evidence for cardiovascular 
effects is coherent across studies of short-term PM2.5 
exposure that have observed associations with a continuum of effects 
ranging from subtle changes in indicators of cardiovascular health to 
serious clinical events, such as increased emergency department visits 
and hospital admissions due to cardiovascular disease and 
cardiovascular mortality. For long-term PM2.5 exposure, 
there is strong and consistent epidemiologic evidence of a relationship 
with cardiovascular mortality. This evidence is supported by 
epidemiologic and animal toxicological studies demonstrating a range of 
cardiovascular effects including coronary heart disease, stroke, 
impaired heart function, and subclinical markers (e.g., coronary artery 
calcification, atherosclerotic plaque progression), which collectively 
provide coherence and biological plausibility.
    Recent studies continue to provide evidence of a relationship 
between both short- and long-term PM2.5 exposure and 
respiratory effects. Epidemiologic and animal toxicological studies 
examining short-term PM2.5 exposure provide consistent 
evidence of asthma and COPD exacerbations, in children and adults, 
respectively. This evidence is supported by epidemiologic studies 
examining asthma and COPD emergency department visits and hospital 
admissions, as well as respiratory mortality. However, there is 
inconsistent evidence of respiratory effects, specifically lung 
function declines and pulmonary inflammation, in controlled human 
exposure studies. Epidemiologic studies conducted in the U.S. and 
abroad provide evidence of a relationship between long-term 
PM2.5 exposure and respiratory effects, including consistent 
changes in lung function and lung function growth rate, increased 
asthma incidence, asthma prevalence, and wheeze in children; 
acceleration of lung function decline in adults; and respiratory 
mortality. The epidemiologic evidence is supported by animal 
toxicological studies, which provide coherence and biological 
plausibility for a range of effects including impaired lung 
development, decrements in lung function growth, and asthma 
development.
    Since the 2009 PM ISA, a growing body of scientific evidence 
examined the relationship between long-term PM2.5 exposure 
and nervous system effects, resulting for the first time in a causality 
determination for this health effects category. The strongest evidence 
for effects on the nervous system come from epidemiologic studies that 
consistently report cognitive decrements and reductions in brain volume 
in adults. The effects observed in epidemiologic studies are supported 
by animal toxicological studies demonstrating effects on the brain of 
adult animals including inflammation, morphologic changes, and 
neurodegeneration of specific regions of the brain. There is more 
limited evidence for neurodevelopmental effects in children with some 
studies reporting positive associations with autism spectrum disorder 
(ASD) and others providing limited evidence of an association with 
cognitive function. While there is some evidence from animal 
toxicological studies indicating effects on the brain (i.e., 
inflammatory and morphological changes) to support a biologically 
plausible pathway, epidemiologic studies of neurodevelopmental effects 
are limited due to their lack of control for potential confounding by 
copollutants, the small number of studies conducted, and uncertainty 
regarding critical exposure windows.
    Building off the decades of research demonstrating mutagenicity, 
DNA damage, and endpoints related to genotoxicity due to whole PM 
exposures, recent experimental and epidemiologic studies focusing 
specifically on PM2.5 provide evidence of a relationship 
between long-term PM2.5 exposure and cancer. Epidemiologic 
studies examining long-term PM2.5 exposure and lung cancer 
incidence and mortality provide evidence of generally positive 
associations in cohort studies spanning different populations, 
locations, and exposure assignment techniques. Additionally, there is 
evidence of positive associations in analyses limited to never smokers. 
The epidemiologic evidence is supported by both experimental and 
epidemiologic evidence of genotoxicity, epigenetic effects, 
carcinogenic potential, and that PM2.5 exhibits several 
characteristics of carcinogens, which collectively provides biological 
plausibility for cancer development.
    For the additional health effects categories evaluated for 
PM2.5 in the 2019 PM ISA, experimental and epidemiologic 
studies provide limited and/or inconsistent evidence of a relationship 
with PM2.5 exposure. As a result, the 2019 PM ISA concluded 
that the evidence is ``suggestive of, but not sufficient to infer a 
causal relationship'' for short-term PM2.5 exposure and 
metabolic effects and nervous system effects, and long-term 
PM2.5 exposures and metabolic effects as well as 
reproductive and developmental effects.
    In addition to evaluating the health effects attributed to short- 
and long-term exposure to PM2.5, the 2019 PM ISA also 
conducted an extensive evaluation as to whether specific components or 
sources of PM2.5 are more strongly related with health 
effects than PM2.5 mass. An evaluation of those studies 
resulted in the 2019 PM ISA concluding that ``many PM2.5 
components and sources are associated with many health effects, and the 
evidence does not indicate that any one source or component is 
consistently more strongly related to health effects than 
PM2.5 mass.'' \153\
---------------------------------------------------------------------------

    \153\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
---------------------------------------------------------------------------

    For both PM10-2.5 and UFPs, for all health effects 
categories evaluated, the 2019 PM ISA concluded that the evidence was 
``suggestive of, but not sufficient to infer, a causal relationship'' 
or ``inadequate to determine the presence or absence of a causal 
relationship.'' For PM10-2.5, although a Federal Reference 
Method (FRM) was instituted in 2011 to measure PM10-2.5 
concentrations nationally, the causality determinations reflect that 
the same uncertainty identified in the 2009 PM ISA with respect to the 
method used to estimate PM10-2.5 concentrations in 
epidemiologic studies persists. Specifically, across epidemiologic 
studies, different approaches are used to estimate PM10-2.5 
concentrations (e.g., direct measurement of PM10-2.5, 
difference between PM10 and PM2.5 
concentrations), and it remains unclear how well correlated 
PM10-2.5 concentrations are both spatially and temporally 
across the different methods used.
    For UFPs, the uncertainty in the evidence for the health effect 
categories evaluated across experimental and epidemiologic studies 
reflects the inconsistency in the exposure metric used (i.e., particle 
number concentration, surface area concentration, mass concentration) 
as well as the size fractions examined. In

[[Page 17447]]

epidemiologic studies the size fraction can vary depending on the 
monitor used and exposure metric, with some studies examining number 
count over the entire particle size range, while experimental studies 
that use a particle concentrator often examine particles up to 0.3 
[mu]m. Additionally, due to the lack of a monitoring network, there is 
limited information on the spatial and temporal variability of UFPs 
within the U.S., as well as population exposures to UFPs, which adds 
uncertainty to epidemiologic study results.
    The 2019 p.m. ISA cites extensive evidence indicating that ``both 
the general population as well as specific populations and life stages 
are at risk for PM2.5-related health effects.'' 
154 155 For example, in support of its ``causal'' and 
``likely to be causal'' determinations, the ISA cites substantial 
evidence for (1) PM-related mortality and cardiovascular effects in 
older adults; (2) PM-related cardiovascular effects in people with pre-
existing cardiovascular disease; (3) PM-related respiratory effects in 
people with pre-existing respiratory disease, particularly asthma 
exacerbations in children; and (4) PM-related impairments in lung 
function growth and asthma development in children. The ISA 
additionally notes that stratified analyses (i.e., analyses that 
directly compare PM-related health effects across groups) provide 
strong evidence for racial and ethnic differences in PM2.5 
exposures and in the risk of PM2.5-related health effects, 
specifically within Hispanic and non-Hispanic Black populations. 
Additionally, evidence spanning epidemiologic studies that conducted 
stratified analyses, experimental studies focusing on animal models of 
disease or individuals with pre-existing disease, dosimetry studies, as 
well as studies focusing on differential exposure suggest that 
populations with pre-existing cardiovascular or respiratory disease, 
populations that are overweight or obese, populations that have 
particular genetic variants, populations that are of low socioeconomic 
status, and current/former smokers could be at increased risk for 
adverse PM2.5-related health effects.
---------------------------------------------------------------------------

    \154\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
    \155\ U.S. EPA. Policy Assessment (PA) for the Review of the 
National Ambient Air Quality Standards for Particulate Matter (Final 
Report, 2020). U.S. Environmental Protection Agency, Washington, DC, 
EPA/452/R-20/002, 2020.
---------------------------------------------------------------------------

3. Nitrogen Oxides
    The most recent review of the health effects of oxides of nitrogen 
completed by EPA can be found in the 2016 Integrated Science Assessment 
for Oxides of Nitrogen--Health Criteria (Oxides of Nitrogen ISA).\156\ 
The primary source of NO2 is motor vehicle emissions, and 
ambient NO2 concentrations tend to be highly correlated with 
other traffic-related pollutants. Thus, a key issue in characterizing 
the causality of NO2-health effect relationships consists of 
evaluating the extent to which studies supported an effect of 
NO2 that is independent of other traffic-related pollutants. 
EPA concluded that the findings for asthma exacerbation integrated from 
epidemiologic and controlled human exposure studies provided evidence 
that is sufficient to infer a causal relationship between respiratory 
effects and short-term NO2 exposure. The strongest evidence 
supporting an independent effect of NO2 exposure comes from 
controlled human exposure studies demonstrating increased airway 
responsiveness in individuals with asthma following ambient-relevant 
NO2 exposures. The coherence of this evidence with 
epidemiologic findings for asthma hospital admissions and ED visits as 
well as lung function decrements and increased pulmonary inflammation 
in children with asthma describe a plausible pathway by which 
NO2 exposure can cause an asthma exacerbation. The 2016 ISA 
for Oxides of Nitrogen also concluded that there is likely to be a 
causal relationship between long-term NO2 exposure and 
respiratory effects. This conclusion is based on new epidemiologic 
evidence for associations of NO2 with asthma development in 
children combined with biological plausibility from experimental 
studies.
---------------------------------------------------------------------------

    \156\ U.S. EPA. Integrated Science Assessment for Oxides of 
Nitrogen--Health Criteria (2016 Final Report). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-15/068, 2016.
---------------------------------------------------------------------------

    In evaluating a broader range of health effects, the 2016 ISA for 
Oxides of Nitrogen concluded that evidence is ``suggestive of, but not 
sufficient to infer, a causal relationship'' between short-term 
NO2 exposure and cardiovascular effects and mortality and 
between long-term NO2 exposure and cardiovascular effects 
and diabetes, birth outcomes, and cancer. In addition, the scientific 
evidence is inadequate (insufficient consistency of epidemiologic and 
toxicological evidence) to infer a causal relationship for long-term 
NO2 exposure with fertility, reproduction, and pregnancy, as 
well as with postnatal development. A key uncertainty in understanding 
the relationship between these non-respiratory health effects and 
short- or long-term exposure to NO2 is copollutant 
confounding, particularly by other roadway pollutants. The available 
evidence for non-respiratory health effects does not adequately address 
whether NO2 has an independent effect or whether it 
primarily represents effects related to other or a mixture of traffic-
related pollutants.
    The 2016 ISA for Oxides of Nitrogen concluded that people with 
asthma, children, and older adults are at increased risk for 
NO2-related health effects. In these groups and lifestages, 
NO2 is consistently related to larger effects on outcomes 
related to asthma exacerbation, for which there is confidence in the 
relationship with NO2 exposure.
4. Carbon Monoxide
    Information on the health effects of carbon monoxide (CO) can be 
found in the January 2010 Integrated Science Assessment for Carbon 
Monoxide (CO ISA).\157\ The CO ISA presents conclusions regarding the 
presence of causal relationships between CO exposure and categories of 
adverse health effects.\158\ This section provides a summary of the 
health effects associated with exposure to ambient concentrations of 
CO, along with the CO ISA conclusions.\159\
---------------------------------------------------------------------------

    \157\ U.S. EPA, (2010). Integrated Science Assessment for Carbon 
Monoxide (Final Report). U.S. Environmental Protection Agency, 
Washington, DC, EPA/600/R-09/019F, 2010. https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=218686.
    \158\ The ISA evaluates the health evidence associated with 
different health effects, assigning one of five ``weight of 
evidence'' determinations: causal relationship, likely to be a 
causal relationship, suggestive of a causal relationship, inadequate 
to infer a causal relationship, and not likely to be a causal 
relationship. For definitions of these levels of evidence, please 
refer to Section 1.6 of the ISA.
    \159\ Personal exposure includes contributions from many 
sources, and in many different environments. Total personal exposure 
to CO includes both ambient and non-ambient components; and both 
components may contribute to adverse health effects.
---------------------------------------------------------------------------

    Controlled human exposure studies of subjects with coronary artery 
disease show a decrease in the time to onset of exercise-induced angina 
(chest pain) and electrocardiogram changes following CO exposure. In 
addition, epidemiologic studies observed associations between short-
term CO exposure and cardiovascular morbidity, particularly increased 
emergency room visits and hospital admissions for

[[Page 17448]]

coronary heart disease (including ischemic heart disease, myocardial 
infarction, and angina). Some epidemiologic evidence is also available 
for increased hospital admissions and emergency room visits for 
congestive heart failure and cardiovascular disease as a whole. The CO 
ISA concludes that a causal relationship is likely to exist between 
short-term exposures to CO and cardiovascular morbidity. It also 
concludes that available data are inadequate to conclude that a causal 
relationship exists between long-term exposures to CO and 
cardiovascular morbidity.
    Animal studies show various neurological effects with in-utero CO 
exposure. Controlled human exposure studies report central nervous 
system and behavioral effects following low-level CO exposures, 
although the findings have not been consistent across all studies. The 
CO ISA concludes that the evidence is suggestive of a causal 
relationship with both short- and long-term exposure to CO and central 
nervous system effects.
    A number of studies cited in the CO ISA have evaluated the role of 
CO exposure in birth outcomes such as preterm birth or cardiac birth 
defects. There is limited epidemiologic evidence of a CO-induced effect 
on preterm births and birth defects, with weak evidence for a decrease 
in birth weight. Animal toxicological studies have found perinatal CO 
exposure to affect birth weight, as well as other developmental 
outcomes. The CO ISA concludes that the evidence is suggestive of a 
causal relationship between long-term exposures to CO and developmental 
effects and birth outcomes.
    Epidemiologic studies provide evidence of associations between 
short-term CO concentrations and respiratory morbidity such as changes 
in pulmonary function, respiratory symptoms, and hospital admissions. A 
limited number of epidemiologic studies considered copollutants such as 
ozone, SO2, and PM in two-pollutant models and found that CO 
risk estimates were generally robust, although this limited evidence 
makes it difficult to disentangle effects attributed to CO itself from 
those of the larger complex air pollution mixture. Controlled human 
exposure studies have not extensively evaluated the effect of CO on 
respiratory morbidity. Animal studies at levels of 50-100 ppm CO show 
preliminary evidence of altered pulmonary vascular remodeling and 
oxidative injury. The CO ISA concludes that the evidence is suggestive 
of a causal relationship between short-term CO exposure and respiratory 
morbidity, and inadequate to conclude that a causal relationship exists 
between long-term exposure and respiratory morbidity.
    Finally, the CO ISA concludes that the epidemiologic evidence is 
suggestive of a causal relationship between short-term concentrations 
of CO and mortality. Epidemiologic evidence suggests an association 
exists between short-term exposure to CO and mortality, but limited 
evidence is available to evaluate cause-specific mortality outcomes 
associated with CO exposure. In addition, the attenuation of CO risk 
estimates which was often observed in copollutant models contributes to 
the uncertainty as to whether CO is acting alone or as an indicator for 
other combustion-related pollutants. The CO ISA also concludes that 
there is not likely to be a causal relationship between relevant long-
term exposures to CO and mortality.
5. Diesel Exhaust
    In EPA's 2002 Diesel Health Assessment Document (Diesel HAD), 
exposure to diesel exhaust was classified as likely to be carcinogenic 
to humans by inhalation from environmental exposures, in accordance 
with the revised draft 1996/1999 EPA cancer 
guidelines.160 161 A number of other agencies (National 
Institute for Occupational Safety and Health, the International Agency 
for Research on Cancer, the World Health Organization, California EPA, 
and the U.S. Department of Health and Human Services) made similar 
hazard classifications prior to 2002. EPA also concluded in the 2002 
Diesel HAD that it was not possible to calculate a cancer unit risk for 
diesel exhaust due to limitations in the exposure data for the 
occupational groups or the absence of a dose-response relationship.
---------------------------------------------------------------------------

    \160\ U.S. EPA. (1999). Guidelines for Carcinogen Risk 
Assessment. Review Draft. NCEA-F-0644, July. Washington, DC: U.S. 
EPA. Retrieved on March 19, 2009 from https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54932.
    \161\ U.S. EPA (2002). Health Assessment Document for Diesel 
Engine Exhaust. EPA/600/8-90/057F Office of research and 
Development, Washington, DC. Retrieved on March 17, 2009 from https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060. pp. 1-1 1-2.
---------------------------------------------------------------------------

    In the absence of a cancer unit risk, the Diesel HAD sought to 
provide additional insight into the significance of the diesel exhaust 
cancer hazard by estimating possible ranges of risk that might be 
present in the population. An exploratory analysis was used to 
characterize a range of possible lung cancer risk. The outcome was that 
environmental risks of cancer from long-term diesel exhaust exposures 
could plausibly range from as low as 10-5 to as high as 
10-3. Because of uncertainties, the analysis acknowledged 
that the risks could be lower than 10-5, and a zero risk 
from diesel exhaust exposure could not be ruled out.
    Noncancer health effects of acute and chronic exposure to diesel 
exhaust emissions are also of concern to EPA. EPA derived a diesel 
exhaust reference concentration (RfC) from consideration of four well-
conducted chronic rat inhalation studies showing adverse pulmonary 
effects. The RfC is 5 [micro]g/m\3\ for diesel exhaust measured as 
diesel particulate matter. This RfC does not consider allergenic 
effects such as those associated with asthma or immunologic or the 
potential for cardiac effects. There was emerging evidence in 2002, 
discussed in the Diesel HAD, that exposure to diesel exhaust can 
exacerbate these effects, but the exposure-response data were lacking 
at that time to derive an RfC based on these then-emerging 
considerations. The Diesel HAD states, ``With [diesel particulate 
matter] being a ubiquitous component of ambient PM, there is an 
uncertainty about the adequacy of the existing [diesel exhaust] 
noncancer database to identify all of the pertinent [diesel exhaust]-
caused noncancer health hazards.'' The Diesel HAD also notes ``that 
acute exposure to [diesel exhaust] has been associated with irritation 
of the eye, nose, and throat, respiratory symptoms (cough and phlegm), 
and neurophysiological symptoms such as headache, lightheadedness, 
nausea, vomiting, and numbness or tingling of the extremities.'' The 
Diesel HAD notes that the cancer and noncancer hazard conclusions 
applied to the general use of diesel engines then on the market and as 
cleaner engines replace a substantial number of existing ones, the 
applicability of the conclusions would need to be reevaluated.
    It is important to note that the Diesel HAD also briefly summarizes 
health effects associated with ambient PM and discusses EPA's then-
annual PM2.5 NAAQS of 15 [micro]g/m\3\. In 2012, EPA revised 
the annual PM2.5 NAAQS to 12 [micro]g/m\3\ and then retained 
that standard in 2020, as of June 10, 2021 EPA is reconsidering the 
PM2.5 NAAQS.\162\ There is a large and extensive body of 
human data showing a wide spectrum of adverse health effects associated 
with exposure to ambient PM, of which diesel exhaust is an important 
component. The PM2.5 NAAQS is designed to provide protection 
from the

[[Page 17449]]

noncancer health effects and premature mortality attributed to exposure 
to PM2.5. The contribution of diesel PM to total ambient PM 
varies in different regions of the country and also, within a region, 
from one area to another. The contribution can be high in near-roadway 
environments, for example, or in other locations where diesel engine 
use is concentrated.
---------------------------------------------------------------------------

    \162\ https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm.
---------------------------------------------------------------------------

    Since 2002, several new studies have been published which continue 
to report increased lung cancer risk associated with occupational 
exposure to diesel exhaust from older engines. Of particular note since 
2011 are three new epidemiology studies which have examined lung cancer 
in occupational populations, for example, truck drivers, underground 
nonmetal miners and other diesel motor-related occupations. These 
studies reported increased risk of lung cancer with exposure to diesel 
exhaust with evidence of positive exposure-response relationships to 
varying degrees.163 164 165 These newer studies (along with 
others that have appeared in the scientific literature) add to the 
evidence EPA evaluated in the 2002 Diesel HAD and further reinforce the 
concern that diesel exhaust exposure likely poses a lung cancer hazard. 
The findings from these newer studies do not necessarily apply to newer 
technology diesel engines (i.e., heavy-duty highway engines from 2007 
and later model years) since the newer engines have large reductions in 
the emission constituents compared to older technology diesel engines.
---------------------------------------------------------------------------

    \163\ Garshick, Eric, Francine Laden, Jaime E. Hart, Mary E. 
Davis, Ellen A. Eisen, and Thomas J. Smith. 2012. Lung cancer and 
elemental carbon exposure in trucking industry workers. 
Environmental Health Perspectives 120(9): 1301-1306.
    \164\ Silverman, D.T., Samanic, C.M., Lubin, J.H., Blair, A.E., 
Stewart, P.A., Vermeulen, R., & Attfield, M.D. (2012). The diesel 
exhaust in miners study: A nested case-control study of lung cancer 
and diesel exhaust. Journal of the National Cancer Institute.
    \165\ Olsson, Ann C., et al. ``Exposure to diesel motor exhaust 
and lung cancer risk in a pooled analysis from case-control studies 
in Europe and Canada.'' American journal of respiratory and critical 
care medicine 183.7 (2011): 941-948.
---------------------------------------------------------------------------

    In light of the growing body of scientific literature evaluating 
the health effects of exposure to diesel exhaust, in June 2012 the 
World Health Organization's International Agency for Research on Cancer 
(IARC), a recognized international authority on the carcinogenic 
potential of chemicals and other agents, evaluated the full range of 
cancer-related health effects data for diesel engine exhaust. IARC 
concluded that diesel exhaust should be regarded as ``carcinogenic to 
humans.'' \166\ This designation was an update from its 1988 evaluation 
that considered the evidence to be indicative of a ``probable human 
carcinogen.''
---------------------------------------------------------------------------

    \166\ IARC [International Agency for Research on Cancer]. 
(2013). Diesel and gasoline engine exhausts and some nitroarenes. 
IARC Monographs Volume 105. [Online at https://monographs.iarc.fr/ENG/Monographs/vol105/index.php].
---------------------------------------------------------------------------

6. Air Toxics
    Heavy-duty engine emissions contribute to ambient levels of air 
toxics that are known or suspected human or animal carcinogens, or that 
have noncancer health effects. These compounds include, but are not 
limited to, benzene, formaldehyde, acetaldehyde, and naphthalene. These 
compounds were identified as national or regional risk drivers or 
contributors in the 2014 National-scale Air Toxics Assessment and have 
significant inventory contributions from mobile 
sources.167 168 Chapter 4 of the draft RIA includes 
additional information on the health effects associated with exposure 
to each of these pollutants.
---------------------------------------------------------------------------

    \167\ U.S. EPA (2018) Technical Support Document EPA's 2014 
National Air Toxics Assessment. https://www.epa.gov/national-air-toxics-assessment/2014-nata-assessment-results.
    \168\ U.S. EPA (2018) 2014 NATA Summary of Results. https://www.epa.gov/sites/production/files/2020-07/documents/nata_2014_summary_of_results.pdf.
---------------------------------------------------------------------------

7. Exposure and Health Effects Associated With Traffic
    Locations in close proximity to major roadways generally have 
elevated concentrations of many air pollutants emitted from motor 
vehicles. Hundreds of such studies have been published in peer-reviewed 
journals, concluding that concentrations of CO, CO2, NO, 
NO2, benzene, aldehydes, particulate matter, black carbon, 
and many other compounds are elevated in ambient air within 
approximately 300-600 meters (about 1,000-2,000 feet) of major 
roadways. The highest concentrations of most pollutants emitted 
directly by motor vehicles are found at locations within 50 meters 
(about 165 feet) of the edge of a roadway's traffic lanes.
    A large-scale review of air quality measurements in the vicinity of 
major roadways between 1978 and 2008 concluded that the pollutants with 
the steepest concentration gradients in vicinities of roadways were CO, 
ultrafine particles, metals, elemental carbon (EC), NO, NOX, 
and several VOCs.\169\ These pollutants showed a large reduction in 
concentrations within 100 meters downwind of the roadway. Pollutants 
that showed more gradual reductions with distance from roadways 
included benzene, NO2, PM2.5, and 
PM10. In the review article, results varied based on the 
method of statistical analysis used to determine the gradient in 
concentration. More recent studies continue to show significant 
concentration gradients of traffic-related air pollution around major 
roads.170 171 172 173 174 175 176 177 There is evidence that 
EPA's regulations for vehicles have lowered the near-road 
concentrations and gradients.\178\ Starting in 2010, EPA required 
through the NAAQS process that air quality monitors be placed near 
high-traffic roadways for determining concentrations of CO, 
NO2, and PM2.5

[[Page 17450]]

(in addition to those existing monitors located in neighborhoods and 
other locations farther away from pollution sources). The monitoring 
data for NO2 indicate that in urban areas, monitors near 
roadways often report the highest concentrations of NO2.
---------------------------------------------------------------------------

    \169\ Karner, A.A.; Eisinger, D.S.; Niemeier, D.A. (2010). Near-
roadway air quality: synthesizing the findings from real-world data. 
Environ Sci Technol 44: 5334-5344.
    \170\ McDonald, B.C.; McBride, Z.C.; Martin, E.W.; Harley, R.A. 
(2014) High-resolution mapping of motor vehicle carbon dioxide 
emissions. J. Geophys. Res.Atmos.,119, 5283-5298, doi:10.1002/
2013JD021219.
    \171\ Kimbrough, S.; Baldauf, R.W.; Hagler, G.S.W.; Shores, 
R.C.; Mitchell, W.; Whitaker, D.A.; Croghan, C.W.; Vallero, D.A. 
(2013) Long-term continuous measurement of near-road air pollution 
in Las Vegas: seasonal variability in traffic emissions impact on 
air quality. Air Qual Atmos Health 6: 295-305. DOI:10.1007/s11869-
012-0171-x.
    \172\ Kimbrough, S.; Palma, T.; Baldauf, R.W. (2014) Analysis of 
mobile source air toxics (MSATs)--Near-road VOC and carbonyl 
concentrations. Journal of the Air & Waste Management Association, 
64:3, 349-359, DOI:10.1080/10962247.2013.863814.
    \173\ Kimbrough, S.; Owen, R.C.; Snyder, M.; Richmond-Bryant, J. 
(2017) NO to NO2 Conversion Rate Analysis and 
Implications for Dispersion Model Chemistry Methods using Las Vegas, 
Nevada Near-Road Field Measurements. Atmos Environ 165: 23-24.
    \174\ Hilker, N.; Wang, J.W.; Jong, C-H.; Healy, R.M.; Sofowote, 
U.; Debosz, J.; Su, Y.; Noble, M.; Munoz, A.; Doerkson, G.; White, 
L.; Audette, C.; Herod, D.; Brook, J.R.; Evans, G.J. (2019) Traffic-
related air pollution near roadways: discerning local impacts from 
background. Atmos. Meas. Tech., 12, 5247-5261. https://doi.org/10.5194/amt-12-5247-2019.
    \175\ Grivas, G.; Stavroulas, I.; Liakakou, E.; Kaskaoutis, 
D.G.; Bougiatioti, A.; Paraskevopoulou, D.; Gerasopoulos, E.; 
Mihalopoulos, N. (2019) Measuring the spatial variability of black 
carbon in Athens during wintertime. Air Quality, Atmosphere & Health 
(2019) 12:1405-1417. https://doi.org/10.1007/s11869-019-00756-y.
    \176\ Apte, J.S.; Messier, K.P.; Gani, S.; Brauer, M.; 
Kirchstetter, T.W.; Lunden, M.M.; Marshall, J.D.; Portier, C.J.; 
Vermeulen, R.C.H.; Hamburg, S.P. (2017) High-Resolution Air 
Pollution Mapping with Google Street View Cars: Exploiting Big Data. 
Environ Sci Technol 51: 6999-7008. https://doi.org/10.1021/acs.est.7b00891.
    \177\ Dabek-Zlotorzynska, E.; Celo, V.; Ding, L.; Herod, D.; 
Jeong, C-H.; Evans, G.; Hilker, N. (2019) Characteristics and 
sources of PM2.5 and reactive gases near roadways in two 
metropolitan areas in Canada. Atmos Environ 218: 116980. https://doi.org/10.1016/j.atmosenv.2019.116980.
    \178\ Sarnat, J.A.; Russell, A.; Liang, D.; Moutinho, J.L; 
Golan, R.; Weber, R.; Gao, D.; Sarnat, S.; Chang, H.H.; Greenwald, 
R.; Yu, T. (2018) Developing Multipollutant Exposure Indicators of 
Traffic Pollution: The Dorm Room Inhalation to Vehicle Emissions 
(DRIVE) Study. Health Effects Institute Research Report Number 196. 
[Online at: https://www.healtheffects.org/publication/developing-multipollutant-exposure-indicators-traffic-pollution-dorm-room-inhalation].
---------------------------------------------------------------------------

    For pollutants with relatively high background concentrations 
relative to near-road concentrations, detecting concentration gradients 
can be difficult. For example, many aldehydes have high background 
concentrations as a result of photochemical breakdown of precursors 
from many different organic compounds. However, several studies have 
measured aldehydes in multiple weather conditions and found higher 
concentrations of many carbonyls downwind of 
roadways.179 180 These findings suggest a substantial 
roadway source of these carbonyls.
---------------------------------------------------------------------------

    \179\ Liu, W.; Zhang, J.; Kwon, J.l; et l. (2006). 
Concentrations and source characteristics of airborne carbonyl 
compounds measured outside urban residences. J Air Waste Manage 
Assoc 56: 1196-1204.
    \180\ Cahill, T.M.; Charles, M.J.; Seaman, V.Y. (2010). 
Development and application of a sensitive method to determine 
concentrations of acrolein and other carbonyls in ambient air. 
Health Effects Institute Research Report 149. Available at https://www.healtheffects.org/system/files/Cahill149.pdf.
---------------------------------------------------------------------------

    In the past 20 years, many studies have been published with results 
reporting that populations who live, work, or go to school near high-
traffic roadways experience higher rates of numerous adverse health 
effects, compared to populations far away from major roads.\181\ In 
addition, numerous studies have found adverse health effects associated 
with spending time in traffic, such as commuting or walking along high-
traffic roadways.182 183 184 185 The health outcomes with 
the strongest evidence linking them with traffic-associated air 
pollutants are respiratory effects, particularly in asthmatic children, 
and cardiovascular effects. ANPR commenters stress the importance of 
consideration of the impacts of traffic-related air pollution on 
children's health.
---------------------------------------------------------------------------

    \181\ In the widely-used PubMed database of health publications, 
between January 1, 1990 and August 18, 2011, 605 publications 
contained the keywords ``traffic, pollution, epidemiology,'' with 
approximately half the studies published after 2007.
    \182\ Laden, F.; Hart, J.E.; Smith, T.J.; Davis, M.E.; Garshick, 
E. (2007) Cause-specific mortality in the unionized U.S. trucking 
industry. Environmental Health Perspect 115:1192-1196.
    \183\ Peters, A.; von Klot, S.; Heier, M.; Trentinaglia, I.; 
H[ouml]rmann, A.; Wichmann, H.E.; L[ouml]wel, H. (2004) Exposure to 
traffic and the onset of myocardial infarction. New England J Med 
351: 1721-1730.
    \184\ Zanobetti, A.; Stone, P.H.; Spelzer, F.E.; Schwartz, J.D.; 
Coull, B.A.; Suh, H.H.; Nearling, B.D.; Mittleman, M.A.; Verrier, 
R.L.; Gold, D.R. (2009) T-wave alternans, air pollution and traffic 
in high-risk subjects. Am J Cardiol 104: 665-670.
    \185\ Adar, S.; Adamkiewicz, G.; Gold, D.R.; Schwartz, J.; 
Coull, B.A.; Suh, H. (2007) Ambient and microenvironmental particles 
and exhaled nitric oxide before and after a group bus trip. Environ 
Health Perspect 115: 507-512.
---------------------------------------------------------------------------

    Numerous reviews of this body of health literature have been 
published as well. In 2010, an expert panel of the Health Effects 
Institute (HEI) published a review of hundreds of exposure, 
epidemiology, and toxicology studies.\186\ The panel rated how the 
evidence for each type of health outcome supported a conclusion of a 
causal association with traffic-associated air pollution as either 
``sufficient,'' ``suggestive but not sufficient,'' or ``inadequate and 
insufficient.'' The panel categorized evidence of a causal association 
for exacerbation of childhood asthma as ``sufficient.'' The panel 
categorized evidence of a causal association for new onset asthma as 
between ``sufficient'' and ``suggestive but not sufficient.'' 
``Suggestive of a causal association'' was how the panel categorized 
evidence linking traffic-associated air pollutants with exacerbation of 
adult respiratory symptoms and lung function decrement. It categorized 
as ``inadequate and insufficient'' evidence of a causal relationship 
between traffic-related air pollution and health care utilization for 
respiratory problems, new onset adult asthma, chronic obstructive 
pulmonary disease (COPD), non-asthmatic respiratory allergy, and cancer 
in adults and children. Currently, HEI is conducting another expert 
review of health studies associated with traffic-related air pollution 
published after the studies included in their 2010 review.\187\ Other 
literature reviews have been published with conclusions generally 
similar to the 2010 HEI panel's.188 189 190 191 However, in 
2014, researchers from the U.S. Centers for Disease Control and 
Prevention (CDC) published a systematic review and meta-analysis of 
studies evaluating the risk of childhood leukemia associated with 
traffic exposure and reported positive associations between 
``postnatal'' proximity to traffic and leukemia risks, but no such 
association for ``prenatal'' exposures.\192\ The U.S. Department of 
Health and Human Services' National Toxicology Program (NTP) recently 
published a monograph including a systematic review of traffic-related 
air pollution (TRAP) and its impacts on hypertensive disorders of 
pregnancy. NTP concluded that exposure to TRAP is ``presumed to be a 
hazard to pregnant women'' for developing hypertensive disorders of 
pregnancy.\193\
---------------------------------------------------------------------------

    \186\ Health Effects Institute Panel on the Health Effects of 
Traffic-Related Air Pollution. (2010). Traffic-related air 
pollution: a critical review of the literature on emissions, 
exposure, and health effects. HEI Special Report 17. Available at 
https://www.healtheffects.org.
    \187\ Health Effects Institute. (2019) Protocol for a Systematic 
Review and Meta-Analysis of Selected Health Effects of Long-Term 
Exposure to Traffic-Related Air Pollution. PROSPERO 2019 
CRD42019150642 Available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42019150642.
    \188\ Boothe, V.L.; Shendell, D.G. (2008). Potential health 
effects associated with residential proximity to freeways and 
primary roads: review of scientific literature, 1999-2006. J Environ 
Health 70: 33-41.
    \189\ Salam, M.T.; Islam, T.; Gilliland, F.D. (2008). Recent 
evidence for adverse effects of residential proximity to traffic 
sources on asthma. Curr Opin Pulm Med 14: 3-8.
    \190\ Sun, X.; Zhang, S.; Ma, X. (2014) No association between 
traffic density and risk of childhood leukemia: a meta-analysis. 
Asia Pac J Cancer Prev 15: 5229-5232.
    \191\ Raaschou-Nielsen, O.; Reynolds, P. (2006). Air pollution 
and childhood cancer: a review of the epidemiological literature. 
Int J Cancer 118: 2920-9.
    \192\ Boothe, VL.; Boehmer, T.K.; Wendel, A.M.; Yip, F.Y. (2014) 
Residential traffic exposure and childhood leukemia: a systematic 
review and meta-analysis. Am J Prev Med 46: 413-422.
    \193\ National Toxicology Program (2019) NTP Monograph n the 
Systematic Review of Traffic-related Air Pollution and Hypertensive 
Disorders of Pregnancy. NTP Monograph 7. https://ntp.niehs.nih.gov/ntp/ohat/trap/mgraph/trap_final_508.pdf.
---------------------------------------------------------------------------

    Health outcomes with few publications suggest the possibility of 
other effects still lacking sufficient evidence to draw definitive 
conclusions. Among these outcomes with a small number of positive 
studies are neurological impacts (e.g., autism and reduced cognitive 
function) and reproductive outcomes (e.g., preterm birth, low birth 
weight).194 195 196 197
---------------------------------------------------------------------------

    \194\ Volk, H.E.; Hertz-Picciotto, I.; Delwiche, L.; et al. 
(2011). Residential proximity to freeways and autism in the CHARGE 
study. Environ Health Perspect 119: 873-877.
    \195\ Franco-Suglia, S.; Gryparis, A.; Wright, R.O.; et al. 
(2007). Association of black carbon with cognition among children in 
a prospective birth cohort study. Am J Epidemiol. doi: 10.1093/aje/
kwm308. [Online at https://dx.doi.org].
    \196\ Power, M.C.; Weisskopf, M.G.; Alexeef, SE; et al. (2011). 
Traffic-related air pollution and cognitive function in a cohort of 
older men. Environ Health Perspect 2011: 682-687.
    \197\ Wu, J.; Wilhelm, M.; Chung, J.; et al. (2011). Comparing 
exposure assessment methods for traffic-related air pollution in and 
adverse pregnancy outcome study. Environ Res 111: 685-6692.
---------------------------------------------------------------------------

    In addition to health outcomes, particularly cardiopulmonary 
effects, conclusions of numerous studies suggest mechanisms by which 
traffic-related air pollution affects health. Numerous studies indicate 
that near-roadway exposures may increase systemic inflammation, 
affecting organ systems,

[[Page 17451]]

including blood vessels and lungs.198 199 200 201 Long-term 
exposures in near-road environments have been associated with 
inflammation-associated conditions, such as atherosclerosis and 
asthma.202 203 204
---------------------------------------------------------------------------

    \198\ Riediker, M. (2007). Cardiovascular effects of fine 
particulate matter components in highway patrol officers. Inhal 
Toxicol 19: 99-105. doi:10.1080/08958370701495238
    \199\ Alexeef, SE; Coull, B.A.; Gryparis, A.; et al. (2011). 
Medium-term exposure to traffic-related air pollution and markers of 
inflammation and endothelial function. Environ Health Perspect 119: 
481-486. doi:10.1289/ehp.1002560
    \200\ Eckel. S.P.; Berhane, K.; Salam, M.T.; et al. (2011). 
Residential Traffic-related pollution exposure and exhaled nitric 
oxide in the Children's Health Study. Environ Health Perspect. 
doi:10.1289/ehp.1103516.
    \201\ Zhang, J.; McCreanor, J.E.; Cullinan, P.; et al. (2009). 
Health effects of real-world exposure diesel exhaust in persons with 
asthma. Res Rep Health Effects Inst 138. [Online at https://www.healtheffects.org].
    \202\ Adar, S.D.; Klein, R.; Klein, E.K.; et al. (2010). Air 
pollution and the microvasculature: a cross-sectional assessment of 
in vivo retinal images in the population-based Multi-Ethnic Study of 
Atherosclerosis. PLoS Med 7(11): E1000372. doi:10.1371/
journal.pmed.1000372. Available at https://dx.doi.org.
    \203\ Kan, H.; Heiss, G.; Rose, K.M.; et al. (2008). Prospective 
analysis of traffic exposure as a risk factor for incident coronary 
heart disease: The Atherosclerosis Risk in Communities (ARIC) study. 
Environ Health Perspect 116: 1463-1468. doi:10.1289/ehp.11290. 
Available at https://dx.doi.org.
    \204\ McConnell, R.; Islam, T.; Shankardass, K.; et al. (2010). 
Childhood incident asthma and traffic-related air pollution at home 
and school. Environ Health Perspect 1021-1026.
---------------------------------------------------------------------------

    Several studies suggest that some factors may increase 
susceptibility to the effects of traffic-associated air pollution. 
Several studies have found stronger respiratory associations in 
children experiencing chronic social stress, such as in violent 
neighborhoods or in homes with high family 
stress.205 206 207
---------------------------------------------------------------------------

    \205\ Islam, T.; Urban, R.; Gauderman, W.J.; et al. (2011). 
Parental stress increases the detrimental effect of traffic exposure 
on children's lung function. Am J Respir Crit Care Med.
    \206\ Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; et al. 
(2007). Synergistic effects of traffic-related air pollution and 
exposure to violence on urban asthma etiology. Environ Health 
Perspect 115: 1140-1146.
    \207\ Chen, E.; Schrier, H.M.; Strunk, R.C.; et al. (2008). 
Chronic traffic-related air pollution and stress interact to predict 
biologic and clinical outcomes in asthma. Environ Health Perspect 
116: 970-5.
---------------------------------------------------------------------------

    The risks associated with residence, workplace, or schools near 
major roads are of potentially high public health significance due to 
the large population in such locations. Every two years from 1997 to 
2009 and in 2011, the U.S. Census Bureau's American Housing Survey 
(AHS) conducted a survey that includes whether housing units are within 
300 feet of an ``airport, railroad, or highway with four or more 
lanes.'' \208\ The 2013 AHS was the last AHS that included that 
question. The 2013 survey reports that 17.3 million housing units, or 
13 percent of all housing units in the U.S., were in such areas. 
Assuming that populations and housing units are in the same locations, 
this corresponds to a population of more than 41 million U.S. residents 
in close proximity to high-traffic roadways or other transportation 
sources. According to the Central Intelligence Agency's World Factbook, 
based on data collected between 2012-2014, the United States had 
6,586,610 km of roadways, 293,564 km of railways, and 13,513 airports. 
As such, highways represent the overwhelming majority of transportation 
facilities described by this factor in the AHS.
---------------------------------------------------------------------------

    \208\ The variable was known as ``ETRANS'' in the questions 
about the neighborhood.
---------------------------------------------------------------------------

    EPA also conducted a recent study to estimate the number of people 
living near truck freight routes in the United States.\209\ Based on a 
population analysis using the U.S. Department of Transportation's 
(USDOT) Freight Analysis Framework 4 (FAF4) and population data from 
the 2010 decennial census, an estimated 72 million people live within 
200 meters of these freight routes.\210\ In addition, relative to the 
rest of the population, people of color and those with lower incomes 
are more likely to live near FAF4 truck routes. They are also more 
likely to live in metropolitan areas. Past work has also shown that, on 
average, Americans spend more than an hour traveling each day, bringing 
nearly all residents into a high-exposure microenvironment for part of 
the day.\211\
---------------------------------------------------------------------------

    \209\ U.S. EPA (2021). Estimation of Population Size and 
Demographic Characteristics among People Living Near Truck Routes in 
the Conterminous United States. Memorandum to the Docket.
    \210\ FAF4 is a model from the USDOT's Bureau of Transportation 
Statistics (BTS) and Federal Highway Administration (FHWA), which 
provides data associated with freight movement in the U.S. It 
includes data from the 2012 Commodity Flow Survey (CFS), the Census 
Bureau on international trade, as well as data associated with 
construction, agriculture, utilities, warehouses, and other 
industries. FAF4 estimates the modal choices for moving goods by 
trucks, trains, boats, and other types of freight modes. It includes 
traffic assignments, including truck flows on a network of truck 
routes. https://ops.fhwa.dot.gov/freight/freight_analysis/faf/.
    \211\ EPA. (2011) Exposure Factors Handbook: 2011 Edition. 
Chapter 16. [Online at https://www.epa.gov/sites/production/files/2015-09/documents/efh-chapter16.pdf.
---------------------------------------------------------------------------

8. Environmental Justice
    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes 
federal executive policy on environmental justice. It directs federal 
agencies, to the greatest extent practicable and permitted by law, to 
make achieving environmental justice part of their mission by 
identifying and addressing, as appropriate, disproportionately high and 
adverse human health or environmental effects of their programs, 
policies, and activities on minority populations and low-income 
populations in the United States. EPA defines environmental justice as 
the fair treatment and meaningful involvement of all people regardless 
of race, color, national origin, or income with respect to the 
development, implementation, and enforcement of environmental laws, 
regulations, and policies.\212\
---------------------------------------------------------------------------

    \212\ Fair treatment means that ``no group of people should bear 
a disproportionate burden of environmental harms and risks, 
including those resulting from the negative environmental 
consequences of industrial, governmental and commercial operations 
or programs and policies.'' Meaningful involvement occurs when ``(1) 
potentially affected populations have an appropriate opportunity to 
participate in decisions about a proposed activity [e.g., 
rulemaking] that will affect their environment and/or health; (2) 
the public's contribution can influence [the EPA's rulemaking] 
decision; (3) the concerns of all participants involved will be 
considered in the decision-making process; and (4) [the EPA will] 
seek out and facilitate the involvement of those potentially 
affected.'' A potential EJ concern is defined as ``the actual or 
potential lack of fair treatment or meaningful involvement of 
minority populations, low-income populations, tribes, and indigenous 
peoples in the development, implementation and enforcement of 
environmental laws, regulations and policies.'' See ``Guidance on 
Considering Environmental Justice During the Development of a 
Regulatory Action.'' Environmental Protection Agency, https://www.epa.gov/environmentaljustice/guidance-considering-environmental-justice-during-development-action. See also https://www.epa.gov/environmentaljustice.
---------------------------------------------------------------------------

    Executive Order 14008 (86 FR 7619, February 1, 2021) also calls on 
federal agencies to make achieving environmental justice part of their 
respective missions ``by developing programs, policies, and activities 
to address the disproportionately high and adverse human health, 
environmental, climate-related and other cumulative impacts on 
disadvantaged communities, as well as the accompanying economic 
challenges of such impacts.'' It declares a policy ``to secure 
environmental justice and spur economic opportunity for disadvantaged 
communities that have been historically marginalized and overburdened 
by pollution and under-investment in housing, transportation, water and 
wastewater infrastructure and health care.''
    Under Executive Order 13563 (76 FR 3821, January 18, 2011), federal 
agencies may consider equity, human dignity, fairness, and 
distributional considerations in their regulatory analyses, where 
appropriate and permitted by law.

[[Page 17452]]

    EPA's 2016 ``Technical Guidance for Assessing Environmental Justice 
in Regulatory Analysis'' provides recommendations on conducting the 
highest quality analysis feasible, recognizing that data limitations, 
time and resource constraints, and analytic challenges will vary by 
media and regulatory context.\213\ When assessing the potential for 
disproportionately high and adverse health or environmental impacts of 
regulatory actions on minority populations, low-income populations, 
Tribes, and/or indigenous peoples, the EPA strives to answer three 
broad questions: (1) Is there evidence of potential environmental 
justice (EJ) concerns in the baseline (the state of the world absent 
the regulatory action)? Assessing the baseline will allow the EPA to 
determine whether pre-existing disparities are associated with the 
pollutant(s) under consideration (e.g., if the effects of the 
pollutant(s) are more concentrated in some population groups). (2) Is 
there evidence of potential EJ concerns for the regulatory option(s) 
under consideration? Specifically, how are the pollutant(s) and its 
effects distributed for the regulatory options under consideration? 
And, (3) do the regulatory option(s) under consideration exacerbate or 
mitigate EJ concerns relative to the baseline? It is not always 
possible to quantitatively assess these questions.
---------------------------------------------------------------------------

    \213\ ``Technical Guidance for Assessing Environmental Justice 
in Regulatory Analysis.'' Epa.gov, Environmental Protection Agency, 
https://www.epa.gov/sites/production/files/2016-06/documents/ejtg_5_6_16_v5.1.pdf. (June 2016).
---------------------------------------------------------------------------

    EPA's 2016 Technical Guidance does not prescribe or recommend a 
specific approach or methodology for conducting an environmental 
justice analysis, though a key consideration is consistency with the 
assumptions underlying other parts of the regulatory analysis when 
evaluating the baseline and regulatory options. Where applicable and 
practicable, the Agency endeavors to conduct such an analysis. EPA is 
committed to conducting environmental justice analysis for rulemakings 
based on a framework similar to what is outlined in EPA's Technical 
Guidance, in addition to investigating ways to further weave 
environmental justice into the fabric of the rulemaking process.
    EPA seeks to ensure that no group of people faces a 
disproportionate burden of exposure to mobile-source pollution. In 
general, we expect reduced tailpipe emissions of NOX from 
heavy-duty diesel engines and reduced tailpipe emissions of 
NOX, CO, PM, and VOCs from heavy-duty gasoline engines. See 
Section VI.B for more detail on the emissions reductions from this 
proposal.
    There is evidence that communities with EJ concerns are 
disproportionately impacted by the emissions associated with this 
proposal.\214\ Numerous studies have found that environmental hazards 
such as air pollution are more prevalent in areas where people of color 
and low-income populations represent a higher fraction of the 
population compared with the general population.215 216 217 
Consistent with this evidence, a recent study found that most 
anthropogenic sources of PM2.5, including industrial sources 
and light- and heavy-duty vehicle sources, disproportionately affect 
people of color.\218\ In addition, compared to non-Hispanic Whites, 
some minorities experience greater levels of health problems during 
some life stages. For example, in 2017-2019, about 14 percent of Black, 
non-Hispanic and 8 percent of Hispanic children were estimated to 
currently have asthma, compared with 6 percent of White, non-Hispanic 
children.\219\
---------------------------------------------------------------------------

    \214\ Mohai, P.; Pellow, D.; Roberts Timmons, J. (2009) 
Environmental justice. Annual Reviews 34: 405-430. https://doi.org/10.1146/annurev-environ-082508-094348.
    \215\ Rowangould, G.M. (2013) A census of the near-roadway 
population: public health and environmental justice considerations. 
Trans Res D 25: 59-67. https://dx.doi.org/10.1016/j.trd.2013.08.003.
    \216\ Marshall, J.D., Swor, K.R.; Nguyen, N.P (2014) 
Prioritizing environmental justice and equality: diesel emissions in 
Southern California. Environ Sci Technol 48: 4063-4068. https://doi.org/10.1021/es405167f.
    \217\ Marshall, J.D. (2008) Environmental inequality: air 
pollution exposures in California's South Coast Air Basin. Atmos 
Environ 21: 5499-5503. https://doi.org/10.1016/j.atmosenv.2008.02.005.
    \218\ C. W. Tessum, D. A. Paolella, S. E. Chambliss, J. S. Apte, 
J. D. Hill, J. D. Marshall, PM2.5 polluters 
disproportionately and systemically affect people of color in the 
United States. Sci. Adv. 7, eabf4491 (2021).
    \219\ https://www.cdc.gov/asthma/most_recent_data.htm.
---------------------------------------------------------------------------

    As discussed in Section II.B.7 of this document, concentrations of 
many air pollutants are elevated near high-traffic roadways. In 
addition, numerous state and local commenters on the ANPR noted that 
truck trips frequently start and end around goods movement facilities 
including marine ports and warehouses, making consideration of truck 
emissions an important element of addressing air quality experienced by 
populations living near those facilities.\220\
---------------------------------------------------------------------------

    \220\ New York State Department of Environmental Conservation 
(2019) Albany South End Community Air Quality Study. Division of Air 
Resources. [Online at https://www.dec.ny.gov/chemical/108978.html].
---------------------------------------------------------------------------

    We conducted an analysis of the populations living in close 
proximity to truck freight routes as identified in USDOT's Freight 
Analysis Framework 4 (FAF4).\221\ FAF4 is a model from the USDOT's 
Bureau of Transportation Statistics (BTS) and Federal Highway 
Administration (FHWA), which provides data associated with freight 
movement in the U.S.\222\ Relative to the rest of the population, 
people living near FAF4 truck routes are more likely to be people of 
color and have lower incomes than the general population. People living 
near FAF4 truck routes are also more likely to live in metropolitan 
areas. Even controlling for region of the country, county 
characteristics, population density, and household structure, race, 
ethnicity, and income are significant determinants of whether someone 
lives near a FAF4 truck route.
---------------------------------------------------------------------------

    \221\ U.S. EPA (2021). Estimation of Population Size and 
Demographic Characteristics among People Living Near Truck Routes in 
the Conterminous United States. Memorandum to the Docket.
    \222\ FAF4 includes data from the 2012 Commodity Flow Survey 
(CFS), the Census Bureau on international trade, as well as data 
associated with construction, agriculture, utilities, warehouses, 
and other industries. FAF4 estimates the modal choices for moving 
goods by trucks, trains, boats, and other types of freight modes. It 
includes traffic assignments, including truck flows on a network of 
truck routes. https://ops.fhwa.dot.gov/freight/freight_analysis/faf/
.
---------------------------------------------------------------------------

    We also reviewed existing scholarly literature examining the 
potential for disproportionate exposure among people of color and 
people with low socioeconomic status (SES), and we conducted our own 
evaluation of two national datasets: The U.S. Census Bureau's American 
Housing Survey for calendar year 2009 and the U.S. Department of 
Education's database of school locations. Numerous studies evaluating 
the demographics and socioeconomic status of populations or schools 
near roadways have found that they include a greater percentage of 
residents of color, as well as lower SES populations (as indicated by 
variables such as median household income). Locations in these studies 
include Los Angeles, CA; Seattle, WA; Wayne County, MI; Orange County, 
FL; and the

[[Page 17453]]

State of California.223 224 225 226 227 228 Such disparities 
may be due to multiple factors.\229\
---------------------------------------------------------------------------

    \223\ Marshall, J.D. (2008) Environmental inequality: Air 
pollution exposures in California's South Coast Air Basin.
    \224\ Su, J.G.; Larson, T.; Gould, T.; Cohen, M.; Buzzelli, M. 
(2010) Transboundary air pollution and environmental justice: 
Vancouver and Seattle compared. GeoJournal 57: 595-608. doi:10.1007/
s10708-009-9269-6
    \225\ Chakraborty, J.; Zandbergen, P.A. (2007) Children at risk: 
Measuring racial/ethnic disparities in potential exposure to air 
pollution at school and home. J Epidemiol Community Health 61: 1074-
1079. doi:10.1136/jech.2006.054130
    \226\ Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.; 
Ostro, B. (2004) Proximity of California public schools to busy 
roads. Environ Health Perspect 112: 61-66. doi:10.1289/ehp.6566
    \227\ Wu, Y; Batterman, S.A. (2006) Proximity of schools in 
Detroit, Michigan to automobile and truck traffic. J Exposure Sci & 
Environ Epidemiol. doi:10.1038/sj.jes.7500484
    \228\ Su, J.G.; Jerrett, M.; de Nazelle, A.; Wolch, J. (2011) 
Does exposure to air pollution in urban parks have socioeconomic, 
racial, or ethnic gradients? Environ Res 111: 319-328.
    \229\ Depro, B.; Timmins, C. (2008) Mobility and environmental 
equity: Do housing choices determine exposure to air pollution? Duke 
University Working Paper.
---------------------------------------------------------------------------

    People with low SES often live in neighborhoods with multiple 
stressors and health risk factors, including reduced health insurance 
coverage rates, higher smoking and drug use rates, limited access to 
fresh food, visible neighborhood violence, and elevated rates of 
obesity and some diseases such as asthma, diabetes, and ischemic heart 
disease. Although questions remain, several studies find stronger 
associations between air pollution and health in locations with such 
chronic neighborhood stress, suggesting that populations in these areas 
may be more susceptible to the effects of air 
pollution.230 231 232 233
---------------------------------------------------------------------------

    \230\ Clougherty, J.E.; Kubzansky, L.D. (2009) A framework for 
examining social stress and susceptibility to air pollution in 
respiratory health. Environ Health Perspect 117: 1351-1358. 
Doi:10.1289/ehp.0900612
    \231\ Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; Ryan, P.B.; 
Franco Suglia, S.; Jacobson Canner, M.; Wright, R.J. (2007) 
Synergistic effects of traffic-related air pollution and exposure to 
violence on urban asthma etiology. Environ Health Perspect 115: 
1140-1146. doi:10.1289/ehp.9863
    \232\ Finkelstein, M.M.; Jerrett, M.; DeLuca, P.; Finkelstein, 
N.; Verma, D.K.; Chapman, K.; Sears, M.R. (2003) Relation between 
income, air pollution and mortality: A cohort study. Canadian Med 
Assn J 169: 397-402.
    \233\ Shankardass, K.; McConnell, R.; Jerrett, M.; Milam, J.; 
Richardson, J.; Berhane, K. (2009) Parental stress increases the 
effect of traffic-related air pollution on childhood asthma 
incidence. Proc Natl Acad Sci 106: 12406-12411. doi:10.1073/
pnas.0812910106
---------------------------------------------------------------------------

    Several publications report nationwide analyses that compare the 
demographic patterns of people who do or do not live near major 
roadways.234 235 236 237 238 239 Three of these studies 
found that people living near major roadways are more likely to be 
minorities or low in SES.240 241 242 They also found that 
the outcomes of their analyses varied between regions within the U.S. 
However, only one such study looked at whether such conclusions were 
confounded by living in a location with higher population density and 
how demographics differ between locations nationwide.\243\ In general, 
it found that higher density areas have higher proportions of low-
income residents and people of color. In other publications based on a 
city, county, or state, the results are similar.244 245
---------------------------------------------------------------------------

    \234\ Rowangould, G.M. (2013) A census of the U.S. near-roadway 
population: Public health and environmental justice considerations. 
Transportation Research Part D; 59-67.
    \235\ Tian, N.; Xue, J.; Barzyk, T.M. (2013) Evaluating 
socioeconomic and racial differences in traffic-related metrics in 
the United States using a GIS approach. J Exposure Sci Environ 
Epidemiol 23: 215-222.
    \236\ CDC (2013) Residential proximity to major highways--United 
States, 2010. Morbidity and Mortality Weekly Report 62(3): 46-50.
    \237\ Clark, L.P.; Millet, D.B., Marshall, J.D. (2017) Changes 
in transportation-related air pollution exposures by race-ethnicity 
and socioeconomic status: Outdoor nitrogen dioxide in the United 
States in 2000 and 2010. Environ Health Perspect https://doi.org/10.1289/EHP959.
    \238\ Mikati, I.; Benson, A.F.; Luben, T.J.; Sacks, J.D.; 
Richmond-Bryant, J. (2018) Disparities in distribution of 
particulate matter emission sources by race and poverty status. Am J 
Pub Health https://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2017.304297?journalCode=ajph.
    \239\ Alotaibi, R.; Bechle, M.; Marshall, J.D.; Ramani, T.; 
Zietsman, J.; Nieuwenhuijsen, M.J.; Khreis, H. (2019) Traffic 
related air pollution and the burden of childhood asthma in the 
continuous United States in 2000 and 2010. Environ International 
127: 858-867. https://www.sciencedirect.com/science/article/pii/S0160412018325388.
    \240\ Tian, N.; Xue, J.; Barzyk, T.M. (2013) Evaluating 
socioeconomic and racial differences in traffic-related metrics in 
the United States using a GIS approach. J Exposure Sci Environ 
Epidemiol 23: 215-222.
    \241\ Rowangould, G.M. (2013) A census of the U.S. near-roadway 
population: Public health and environmental justice considerations. 
Transportation Research Part D; 59-67.
    \242\ CDC (2013) Residential proximity to major highways--United 
States, 2010. Morbidity and Mortality Weekly Report 62(3): 46-50.
    \243\ Rowangould, G.M. (2013) A census of the U.S. near-roadway 
population: Public health and environmental justice considerations. 
Transportation Research Part D; 59-67.
    \244\ Pratt, G.C.; Vadali, M.L.; Kvale, D.L.; Ellickson, K.M. 
(2015) Traffic, air pollution, minority, and socio-economic status: 
Addressing inequities in exposure and risk. Int J Environ Res Public 
Health 12: 5355-5372. https://dx.doi.org/10.3390/ijerph120505355.
    \245\ Sohrabi, S.; Zietsman, J.; Khreis, H. (2020) Burden of 
disease assessment of ambient air pollution and premature mortality 
in urban areas: The role of socioeconomic status and transportation. 
Int J Env Res Public Health doi:10.3390/ijerph17041166.
---------------------------------------------------------------------------

    We analyzed two national databases that allowed us to evaluate 
whether homes and schools were located near a major road and whether 
disparities in exposure may be occurring in these environments. The 
American Housing Survey (AHS) includes descriptive statistics of over 
70,000 housing units across the nation. The survey is conducted every 
two years by the U.S. Census Bureau.\246\ The second database we 
analyzed was the U.S. Department of Education's Common Core of Data, 
which includes enrollment and location information for schools across 
the U.S.\247\
---------------------------------------------------------------------------

    \246\ U.S. Department of Housing and Urban Development, & U.S. 
Census Bureau. (n.d.). Age of other residential buildings within 300 
feet. In American Housing Survey for the United States: 2009 (pp. A-
1). Retrieved from https://www.census.gov/programs-surveys/ahs/data/2009/ahs-2009-summary-tables0/h150-09.html.
    \247\ https://nces.ed.gov/ccd/.
---------------------------------------------------------------------------

    In analyzing the 2009 AHS, we focused on whether a housing unit was 
located within 300 feet, the distance provided in the AHS data, of a 
``4-or-more lane highway, railroad, or airport.'' \248\ We analyzed 
whether there were differences between households in such locations 
compared with those in locations farther from these transportation 
facilities.\249\ We included other variables, such as land use 
category, region of country, and housing type. We found that homes with 
a non-White householder were 22-34 percent more likely to be located 
within 300 feet of these large transportation facilities than homes 
with White householders. Homes with a Hispanic householder were 17-33 
percent more likely to be located within 300 feet of these large 
transportation facilities than homes with non-Hispanic householders. 
Households near large transportation facilities were, on average, lower 
in income and educational attainment and more likely to be a rental 
property and located in an urban area compared with households more 
distant from transportation facilities.
---------------------------------------------------------------------------

    \248\ This variable primarily represents roadway proximity. 
According to the Central Intelligence Agency's World Factbook, in 
2010, the United States had 6,506,204 km of roadways, 224,792 km of 
railways, and 15,079 airports. Highways thus represent the 
overwhelming majority of transportation facilities described by this 
factor in the AHS.
    \249\ Bailey, C. (2011) Demographic and Social Patterns in 
Housing Units Near Large Highways and other Transportation Sources. 
Memorandum to docket.
---------------------------------------------------------------------------

    In examining schools near major roadways, we examined the Common 
Core of Data (CCD) from the U.S. Department of Education, which 
includes information on all public elementary and secondary schools and 
school districts nationwide.\250\ To determine school proximities to 
major

[[Page 17454]]

roadways, we used a geographic information system (GIS) to map each 
school and roadways based on the U.S. Census's TIGER roadway file.\251\ 
We found that students of color were overrepresented at schools within 
200 meters of the largest roadways, and schools within 200 meters of 
the largest roadways had higher than expected numbers of students 
eligible for free or reduced-price lunches.\252\ For example, Black 
students represent 22 percent of students at schools located within 200 
meters of a primary road, compared to 17 percent of students in all 
U.S. schools. Hispanic students represent 30 percent of students at 
schools located within 200 meters of a primary road, compared to 22 
percent of students in all U.S. schools.
---------------------------------------------------------------------------

    \250\ https://nces.ed.gov/ccd/.
    \251\ Pedde, M.; Bailey, C. (2011) Identification of Schools 
within 200 Meters of U.S. Primary and Secondary Roads. Memorandum to 
the docket.
    \252\ For this analysis we analyzed a 200-meter distance based 
on the understanding that roadways generally influence air quality 
within a few hundred meters from the vicinity of heavily traveled 
roadways or along corridors with significant trucking traffic. See 
U.S. EPA, 2014. Near Roadway Air Pollution and Health: Frequently 
Asked Questions. EPA-420-F-14-044.
---------------------------------------------------------------------------

    Overall, there is substantial evidence that people who live or 
attend school near major roadways are more likely to be of a non-White 
race, Hispanic, and/or have a low SES. Although proximity to an 
emissions source is an indicator of potential exposure, it is important 
to note that the impacts of emissions from tailpipe sources are not 
limited to communities in close proximity to these sources. For 
example, the effects of potential decreases in emissions from sources 
that would be affected by this proposal might also be felt many miles 
away, including in communities with EJ concerns. The spatial extent of 
these impacts depends on a range of interacting and complex factors 
including the amount of pollutant emitted, atmospheric lifetime of the 
pollutant, terrain, atmospheric chemistry and meteorology.
    We also conducted an analysis of how the air quality impacts from 
this proposed rule would be distributed among different populations, 
specifically focusing on PM2.5 and ozone concentrations in 
the contiguous U.S. This analysis assessed whether areas with the worst 
projected baseline air quality in 2045 have larger numbers of people of 
color living in them, and if those with the worst projected air quality 
would benefit more from the proposed rule. We found that in the 2045 
baseline, nearly double the number of people of color live within areas 
with the worst air quality, compared to non-Hispanic Whites (NH-
Whites). We also found that the largest improvements in both ozone and 
PM2.5 are estimated to occur in these areas with the worst 
baseline air quality. See Section VII.H for additional information on 
the demographic analysis.
    In summary, we expect this proposed rule would result in reductions 
of emissions that contribute to ozone, PM2.5, and other 
harmful pollution. The emission reductions from this proposed rule 
would result in widespread air quality improvements, including in the 
areas with the worst baseline air quality, where a larger number of 
people of color are projected to reside.

C. Environmental Effects Associated With Exposure to Pollutants 
Impacted by This Proposal

    This section discusses the environmental effects associated with 
pollutants affected by this proposed rule, specifically particulate 
matter, ozone, NOX and air toxics.
1. Visibility
    Visibility can be defined as the degree to which the atmosphere is 
transparent to visible light.\253\ Visibility impairment is caused by 
light scattering and absorption by suspended particles and gases. It is 
dominated by contributions from suspended particles except under 
pristine conditions. Visibility is important because it has direct 
significance to people's enjoyment of daily activities in all parts of 
the country. Individuals value good visibility for the well-being it 
provides them directly, where they live and work, and in places where 
they enjoy recreational opportunities. Visibility is also highly valued 
in significant natural areas, such as national parks and wilderness 
areas, and special emphasis is given to protecting visibility in these 
areas. For more information on visibility see the final 2019 PM 
ISA.\254\
---------------------------------------------------------------------------

    \253\ National Research Council, (1993). Protecting Visibility 
in National Parks and Wilderness Areas. National Academy of Sciences 
Committee on Haze in National Parks and Wilderness Areas. National 
Academy Press, Washington, DC. This book can be viewed on the 
National Academy Press website at https://www.nap.edu/catalog/2097/protecting-visibility-in-national-parks-and-wilderness-areas.
    \254\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
---------------------------------------------------------------------------

    EPA is working to address visibility impairment. Reductions in air 
pollution from implementation of various programs associated with the 
Clean Air Act Amendments of 1990 provisions have resulted in 
substantial improvements in visibility and will continue to do so in 
the future. Because trends in haze are closely associated with trends 
in particulate sulfate and nitrate due to the relationship between 
their concentration and light extinction, visibility trends have 
improved as emissions of SO2 and NOX have 
decreased over time due to air pollution regulations such as the Acid 
Rain Program.\255\
---------------------------------------------------------------------------

    \255\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
---------------------------------------------------------------------------

    In the Clean Air Act Amendments of 1977, Congress recognized 
visibility's value to society by establishing a national goal to 
protect national parks and wilderness areas from visibility impairment 
caused by manmade pollution.\256\ In 1999, EPA finalized the regional 
haze program to protect the visibility in Mandatory Class I Federal 
areas.\257\ There are 156 national parks, forests and wilderness areas 
categorized as Mandatory Class I Federal areas.\258\ These areas are 
defined in CAA section 162 as those national parks exceeding 6,000 
acres, wilderness areas and memorial parks exceeding 5,000 acres, and 
all international parks which were in existence on August 7, 1977.
---------------------------------------------------------------------------

    \256\ See Section 169(a) of the Clean Air Act.
    \257\ 64 FR 35714, July 1, 1999.
    \258\ 62 FR 38680-38681, July 18, 1997.
---------------------------------------------------------------------------

    EPA has also concluded that PM2.5 causes adverse effects 
on visibility in other areas that are not targeted by the Regional Haze 
Rule, such as urban areas, depending on PM2.5 concentrations 
and other factors such as dry chemical composition and relative 
humidity (i.e., an indicator of the water composition of the 
particles). EPA revised the PM2.5 NAAQS in 2012, retained it 
in 2020, and established a target level of protection that is expected 
to be met through attainment of the existing secondary standards for 
PM2.5.\259\
---------------------------------------------------------------------------

    \259\ On June 10, 2021, EPA announced that it will reconsider 
the previous administration's decision to retain the PM NAAQS. 
https://www.epa.gov/pm-pollution/national-ambient-air-quality-standards-naaqs-pm.
---------------------------------------------------------------------------

2. Plant and Ecosystem Effects of Ozone
    The welfare effects of ozone include effects on ecosystems, which 
can be observed across a variety of scales, i.e., subcellular, 
cellular, leaf, whole plant, population and ecosystem. Ozone effects 
that begin at small spatial scales, such as the leaf of an individual 
plant, when they occur at sufficient magnitudes (or to a sufficient 
degree) can result in effects being propagated along a continuum to 
higher and higher levels of biological organization. For example, 
effects at the individual plant level, such as altered rates of leaf 
gas exchange, growth and reproduction,

[[Page 17455]]

can, when widespread, result in broad changes in ecosystems, such as 
productivity, carbon storage, water cycling, nutrient cycling, and 
community composition.
    Ozone can produce both acute and chronic injury in sensitive plant 
species depending on the concentration level and the duration of the 
exposure.\260\ In those sensitive species,\261\ effects from repeated 
exposure to ozone throughout the growing season of the plant can tend 
to accumulate, so that even relatively low concentrations experienced 
for a longer duration have the potential to create chronic stress on 
vegetation.262 263 Ozone damage to sensitive plant species 
includes impaired photosynthesis and visible injury to leaves. The 
impairment of photosynthesis, the process by which the plant makes 
carbohydrates (its source of energy and food), can lead to reduced crop 
yields, timber production, and plant productivity and growth. Impaired 
photosynthesis can also lead to a reduction in root growth and 
carbohydrate storage below ground, resulting in other, more subtle 
plant and ecosystems impacts.\264\ These latter impacts include 
increased susceptibility of plants to insect attack, disease, harsh 
weather, interspecies competition and overall decreased plant vigor. 
The adverse effects of ozone on areas with sensitive species could 
potentially lead to species shifts and loss from the affected 
ecosystems,\265\ resulting in a loss or reduction in associated 
ecosystem goods and services. Additionally, visible ozone injury to 
leaves can result in a loss of aesthetic value in areas of special 
scenic significance like national parks and wilderness areas and 
reduced use of sensitive ornamentals in landscaping.\266\ In addition 
to ozone effects on vegetation, newer evidence suggests that ozone 
affects interactions between plants and insects by altering chemical 
signals (e.g., floral scents) that plants use to communicate to other 
community members, such as attraction of pollinators.
---------------------------------------------------------------------------

    \260\ 73 FR 16486, March 27, 2008.
    \261\ 73 FR 16491, March 27, 2008. Only a small percentage of 
all the plant species growing within the U.S. (over 43,000 species 
have been catalogued in the USDA PLANTS database) have been studied 
with respect to ozone sensitivity.
    \262\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone 
and Related Photochemical Oxidants (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012, 
2020.
    \263\ The concentration at which ozone levels overwhelm a 
plant's ability to detoxify or compensate for oxidant exposure 
varies. Thus, whether a plant is classified as sensitive or tolerant 
depends in part on the exposure levels being considered.
    \264\ 73 FR 16492, March 27, 2008.
    \265\ 73 FR 16493-16494, March 27, 2008. Ozone impacts could be 
occurring in areas where plant species sensitive to ozone have not 
yet been studied or identified.
    \266\ 73 FR 16490-16497, March 27, 2008.
---------------------------------------------------------------------------

    The Ozone ISA presents more detailed information on how ozone 
affects vegetation and ecosystems.267 268 The Ozone ISA 
reports causal and likely causal relationships between ozone exposure 
and a number of welfare effects and characterizes the weight of 
evidence for different effects associated with ozone.\269\ The ISA 
concludes that visible foliar injury effects on vegetation, reduced 
vegetation growth, reduced plant reproduction, reduced productivity in 
terrestrial ecosystems, reduced yield and quality of agricultural 
crops, alteration of below-ground biogeochemical cycles, and altered 
terrestrial community composition are causally associated with exposure 
to ozone. It also concludes that increased tree mortality, altered 
herbivore growth and reproduction, altered plant-insect signaling, 
reduced carbon sequestration in terrestrial ecosystems, and alteration 
of terrestrial ecosystem water cycling are likely to be causally 
associated with exposure to ozone.
---------------------------------------------------------------------------

    \267\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone 
and Related Photochemical Oxidants (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012, 
2020.
    \268\ U.S. EPA. Integrated Science Assessment (ISA) for Ozone 
and Related Photochemical Oxidants (Final Report). U.S. 
Environmental Protection Agency, Washington, DC, EPA/600/R-20/012, 
2020.
    \269\ The Ozone ISA evaluates the evidence associated with 
different ozone related health and welfare effects, assigning one of 
five ``weight of evidence'' determinations: Causal relationship, 
likely to be a causal relationship, suggestive of a causal 
relationship, inadequate to infer a causal relationship, and not 
likely to be a causal relationship. For more information on these 
levels of evidence, please refer to Table II of the ISA.
---------------------------------------------------------------------------

3. Atmospheric Deposition
    The Integrated Science Assessment for Oxides of Nitrogen, Oxides of 
Sulfur, and Particulate Matter--Ecological Criteria documents the 
ecological effects of the deposition of these criteria air 
pollutants.\270\ It is clear from the body of evidence that oxides of 
nitrogen, oxides of sulfur, and particulate matter contribute to total 
nitrogen (N) and sulfur (S) deposition. In turn, N and S deposition 
cause either nutrient enrichment or acidification depending on the 
sensitivity of the landscape or the species in question. Both 
enrichment and acidification are characterized by an alteration of the 
biogeochemistry and the physiology of organisms, resulting in harmful 
declines in biodiversity in terrestrial, freshwater, wetland, and 
estuarine ecosystems in the U.S. Decreases in biodiversity mean that 
some species become relatively less abundant and may be locally 
extirpated. In addition to the loss of unique living species, the 
decline in total biodiversity can be harmful because biodiversity is an 
important determinant of the stability of ecosystems and their ability 
to provide socially valuable ecosystem services.
---------------------------------------------------------------------------

    \270\ U.S. EPA. Integrated Science Assessment (ISA) for Oxides 
of Nitrogen, Oxides of Sulfur and Particulate Matter Ecological 
Criteria (Final Report). U.S. Environmental Protection Agency, 
Washington, DC, EPA/600/R-20/278, 2020.
---------------------------------------------------------------------------

    Terrestrial, wetland, freshwater, and estuarine ecosystems in the 
U.S. are affected by N enrichment/eutrophication caused by N 
deposition. These effects have been consistently documented across the 
U.S. for hundreds of species. In aquatic systems increased nitrogen can 
alter species assemblages and cause eutrophication. In terrestrial 
systems nitrogen loading can lead to loss of nitrogen-sensitive lichen 
species, decreased biodiversity of grasslands, meadows and other 
sensitive habitats, and increased potential for invasive species. For a 
broader explanation of the topics treated here, refer to the 
description in Chapter 4 of the draft RIA.
    The sensitivity of terrestrial and aquatic ecosystems to 
acidification from nitrogen and sulfur deposition is predominantly 
governed by geology. Prolonged exposure to excess nitrogen and sulfur 
deposition in sensitive areas acidifies lakes, rivers, and soils. 
Increased acidity in surface waters creates inhospitable conditions for 
biota and affects the abundance and biodiversity of fishes, zooplankton 
and macroinvertebrates and ecosystem function. Over time, acidifying 
deposition also removes essential nutrients from forest soils, 
depleting the capacity of soils to neutralize future acid loadings and 
negatively affecting forest sustainability. Major effects in forests 
include a decline in sensitive tree species, such as red spruce (Picea 
rubens) and sugar maple (Acer saccharum).
    Building materials including metals, stones, cements, and paints 
undergo natural weathering processes from exposure to environmental 
elements (e.g., wind, moisture, temperature fluctuations, sunlight, 
etc.). Pollution can worsen and accelerate these effects. Deposition of 
PM is associated with both physical damage (materials damage effects) 
and impaired aesthetic qualities (soiling effects). Wet and dry 
deposition of PM can physically affect materials, adding to the effects 
of natural weathering processes, by potentially promoting or 
accelerating the corrosion of metals, by degrading paints and by 
deteriorating building materials such as

[[Page 17456]]

stone, concrete and marble.\271\ The effects of PM are exacerbated by 
the presence of acidic gases and can be additive or synergistic due to 
the complex mixture of pollutants in the air and surface 
characteristics of the material. Acidic deposition has been shown to 
have an effect on materials including zinc/galvanized steel and other 
metal, carbonate stone (as monuments and building facings), and surface 
coatings (paints).\272\ The effects on historic buildings and outdoor 
works of art are of particular concern because of the uniqueness and 
irreplaceability of many of these objects. In addition to aesthetic and 
functional effects on metals, stone and glass, altered energy 
efficiency of photovoltaic panels by PM deposition is also becoming an 
important consideration for impacts of air pollutants on materials.
---------------------------------------------------------------------------

    \271\ U.S. EPA. Integrated Science Assessment (ISA) for 
Particulate Matter (Final Report, 2019). U.S. Environmental 
Protection Agency, Washington, DC, EPA/600/R-19/188, 2019.
    \272\ Irving, P.M., e.d. 1991. Acid Deposition: State of Science 
and Technology, Volume III, Terrestrial, Materials, Health, and 
Visibility Effects, The U.S. National Acid Precipitation Assessment 
Program, Chapter 24, page 24-76.
---------------------------------------------------------------------------

4. Environmental Effects of Air Toxics
    Emissions from producing, transporting and combusting fuel 
contribute to ambient levels of pollutants that contribute to adverse 
effects on vegetation. Volatile organic compounds (VOCs), some of which 
are considered air toxics, have long been suspected to play a role in 
vegetation damage.\273\ In laboratory experiments, a wide range of 
tolerance to VOCs has been observed.\274\ Decreases in harvested seed 
pod weight have been reported for the more sensitive plants, and some 
studies have reported effects on seed germination, flowering and fruit 
ripening. Effects of individual VOCs or their role in conjunction with 
other stressors (e.g., acidification, drought, temperature extremes) 
have not been well studied. In a recent study of a mixture of VOCs 
including ethanol and toluene on herbaceous plants, significant effects 
on seed production, leaf water content and photosynthetic efficiency 
were reported for some plant species.\275\
---------------------------------------------------------------------------

    \273\ U.S. EPA. (1991). Effects of organic chemicals in the 
atmosphere on terrestrial plants. EPA/600/3-91/001.
    \274\ Cape JN, ID Leith, J Binnie, J Content, M Donkin, M 
Skewes, DN Price AR Brown, AD Sharpe. (2003). Effects of VOCs on 
herbaceous plants in an open-top chamber experiment. Environ. 
Pollut. 124:341-343.
    \275\ Cape JN, ID Leith, J Binnie, J Content, M Donkin, M 
Skewes, DN Price AR Brown, AD Sharpe. (2003). Effects of VOCs on 
herbaceous plants in an open-top chamber experiment. Environ. 
Pollut. 124:341-343.
---------------------------------------------------------------------------

    Research suggests an adverse impact of vehicle exhaust on plants, 
which has in some cases been attributed to aromatic compounds and in 
other cases to nitrogen oxides.276 277 278 The impacts of 
VOCs on plant reproduction may have long-term implications for 
biodiversity and survival of native species near major roadways. Most 
of the studies of the impacts of VOCs on vegetation have focused on 
short-term exposure and few studies have focused on long-term effects 
of VOCs on vegetation and the potential for metabolites of these 
compounds to affect herbivores or insects.
---------------------------------------------------------------------------

    \276\ Viskari E.-L. (2000). Epicuticular wax of Norway spruce 
needles as indicator of traffic pollutant deposition. Water, Air, 
and Soil Pollut. 121:327-337.
    \277\ Ugrekhelidze D, F Korte, G Kvesitadze. (1997). Uptake and 
transformation of benzene and toluene by plant leaves. Ecotox. 
Environ. Safety 37:24-29.
    \278\ Kammerbauer H, H Selinger, R Rommelt, A Ziegler-Jons, D 
Knoppik, B Hock. (1987). Toxic components of motor vehicle emissions 
for the spruce Picea abies. Environ. Pollut. 48:235-243.
---------------------------------------------------------------------------

III. Proposed Test Procedures and Standards

    In applying heavy-duty criteria pollutant emission standards, EPA 
divides engines primarily into two types: Compression ignition (CI) 
(primarily diesel-fueled engines) and spark-ignition (SI) (primarily 
gasoline-fueled engines). The CI standards and requirements also apply 
to the largest natural gas engines. Battery-electric and fuel-cell 
vehicles are also subject to criteria pollutant standards and 
requirements. All heavy-duty highway engines are subject to brake-
specific (g/hp-hr) exhaust emission standards for four criteria 
pollutants: Oxides of nitrogen (NOX), particulate matter 
(PM), hydrocarbons (HC), and carbon monoxide (CO).\279\ In this section 
we describe two regulatory options for new emissions standards: 
Proposed Option 1 and proposed Option 2 and updates we are proposing to 
the test procedures that apply for these pollutants. Unless explicitly 
stated otherwise, the proposed provisions in this section and Section 
IV would apply to proposed Options 1 and 2, as well as the full range 
of options in between them.\280\
---------------------------------------------------------------------------

    \279\ Reference to hydrocarbon (HC) standards includes 
nonmethane hydrocarbon (NMHC), nonmethane-nonethane hydrocarbon 
(NMNEHC) and nonmethane hydrocarbon equivalent (NMHCE). See 40 CFR 
86.007-11.
    \280\ As detailed throughout Sections III and IV, we provide 
proposed regulatory text for the proposed Option 1. We expect that 
the proposed Option 2 regulatory text would be the same as text for 
the proposed Option 1 except for the number of steps and numeric 
values of the criteria pollutant standards and lengths of useful 
life and warranty periods.
---------------------------------------------------------------------------

A. Overview

    In the following section, we provide an overview of our proposal to 
migrate and update our criteria pollutant regulations for model year 
2027 and later heavy-duty highway engines, our proposed Options 1 and 2 
standards and test procedures, and our analysis demonstrating the 
feasibility of the proposed standards. The sections that follow provide 
more detail on each of these topics. Section III.B and Section III.D 
include the proposed changes to our laboratory-based standards and test 
procedures for heavy-duty compression-ignition and spark-ignition 
engines, respectively. Section III.C introduces our proposed off-cycle 
standards and test procedures that extend beyond the laboratory to on-
the-road, real-world conditions. Section III.E describes our proposal 
for new refueling standards for certain heavy-duty spark-ignition 
engines. Each of these sections include descriptions of the current 
standards and test procedures and our proposed updates, including our 
feasibility demonstrations and the data we relied on to support our 
proposals.
1. Migration and Clarifications of Regulatory Text
    As noted in Section I of this preamble, we are proposing to migrate 
our criteria pollutant regulations for model year 2027 and later heavy-
duty highway engines from their current location in 40 CFR part 86, 
subpart A, to 40 CFR part 1036.\281\ Consistent with this migration, 
the proposed compliance provisions discussed in this section refer to 
the proposed regulations in their new location in part 1036. In 
general, this migration is not intended to change the compliance 
program previously specified in part 86, except as specifically 
proposed in this rulemaking. See our memorandum to the docket for a 
detailed description of the proposed migration.\282\ The proposal 
includes updating cross references to 40 CFR parts 86 and 1036 in 
several places to properly cite the new rulemaking provisions in this 
rule.
---------------------------------------------------------------------------

    \281\ As noted in the following sections, we are proposing some 
updates to 40 CFR parts 1037, 1065, and 1068 to apply to other 
sectors in addition to heavy-duty highway engines.
    \282\ Stout, Alan; Brakora, Jessica. Memorandum to docket EPA-
HQ-OAR-2019-0055. ``Technical Issues Related to Migrating Heavy-Duty 
Highway Engine Certification Requirements from 40 CFR part 86, 
subpart A, to 40 CFR part 1036''. October 1, 2021.
---------------------------------------------------------------------------

i. Compression- and Spark-Ignition Engines Regulatory Text
    For many years, the regulations of 40 CFR part 86 have referred to 
``diesel

[[Page 17457]]

heavy-duty engines'' and ``Otto-cycle heavy-duty engines''; however, as 
we migrate the heavy-duty provisions of 40 CFR part 86, subpart A, to 
40 CFR part 1036 in this proposal, we refer to these engines as 
``compression-ignition'' (CI) and ``spark-ignition'' (SI), 
respectively, which are more comprehensive terms and consistent with 
existing language in 40 CFR part 1037 for heavy-duty motor vehicle 
regulations. In this section, and throughout the preamble, reference to 
diesel and Otto-cycle engines is generally limited to discussions 
relating to current test procedures and specific terminology used in 40 
CFR part 86. We are also proposing to update the terminology for the 
primary intended service classes in 40 CFR 1036.140 to replace Heavy 
heavy-duty engine with Heavy HDE, Medium heavy-duty engine with Medium 
HDE, Light heavy-duty engine with Light HDE, and Spark-ignition heavy-
duty engine with Spark-ignition HDE.\283\ Our proposal includes 
revisions throughout 40 CFR parts 1036 and 1037 to reflect this updated 
terminology.
---------------------------------------------------------------------------

    \283\ This proposed terminology for engines is also consistent 
with the ``HDV'' terminology used for vehicle classifications in 40 
CFR 1037.140.
---------------------------------------------------------------------------

ii. Heavy-Duty Hybrid Regulatory Text
    Similar to our updates to more comprehensive and consistent 
terminology for CI and SI engines, as part of this proposal we are also 
updating and clarifying regulatory language for hybrid engines and 
hybrid powertrains. We propose to update the definition of ``engine 
configuration'' in 40 CFR 1036.801 to clarify that an engine 
configuration would include hybrid components if it is certified as a 
hybrid engine or hybrid powertrain. We are proposing first to clarify 
in 40 CFR 1036.101(b) that regulatory references in part 1036 to 
engines generally apply to hybrid engines and hybrid powertrains. We 
are also proposing to clarify in 40 CFR 1036.101(b) that manufacturers 
may optionally test the hybrid engine and powertrain together, rather 
than testing the engine alone; this option would allow manufacturers to 
demonstrate emission performance of the hybrid technology that are not 
apparent when testing the engine alone.
    To certify a hybrid engine or hybrid powertrain to criteria 
pollutant standards, we propose that manufacturers would declare a 
primary intended service class of the engine configuration using the 
proposed updated 40 CFR 1036.140. The current provisions of 40 CFR 
1036.140 distinguish classes based on engine characteristics and 
characteristics of the vehicles for which manufacturers intend to 
design and market their engines. Under this proposal, manufacturers 
certifying hybrid engines and hybrid powertrains would use good 
engineering judgment to identify the class that best describes their 
engine configuration.\284\ Once a primary intended service class is 
declared, the engine configuration would be subject to all the criteria 
pollutant emission standards and related compliance provisions for that 
class.
---------------------------------------------------------------------------

    \284\ For example, an engine configuration that includes an SI 
engine and hybrid powertrain intended for a Class 4 vehicle would 
certify to the proposed Spark-ignition HDE provisions.
---------------------------------------------------------------------------

    We propose to update 40 CFR 1036.230(c) to include hybrid 
powertrains and are proposing that engine configurations certified as 
hybrid engine or hybrid powertrain may not be included in an engine 
family with conventional engines, consistent with the current 
provisions. We note that this provision would result in more engine 
families for manufacturers certifying hybrids. We request comment on 
our proposed clarification in 40 CFR 1036.101(b) that manufacturers may 
optionally test the hybrid engine and powertrain together, rather than 
testing the engine alone. Specifically, we are interested in 
stakeholder input on whether EPA should require all hybrid engines and 
powertrains to be certified together, rather than making it optional. 
We are interested in commenters' views on the impact of additional 
engine/powertrain families if we were to require powertrain testing for 
all hybrid engine and powertrain engine configurations, including a 
manufacturers' ability to conduct certification testing and any 
recommended steps EPA should take to address such effects. We are also 
interested in commenters' views on whether the powertrain test always 
provides test results that are more representative of hybrid emission 
performance in the real world, or if for some hybrid systems the engine 
test procedure provides equally or more representative results. For 
instance, we solicit comment on whether for some hybrids, such as mild-
hybrids, the powertrain test should continue to be an option, even if 
we were to require that all other hybrids must use the powertrain test.
    We are also interested in stakeholder input on potential 
alternative approaches, such as if EPA were to add new, separate 
service classes for hybrid engines and powertrains in the final rule. 
Distinct service classes for hybrid engines and powertrains could allow 
EPA to consider separate emission standards, useful life, and/or test 
procedures for hybrids based on unique performance attributes; however, 
it could also add burden to EPA and manufacturers by creating 
additional categories to track and maintain. We request that commenters 
suggesting separate primary intended service classes for hybrid engines 
and powertrains include data, if possible, to support an analysis of 
appropriate corresponding emission standards, useful life periods, and 
other compliance requirements.
iii. Heavy-Duty Electric Vehicles Regulatory Text
    Similar to our updates to more comprehensive and consistent 
terminology, as part of this proposal we are also updating and 
consolidating regulatory language for battery-electric vehicles and 
fuel cell electric vehicles (BEVs and FCEVs). For BEVs and FCEVs, we 
are proposing to consolidate and update our regulations as part of a 
migration of heavy-duty vehicle regulations from 40 CFR part 86 to 40 
CFR part 1037. In the GHG Phase 1 rulemaking, EPA revised the heavy-
duty vehicle and engine regulations to make them consistent with our 
regulatory approach to electric vehicles (EVs) under the light-duty 
vehicle program. Specifically, we applied standards for all regulated 
criteria pollutants and GHGs to all heavy-duty vehicle types, including 
EVs.\285\ Starting in MY 2016, criteria pollutant standards and 
requirements applicable to heavy-duty vehicles at or below 14,000 
pounds GVWR in 40 CFR part 86, subpart S, applied to heavy-duty EVs 
above 14,000 pounds GVWR through the use of good engineering judgment 
(see current 40 CFR 86.016-1(d)(4)). Under the current 40 CFR 86.016-
1(d)(4), heavy-duty vehicles powered solely by electricity are deemed 
to have zero emissions of regulated pollutants; this provision also 
provides that heavy-duty EVs may not generate NOX or PM 
emission credits. Additionally, part 1037 applies to heavy-duty EVs 
above 14,000 pounds GVWR (see current 40 CFR 1037.1).
---------------------------------------------------------------------------

    \285\ 76 FR 57106, September 15, 2011.
---------------------------------------------------------------------------

    In this rulemaking, we are proposing to consolidate certification 
requirements for BEVs and FCEVs over 14,000 pounds GVWR in 40 CFR part 
1037 such that manufacturers of BEVs and FCEVs over 14,000 pounds GVWR 
would certify to meeting the emission standards and requirements of 
part 1037, as provided

[[Page 17458]]

in the current 40 CFR 1037.1.\286\ In the proposed 40 CFR 1037.102(b), 
we clarify that BEVs and FCEVs are subject to criteria pollutant 
standards as follows: Prior to MY 2027, the emission standards under 
the current 40 CFR 86.007-11 would apply, while the emission standards 
under the proposed 40 CFR 1036.104 would apply starting in MY 2027. As 
specified in the proposed 40 CFR 1037.205(q), starting in MY 2027, BEV 
and FCEV manufacturers could choose to attest that vehicles comply with 
the standards of 40 CFR 1037.102 instead of submitting test data.\287\ 
As discussed in Section IV.I, we are proposing in 40 CFR 1037.616 that, 
starting in MY 2024, manufacturers may choose to generate 
NOX emission credits from BEVs and FCEVs if the vehicle 
meets durability requirements described in proposed 40 CFR 
1037.102(b)(3).\288\ Manufacturers choosing to generate NOX 
emission credits under proposed 40 CFR 1037.616 may attest to meeting 
durability requirements while also submitting test results required for 
calculating NOX emission credits and quantifying initial 
battery or fuel cell performance.289 290 We are proposing to 
continue to not to allow heavy-duty EVs to generate PM emission credits 
since we are proposing not to allow any manufacturer to generate PM 
emission credits for use in MY 2027 and later under the proposed 
averaging, banking, and trading program presented in Section IV.G.
---------------------------------------------------------------------------

    \286\ Manufacturers of battery-electric and fuel cell electric 
vehicles at or below 14,000 pounds GVWR would continue complying 
with the standards and requirements in CFR 40 part 86, subpart S, 
instead of the requirements in 40 CFR 1037.
    \287\ Prior to MY 2027, BEVs or FCEVs that are not used to 
generate NOX emission credits would continue to be deemed 
to have zero tailpipe emissions of criteria pollutants, as specified 
in current 40 CFR 86.016-1(d)(4). See Section IV.I and the proposed 
40 CFR 1037.205(q)(2) for information relevant to manufacturers 
choosing to generate NOX emission credits from BEVs and 
FCEVs starting in MY 2024.
    \288\ Our proposal for how manufacturers could generate 
NOX emissions credits from BEVs and FCEVs would be 
available under any of the regulatory options that we are 
considering for revised NOX standards (see Section IV.I 
for details and requests for comments on this topic).
    \289\ As provided in the current 40 CFR 1037.150(f), no 
CO2-related emission testing is required for electric 
vehicles and manufacturers would continue to use good engineering 
judgment to apply other requirements of 40 CFR 1037.
    \290\ See the proposed 40 CFR 1037.205(q) for information 
required in a certification application for BEVs or FCEVs; Section 
III.B.2.v.c includes additional discussion on proposed test 
procedures for BEVs and FCEVs, with details included in 40 CFR 
1037.552 or 40 CFR 1037.554 for BEVs or FCEVs, respectively.
---------------------------------------------------------------------------

2. Proposed Numeric Standards and Test Procedures for Compression-
Ignition and Spark-Ignition Engines
    EPA is proposing new NOX, PM, HC, and CO emission 
standards for heavy-duty engines that will be certified under 40 CFR 
part 1036.291 292 As noted in the introduction to this 
preamble, the highway heavy-duty vehicle market is largely segmented in 
that a majority of the lightest weight class vehicles are powered by 
gasoline-fueled spark-ignition engines and most of the heaviest weight 
class vehicles are powered by diesel-fueled compression-ignition 
engines. There is significant overlap in the engines installed in Class 
4-6 applications.\293\ Considering the interchangeable nature of these 
middle range vehicles, we have designed our proposed program options so 
that, regardless of what the market chooses (e.g., gasoline- or diesel-
fueled engines), similar emission reductions would be realized over 
their expected operational lives. We believe it is appropriate to 
propose standards that are numerically fuel neutral yet account for the 
fundamental differences between CI and SI engines.\294\ We believe this 
proposed approach would result in roughly equivalent implementation 
burdens for manufacturers. As described in this section, the proposed 
Options 1 and 2 NOX and PM standards are based on test data 
from our CI engine feasibility demonstration program. We also find that 
they are feasible for SI engines based on currently available 
technologies and we are adopting them for SI engines to maintain fuel 
neutral standards. The proposed Options 1 and 2 HC and CO standards are 
based on HD SI engine emission performance. We also find that they are 
feasible for CI engines based on currently available technologies and 
we are adopting them for CI engines to maintain fuel neutral standards. 
We have not relied on the use of HEV, BEV, or FCEV technologies in the 
development of our proposed Options 1 and 2 or the Alternative 
standards; however, as discussed in Section IV, we are proposing to 
allow these technologies to generate NOX emission credits as 
a flexibility for manufacturers to spread out their investment and 
prioritize technology adoption to the applications that make the most 
sense for their businesses during their transition to meeting the 
proposed more stringent standards (see Sections IV.G, IV.H, and, IV.I 
for details on our proposed approach to NOX emission 
credits). We do not expect that current market penetration of BEVs 
(0.06 percent in MY 2019) or projected penetration rate in the MY 2027 
timeframe (1.5 percent) would meaningfully impact our analysis for 
developing the numeric level of the proposed Options 1 and 2 standards; 
\295\ however, as noted in III.B.5, we are requesting comment on 
whether to include HEV, BEV, and/or FCEV technologies in our 
feasibility analysis for the final rule and may re-evaluate our 
approach, especially if we receive information showing higher BEV/FCEV 
market penetration in the MY 2027 or later timeframe.\296\
---------------------------------------------------------------------------

    \291\ See proposed 40 CFR 1036.104.
    \292\ We are proposing to migrate the current alternate 
standards available for engines used in certain specialty vehicles 
from 40 CFR 86.007-11 and 86.008-10 into 40 CFR 1036.605 without 
modification, and are requesting comment on alternative options to 
our proposal. See Section XII.B of this preamble for a discussion of 
these standards and further details regarding our request for 
comment.
    \293\ The heavy-duty highway engines installed in vehicles with 
a GVWR between 8,501 and 14,000 pounds (Class 2b and 3) that are not 
chassis-certified, are subject to standards defined in 40 CFR 
86.007-11 and 40 CFR 86.008-10. For CI engines this is only small 
fraction of the Class 2b and 3 vehicles. For SI engines all Class 2b 
and 3 gasoline-fueled vehicles are chassis-certified and would not 
be affected by the proposals in this rulemaking.
    \294\ Current emission controls for heavy-duty engines largely 
target the emissions produced by the engine-specific combustion 
process. The combustion process of diesel-fueled CI engines 
inherently produces elevated NOX and PM that are 
controlled by selective catalytic reduction (SCR) and diesel 
particulate filter (DPF) technologies, while gasoline-fueled SI 
engines are more likely to produce higher levels of HC and CO that 
are controlled by three-way catalyst (TWC) technology. See Chapter 2 
of the draft RIA for additional background on these emission control 
technologies.
    \295\ As discussed in IV.I, we are proposing that BEVs and FCEVs 
can generate NOX credits that reflect the zero tailpipe 
emission performance of these technologies; however, the value of 
the NOX emission credits for BEVs and FCEVs relative to 
the difference in the proposed versus current NOX 
emission standards results in larger numbers of BEVs or FCEVs being 
needed to offset the projected improvement in NOX 
emission control from CI or SI engines relative to the number of 
BEVs or FCEVs needed to offset the projected improvement in 
CO2 emission control. This difference in the magnitude of 
potential impact from BEVs or FCEVs on NOX versus 
CO2 emission standards is further amplified by the 
advanced technology emission credit multipliers included the HD GHG 
Phase 2 program, which we are choosing not to propose for 
NOX emission credits. In addition to this, we are 
proposing an FEL for cap for NOX emissions that would 
require all engines to certify below the current NOX 
emission standard.
    \296\ See Preamble XI for more discussion on BEV/FCEV market 
projections and our proposal to account for them in revised HD GHG 
Phase 2 standards.
---------------------------------------------------------------------------

    Engine manufacturers historically have demonstrated compliance with 
EPA emission standards by measuring emissions while the engine is 
operating over precisely defined duty cycles in an emissions testing 
laboratory. The primary advantage of this approach is that it provides 
very repeatable emission

[[Page 17459]]

measurements. In other words, the results should be the same no matter 
when or where the test is performed, as long as the specified test 
procedures are used. We continue to consider pre-production laboratory 
engine testing (and durability demonstrations) as the cornerstone of 
ensuring in-use emission standards compliance. However, tying each 
emission standard to a specific, defined test cycle leaves open the 
possibility of emission controls being designed more to the limited 
conditions of the test procedures than to the full range of in-use 
operation. Since 2004, we have applied additional off-cycle standards 
for diesel engines that allow higher emission levels but are not 
limited to a specific duty cycle, and instead measure emissions over 
real-world, non-prescribed driving routes that cover a range of in-use 
operation.\297\ Our proposal includes new and updated heavy-duty engine 
test procedures and standards, both for duty cycle standards to be 
tested in an emissions testing laboratory and for off-cycle standards 
that can be tested on the road in real-world conditions, as described 
in the following sections.
---------------------------------------------------------------------------

    \297\ As discussed in Section IV.K, EPA regulations provide for 
testing engines at various stages in the life of an engine; duty 
cycle or off-cycle procedures may be used pre- or post-production to 
verify that the engine meets applicable duty cycle or off-cycle 
emission standards throughout useful life.
---------------------------------------------------------------------------

3. Implementation of Proposed Program
    As discussed in this section, we have evaluated the proposed 
standards in terms of technological feasibility, lead time, stability, 
cost, energy, and safety, consistent with the requirements in CAA 
section 202(a)(3). We are proposing standards based on our CI and SI 
engine feasibility demonstration programs, with Option 1 standards in 
two steps for MY 2027 and MY 2031 and Option 2 standards in one step 
starting in MY 2027. Our evaluation of available data shows that the 
standards and useful life periods in both steps of proposed Option 1 
are feasible and would result in the greatest emission reductions 
achievable for the model years to which they are proposed to apply, 
pursuant to CAA section 202(a)(3), giving appropriate consideration to 
cost, lead time, and other factors. Our analysis further shows that the 
standards and useful life periods in proposed Option 2 are feasible in 
the 2027 model year, but would result in lower levels of emission 
reductions compared to proposed Option 1. As explained further in this 
section and Chapter 3 of the draft RIA, we expect that additional data 
from EPA's ongoing work to demonstrate the performance of emission 
control technologies, as well as information received in public 
comments, will allow us to refine our assessments and consideration of 
the feasibility of the combination of the standards and useful life 
periods, particularly for the largest CI engines (HHDEs), in proposed 
Options 1 and 2, after consideration of lead time, costs, and other 
factors. Therefore, we are co-proposing Options 1 and 2 standards and 
useful life periods, and the range of options in between them, as the 
options that may potentially be appropriate to finalize pursuant to CAA 
section 202(a)(3) once EPA has considered that additional data and 
other information.
    We are proposing MY 2027 as the first implementation year for both 
options to align with the final step of the HD GHG Phase 2 standards, 
which would provide at least four years of lead time from a final 
rulemaking in 2022. As discussed in Section I and detailed in this 
section, the four-year lead time for the proposed criteria pollutant 
standards allows manufacturers to develop and apply the emission 
control technologies needed to meet the proposed standards, and to 
ensure those technologies will be durable for the proposed longer 
useful life periods; four years of lead time is also consistent with 
the CAA requirements.
    In the event that manufacturers start production of some engine 
families sooner than four years from our final rule, we are proposing 
an option to split the 2027 model year.\298\ Specifically, we are 
proposing that a MY 2027 engine family that starts production within 
four years of the final rule could comply with the proposed MY 2027 
standards for all engines produced for that engine family in MY2027 or 
could split the engine family by production date in MY 2027 such that 
engines in the family produced prior to four years after the final rule 
would continue to be subject to the existing standards.\299\ This 
proposed option to split the first model year provides assurance that 
all manufacturers, regardless of when they start production of their 
engine families, will have four years of lead time to the proposed 
first implementation step in MY 2027.
---------------------------------------------------------------------------

    \298\ We are proposing an option to split the 2027 model year 
for new MY 2027 criteria pollutant standards under any regulatory 
option with such standards in MY 2027 that EPA may adopt for the 
final rule.
    \299\ See 40 CFR 86.007-11.
---------------------------------------------------------------------------

    For Option 1, the phased implementation would also provide four 
years of stability before increasing stringency again in MY 2031. 
Through comments received on our ANPR, we have heard from manufacturers 
that given the challenge of implementing the third step of the HD GHG 
rules in MY 2027, they believe it would take closer to four years to 
adequately fine-tune and validate their products for a second step of 
more stringent criteria pollutant control that also extends useful 
life.\300\ In response to this concern, and the general request by 
suppliers and environmental stakeholders for a nationally aligned 
criteria pollutant program, we are proposing MY 2031 for the final step 
of the proposed Option 1 standards to provide four additional years for 
manufacturers to design and build engines that will meet the proposed 
second step of the Option 1 standards and associated compliance 
provisions.\301\ A MY 2031 final step would also align with the 
Omnibus.\302\ We request comment on the general approach of a two-step 
versus one-step program, and the advantages or disadvantages of the 
proposed Option 1 two-step approach that EPA should consider in 
developing the final rule. For instance, we seek commenters' views on 
whether the Agency should adopt a first step of standards but defer any 
second step of standards to a planned future rulemaking on heavy-duty 
GHG emissions instead of adopting a second step of standards in this 
rulemaking.\303\ We also request comment on whether there are 
additional factors that we should consider when setting standards out 
to the MY 2031 timeframe.
---------------------------------------------------------------------------

    \300\ See comments from Volvo. Docket ID: EPA-HQ-OAR-2019-0055-
0463.
    \301\ See comments from MECA, MEMA and Union of Concerned 
Scientists. Docket ID: EPA-HQ-OAR-2019-0055-0463.
    \302\ California Air Resources Board. Heavy-Duty Omnibus 
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \303\ As noted in the Executive Summary and discussed in 
Sections XI and XIII, this proposal is consistent with E.O. 14037, 
which also directs EPA to consider undertaking a separate rulemaking 
to establish new GHG emission standards for heavy-duty engines and 
vehicles to begin as soon as MY 2030.
---------------------------------------------------------------------------

    As explained in Section III.B.3, we have evaluated and considered 
the costs of these technologies in our assessment of the proposed 
Options 1 and 2 standards. The proposed Options 1 and 2 standards are 
achievable without increasing the overall fuel consumption and 
CO2 emissions of the engine for each of the duty cycles 
(FTP, SET, and LLC) and the fuel mapping test procedures defined in 40 
CFR 1036.535 and 1036.540, as discussed in the Chapter 3 of the draft 
RIA.\304\ Finally,

[[Page 17460]]

the proposed Options 1 and 2 standards would have no negative impact on 
safety, based on the existing use of these technologies in light-duty 
vehicles and heavy-duty engines on the road today.
---------------------------------------------------------------------------

    \304\ The proposed ORVR requirements discussed in Section 
III.E.2 would reduce fuel consumed from gasoline fuel engines, but 
these fuel savings would not be measured on the duty cycles since 
the test procedures for these tests measure tailpipe emissions and 
do not measure emissions from refueling. We describe our estimate of 
the fuel savings in Chapter 7.2.2 of the draft RIA.
---------------------------------------------------------------------------

B. Summary of Proposed Compression-Ignition Exhaust Emission Standards 
and Proposed Duty Cycle Test Procedures

1. Current Duty Cycle Test Procedures and Standards
    Current criteria pollutant standards must be met by compression-
ignition engines over both the Federal Test Procedure (FTP) \305\ and 
the Supplemental Emission Test (SET) duty cycles. The FTP duty cycles, 
which date back to the 1970s, are composites of a cold-start and a hot-
start transient duty cycle designed to represent urban driving. There 
are separate duty cycles for both SI and CI engines. The cold-start 
emissions are weighted by one-seventh and the hot-start emissions are 
weighted by six-sevenths.\306\ The SET is a more recent duty cycle for 
diesel engines that is a continuous cycle with ramped transitions 
between the thirteen steady-state modes.\307\ The SET does not include 
engine starting and is intended to represent fully warmed-up operating 
modes not emphasized in the FTP, such as more sustained high speeds and 
loads.
---------------------------------------------------------------------------

    \305\ EPA specifies different FTP duty cycles for compression-
ignition and spark-ignition engines.
    \306\ See 40 CFR 86.007-11 and 40 CFR 86.008-10.
    \307\ See 40 CFR 86.1362.
---------------------------------------------------------------------------

    Emission standards for criteria pollutants are currently set to the 
same numeric value for FTP and SET test cycles. Manufacturers of 
compression-ignition engines have the option to participate in our 
averaging, banking, and trading (ABT) program for NOX and PM 
as discussed in Section IV.G.\308\ These pollutants are subject to 
family emission limit (FEL) caps of 0.50 g/hp-hr for NOX and 
0.02 g/hp-hr for PM.\309\
---------------------------------------------------------------------------

    \308\ See 40 CFR 86.007-15.
    \309\ See 40 CFR 86.007-11.

 Table III-1--Current Diesel-Cycle Engine Standards Over the FTP and SET
                               Duty Cycles
------------------------------------------------------------------------
 NOX \a\  (g/hp-
       hr)          PM \b\ (g/hp-hr)    HC (g/hp-hr)      CO (g/hp-hr)
------------------------------------------------------------------------
         0.20               0.01              0.14              15.5
------------------------------------------------------------------------
\a\ Engine families participating in the ABT program are subject to a
  FEL cap of 0.50 g/hp-hr for NOX.
\b\ Engine families participating in the ABT program are subject to a
  FEL cap of 0.02 g/hp-hr for PM.

    EPA developed powertrain and hybrid powertrain test procedures for 
the HD GHG Phase 2 Heavy-Duty Greenhouse Gas rulemaking (81 FR 73478, 
October 25, 2016) with updates in the HD Technical Amendments rule (86 
FR 34321, June 29, 2021).\310\ The powertrain and hybrid powertrain 
tests allow manufacturers to directly measure the effectiveness of the 
engine, the transmission, the axle and the integration of these 
components as an input to the Greenhouse gas Emission Model (GEM) for 
compliance with the greenhouse gas standards. As part of the technical 
amendments, EPA allowed the powertrain test procedure to be used beyond 
the current GEM drive cycles to include the FTP and SET engine-based 
test cycles and to facilitate hybrid powertrain testing (40 CFR 
1036.505 and 1036.510 and 40 CFR 1037.550).
---------------------------------------------------------------------------

    \310\ See 40 CFR 1037.550.
---------------------------------------------------------------------------

    These heavy-duty diesel-cycle engine standards are applicable for a 
useful life period based on the primary intended service class of the 
engine.\311\ For certification, manufacturers must demonstrate that 
their engines will meet these standards throughout the useful life by 
performing a durability test and applying a deterioration factor (DF) 
to their certification value.\312\
---------------------------------------------------------------------------

    \311\ 40 CFR 86.004-2.
    \312\ See 40 CFR 86.004-26(c) and (d) and 86.004-28(c) and (d).
---------------------------------------------------------------------------

    Additionally, manufacturers must adjust emission rates for engines 
with exhaust aftertreatment to account for infrequent regeneration 
events accordingly.\313\ To account for variability in these 
measurements, as well as production variability, manufacturers 
typically add margin between the DF and infrequent regeneration 
adjustment factor (IRAF) adjusted test result, and the family emission 
limit (FEL). A summary of the margins manufacturers have included for 
MY 2019 and newer engines is summarized in Chapter 3.1.2 of the draft 
RIA.
---------------------------------------------------------------------------

    \313\ See 40 CFR 1036.501(d).
---------------------------------------------------------------------------

2. Proposed Test Procedures and Standards
    EPA is proposing new NOX, PM, HC, and CO emission 
standards for heavy-duty compression-ignition engines that will be 
certified under 40 CFR part 1036.314 315 We are proposing 
updates to emission standards for our existing laboratory test cycles 
(i.e., FTP and SET) and proposing NOX, PM, HC and CO 
emission standards based on a new low-load test cycle (LLC) as 
described below.\316\ The proposed standards for NOX, PM, 
and HC are in units of milligrams/horsepower-hour instead of grams/
horsepower-hour because using units of milligrams better reflects the 
precision of the new standards, rather than adding multiple zeros after 
the decimal place. Making this change would require updates to how 
manufacturers report data to the EPA in the certification application, 
but it does not require changes to the test procedures that define how 
to determine emission values. We describe compression-ignition engine 
technology packages that demonstrate the feasibility of achieving these 
proposed Options 1 and 2 standards in Section III.B.3.ii and provide 
additional details in Chapters 2 and 3 of the draft RIA for this 
rulemaking.
---------------------------------------------------------------------------

    \314\ See proposed 40 CFR 1036.104.
    \315\ See proposed 40 CFR 1036.605 and Section XII.B of this 
preamble for a discussion of our proposal for engines installed in 
specialty vehicles.
    \316\ See proposed 40 CFR 1036.104.
---------------------------------------------------------------------------

    As part of this rulemaking, we are proposing two options to 
increase the useful life for each engine class as described in Section 
IV.A. The proposed Options 1 and 2 emission standards outlined in this 
section would apply for the longer useful life periods and 
manufacturers would be responsible for demonstrating that their engines 
will meet these standards as part of the proposed revisions to 
durability requirements described in Section IV.F. In Section IV.G, we 
discuss our proposed updates to the ABT program to account for our 
proposal of three laboratory cycles (FTP, SET and LLC) with unique 
standards.
    As discussed in Section III.B.2, the proposal includes two sets of 
standards: Proposed Option 1 and proposed Option

[[Page 17461]]

2. As described in Section III.B.3.ii, we believe the technology 
packages evaluated for this proposal can achieve our proposed Options 1 
and 2 duty-cycle standards. For Option 1, we are proposing the 
standards in two steps in MY 2027 and MY 2031, because the proposed 
Option 1 program includes not only numerical updates to existing 
standards but also other new and revised standards and compliance 
provisions such as a new duty-cycle procedure and standards, revised 
off-cycle procedures and standards, longer useful life periods, and 
other proposed requirements that, when considered collectively, merit a 
phased approach to lead time. As discussed in Section I.G and in 
Section III.B.4, we also present an alternative set of standards 
(Alternative) that we also considered. The Alternative is more 
stringent than either the proposed Option 1 MY 2031 standards or 
proposed Option 2 because the Alternative has shorter lead time, lower 
numeric NOX emission standards and longer useful life 
periods. We note that we currently are unable to conclude that the 
Alternative is feasible in the MY 2027 timeframe over the useful life 
periods in this Alternative in light of deterioration in the emission 
control technologies that we have evaluated to date, and we expect that 
we would need additional supporting data or other information in order 
to determine that the Alternative is feasible in the MY 2027 timeframe 
to consider adopting it in the final rule.
    The proposed options for NOX standards were derived to 
consider the range of options that may potentially be appropriate to 
adopt to achieve the maximum feasible emissions reductions from heavy-
duty diesel engines considering lead time, stability, cost, energy and 
safety. To accomplish this, we evaluated what operation made up the 
greatest part of the inventory as discussed in Section VI.B and what 
technologies could be used to reduce emissions in these areas. As 
discussed in Section I, we project that emissions from operation at low 
power, medium-to-high power, and mileages beyond the current regulatory 
useful life of the engine would account for the majority of heavy-duty 
highway emissions in 2045. To achieve reductions in these three areas 
we identified options for cycle-specific standards to ensure that the 
maximum achievable reductions are seen across the operating range of 
the engine. As described in Section IV, we are proposing to increase 
both the regulatory useful life and the emission-related warranty 
periods to ensure these proposed standards are met for a greater 
portion of the engine's operational life.
    To achieve the goal of reducing emissions across the operating 
range of the engine, we are proposing two options for standards for 
three duty cycles (FTP, SET and LLC). In proposing these standards, we 
assessed the performance of the best available aftertreatment systems, 
which are more efficient at reducing NOX emissions at the 
higher exhaust temperatures that occur at high engine power, than they 
are at reducing NOX emissions at low exhaust temperatures 
that occur at low engine power. To achieve the maximum NOX 
reductions from the engine at maximum power, the aftertreatment system 
was designed to ensure that the downstream selective catalytic 
reduction (SCR) catalyst was properly sized, diesel exhaust fluid (DEF) 
was fully mixed with the exhaust gas ahead of the SCR catalyst and the 
diesel oxidation catalyst (DOC) was designed to provide a molar ratio 
of NO to NO2 of near one. To reduce emissions under low 
power operation and under cold-start conditions, we selected standards 
for proposed Option 1, for the LLC and the FTP that would achieve an 80 
to 90 percent, or more, reduction in emissions under these operating 
conditions as compared to current standards. The proposed Options 1 and 
2 standards are achievable by utilizing cylinder deactivation (CDA), 
dual-SCR aftertreatment configuration and heated diesel exhaust fluid 
(DEF) dosing. To reduce emissions under medium to high power, we 
selected standards for proposed Option 1, for the SET that would 
achieve a greater than 80 percent reduction in emissions under these 
operating conditions. The proposed Options 1 and 2 SET standards are 
achievable by utilizing improvements to the SCR formulation, SCR 
catalyst sizing, and improved mixing of DEF with the exhaust. Further 
information about these technologies can be found in Chapters 1 and 3 
of the draft RIA.
    For the proposed Options 1 and 2 PM standards, they were set at a 
level to maintain the current emissions performance of diesel engines. 
For the proposed Options 1 and 2 standards for HC and CO, they were 
generally set at a level that is achievable by spark-ignition engines. 
Each of these standards are discussed in more detail in the following 
sections.
    In proposed Option 1 for MY 2031 and later Heavy HDE, we are 
proposing NOX standards at an intermediate useful life (IUL) 
of 435,000 miles as discussed later in Section III.B.2. We believe that 
the proposed Option 1 useful life for these engines of 800,000 miles 
justifies the need for standards at IUL. It could be many years after 
the engines are on the road before EPA could verify that the engines 
meet the standards out to useful life if there is no IUL standard. As 
discussed further in Section III.B.3.ii.a, IUL standards ensure that 
the emissions from the engine are as low as feasible for the entire 
useful life and provides an intermediate check on emission performance 
deterioration over the UL.
    As discussed in Section III.B.3, we have assessed the feasibility 
of the proposed Options 1 and 2 standards for compression-ignition 
engines by testing a Heavy HDE equipped with cylinder CDA technology 
and dual-SCR aftertreatment configuration with heated DEF dosing. The 
demonstration work consisted of two phases. The first phase of the 
demonstration was led by CARB and is referred to as CARB Stage 3. In 
this demonstration the aftertreatment was chemically- and 
hydrothermally-aged to the equivalent of 435,000 miles. During this 
aging the emissions performance of the engine was assessed after the 
aftertreatment was degreened, at the equivalent of 145,000 miles, 
290,000 miles and 435,000 miles. The second phase of the demonstration 
was led by EPA and is referred to as the EPA Stage 3 engine. In this 
phase, improvements were made to the aftertreatment by replacing the 
zone-coated catalyzed soot filter with a separate DOC and diesel 
particulate filter (DPF) that were chemically- and hydrothermally-aged 
to the equivalent of 800,000 miles and improving the mixing of the DEF 
with exhaust prior to the downstream SCR catalyst. The EPA Stage 3 
engine was tested at an age equivalent to 435,000 and 600,000 miles. 
The EPA Stage 3 engine will be tested at an age equivalent of 800,000 
miles. Additionally, we plan to test a second aftertreatment system 
referred to as ``Team A'' which is also a dual-SCR aftertreatment 
configuration with heated DEF dosing, but has greater SCR catalyst 
volume and a different catalyst washcoat formulation.
i. FTP
    We are proposing new emission standards for testing over the FTP 
duty-cycle as shown in Table III-2.\317\ These brake-specific FTP 
standards would apply across the primary intended service classes over 
the useful life periods shown in Table III-3. These Options 1 and 2 
standards have been shown to be feasible for compression-ignition 
engines based on testing of the

[[Page 17462]]

CARB Stage 3 and EPA Stage 3 engine with a chemically- and 
hydrothermally-aged aftertreatment system.\318\ At the time of this 
proposal, the catalyst was aged to an equivalent of 800,000 miles, but 
the test data at the equivalent of 800,000 miles was not yet available. 
EPA will continue to assess the feasibility of the proposed standards 
as additional demonstration data becomes available during the course of 
this rulemaking. For example, the EPA Stage 3 engine, and EPA's Team A 
demonstration engine will be aged to and tested at the equivalent of 
800,000 miles.\319\ A summary of the data used for EPA's feasibility 
analysis can be found in Section III.B.3. To provide for additional 
margin, in our technology cost analysis we increased the SCR catalyst 
volume from what was used on the EPA and CARB Stage 3 engine. We are 
proposing to continue an averaging, banking, and trading (ABT) program 
for NOX credits as a flexibility for manufacturers. Our 
proposal includes targeted revisions to the current ABT program, 
including new provisions to clarify how FELs apply for additional duty 
cycles, lower FEL caps for NOX and restrictions for using 
NOX emission credits (see Section IV.G for details on the 
ABT program).
---------------------------------------------------------------------------

    \317\ See 40 CFR 1036.510 for FTP duty-cycle test procedure.
    \318\ See Section III.B.2 for a description of the engine.
    \319\ Data will be added to the public docket once it becomes 
available.

                                   Table III-2--Proposed Compression-Ignition Engine Standards Over the FTP Duty Cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               NOX \a\
                                                    Model year                Primary intended service class   (mg/hp-   PM (mg/hp- HC (mg/hp- CO (g/hp-
                                                                                                                 hr)        hr)        hr)        hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1....................  2027-2030...........................  All HD Engines.................         35          5         60        6.0
                                       2031 and later......................  Light HDE and Medium HDE.......         20          5         40        6.0
                                       2031 and later......................  Heavy HDE through IUL..........         20          5         40        6.0
                                       2031 and later......................  Heavy HDE from IUL to FUL......         40          5         40        6.0
Proposed Option 2....................  2027 and later......................  All HD Engines.................         50          5         40        6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Engine families participating in the ABT program would be subject to a NOX FEL cap, discussed in Section IV.G.3.


 Table III-3--Proposed Useful Life Periods for Heavy-Duty Compression-Ignition Primary Intended Service Classes
----------------------------------------------------------------------------------------------------------------
                          Current                        Proposed Option 1                   Proposed Option 2
                 -----------------------------------------------------------------------------------------------
Primary intended                               MY 2027-2030              MY 2031+
  service class  -----------------------------------------------------------------------------------------------
                     Miles       Years       Miles       Years       Miles       Years       Miles       Years
----------------------------------------------------------------------------------------------------------------
Light HDE \a\...      110,000         10      190,000         12      270,000         15      250,000         10
Medium HDE......      185,000         10      270,000         11      350,000         12      325,000         10
Heavy HDE \b\...      435,000         10      600,000         11  800,000 \c\         12      650,000         10
----------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Light HDE for GHG emission standards is 15 years or 150,000 miles. See 40 CFR
  1036.108(d).
\b\ Proposed Option 1 includes an hours-based useful life for Heavy HDE of 32,000 operating hours for model year
  2027 through 2030, and 40,000 operating hours for model year 2031 and later.
\c\ For MY 2031 and later Heavy HDE under proposed Option 1, we are proposing intermediate useful life periods
  of 435,000 miles, 10 years, or 22,000 hours, whichever comes first. See Section III for a discussion of the
  Option 1 standards we propose to apply for the intermediate and full useful life periods.

    The proposed Options 1 and 2, 5 mg/hp-hr (0.005 g/hp-hr) FTP 
standard for PM is intended to ensure that there is not an increase in 
PM emissions from future engines. As summarized in Section 
III.B.3.ii.b, manufacturers are submitting certification data to the 
agency for current production engines well below the proposed PM 
standard over the FTP duty cycle. Lowering the standard to 5 mg/hp-hr 
would ensure that future engines will maintain the low level of PM 
emissions of the current engines. Taking into account measurement 
variability of the PM measurement test procedure in the proposed PM 
standards, we believe that PM emissions from current diesel engines are 
at the lowest feasible level for MY 2027 and later engines. We request 
comment on whether 5 mg/hp-hr provides enough margin for particular 
engine designs. For example, would 6 or 7 mg/hp-hr be a more 
appropriate standard to maintain current PM emissions levels while 
providing enough margin to account for the measurement variability of 
the PM measurement test procedure.
    We are proposing two options HC and CO standards based on the 
feasibility demonstration for SI engines. As summarized in Section 
III.B.3.ii.b, manufacturers are submitting data to the agency that show 
emissions performance for current production CI engines is well below 
the current and proposed standards. Keeping standards at the same value 
for all fuels is consistent with the agency's approach to previous 
criteria pollutant standards. See Section III.C for more information on 
how the numeric values of these two options for proposed HC and CO 
standards were determined.
    In the ANPR, we requested comment on changing the weighting factors 
for the FTP cycle for heavy-duty engines. The current FTP weighting of 
cold-start and hot-start emissions was promulgated in 1980 (45 FR 4136, 
January 21, 1980). It reflects the overall ratio of cold and hot 
operation for heavy-duty engines generally and does not distinguish by 
engine size or intended use. Specifically, we asked if FTP weighting 
factors should vary by engine class and any challenges manufacturers 
may encounter to implement changes to the weighting factors. We did not 
receive any comments to change the weighting and received comments from 
Roush and MECA that the current weighting factors are appropriate. 
After considering these comments, we are not proposing any changes to 
the weighting factors.

[[Page 17463]]

ii. SET
    We are proposing new emissions standards for the SET test procedure 
as shown in Table III-4 over the same useful life periods shown in 
Table III-3. Consistent with our current standards, we are proposing 
the same numeric values for the standards over the FTP and SET duty 
cycles, and the brake-specific SET standards apply across engine 
classes (primary intended service class). As with the FTP cycle, the 
Options 1 and 2 standards have been shown to be feasible for 
compression-ignition engines based on testing of the CARB Stage 3 and 
EPA Stage 3 engines with a chemically- and hydrothermally-aged 
aftertreatment system. At the time of this proposal, the catalyst was 
aged to an equivalent of 800,000 miles, but the test data at the 
equivalent of 800,000 miles was not yet available. EPA will continue to 
assess the feasibility of the proposed standards as additional data 
becomes available. To provide additional margin for meeting the SET 
standards, we have accounted for additional SCR catalyst volume in our 
cost analysis. A summary of the data used for EPA's feasibility 
analysis can be found in Section III.B.3.

                                   Table III-4--Proposed Compression-Ignition Engine Standards Over the SET Duty Cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               NOX (mg/
                                                    Model year                Primary intended service class    hp-hr)   PM (mg/hp- HC (mg/hp- CO (g/hp-
                                                                                                                            hr)        hr)        hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1....................  2027-2030...........................  All HD Engines.................         35          5         60        6.0
                                       2031 and later......................  Light HDE and Medium HDE.......         20          5         40        6.0
                                       2031 and later......................  Heavy HDE through IUL..........         20          5         40        6.0
                                       2031 and later......................  Heavy HDE from IUL to FUL......         40          5         40        6.0
Proposed Option 2....................  2027 and later......................  All HD Engines.................         50          5         40        6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As with the proposed PM standards for the FTP (see Section 
III.B.2.i), the proposed Options 1 and 2 P.M. standards for SET is 
intended to ensure that there is not an increase in PM emissions from 
future engines. We request comment on whether 5 mg/hp-hr provides 
enough margin for particular engine designs. For example, would 6 or 7 
mg/hp-hr be a more appropriate standard to maintain current PM 
emissions levels while providing enough margin to account for the 
measurement variability of the PM measurement test procedure. As with 
the options for proposed HC and CO standards for the FTP (see Section 
III.B.2.i), we are proposing two options for standards for HC and CO 
based on the feasibility demonstration for SI engines (see Section 
III.C).
    We have also observed an industry trend toward engine down-
speeding--that is, designing engines to do more of their work at lower 
engine speeds where frictional losses are lower. To better reflect this 
trend in our duty cycle testing, in the HD GHG Phase 2 final rule, we 
promulgated new SET weighting factors for measuring CO2 
emissions (81 FR 73550, October 25, 2016). Since we believe these new 
weighting factors better reflect in-use operation of current and future 
heavy-duty engines, we are proposing to apply these new weighting 
factors to criteria pollutant measurement, as show in Table III-5, for 
NOX and other criteria pollutants as well. To assess the 
impact of the new test cycle on criteria pollutant emissions, we 
analyzed data from the EPA Stage 3 engine that was tested on both 
versions of the SET. The data summarized in Section III.B.3.ii.a show 
that the NOX emissions from the EPA Stage 3 engine at an 
equivalent of 435,000 miles are slightly lower using the proposed SET 
weighting factors in 40 CFR 1036.505 versus the current SET procedure 
in 40 CFR 86.1362. The lower emissions using the proposed SET cycle 
weighting factors are reflected in the stringency of the proposed 
Options 1 and 2 SET standards.

           Table III-5 Proposed Weighting Factors for the SET
------------------------------------------------------------------------
                                                               Weighting
                         Speed/% load                            factor
                                                                  (%)
------------------------------------------------------------------------
Idle.........................................................         12
A, 100.......................................................          9
B, 50........................................................         10
B, 75........................................................         10
A, 50........................................................         12
A, 75........................................................         12
A, 25........................................................         12
B, 100.......................................................          9
B, 25........................................................          9
C, 100.......................................................          2
C, 25........................................................          1
C, 75........................................................          1
C, 50........................................................          1
                                                              ----------
    Total....................................................        100
Idle Speed...................................................         12
    Total A Speed............................................         45
    Total B Speed............................................         38
    Total C Speed............................................          5
------------------------------------------------------------------------

iii. LLC
    EPA is proposing the addition of a low-load test cycle and standard 
that would require CI engine manufacturers to demonstrate that the 
emission control system maintains functionality during low-load 
operation where the catalyst temperatures have historically been found 
to be below their operational temperature (see Chapter 2.2.2 of the 
draft RIA). We believe the addition of a low-load cycle would 
complement the expanded operational coverage of our proposed off-cycle 
testing requirements (see Section III.C).
    During ``Stage 2'' of their Low NOX Demonstration 
program, SwRI and NREL developed several candidate cycles with average 
power and duration characteristics intended to test current diesel 
engine emission controls under three low-load operating conditions: 
Transition from high- to low-load, sustained low-load, and transition 
from low- to high-load.\320\ In September 2019, CARB selected the 92-
minute ``LLC Candidate #7'' as the low load cycle they adopted for 
their Low NOX Demonstration program and subsequent Omnibus 
regulation.321 322
---------------------------------------------------------------------------

    \320\ California Air Resources Board. ``Heavy-Duty Low 
NOX Program Public Workshop: Low Load Cycle 
Development''. Sacramento, CA. January 23, 2019. Available online: 
https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190123/02-llc_ws01232019-1.pdf.
    \321\ California Air Resources Board. Heavy-Duty Omnibus 
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \322\ California Air Resources Board. ``Heavy-Duty Low 
NOX Program: Low Load Cycle'' Public Workshop. Diamond 
Bar, CA. September 26, 2019. Available online: https://ww3.arb.ca.gov/msprog/hdlownox/files/workgroup_20190926/staff/03_llc.pdf.
---------------------------------------------------------------------------

    We are proposing to adopt CARB's Omnibus LLC as a new test cycle, 
the LLC. This cycle is described in Chapter 2 of the draft RIA for this 
rulemaking and test procedures are specified in the proposed 40 CFR 
1036.512. The proposed LLC includes applying the accessory loads 
defined in the HD GHG Phase 2 rule. These accessory loads are 1.5, 2.5 
and 3.5 kW for Light HDE,

[[Page 17464]]

Medium HDE, and Heavy HDE engines, respectively. To allow vehicle level 
technologies to be recognized on this cycle we are proposing the 
powertrain test procedure to include the LLC. More information on the 
powertrain test procedure can be found in Section III.A.2.v. For the 
determination of IRAF for the LLC, we are proposing the test procedures 
defined in 40 CFR 1036.522, which is the same test procedure that is 
used for the FTP and SET. We believe that the IRAF test procedures that 
apply to the FTP and SET are appropriate for the LLC, but we request 
comment on whether to modify how the regeneration frequency value in 40 
CFR 1065.680 is determined, to account for the fact that a regeneration 
frequency value is needed for three duty cycles and not just two.
    Our proposed Options 1 and 2 emission standards for this proposed 
LLC are presented in Table III-6. The brake-specific LLC standards 
would apply across engine classes. As with the FTP cycle, the data from 
the EPA Stage 3 demonstration engine with an aged aftertreatment system 
shows that these proposed Options 1 and 2 standards are feasible with 
available margins between the data and the proposed standards. In fact, 
the margin between the proposed Option 1 MY 2031 standards and the 
Stage 3 engine data is the largest on the LLC, suggesting that a lower 
numeric NOX standard would be feasible at 435,000 and 
600,000 miles than included in the proposed Option 1 IUL NOX 
standard. The summary of this data can be found in Section III.B.3.
    We request comment on the addition of a low-load test cycle and 
standard, as well as the proposed accessory loads, or other engine 
operation a low-load cycle should encompass, if finalized.

                                   Table III-6--Proposed Compression-Ignition Engine Standards Over the LLC Duty Cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Primary intended service    NOX (mg/hp-   PM (mg/hp-   HC (mg/hp-   CO (g/hp-
                                                Model year                          class                 hr)          hr)          hr)          hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1.................  2027-2030.........................  All HD Engines..............           90            5          140          6.0
                                    2031 and later....................  Light HDE and Medium HDE....           50            5           60          6.0
                                    2031 and later....................  Heavy HDE through IUL.......           50            5           60          6.0
                                    2031 and later....................  Heavy HDE from IUL to FUL...          100            5           60          6.0
Proposed Option 2.................  2027 and later....................  All HD Engines..............          100            5           60          6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The proposed LLC standards for PM are based on the effectiveness of 
the diesel particulate filter (DPF) to reduce PM emissions across the 
operating range of the engine, including under low loads. We request 
comment on whether 5 mg/hp-hr provides enough margin for particular 
engine designs. For example, would 6 or 7 mg/hp-hr be a more 
appropriate standard for the LLC to maintain current PM emissions 
levels while providing enough margin to account for the measurement 
variability of the PM measurement test procedure. Since we are not 
proposing standards on the LLC for SI engines, the data from the CARB 
and EPA Stage 3 engine discussed in Section III.B.3 were used to assess 
the feasibility of the proposed CO and HC standards. For both proposed 
Option 1 and Option 2 standards, we are proposing the same numeric 
standards for CO on the LLC as we have respectively proposed in Option 
1 and Option 2 for the FTP and SET cycles. This is because the 
demonstration data of the EPA Stage 3 engine shows that CO emissions on 
the LLC are in similar to CO emissions from the FTP and SET. For the 
proposed Options 1 and 2 for HC standards on the LLC, we are proposing 
standards that are different than the standards of the FTP and SET 
cycles, to reflect the performance of the EPA Stage 3 engine on the 
LLC. The data discussed in Section III.B.3 of the preamble shows that 
the proposed Options 1 and 2 standards are feasible for both current 
and future new engines.
iv. Idle
    CARB currently has an idle test procedure and accompanying standard 
of 30 g/h of NOX for diesel engines to be ``Clean Idle 
Certified''.\323\ In the Omnibus rule the CARB lowered the 
NOX standard to 10 g/h for MY 2024 to MY 2026 engines and 5 
g/h for MY 2027 and beyond. In the ANPR, we requested comment on the 
need or appropriateness of setting a federal idle standard for diesel 
engines. We received comments supporting action by EPA to adopt 
California's Clean Idle NOX standard as a voluntary emission 
standard for federal certification.\324\ For proposed Option 1 we are 
proposing an optional idle standard in 40 CFR 1036.104(b) and a new 
test procedure in 40 CFR 1036.514, based on CARB's test procedure,\325\ 
to allow compression-ignition engine manufacturers to voluntarily 
choose to certify (i.e., it would be optional for a manufacturer to 
include the idle standard in an EPA certification but once included the 
idle standard would become mandatory and full compliance would be 
required) to an idle NOX standard of 30.0 g/hr for MY 2023, 
10.0 g/hr for MY 2024 to MY 2026 and 5.0 g/hr for MY 2027 and beyond. 
As part of this optional idle standard, we are proposing to require 
that the brake-specific HC, CO, and PM emissions during the Clean Idle 
test may not exceed measured emission rates from the idle segments of 
the FTP or the idle mode in the SET, in addition to meeting the 
applicable idle NOX standard.\326\ For proposed Option 2 we 
are proposing an idle NOX standard of 10.0 g/hr for MY 2027 
and beyond. We request comment on whether EPA should make the idle 
standards mandatory instead of voluntary for MY 2027 and beyond, as 
well as whether EPA should set clean idle standards for HC, CO, and PM 
emissions (in g/hr) rather than capping the idle emissions for those 
pollutants based on the measured emission levels during the idle 
segments of the FTP or the idle mode in the SET. We request comment on 
the need for EPA to define a label that would be put on the vehicles 
that are certified to the optional idle standard.
---------------------------------------------------------------------------

    \323\ 13 CCR 1956.8 (a)(6)(C)--Optional NOX idling 
emission standard.
    \324\ See comments from CARB, Volvo, and Union of Concerned 
Scientists, and Eaton. Docket ID: EPA-HQ-OAR-2019-0055-0463.
    \325\ 86.1360-2007.B.4, California Exhaust Emission Standards 
and Test Procedures for 2004 and Subsequent Model Heavy-Duty Diesel 
Engines and Vehicles, April 18, 2019.
    \326\ See 40 CFR 1036.104(b).
---------------------------------------------------------------------------

v. Powertrain
    EPA recently finalized a separate rulemaking that included an 
option for manufacturers to certify a hybrid powertrain to the FTP and 
SET greenhouse gas engine standards by using a powertrain test 
procedure (86 FR 34321, June 29, 2021).\327\ In this

[[Page 17465]]

rulemaking, we similarly propose to allow manufacturers to certify 
hybrid powertrains, BEVs, and FCEVs to criteria pollutant emissions 
standards by using the powertrain test procedure. In this section we 
describe how manufacturers could apply the powertrain test procedure to 
certify hybrid powertrains, and, separately, BEVs or FCEVs.
---------------------------------------------------------------------------

    \327\ The powertrain test procedure was established in the GHG 
Phase 1 rulemaking but the recent rulemaking included adjustments to 
apply the test procedure to the engine test cycles.
---------------------------------------------------------------------------

a. Development of Powertrain Test Procedures
    Powertrain testing allows manufacturers to demonstrate emission 
benefits that cannot be captured by testing an engine alone on a 
dynamometer. For hybrid engines and powertrains, powertrain testing 
captures when the engine operates less or at lower power levels due to 
the use of the hybrid powertrain function; for BEVs and FCEVs 
powertrain testing allows the collection of data on work produced, 
energy used and other parameters that would normally be collected for 
an engine during a dynamometer test. However, powertrain testing 
requires the translation of an engine test procedure to a powertrain 
test procedure. Chapter 2 of the draft RIA describes how we translated 
the FTP, proposed SET for criteria pollutants, and proposed LLC engine 
test cycles to the proposed powertrain test cycles.\328\ The two 
primary goals of this process were to make sure that the powertrain 
version of each test cycle was equivalent to each respective engine 
test cycle in terms of positive power demand versus time and that the 
powertrain test cycle had appropriate levels of negative power demand. 
To achieve this goal, over 40 engine torque curves were used to create 
the powertrain test cycles. We request comment on ways to further 
improve the proposed powertrain test procedures, including approaches 
to apply the proposed procedures to powertrains that include a 
transmission as part of the certified configuration to make the idle 
accessory load more representative.
---------------------------------------------------------------------------

    \328\ As discussed in Section III.B.1, as part of the technical 
amendments rulemaking, EPA allowed the powertrain test procedure to 
be used for GHG emission standards on the FTP and SET engine-based 
test cycles. In this rulemaking we are proposing to allow the 
powertrain test procedure to be used for criteria emission standards 
on these test cycles and the proposed LLC. As discussed in Section 
2.ii, we are proposing new weighting factors for the engine-based 
SET procedure for criteria pollutant emissions, which would be 
reflected in the SET powertrain test cycle.
---------------------------------------------------------------------------

b. Testing Hybrid Engines and Hybrid Powertrains
    As noted in the introduction of this Section III, we are proposing 
to clarify in 40 CFR 1036.101 that manufacturers may optionally test 
the hybrid engine and hybrid powertrain to demonstrate compliance. We 
propose that the powertrain test procedures specified in 40 CFR 
1036.505 and 1036.510, which were previously developed for 
demonstrating compliance with GHG emission standards on the SET and FTP 
test cycles, are applicable for demonstrating compliance with criteria 
pollutant standards on the SET and FTP test cycles. In addition, for 
GHG emission standards we are proposing updates to 40 CFR 1036.505 and 
1036.510 to further clarify how to carry out the test procedure for 
plug-in hybrids. We have done additional work for this rulemaking to 
translate the proposed LLC to a powertrain test procedure, and we are 
proposing that manufacturers could similarly certify hybrid engines and 
hybrid powertrains to criteria pollutant emission standards on the 
proposed LLC using the proposed test procedures defined in 40 CFR 
1036.512.
    We thus propose to allow manufacturers to use the powertrain test 
procedures to certify hybrid engine and powertrain configurations to 
all MY 2027 and later criteria pollutant engine standards. We also 
propose to allow manufacturers to begin using powertrain test 
procedures to certify hybrid configurations to criteria pollutant 
standards in MY 2023. Manufacturers could choose to use either the SET 
duty-cycle in 40 CFR 86.1362 or the proposed SET in 40 CFR 1036.505 in 
model years prior to 2027.329 330
---------------------------------------------------------------------------

    \329\ We proposing to allow either the SET duty-cycle in 40 CFR 
86.1362 or 40 CFR 1036.505 because the duty cycles are similar and 
as shown in Chapter 3.1.2 of the Draft RIA the criteria pollutant 
emissions level of current production engines is similar between the 
two cycles.
    \330\ Prior to MY 2027, only manufacturers choosing to 
participate in the Early Adoption Incentive Program would need to 
conduct LLC powertrain testing (see Section IV.H for details on the 
Early Adoption Incentive Program).
---------------------------------------------------------------------------

    We are proposing to allow these procedures starting in MY 2023 for 
plug-in hybrids and, to maintain consistency with the requirements for 
LD plug-in hybrids, we are proposing that the applicable criteria 
pollutant standards must be met under the worst case condition, which 
is achieved by testing and evaluating emission under both charge 
depleting and charge sustaining operation. This is to ensure that under 
all drive cycles the powertrain meets the criteria pollutant standards 
and is not based on an assumed amount of zero emissions range. We are 
proposing changes to the test procedures defined in 40 CFR 1036.505 and 
1036.510 to clarify how to weight together the charge depleting and 
charge sustaining greenhouse gas emissions for determining the 
greenhouse gas emissions of plug-in hybrids for the FTP and SET duty 
cycles. This weighting would be done using an application specific 
utility factor curve that is approved by EPA. We are also proposing to 
not apply the cold and hot weighting factors for the determination of 
the FTP composite emission result for greenhouse gas pollutants because 
the charge depleting and sustaining test procedures proposed in 40 CFR 
1036.510 include both cold and hot start emissions by running repeat 
FTP cycles back-to-back. By running back-to-back FTPs, the proposed 
test procedure captures both cold and hot emissions and their relative 
contribution to daily greenhouse gas emissions per unit work, removing 
the need for weighting the cold and hot emissions. We request comment 
on our proposed approach to the FTP duty cycle for plug-in hybrids and 
the proposed approach to the determination of the FTP composite 
emissions result, including whether EPA should instead include cold and 
hot weighting factors for the latter. If you comment that EPA should 
include the cold and hot weighting factors, we request that you also 
include an example of how these calculations would be carried out with 
such an approach (how the calculations would include both the weighting 
of charge sustaining and charge depleting emissions in conjunction with 
the weighting of the cold and hot emissions results).
    We propose to limit this test procedure to hybrid powertrains to 
avoid having two different testing pathways for non-hybrid engines for 
the same standards. On the other hand, there may be other technologies 
where the emissions performance is not reflected on the engine test 
procedures, so we request comment on whether this test procedure should 
be available to other powertrains, and if so how to define those 
powertrains.
    Finally, for all pollutants, we request comment on if we should 
remove 40 CFR 1037.551 or limit the use of it to only selective 
enforcement audits (SEA). 40 CFR 1037.551 was added as part of the 
Heavy-Duty Phase 2 GHG rulemaking to provide flexibility for an SEA or 
a confirmatory test, by allowing just the engine of the powertrain to 
be tested. Allowing just the engine to be tested over the engine speed 
and torque cycle that was recorded during the powertrain test enables 
the testing to be conducted in more widely available engine dynamometer 
test cells, but this

[[Page 17466]]

flexibility could increase the variability of the test results. If you 
submit comment in support of removing or limiting the use of 40 CFR 
1037.551 to just SEA, we request that you include data supporting your 
comment.
c. Testing Battery-Electric and Fuel Cell Electric Vehicles
    As noted in the introduction to this Section III, and detailed in 
Section IV.I, we are proposing to recognize the zero tailpipe emission 
benefits of BEV and FCEV technologies by allowing manufacturers to 
generate NOX emission credits with these technologies.\331\ 
We are further proposing that manufacturers who choose to generate 
NOX emission credits from BEVs or FCEVs would be required to 
conduct testing to measure work produced over a defined duty-cycle 
test, and either useable battery energy (UBE) for BEVs or fuel cell 
voltage (FCV) for FCEVs (see Section IV.I for details).
---------------------------------------------------------------------------

    \331\ See Section IV.I, proposed 40 CFR 1037.616, and proposed 
40 CFR 1036.741 for details on the proposed NOX emission 
credits for BEVs and FCEVs. Briefly, manufacturers would generate 
vehicle emissions credits, which would then be fungible between 
vehicle and engine certification programs, such that NOX 
credits generated through the vehicle program could be applied to 
the proposed engine ABT program described in Section IV.G and 
specified in proposed 40 CFR 1036.705.
---------------------------------------------------------------------------

    To conduct the testing necessary for generating NOX 
emission credits from BEVs or FCEVs, we are proposing that 
manufacturers would use the powertrain test procedures for the FTP, 
proposed SET and proposed LLC. Specifically, for BEVs, manufacturers 
would run a series of powertrain FTP, SET and LLC tests over a defined 
sequence referred to as a ``Multicycle Test'' (MCT), which is specified 
in proposed 40 CFR 1037.552. For FCEVs, manufacturers would operate the 
powertrain over an FTP, SET, and LLC and determine the average fuel 
cell voltage (FCV) by taking the average of the FCV when the fuel cell 
current is between 55 percent and 65 percent of rated fuel cell 
current, as specified in proposed 40 CFR 1037.554.\332\
---------------------------------------------------------------------------

    \332\ The MCT for BEVs (specified in 40 CFR 1037.552) and FCEVs 
(specified in 40 CFR 1037.554) use the same foundational powertrain 
test procedures for the FTP, SET, and LLC test cycles; however, the 
MCT for BEVs includes additional iterations of the test cycles that 
are needed to deplete the battery and measure UBE, while the MCT for 
FCEVs includes the measurement of FCV, rather than UBE.
---------------------------------------------------------------------------

    The MCT for BEVs consists of a fixed number of dynamic drive cycles 
combined with constant-speed driving phases. The heavy-duty transient 
cycle (HDTC) described in current 40 CFR 1036.510(a)(4), LLC described 
in proposed 40 CFR 1036.512, and SET described in proposed 40 CFR 
1036.505 are used to determine the energy consumption associated with 
specific and established driving patterns. These dynamic drive cycles 
make up a combined 57.92 miles of driving distance. The constant speed 
cycles (CSC), which are located in the middle and the end of the test, 
are intended to: Reduce test duration by depleting the battery more 
rapidly than the established certification drive schedules; improve the 
robustness of the energy determination by minimizing the impact of 
drive style variation; and prevent inconsistent triggering of end-of-
test criteria that can occur at high power-demand points when a BEV is 
following a dynamic drive schedule at low states-of-charge.
    The CSC middle phase is located after the initial run through two 
HDTCs, one LLC, and one SET. This CSC depletes the battery and allows 
determination of the vehicle's performance on the HDTC, LLC, and SET 
for both high and low states of charge. The distance traveled during 
the CSC middle phase that is determined by this procedure ensures that 
the second run through two HDTCs, one LLC, and one SET is conducted at 
a substantially lower state of charge. The target distance traveled 
over the CSC end phase is 20 percent or less of the total driven 
distance for the combined initial and second runs through the HDTC, 
LLC, or SET cycles.
    The MCT for FCEVs consists of running a powertrain on the FTP, LLC, 
and SET to determine the FCV when the fuel cell current (FCC) is 
between 55 percent and 65 percent of rated FCC. Work is also measured 
during the second HDTC in the FTP and used in the determination of the 
FCEV conversion factor (CF) value for credit generation in proposed 40 
CFR 1037.616.
    We request comment on our proposed approach to powertrain testing 
for BEVs and FCEVs, and specifically whether any modifications of the 
FTP, SET and LLC powertrain test cycles would be needed for BEVs and 
FCEVs. We further request comment on whether the MCT, as defined in 
proposed 40 CFR 1037.552, would require modifications to accurately 
measure work produced over the FTP cycle or the measure of UBE. We 
request comment on whether the procedure in proposed 40 CFR 1037.554 is 
appropriate for determining FCV. Finally, we request comment on if 
current 40 CFR 1036.527 should be used to determine rated FCC.
vi. Closed Crankcase
    During combustion, gases can leak past the piston rings sealing the 
cylinder and into the crankcase. These gases are called blowby gases 
and generally include unburned fuel and other combustion products. 
Blowby gases that escape from the crankcase are considered crankcase 
emissions (see 40 CFR 86.402-78). Current regulations restrict the 
discharge of crankcase emissions directly into the ambient air. Blowby 
gases from gasoline engine crankcases have been controlled for many 
years by sealing the crankcase and routing the gases into the intake 
air through a positive crankcase ventilation (PCV) valve. However, in 
the past there have been concerns about applying a similar technology 
for diesel engines. For example, high PM emissions venting into the 
intake system could foul turbocharger compressors. As a result of this 
concern, diesel-fueled and other compression-ignition engines equipped 
with turbochargers (or other equipment) were not required to have 
sealed crankcases (see 40 CFR 86.007-11(c)). For these engines, 
manufacturers are allowed to vent the crankcase emissions to ambient 
air as long as they are measured and added to the exhaust emissions 
during all emission testing to ensure compliance with the emission 
standards.
    Because all new highway heavy-duty diesel engines on the market 
today are equipped with turbochargers, they are not required to have 
closed crankcases under the current regulations. Manufacturer 
compliance data indicate approximately one-third of current highway 
heavy-duty diesel engines have closed crankcases, indicating that some 
heavy-duty engine manufacturers have developed systems for controlling 
crankcase emissions that do not negatively impact the turbocharger. EPA 
is proposing provisions in 40 CFR 1036.115(a) to require a closed 
crankcase ventilation system for all highway compression-ignition 
engines to prevent crankcase emissions from being emitted directly to 
the atmosphere starting for MY 2027 engines.\333\ These emissions could 
be routed upstream of the aftertreatment system or back into the intake 
system. Unlike many other standards, this standard is a design standard 
rather than a performance standard.
---------------------------------------------------------------------------

    \333\ We are proposing to move the current crankcase emissions 
provisions to a new paragraph (u) in the interim provisions of 40 
CFR 1036.150, which would apply through model year 2026.
---------------------------------------------------------------------------

    Our reasons for proposing a requirement for closed crankcases are 
twofold. While the exception in the current regulations for certain 
compression-ignition engines requires manufacturers to quantify their 
engines'

[[Page 17467]]

crankcase emissions during certification, they report non-methane 
hydrocarbons in lieu of total hydrocarbons. As a result, methane 
emissions from the crankcase are not quantified. Methane emissions from 
diesel-fueled engines are generally low; however, they are a concern 
for compression-ignition-certified natural gas-fueled heavy-duty 
engines because the blowby gases from these engines have a higher 
potential to include methane emissions. EPA proposed to require that 
all natural gas-fueled engines have closed crankcases in the Heavy-Duty 
Phase 2 GHG rulemaking, but opted to wait to finalize any updates to 
regulations in a future rulemaking, where we could then propose to 
apply these requirements to natural gas-fueled engines and to the 
diesel fueled engines that many of the natural gas-fueled engines are 
based off of (81 FR 73571, October 25, 2016).
    In addition to our concern of unquantified methane emissions, we 
believe another benefit to closed crankcases would be better in-use 
durability. We know that the performance of piston seals reduces as the 
engine ages, which would allow more blowby gases and could increase 
crankcase emissions. While crankcase emissions are included in the 
durability tests that estimate an engine's deterioration, those tests 
were not designed to capture the deterioration of the crankcase. These 
unquantified age impacts continue throughout the operational life of 
the engine. Closing crankcases could be a means to ensure those 
emissions are addressed long-term to the same extent as other exhaust 
emissions.
    Chapter 1.1.4 of the draft RIA describes EPA's recent test program 
to evaluate the emissions from open crankcase systems on two modern 
heavy-duty diesel engines. Results suggest THC and CO emitted from the 
crankcase can be a notable fraction of overall tailpipe emissions. By 
closing the crankcase, those emissions would be rerouted to the engine 
or aftertreatment system to ensure emission control.
3. Feasibility of the Diesel (Compression-Ignition) Engine Standards
i. Summary of Technologies Considered
    Our proposed Options 1 and 2 standards for compression-ignition 
engines are based on the performance of technology packages described 
in Chapters 1 and 3 of the draft RIA for this rulemaking. Specifically, 
we are evaluating the performance of next-generation catalyst 
formulations in a dual SCR catalyst configuration with a smaller SCR 
catalyst as the first substrate in the aftertreatment system for 
improved low-temperature performance, and a larger SCR catalyst 
downstream of the diesel particulate filter to improve NOX 
conversion efficiency during high power operation and to allow for 
passive regeneration of the particulate filter.\334\ Additionally, the 
technology package includes CDA that reduces the number of active 
cylinders, resulting in increased exhaust temperatures for improved 
catalyst performance under light-load conditions and can be used to 
reduce fuel consumption and CO2 emissions. The technology 
package also includes the use of a heated DEF injector for the upfront 
SCR catalyst; the heated DEF injector allows DEF injection at 
temperatures as low as approximately 140 [deg]C. The heated DEF 
injector also improves the mixing of DEF and exhaust gas within a 
shorter distance than with unheated DEF injectors, which enables the 
aftertreatment system to be packaged in a smaller space. Finally, the 
technology package includes hardware needed to close the crankcase of 
diesel engines.
---------------------------------------------------------------------------

    \334\ As described in Chapter 3 of the draft RIA, we are 
evaluating 3 different aftertreatment systems that contain different 
catalyst formulation.
---------------------------------------------------------------------------

ii. Summary of Feasibility Analysis
a. Projected Technology Package Effectiveness and Cost
    Based upon preliminary data from EPA's diesel demonstration 
research and the CARB Heavy-duty Low NOX Stage 3 Research 
Program (see Chapter 3.1.1.1 and Chapter 3.1.3.1 of the draft RIA), 
Heavy HDE NOX reductions of 90 percent from current 
NOX standards are technologically feasible when using CDA or 
other valvetrain-related air control strategies in combination with 
dual SCR systems. EPA has continued to evaluate aftertreatment system 
durability via accelerated aging of advanced emissions control systems 
as part of EPA's diesel engine demonstration program that is described 
in Chapter 3 of the draft RIA. In assessing the feasibility of our 
proposed standards, we have taken into consideration the proposed level 
of the standards, the additional emissions from infrequent 
regenerations, the proposed longer useful life, and lead time for 
manufacturers.
    Manufacturers are required to design engines that meet the duty 
cycle and off-cycle standards throughout their useful life. In 
recognition that emissions performance will degrade over time, 
manufacturers design their engines to perform significantly better than 
the standards when first sold to ensure that the emissions are below 
the standard throughout useful life even as the emissions controls 
deteriorate. As discussed below and in Chapter 3 of the draft RIA, 
manufacturer margins can range from less than 25 percent to 100 percent 
of the FEL. For Option 1, for Heavy HDEs that have the longest proposed 
useful life, we are proposing intermediate useful life standards that 
ensure that engines do not degrade in performance down to the duty 
cycle and off-cycle standards too quickly and allow for an intermediate 
check on emissions performance deterioration over the useful life.
    To assess the feasibility of the proposed Option 1 MY 2031 
standards for heavy HDE at the IUL of 435,000 miles, the data from the 
EPA Stage 3 engine was used. As discussed in Section III.B.2 the EPA 
Stage 3 engine includes improvements beyond the CARB Stage 3 engine, 
namely replacing the zone-coated catalyzed soot filter with a separate 
DOC and DPF and improving the mixing of the DEF with exhaust for the 
downstream SCR. These improvements lowered the emissions on the FTP, 
SET and LLC below what was measured with the CARB Stage 3 engine. The 
emissions for the EPA Stage 3 engine on the FTP, SET and LLC aged to an 
equivalent of 435,000 and 600,000 miles are shown in Table III-7 and 
Table III-8. To assess the feasibility of the proposed Option 1 
NOX standards for MY 2027 and MY 2031 for Heavy HDE at the 
respective proposed Option 1 useful life periods, the data from the EPA 
Stage 3 engine was used. The data from the EPA Stage 3 engine was used 
because it included emission performance with the aftertreatment at the 
equivalent age of 435,000 and 600,000 miles. Having data at multiple 
points allowed us to use linear regression to project out the 
performance of the EPA Stage 3 engine at 800,000 miles.\335\ To account 
for the IRAF for both particulate matter and sulfur on the 
aftertreatment system, we relied on an analysis by SwRI that is 
summarized in Chapter 3 of the draft RIA. In this analysis SwRI 
determined the IRAF at 2 mg/hp-hr for both the FTP and SET cycles and 5 
mg/hp-hr for the LLC. Based on our analysis, the proposed Option 1 MY 
2027 and MY 2031 emissions standards for Heavy HDE are feasible at the 
respective proposed useful life periods. To provide for additional 
margin, in our technology

[[Page 17468]]

cost analysis we increased the SCR catalyst volume from what was used 
on the EPA and CARB Stage 3 engine. The increase in total SCR catalyst 
volume relative to the EPA and CARB Stage 3 SCR was approximately 23.8 
percent. We believe this further supports our conclusion that the 
proposed Option 1 standards are achievable for the proposed useful life 
of 800,000 miles for MY 2031 Heavy HDE. In addition to NOX, 
the proposed Option 1 HC and CO standards are feasible for CI engines 
on all three cycles. This is shown in Table III-7, where the 
demonstrated HC and CO emissions results are below the proposed Option 
1 standards discussed in Section III.B.2. The proposed Option 1 
standards for PM of 5 mg/hp-hr for the FTP, SET and LLC, continue to be 
feasible with the additional technology and control strategies needed 
to meet the proposed Option 1 NOX standards, as seen by the 
PM emissions results in Table III-7 below. As discussed in Section 
III.B.2, taking into account measurement variability of the PM 
measurement test procedure, we believe that PM emissions from current 
diesel engines are at the lowest feasible level for MY 2027 and later 
engines. We request comment on whether 5 mg/hp-hr provides enough 
margin for particular engine designs or for any of the duty cycles 
(FTP, SET, or LLC). For example, would 6 or 7 mg/hp-hr be a more 
appropriate standard for the LLC to maintain current PM emissions 
levels while providing enough margin to account for the measurement 
variability of the PM measurement test procedure. In addition, we 
request comment on if there are technologies that EPA could consider 
that would enable a PM standard lower than 5 mg/hp-hr. Commenters 
requesting a higher standard are encouraged to provide data supporting 
such comments.
---------------------------------------------------------------------------

    \335\ See Chapter 3.1.3 of the draft RIA for our analysis on 
projecting emissions performance beyond 600,000 miles.

    Table III-7--Stage 3 Engine Emissions at 435,000 Mile Equivalent Test Point Without Adjustments for IRAF
----------------------------------------------------------------------------------------------------------------
                                                 NOX (mg/  PM (mg/hp- NMHC (mg/  CO  (g/hp-  CO2  (g/   N2O  (g/
                  Duty cycle                      hp-hr)      hr)       hp-hr)      hr)       hp-hr)     hp-hr)
----------------------------------------------------------------------------------------------------------------
FTP...........................................         20          2         12      0.141        514      0.076
SET \a\.......................................         17          1          1      0.030        455      0.024
LLC...........................................         29          3         35      0.245        617      0.132
----------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our proposed test procedures (40 CFR 1036.505).


    Table III-8--Stage 3 Engine Emissions at 600,000 Mile Equivalent Test Point Without Adjustments for IRAF
----------------------------------------------------------------------------------------------------------------
                                                NOX  (mg/   PM  (mg/  NMHC  (mg/ CO  (g/hp-  CO2  (g/   N2O  (g/
                  Duty cycle                      hp-hr)     hp-hr)     hp-hr)      hr)       hp-hr)     hp-hr)
----------------------------------------------------------------------------------------------------------------
FTP...........................................         27          1          9      0.144        519      0.058
SET \a\.......................................         24          1          1      0.015        460      0.030
LLC...........................................         33          4         16      0.153        623      0.064
----------------------------------------------------------------------------------------------------------------
\a\ Using the weighting factors in our proposed test procedures (40 CFR 1036.505).

    As additional data is received from the EPA led demonstration 
project, the demonstration data will inform whether the proposed Option 
1 IUL standards for MY 2031 are needed. For example, if the 
demonstration data shows much lower emissions for the first half of 
useful life than for the second half of useful life, then this would 
confirm our assumption that the proposed Option 1 IUL standard would 
ensure that the emission reductions during the earlier portion of an 
engine's useful life are achieved, while preserving sufficient margin 
for deterioration during the second half of useful life. On the other 
hand, if we find that the emissions values are relatively constant 
through useful life, this may support that an IUL standard may not be 
needed. This data will also inform whether the proposed Option 1 IUL 
standard of 20 mg/hp-hr at 435,000 miles is appropriate for Heavy HDE 
in MY 2031 and whether an IUL standard is also needed for MY 2027 to 
account for deterioration out to the proposed Option 1 600,000-mile 
useful life for MY 2027.
    Our analysis also shows that the proposed Option 2 standards could 
be met starting in MY 2027 with CDA and dual-SCR with heated dosing 
(see draft RIA Chapter 3 for details of our analysis) as shown in Table 
III-7. The proposed Option 2 includes a higher (less stringent) 
NOX emission level for all CI engine classes over the FTP 
and SET compared to either step of our proposed Option 1 NOX 
FTP and SET standards. The FTP and SET standards in proposed Option 2 
for PM, HC, and CO are numerically equivalent to our proposed Option 1 
MY 2031 standards. As shown in Table III-7, we currently have data 
demonstrating that the proposed Option 2 standards could be met out to 
600,000 miles. These data show the proposed Option 2 standards are 
feasible through the proposed Option 2 useful life periods for Light 
HDE, Medium HDEs. Our evaluation of the current data suggests that the 
proposed Option 2 standards would also be feasible out to the proposed 
Option 2 Heavy HDE useful life; we are continuing to collect data to 
confirm our extrapolation of data out to the longer useful life 
mileage. As discussed in Section IV.A, useful life mileages for 
proposed Option 2 are higher than our MY 2027 proposed useful life, but 
lower than our proposed Option 2 useful life values for MY 2031.
    In addition to evaluating the feasibility of the new criteria 
pollutant standards, we also evaluated how CO2 was impacted 
on the CARB Stage 3 engine. To do this we evaluated how CO2 
emissions changed from the base engine on the FTP, SET, and LLC, as 
well as the fuel mapping test procedures defined in 40 CFR 1036.535 and 
1036.540. For all three cycles the Stage 3 engine emitted 
CO2 with no measurable difference compared to the base 2017 
Cummins X15 engine. Specifically, we compared the CARB Stage 3 engine 
including the 0-hour (degreened) aftertreatment with the 2017 Cummins 
X15 engine including degreened aftertreatment and found the percent 
reduction in CO2 for the FTP, SET and LLC, was 1, 0 and 1 
percent

[[Page 17469]]

respectively.\336\ We note that after this data was taken SwRI made 
changes to the thermal management strategies of the CARB Stage 3 engine 
to improve NOX reduction at low SCR temperatures. The data 
from the EPA Stage 3 engine at the equivalent age of 435,000 miles 
includes these calibration changes, and although there was an increase 
in CO2, which resulted in the CO2 emissions for 
the EPA Stage 3 engine being higher than the 2017 Cummins X15 engine 
for the FTP, SET and LLC of 0.6, 0.7 and 1.3 percent respectively, this 
was not a direct comparison because the 2017 Cummins X15 aftertreatment 
had not been aged to an equivalent of 435,000 miles. As discussed in 
Chapter 3 of the draft RIA, aging the EPA Stage 3 engine included 
exposing the aftertreatment to ash, that increased the back pressure on 
the engine, which contributed to the increase in CO2 
emissions from the EPA Stage 3. To evaluate how the technology on the 
CARB Stage 3 engine compares to the 2017 Cummins X15 with respect to 
the HD GHG Phase 2 vehicle CO2 standards, both engines were 
tested on the fuel mapping test procedures defined in 40 CFR 1036.535 
and 1036.540. These test procedures define how to collect the fuel 
consumption data from the engine for use in GEM. For these tests the 
CARB Stage 3 engine was tested with the development aged 
aftertreatment.\337\ The fuel maps from these tests were run in GEM and 
the results from this analysis showed that the Stage 3 engine emitted 
CO2 at the same rate as the 2017 Cummins X15. The details of 
this analysis are described in Chapter 3.1 of the draft RIA. The 
technologies included in the EPA demonstration engine were selected to 
both demonstrate the lowest criteria pollutant emissions and have a 
negligible effect on GHG emissions. Manufactures may choose to use 
other technologies to meet the proposed standards, but manufacturers 
will still also need to comply with the GHG standards that apply under 
HD GHG Phase 2.\338\ Because of this we have not projected an increase 
in GHG emissions resulting from compliance with the proposed standards.
---------------------------------------------------------------------------

    \336\ See Chapter 3 of the draft RIA for the CO2 
emissions of the 2017 Cummins X15 engine and the CARB Stage 3 
engine.
    \337\ The CARB Stage 3 0 hour (degreened) aftertreatment could 
not be used for these tests, because it had already been aged past 
the 0 hour point when these tests were conducted.
    \338\ As explained in Section XI, EPA is also proposing targeted 
updates to the Phase 2 Heavy-Duty Greenhouse Gas Emissions program.
---------------------------------------------------------------------------

    Table III-9 summarizes the incremental technology costs for the 
proposed Options 1 and 2 standards, from the baseline costs shown in 
Table III-13. While the standards vary between the proposed Option 1 
and the proposed Option 2 standards, we are evaluating the same 
technologies to assess the feasibility of the two sets of standards. 
These values include aftertreatment system and CDA costs. The details 
of this analysis can be found in Chapter 3 of the draft RIA. 
Differences in the useful life and warranty periods between the 
proposed Options 1 and 2 are accounted for in the indirect costs as 
discussed in Chapter 7.1.2 of the draft RIA.\339\
---------------------------------------------------------------------------

    \339\ See Table III-3 for the proposed useful life values and 
Section IV.B.1 for the proposed emissions warranty periods for each 
option.

Table III-9--Incremental Direct Manufacturing Cost of Proposed Options 1
        and 2 Standards for the Aftertreatment and CDA Technology
                                [2019 $]
------------------------------------------------------------------------
                                           Medium
               Light HDE                    HDE     Heavy HDE  Urban bus
------------------------------------------------------------------------
$1,685.................................     $1,648     $2,266     $1,684
------------------------------------------------------------------------

    As described in Chapter 3.1 of the draft RIA, we have estimated the 
incremental technology cost for closed crankcase filtration systems for 
all CI engines to be $37 (2017 $), noting that these technologies are 
on some engines available in the market today.
b. Baseline Emissions and Cost
    The basis for our baseline technology assessment is the data 
provided by manufacturers in the heavy-duty in-use testing program. 
This data encompasses in-use operation from nearly 300 LHD, MHD, and 
HHD vehicles. Chapter 5 of the draft RIA describes how the data was 
used to update the MOVES model emissions rates for HD diesel engines. 
Chapter 3 of the draft RIA summarizes the in-use emissions performance 
of these engines.
    We also evaluated the certification data submitted to the agency. 
The data includes test results adjusted for IRAF and FEL that includes 
adjustments for deterioration and margin. The certification data, 
summarized in Table III-10, shows that manufacturers vary in their 
approach to how much margin is built into the FEL. Some manufactures 
have greater than 100 percent margin built into the FEL, while other 
manufacturers have less than 25 percent.

                            Table III-10--Summary of Certification Data for FTP Cycle
----------------------------------------------------------------------------------------------------------------
                                                            NOX  (g/  PM  (g/hp- NMHC  (g/  CO  (g/hp-  N2O  (g/
                                                             hp-hr)      hr)       hp-hr)      hr)       hp-hr)
----------------------------------------------------------------------------------------------------------------
Average..................................................       0.13       0.00       0.01       0.18       0.07
Minimum..................................................       0.05       0.00       0.00       0.00       0.04
Maximum..................................................       0.18       0.00       0.04       1.10       0.11
----------------------------------------------------------------------------------------------------------------


                            Table III-11--Summary of Certification Data for SET Cycle
----------------------------------------------------------------------------------------------------------------
                                                            NOX  (g/  PM  (g/hp- NMHC  (g/  CO  (g/hp-  N2O  (g/
                                                             hp-hr)      hr)       hp-hr)      hr)       hp-hr)
----------------------------------------------------------------------------------------------------------------
Average..................................................       0.11       0.00       0.01       0.00       0.06
Minimum..................................................       0.00       0.00       0.00       0.00       0.00
Maximum..................................................       0.18       0.00       0.04       0.20       0.11
----------------------------------------------------------------------------------------------------------------


[[Page 17470]]

    In addition to analyzing the on-cycle certification data submitted 
by manufacturers, we tested three modern HD diesel engines on an engine 
dynamometer and analyzed the data. These engines were a 2018 Cummins 
B6.7, 2018 Detroit DD15 and 2018 Navistar A26. These engines were 
tested on cycles that range in power demand from the creep mode of the 
Heavy Heavy-Duty Diesel Truck (HHDDT) schedule to the HD SET cycle 
defined in 40 CFR 1036.505. Table III-12 summarizes the range of 
results from these engines on the FTP, SET and LLC. As described in 
Chapter 3 of the draft RIA, the emissions of current production Heavy-
Duty engines vary from engine to engine but the largest difference in 
NOX between engines is seen on the LLC.

  Table III-12--Range of NOX Emissions From MY2017 to MY2019 Heavy-Duty
                             Diesel Engines
------------------------------------------------------------------------
                                           SET in     SET in
        NOX (g/hp-hr)            FTP       40 CFR     40 CFR      LLC
                              composite   86.1333    1036.505
------------------------------------------------------------------------
Minimum.....................       0.10       0.01       0.01       0.35
Maximum.....................       0.15       0.12       0.05       0.81
Average.....................       0.13       0.06       0.03       0.59
------------------------------------------------------------------------

    Table III-13 summarizes the baseline sales-weighted total 
aftertreatment cost of Light HDE, Medium HDE, Heavy HDE and urban bus 
engines. The details of this analysis can be found in Chapter 3 of the 
draft RIA.

     Table III-13--Baseline Direct Manufacturing Aftertreatment Cost
                                [2019 $]
------------------------------------------------------------------------
                                           Medium
               Light HDE                    HDE     Heavy HDE  Urban bus
------------------------------------------------------------------------
$ 2,804................................    $ 2,877    $ 4,587    $ 2,929
------------------------------------------------------------------------

4. Potential Alternative
    We evaluated one alternative (the Alternative) to our proposed HD 
CI exhaust emission standards (summarized in Table III-14, Table III-
15, and Table III-16). As discussed in this section and based on 
information we have collected to date, we do not project that the 
Alternative standards are feasible in the MY 2027 timeframe with the 
technology we have evaluated (Table III-9).
    The Alternative we considered includes lower (more stringent) 
numeric NOX emission levels for Heavy HDEs, and lower HC 
emission levels for all CI engine classes, combined with longer useful 
life periods and shorter lead time compared to the proposed Option 1 MY 
2031 standards. As shown in Table III-7, the test data we currently 
have from the EPA Stage 3 engine is not sufficient to conclude that the 
Alternative standards would be feasible in the MY 2027 timeframe. 
Specifically, our data suggest that the numeric level of the FTP and 
SET NOX emission standards would be very challenging to meet 
through 435,000 miles (see draft RIA Chapter 3.1). For Light HDEs and 
Medium HDEs, these data suggest that to meet the combination of numeric 
levels of the NOX emission standards and useful life periods 
of the Alternative, it may be appropriate for EPA to consider providing 
manufacturers with additional lead time, beyond the MY 2027 
implementation date of the Alternative. For Heavy HDEs, our 
extrapolation of the data from 600,000 miles through the 850,000 miles 
useful life period of the Alternative suggests that the numeric level 
of the NOX emission control in the Alternative could not be 
maintained through the Alternative useful life period (see draft RIA 
Chapter 3.1 for details on available data and our evaluation). Wholly 
different emission control technologies than we have evaluated to date 
(i.e., not based on CDA and a dual SCR) would be needed to meet the 
Alternative standards for Heavy HDEs; we request comment on this 
conclusion and on the availability, or potential development and 
timeline, of such additional technologies. We also note that the 
Alternative is significantly more stringent than the CARB Omnibus 
because of the combination of numeric level of the NOX 
emission standards and useful life periods in the Alternative compared 
to the CARB Omnibus. Specifically, for heavy HDEs, the Alternative 
includes a 20 mg/hp-hr standard at a useful life of 850,000 miles, 
whereas for MYs 2027 through 2030 the CARB Omnibus includes a 20 mg/hp-
hr standard at 435,000 miles and a 35 mg/hp-hr standard at 600,000 
miles for heavy HDEs. Thus, the heavy HDE useful life period of the 
Alternative is substantially longer than the CARB Omnibus useful life 
periods that start in MY 2027, particularly when comparing the useful 
life period for the 20 mg/hp-hr standard. Starting in MY 2031, the CARB 
Omnibus NOX standard for heavy HDEs is 40 mg/hp-hr at a 
useful life of 800,000 miles, which is again a higher numeric level of 
the standard at a shorter useful life than the Alternative.

                         Table III-14--Proposed and Alternative Compression-Ignition Engine Standards for the FTP Test Procedure
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              NOX  (mg/   PM  (mg/   HC  (mg/  CO  (g/hp-
                                                    Model year                Primary intended service class    hp-hr)     hp-hr)     hp-hr)      hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1....................  2027-2030...........................  All HD Engines.................         35          5         60        6.0
                                       2031 and later......................  Light HDE and Medium HDE.......         20          5         40        6.0
                                       2031 and later......................  Heavy HDE......................     40 \a\          5         40        6.0
Proposed Option 2....................  2027 and later......................  All HD Engines.................         50          5         40        6.0
Alternative..........................  2027 and later......................  All HD Engines.................         20          5         10        6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Proposed Option 1 MY 2031 and later IUL NOX standard for Heavy HDE is 20 mg/hp-hr.


[[Page 17471]]


                         Table III-15--Proposed and Alternative Compression-Ignition Engine Standards for the SET Test Procedure
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              NOX  (mg/   PM  (mg/   HC  (mg/  CO  (g/hp-
                                                    Model year                Primary intended service class    hp-hr)     hp-hr)     hp-hr)      hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1....................  2027-2030...........................  All HD Engines.................         35          5         60        6.0
                                       2031 and later......................  Light HDE and Medium HDE.......         20          5         40        6.0
                                       2031 and later......................  Heavy HDE......................     \a\ 40          5         40        6.0
Proposed Option 2....................  2027 and later......................  All HD Engines.................         50          5         40        6.0
Alternative..........................  2027 and later......................  All HD Engines.................         20          5         10        6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Proposed Option 1 MY 2031 and later IUL NOX standard for Heavy HDE is 20 mg/hp-hr.


                         Table III-16--Proposed and Alternative Compression-Ignition Engine Standards for the LLC Test Procedure
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              NOX  (mg/   PM  (mg/   HC  (mg/  CO  (g/hp-
                                                    Model year                Primary intended service class    hp-hr)     hp-hr)     hp-hr)      hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1....................  2027-2030...........................  All HD Engines.................         90          5        140        6.0
                                       2031 and later......................  Light HDE and Medium HDE.......         50          5         60        6.0
                                       2031 and later......................  Heavy HDE......................    \a\ 100          5         60        6.0
Proposed Option 2....................  2027 and later......................  All HD Engines.................        100          5         60        6.0
Alternative..........................  2027 and later......................  All HD Engines.................        100          5         60        6.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Proposed Option 1 MY 2031 and later IUL NOX standard for Heavy HDE is 50 mg/hp-hr.

    For the optional idle NOX standard, the Alternative 
includes a standard of 10.0 g/hr for MY 2027 and beyond. The proposed 
Options 1 and 2 standards generally represent the range of options, 
including the standards, regulatory useful life and emission-related 
warranty periods and lead time provided, that we are currently 
considering in this rule, depending in part on any additional 
information we receive on the feasibility, costs, and other impacts of 
the proposed Options 1 and 2 standards. In order to consider adopting 
the Alternative in the final rule, we would need additional data to 
project that the Alternative is feasible for the MY 2027 time frame. As 
discussed in Section III.B.5, we are soliciting comment on the 
feasibility of the Alternative and other alternatives outside the range 
of options covered by the proposed Options 1 and 2 standards.
5. Summary of Requests for Comment on the Stringency of the CI Duty 
Cycle Standards
    We request comment on the following items related to the proposed 
CI duty cycle standards. First, we request comment on the numeric value 
of each proposed, or alternative, standard for each duty cycle and off-
cycle emissions and the proposed Option 1 two step, or the proposed 
Option 2 one step, approach and implementation timetable, as well as 
other standards or approaches recommended by the commenter, within the 
approximate range of the proposed Options 1 and 2 standards. We request 
comment, including relevant data and other information, on the 
feasibility of the implementation model year, numeric levels of the 
emission standards, and useful life and warranty periods included in 
the Alternative, or other alternatives outside the range of options 
covered by the proposed Options 1 and 2 standards. We request comment 
on if a margin between the demonstrated emissions performance and the 
proposed standards should be included and if so, we request comment on 
if a specific margin should be used and what that value should be. 
Commenters requesting a specific margin are encouraged to provide data 
and analysis to support the numeric value of the margin(s).
    We request comment on whether a lower numeric standard for 
NOX should be set for the LLC based on the emission levels 
achieved with the CARB Stage 3 engine or EPA Stage 3 engine. We request 
comment on whether EPA should make the idle standards mandatory for MY 
2027 and beyond. We request comment on whether the test procedures 
defined in 40 CFR 1036.522 for IRAF should be applied to the LLC or if 
alternative procedures should be considered. We request comment on 
whether the proposed PM standards of 5 mg/hp-hr for the FTP, SET and 
LLC provide enough margin to account for the measurement variability of 
the PM measurement test procedure, while ensuring that the PM emissions 
from HD CI engines do not increase. We are requesting comment on 
whether we should include HEV, BEV, and/or FCEV technologies in our 
feasibility analysis for the final rule.
    As discussed in Section III.B.2.v, EPA requests comment on the 
proposed powertrain test procedure, including any additional 
requirements that are needed to ensure that the engine and respective 
powertrain cycles are equivalent. We request comment on other 
improvements that could be made specifically to make the idle accessory 
load more representative for powertrains that include a transmission as 
part of the certified configuration. EPA requests comment on whether 
the powertrain test procedure option is needed for specific non-hybrid 
powertrains where the engine test procedure is not representative of 
in-use operation of the powertrain in a vehicle, and if so how should 
we define these powertrains so that the powertrain test option is only 
available for these powertrains. We request comment on our proposed 
approach to powertrain testing for BEVs and FCEVs, and specifically 
whether any modifications of the FTP, SET and LLC powertrain test 
cycles would be needed for BEVs and FCEVs. We further request comment 
on whether the MCT as defined in 40 CFR 1037.552 would require 
modifications to accurately measure work produced over the FTP cycle or 
the measure of useable battery energy (UBE). We request comment on 
whether the procedure in 40 CFR 1037.554 is appropriate for determining 
fuel cell voltage (FCV). In addition, we request

[[Page 17472]]

comment on if 40 CFR 1036.527 should be used to determine rated FCC.
    Finally, we request comment on whether the standards should be 
expressed in units of milligrams per kilowatt-hour, so that each value 
of the standards is in the international system of units (SI units), as 
we have done for the HD nonroad and locomotive standards.

C. Summary of Compression-Ignition Off-Cycle Standards and In-Use Test 
Procedures

1. Current NTE Standards and Need for Changes to Off-Cycle Test 
Procedures
    Heavy-duty CI engines are currently subject to Not-To-Exceed (NTE) 
standards that are not limited to specific test cycles, which means 
they can be evaluated not only in the laboratory but also in-use. NTE 
standards and test procedures are generally referred to as ``off-
cycle'' standards and test procedures. These off-cycle emission limits 
are 1.5 (1.25 for CO) times the laboratory certification standard or 
family emission limit (FEL) for NOX, HC, PM and CO and can 
be found in 40 CFR 86.007-11. NTE standards have been successful in 
broadening the types of operation for which manufacturers design their 
emission controls to remain effective, including steady cruise 
operation. However, there remains significant operation not covered by 
NTE standards.
    Compliance with an NTE standard is based on emission test data 
(whether collected in a laboratory or in use) analyzed pursuant to 40 
CFR 86.1370 to identify NTE events, which are intervals of at least 30 
seconds when engine speeds and loads remain in the NTE control area or 
``NTE zone''. The NTE zone excludes engine operation that falls below 
certain torque, power, and speed values.\340\ The NTE procedure also 
excludes engine operation that occurs in certain ambient conditions 
(i.e., high altitudes, high intake manifold humidity), or when 
aftertreatment temperatures are below 250[deg]C. Collected data is 
considered a valid NTE event if it occurs within the NTE zone, lasts at 
least 30 seconds, and does not occur during any of the exclusion 
conditions (ambient conditions, or aftertreatment temperature).
---------------------------------------------------------------------------

    \340\ Specifically, engine operations are excluded if they fall 
below 30 percent of maximum torque, 30 percent of maximum power, or 
15 percent of the European Stationary Cycle speed.
---------------------------------------------------------------------------

    The purpose of the NTE test procedure is to measure emissions 
during engine operation conditions that could reasonably be expected to 
occur during normal vehicle use; however, only data in a valid NTE 
event is then compared to the NTE emission standard. Our analysis of 
existing heavy-duty in-use vehicle test data indicates that less than 
ten percent of a typical time-based dataset are part of valid NTE 
events, and hence subject to the NTE standards; the remaining test data 
are excluded from consideration. We also found that emissions are high 
during many of the excluded periods of operation, such as when the 
aftertreatment temperature drops below the 250[deg]C exclusion 
criterion. Our review of in-use data indicates that extended time at 
low load and idle operation results in low aftertreatment temperatures, 
which in turn lead to diesel engine SCR-based emission control systems 
not functioning over a significant fraction of real-world 
operation.\341\ \342\ \343\ Test data collected as part of EPA's 
manufacturer-run in-use testing program indicate that low-load 
operation could account for greater than 50 percent of the 
NOX emissions from a vehicle over a given workday.\344\
---------------------------------------------------------------------------

    \341\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of 
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel 
Engines Using Portable Emissions Measurement System (PEMS)''. 29th 
CRC Real World Emissions Workshop, March 10-13, 2019.
    \342\ Sandhu, Gurdas, et al. ``Identifying Areas of High 
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
    \343\ Sandhu, Gurdas, et al. ``In-Use Emission Rates for MY 
2010+ Heavy-Duty Diesel Vehicles''. 27th CRC Real-World Emissions 
Workshop, March 26-29, 2017.
    \344\ Sandhu, Gurdas, et al. ``Identifying Areas of High 
NOX Operation in Heavy-Duty Vehicles''. 28th CRC Real-
World Emissions Workshop, March 18-21, 2018.
---------------------------------------------------------------------------

    For example, 96 percent of tests in response to 2014, 2015, and 
2016 EPA in-use testing orders passed with NOX emissions for 
valid NTE events well below the 0.3 g/hp-hr NOX NTE 
standard. When we used the same data to calculate NOX 
emissions over all operation measured, not limited to valid NTE events, 
the NOX emissions were more than double those within the 
valid NTE events (0.5 g/hp-hr).\345\ The results were even higher when 
we analyzed the data to consider only NOX emissions that 
occur during low load events.
---------------------------------------------------------------------------

    \345\ Hamady, Fakhri, Duncan, Alan. ``A Comprehensive Study of 
Manufacturers In-Use Testing Data Collected from Heavy-Duty Diesel 
Engines Using Portable Emissions Measurement System (PEMS)''. 29th 
CRC Real World Emissions Workshop, March 10-13, 2019.
---------------------------------------------------------------------------

    EPA and others have compared the performance of US-certified 
engines and those certified to European Union emission standards and 
concluded that the European engines' NOX emissions are lower 
in low-load conditions, but comparable to US-certified engines subject 
to MY 2010 standards under city and highway operation.\346\ This 
suggests that manufacturers are responding to the European 
certification standards by designing their emission controls to perform 
well under low-load operations, as well as highway operations.
---------------------------------------------------------------------------

    \346\ Rodriguez, F.; Posada, F. ``Future Heavy-Duty Emission 
Standards An Opportunity for International Harmonization''. The 
International Council on Clean Transportation. November 2019. 
Available online: https://theicct.org/sites/default/files/publications/Future%20_HDV_standards_opportunity_20191125.pdf.
---------------------------------------------------------------------------

    The European Union ``Euro VI'' emission standards for heavy-duty 
engines require manufacturers to check for ``in-service conformity'' by 
operating their engines over a mix of urban, rural, and motorway 
driving on prescribed routes using portable emission measurement system 
(PEMS) equipment to measure emissions.347 348 Compliance is 
determined using a work-based windows approach where emissions data are 
evaluated over segments or ``windows.'' A window consists of 
consecutive 1 Hz data points that are summed until the engine performs 
an amount of work equivalent to the European transient engine test 
cycle (World Harmonized Transient Cycle).
---------------------------------------------------------------------------

    \347\ COMMISSION REGULATION (EU) No 582/2011, May 25, 2011. 
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02011R0582-20180118&from=EN.
    \348\ COMMISSION REGULATION (EU) 2018/932, June 29, 2018. 
Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0932&from=EN.
---------------------------------------------------------------------------

    EPA is proposing an approach similar to the European in-use 
program, with key distinctions that build upon the Euro VI approach, as 
discussed below.
2. Proposed Off-Cycle Standards and Test Procedures
    As described in Section III.C.1, our current NTE test procedures 
were not designed to capture low-load operation. We are proposing to 
replace the NTE test procedures and standards (for NOX, PM, 
HC and CO) for model year 2027 and later engines. Engine operation and 
emissions test data would be assessed in 300-second moving average 
windows (MAWs) of continuous engine operation.\349\ In contrast to the 
current NTE approach that divides engine operation into two categories 
(in the NTE zone and out of the NTE zone), the proposed approach would 
divide engine operation into three categories (or ``bins'') based on 
the time-weighted average engine power of each MAW of

[[Page 17473]]

engine data as described in more detail below.
---------------------------------------------------------------------------

    \349\ Our evaluation includes our current understanding that 
shorter windows are more sensitive to measurement variability and 
longer windows make it difficult to distinguish between duty cycles.
---------------------------------------------------------------------------

    Although the proposed program has similarities to the European 
approach, we are not proposing to limit our standards to operation on 
prescribed routes. Our current NTE program is not limited to prescribed 
routes and we would consider it an unnecessary step backward to change 
that aspect of the procedure.
    In Section IV.G, we discuss our proposed updates to the ABT program 
to account for our proposal of unique off-cycle standards.
i. Bins
    We are proposing two options of off-cycle standards for three bins 
of operation that cover the range of operation included in the duty 
cycle test procedures and operation that is outside of the duty cycle 
test procedures for each regulated pollutant (NOX, HC, CO, 
and PM). The three bins represent three different domains of emission 
performance. The idle bin represents extended idle operation and other 
very low load operation where engine exhaust temperatures may drop 
below the optimal temperature for aftertreatment function. The medium/
high load bin represents higher power operation including much of the 
operation currently covered by the NTE. Operation in the medium/high 
load bin naturally involves higher exhaust temperatures and catalyst 
efficiencies. The low load bin represents intermediate operation and 
could include a large fraction of urban driving. Because the proposed 
approach divides 300 second windows into bins based on time-averaged 
engine power of the window, any of the bins could include some idle or 
high power operation. Like the duty cycle standards, we believe that 
more than a single standard is needed to apply to the entire range of 
operation that heavy-duty engines experience. A numerical standard that 
would be technologically feasible under worst case conditions such as 
idle would necessarily be much higher than the levels that are 
achievable when the aftertreatment is functioning optimally. Similarly, 
since the low load bin will consist of operation either between the 
idle and medium/high load bins or be an average of the operation in the 
two bins, the work specific emissions of the low load bin will 
generally be lower than the idle bin and higher than the medium/high 
load bin. Section III.C.2.iii includes the proposed Options 1and 2 off-
cycle standards.
    Given the challenges of measuring engine power directly in-use, we 
are proposing to use the CO2 emission rate (grams per 
second) as a surrogate for engine power in defining the bins for an 
engine. We are further proposing to normalize CO2 emission 
rates relative to the nominal maximum CO2 rate of the 
engine. So, if an engine with a maximum CO2 emission rate of 
50 g/sec was found to be emitting CO2 at a rate of 10 g/sec, 
its normalized CO2 emission rate would be 20 percent. We are 
proposing that the maximum CO2 rate be defined as the 
engine's rated maximum power multiplied by the engine's family 
certification level (FCL) for the FTP certification cycle. We request 
comment on whether the maximum CO2 mass emission rate should 
instead be determined from the steady-state fuel mapping procedure in 
40 CFR 1036.535 or the torque mapping procedure defined in 40 CFR 
1065.510. We propose the bins to be defined as follows:

 Idle bin: 300 second windows with normalized average 
CO2 rate <= 6 percent
 Low-load bin: 300 second windows with normalized average 
CO2 rate > 6 percent and <= 20 percent
 Medium/high-load bin: 300 second windows with normalized 
average CO2 rate > 20 percent

    The proposed bin cut points of six and twenty percent are near the 
average power of the proposed low-load cycle and the FTP, respectively. 
We request comment on whether the cut points should be defined at 
different power levels or if other metrics should be used to define the 
bins. We also request comment on whether it would be more appropriate 
to divide in-use operation into two bins rather than three bins and, if 
so, what the cut point should be.
    To ensure that there is adequate data in each of the bins to 
compare to the off-cycle standards, we are proposing a minimum of 2,400 
moving average windows per bin. We are proposing that if during the 
first shift day each of the bins does not include at least 2,400 
windows, then the engine would need to be tested for additional day(s) 
until the minimum requirement is met. We are also proposing that the 
engine can be idled at the end of the shift-day to meet the minimum 
window count requirement for the idle bin. This is to ensure that even 
for duty cycles that do not include significant idle operation the 
minimum window count requirement for the idle bin can be met without 
testing additional days. We request comment on whether 2,400 windows is 
the appropriate minimum to sufficiently reduce variability in the 
results while not requiring an unnecessary number of shift-days to be 
tested to meet the requirement.
ii. Off-Cycle Test Procedures
    We are proposing to measure off-cycle emissions using the existing 
test procedures that specify measurement equipment and the process of 
measuring emissions during field testing in 40 CFR part 1065. We are 
proposing in part 1036 subpart F the process for recruiting test 
vehicles, how to test over the shift-day, how to evaluate the data, 
what constitutes a valid test, and how to determine if an engine family 
passes. Measurements may use either the general laboratory test 
procedures in 40 CFR 1065, or the field test procedures in 40 CFR part 
1065, subpart J. However, we are proposing special calculations for low 
load and medium/high load bins in 40 CFR 1036.515 that would supersede 
the brake-specific emission calculations in 40 CFR part 1065. The 
proposed test procedures would require second-by-second measurement of 
the following parameters:

 Molar concentration of CO2 (ppm)
 Molar concentration of NOX (ppm)
 Molar concentration of HC (ppm)
 Molar concentration of CO (ppm)
 Concentration of PM (g/m3)
 Exhaust flow rate (m3/s)

    Mass emissions of CO2 and each regulated pollutant would 
be separately determined for each 300-second window and would be binned 
based on the normalized CO2 rate for each window.
    The standards described in Section III.C.2.iii are expressed in 
units of g/hr for the idle bin and g/hp-hr for the low and medium/high 
load bins. However, unlike most of our exhaust standards, the hp-hr 
values for the off-cycle standards do not refer to actual brake work. 
Rather, they refer to nominal equivalent work calculated proportional 
to the CO2 emission rate. Thus, we are proposing in 40 CFR 
1036.515 that the NOX emissions (``e'') in g/hp-hr would be 
calculated as:
[GRAPHIC] [TIFF OMITTED] TP28MR22.000


[[Page 17474]]


    We are proposing a limited number of exclusions that would exclude 
some data from being subject to the off-cycle standards. The first 
exclusion is for data collected during periodic PEMS zero and span 
drift checks or calibrations, where the emission analyzers are not 
available to measure emissions during that time and these checks/
calibrations are needed to ensure the robustness of the data. Data 
would also be excluded anytime the engine is off during the course of 
the shift-day, including engine off due to automated start/stop, as no 
exhaust emissions are being generated by the engine while it is not 
operating. We are also proposing to exclude data when ambient 
temperatures are below -7 [deg]C, or when ambient temperatures are 
above the altitude-based value determined using Equation 40 CFR 
1036.515-1. The colder temperatures can significantly inhibit the 
engine's ability to maintain aftertreatment temperature above the 
minimum operating temperature of the SCR catalyst while the higher 
temperature conditions at altitude can limit the mass airflow through 
the engine, which can adversely affect the engine's ability to reduce 
engine out NOX through the use of exhaust gas recirculation 
(EGR). In addition to affecting EGR, the air-fuel ratio of the engine 
can decrease under high load, which can increase exhaust temperatures 
above the conditions where the SCR catalyst is most efficient at 
reducing NOX. Data would also be excluded for operation at 
altitudes greater than 5,500 feet above sea level for the same reasons 
as for high temperatures at altitude. We would also exclude data when 
any approved Auxiliary Emission Control Device (AECD) for emergency 
vehicles are active because the engines are allowed to exceed the 
emission standards while these AECDs are active. Data collected during 
infrequent regeneration events would also be excluded due to the fact 
that the data collected may not include enough operation during the 
infrequent regeneration to properly weight the emissions rates during 
an infrequent regeneration event with emissions that occur without an 
infrequent regeneration event. We request comment on the 
appropriateness of these exclusions and whether other exclusions should 
be included. We request comment on whether emissions during infrequent 
regeneration should be included in determining compliance with the 
proposed off-cycle standards and if so, how these emissions should be 
included such that the emissions are properly weighted with the 
emissions when infrequent regenerations are not occuring. While data is 
excluded when any approved ACEDs for emergency vehicles are active, 
data generated while other approved ACEDs are active may not be 
excluded from the emissions calculations under the proposed 40 CFR 
1036.515.
    To reduce the influence of environmental conditions on the accuracy 
and precision of the PEMS, we are proposing additional requirements in 
40 CFR 1065.910(b). These requirements are to minimize the influence of 
temperature, pressure, electromagnetic frequency, shock, and vibration 
on the emissions measurement. If the design of the PEMS or the 
installation of the PEMS does not minimize the influence of these 
environmental conditions the PEMS must be installed in an environmental 
chamber during the off-cycle test.
iii. Off-Cycle Standards
    For NOX and HC, we are proposing separate standards for 
distinct modes of operation. To ensure that the proposed duty-cycle 
NOX standards and the proposed off-cycle NOX 
standards are set at the same relative stringency level for each 
option, the idle bin standard is proportional to the voluntary Idle 
standard discussed in Section III.B.2.iv, the low load bin standard is 
proportional to the proposed LLC standard discussed in Section 
III.B.2.iii and the medium/high load bin standard is proportional to 
the proposed SET standard discussed in Section III.B.2.ii. For HC for 
each option the proposed low load bin standards are set at values 
proportional to the LLC standard and the medium/high load bin standard 
is proportional to the SET proposed standard. For PM and CO for each 
option the standards for the FTP, SET and LLC are the same numeric 
value, so the low load and medium/high load bin have the same 
standards. The proposed Options 1 and 2 off-cycle standards for the low 
load and medium/high load bin are shown in Table III-17. For the idle 
bin, the proposed Option 1 NOX emission standard for all CI 
primary intended service classes is 10.0 g/hr starting in model years 
2027 through 2030 and 7.5 g/hr starting in model year 2031. For 
proposed Option 2, the idle bin NOX standard for all CI 
primary intended service classes is 15.0 g/hr starting in model year 
2027. For PM, HC and CO we are not proposing standards for the idle bin 
because the emissions from these pollutants are very small under idle 
conditions and idle operation is extensively covered by the FTP, SET 
and LLC duty cycles discussed in Section III.B.2. We request comment on 
appropriate scaling factors or other approaches to setting off-cycle 
standards. Finally, we request comment on whether there is a continued 
need for measurement allowances in an in-use program such as described 
below. A discussion of the measurement allowance values can be found in 
Section III.C.5.iii.

                                        Table III-17--Proposed Off-Cycle Low Load and Medium/High Load Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                   NOX (mg/hp-   PM (mg/hp-    HC (mg/hp-
               Option/MY                Primary intended service class             Bin                 hr)           hr)           hr)      CO (g/hp-hr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1.....................  All HD Engines................  Low load................           180            10           280            12
MY 2027-2030                            ..............................  Medium/high load........            70  ............           120  ............
Proposed Option 1.....................  Light HDE and Medium HDE......  Low load................            75             8            90             9
                                                                        Medium/high load........            30  ............            60  ............
MY 2031 and later.....................  Heavy HDE.....................  Low load................       \a\ 150             8            90             9
                                                                        Medium/high load........        \b\ 60  ............            60  ............
Proposed Option 2.....................  All HD Engines................  Low load................           150             8            90             9
MY 2027 and later                       ..............................  Medium/high load........            75  ............            60  ............
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Proposed Option 1 2031 and later low load bin IUL NOX standard is 75 mg/hp-hr for Heavy HDE.
\b\ Proposed Option 1 2031 and later medium/high load bin IUL NOX standard is 30 mg/hp-hr for Heavy HDE.


[[Page 17475]]

3. Feasibility of the Diesel (Compression-Ignition) Off-Cycle Standards
i. Technologies
    As a starting point for our determination of the appropriate 
numeric levels of our proposed off-cycle emission standards, we 
considered whether manufacturers could meet the duty-cycle standard 
corresponding to the type of engine operation included in a given bin, 
as follows:
     Idle bin operation is generally similar to operation at 
idle and the lower speed portions of the LLC.
     Low load bin operation is generally similar to operation 
over the LLC and the FTP.
     Medium/high load bin operation is generally similar to 
operation over the FTP and much of the SET.
    An important question is whether the proposed off-cycle standards 
would require technology beyond what we are projecting would be 
necessary to meet the duty-cycle standards. As described below, we do 
not expect our proposed Options 1 and 2 off-cycle standards to require 
different technologies. However, the proposed Option 1 standard for the 
medium/high load bin would likely require manufacturers to increase the 
volume of the SCR catalyst.
    This is not to say that we expect manufacturers to be able to meet 
these proposed Options 1 and 2 standards with no additional work. 
Rather, we project that the proposed Options 1 and 2 off-cycle 
standards could be met primarily through additional effort to calibrate 
the duty-cycle technologies to function properly over the broader range 
of in-use conditions. We also recognize that manufacturers could choose 
to include additional technology, if it provided a less expensive or 
otherwise preferred option.
    When we evaluated the technologies discussed in Section III.B.3.i 
with emissions controls that were designed to cover a broad range of 
operation, it was clear that we should set the off-cycle standards to 
higher numerical values than the duty-cycle standards for the off-cycle 
test procedures being proposed. Section III.C.3.ii explains how the 
technology and controls performed when testing with the off-cycle test 
procedures over a broad range of operation. The data presented in 
Section III.C.3.ii shows that even though there are similarities in the 
operation between the duty cycles (LLC, FTP, and SET) and the off-cycle 
bins (Idle bin, Low load bin, and Medium/high load bin), the broader 
range of operation covered by the off-cycle test procedure results in a 
broader range in emissions performance, which justifies the need for 
higher off-cycle standards than the corresponding duty cycle standards. 
In addition to this, the off-cycle test procedures and standards cover 
a broader range of ambient temperature and pressure, which can also 
increase the emissions from the engine as discussed in Section 
III.C.2.ii. Commenters supporting lower or higher numerical standards 
are encouraged to consider the proposed level of the standards in the 
full context of the test procedures and compliance provisions. See 
Section III.C.6.
ii. Summary of Feasibility Analysis
    To identify appropriate numerical levels for the off-cycle 
standards, we evaluated the performance of the EPA Stage 3 engine in 
the laboratory on five different cycles that were created from field 
data of HD engines that cover a range of off-cycle operation. These 
cycles are the CARB Southern Route Cycle, Grocery Delivery Truck Cycle, 
Drayage Truck Cycle, Euro-VI ISC Cycle (EU ISC) and the Advanced 
Collaborative Emissions Study (ACES) cycle. The CARB Southern Route 
Cycle is dominantly highway operation with elevation changes resulting 
in extended motoring sections followed by high power operation. The 
Grocery Delivery Truck Cycle represents goods delivery from regional 
warehouses to downtown and suburban supermarkets and extended engine-
off events characteristic of unloading events at supermarkets. Drayage 
Truck Cycle includes near dock and local operation of drayage trucks, 
with extended idle and creep operation. Euro-VI ISC Cycle is modeled 
after Euro VI ISC route requirements with a mix of 30 percent urban, 25 
percent rural and 45 percent highway operation. ACES Cycle is a 5-mode 
cycle developed as part of ACES program. Chapter 3 of the draft RIA 
includes figures that show the engine speed, engine torque and vehicle 
speed of the cycles.
    The engine was initially calibrated to minimize NOX 
emissions for the proposed duty cycles (FTP, SET, and LLC). It was then 
further calibrated to achieve more optimal performance over the off-
cycle operation. Although the engine did not include the SCR catalyst 
volume that is included in our cost analysis and that would enable 
lower medium/high load bin NOX emissions, the test results 
shown in Table III-18 provide a reasonable basis for evaluating the 
feasibility of controlling off-cycle emissions to a useful life of 
435,000 miles. Using this data along with the data from the CARB Stage 
3 that was measured at multiple points in the age of the aftertreatment 
to project out the emissions level to 800,000 miles, the proposed 
Options 1 and 2 off-cycle NOX standards at each respective 
useful life value are shown to be feasible. The summary of the results 
is in Chapter 3 of the draft RIA.

                           Table III-18--EPA Stage 3 NOX Emissions Off-Cycle Operation
----------------------------------------------------------------------------------------------------------------
                                                      Grocery
               Bin                CARB  southern     delivery          ACES           EU ISC          Drayage
                                       route           cycle
----------------------------------------------------------------------------------------------------------------
Idle bin (g/hr).................             0.7             1.0             0.9             0.4             0.3
Low load bin (mg/hp-hr).........              41              25              29              25              15
Medium/high load bin (mg/hp-hr).              30              18              16              33              23
----------------------------------------------------------------------------------------------------------------

a. Idle Bin Evaluation
    The proposed idle bin would include the idle operation and some of 
the lower speed operation that occurs during the LLC and FTP. However, 
it would also include other types of low-load operation observed with 
in-use vehicles, such as operation involving longer idle times than 
occur in the LLC. To ensure that the idle bin standard would be 
feasible, we set the proposed Option 1 idle bin standard in MY 2027 and 
MY 2031 at the level projected to be achievable engine-out with exhaust 
temperatures below the light-off temperature. As can be seen see from 
the results in Table III-18, the EPA Stage 3 engine performed well 
below the proposed Options 1 and 2 NOX standards. The 
summary of the results is located in Chapter 3 of the draft RIA.

[[Page 17476]]

b. Low and Medium/High Load Bin Evaluations
    As can be seen see from the results in Table III-18, the emissions 
from the Stage 3 engine in the low load bin were below the proposed 
Options 1 and 2 standards for each of the off-cycles standards. The HC 
and CO emissions measured for each of these off-cycle duty cycles was 
well below the proposed Options 1 and 2 off-cycle standards for the low 
and medium/high load bins. The summary of the results is located in 
Chapter 3 of the draft RIA.
    For the medium/high load bin, four of the five off-cycle duty 
cycles had emission results below the proposed Option 1 NOX 
standard for MY 2031 of 30 mg/hp-hr shown in Table III-17. As 
mentioned, in Section III.B.2 the engine did not include the SCR 
catalyst volume that is included in our cost analysis, so we will 
continue to evaluate the emissions performance from the EPA Stage 3 
engine and we will evaluate an aftertreatment that includes this 
additional SCR volume referred to as EPA Team A. In addition, we will 
conduct testing with these aftertreatments after they have been aged to 
the equivalent of 800,000 miles to further evaluate the feasibility of 
the proposed Option 1 off-cycle standards for the full proposed MY 2031 
useful life period. For the proposed Option 2 medium/high load 
standards, our extrapolation of the data from 435,000 miles to the 
650,000 useful life of proposed Option 2 indicates that the standards 
would be feasible starting in MY 2027.
    We request comment on the proposed Options 1 and 2 off-cycle 
standards, as well as the overall structure of the off-cycle program. 
We also request comment on the need for fewer or more than 3 bins. As 
described in Section III.C.3.ii, the emissions from CARB Stage 3 engine 
have been demonstrated to be very similar across the three bins, which 
may indicate that some or all bins can be combined. On the other hand, 
this data was generated on the EPA Stage 3 engine with aftertreatment 
that was chemically- and hydrothermally-aged to the equivalent of 
435,000 miles and as the aftertreatment is aged beyond 435,000 miles it 
may show a larger difference in NOX emissions performance 
between the bins. See Chapter 3 of the draft RIA for more information 
on how the FTP, SET, and LLC NOX emissions performance has 
changed from the degreened system to the aftertreatment aged to an 
equivalent of 600,000 miles.
4. Potential Alternatives
    Following our approach for duty-cycle standards, we evaluated one 
set of alternative off-cycle exhaust emission standards (the 
Alternative) for CI HDE. These alternative off-cycle standards were 
derived using the same approach as the proposed off-cycle standards. 
(i.e., by setting the alternative off-cycle standards as a multiple of 
the alternative certification duty-cycle standards). These off-cycle 
standards for the Alternative are set at 1.5 times the Clean Idle test 
standard (NOX only) for the idle bin, 1.5 times the LLC 
standard for the low load bin, and 1.5 times the SET standard for the 
medium/high load bin. This approach resulted in the same standards in 
the Alternative and the proposed Options 1 and 2 standards for PM, but 
different standards for NOX, HC and CO.
    For the Alternative, data in Table III-18 show that the medium/high 
load bin off-cycle NOX standard would be challenging to meet 
at a useful life of 435,000 miles. Our extrapolation of the data out to 
the 850,000 useful life for Heavy HDEs in this alternative suggests 
that this off-cycle standard is not feasible in the MY 2027 timeframe. 
We expect that wholly different emission control technologies than we 
have evaluated to date (i.e., not based on CDA and a dual SCR) would be 
needed to meet the standards in the Alternative; we request comment on 
this conclusion and on the availability, or potential development and 
timeline, of such additional technologies.
    As with the proposed standards, the data presented in Chapter 3 of 
the draft RIA shows that the Alternative PM, HC and CO standards are 
feasible for CI engines in MY 2027.

                                                  Table III-19--Off-Cycle Standards for the Alternative
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              NOX  (g/hr)
                                                            for idle, (mg/
                                                            hp-hr) for low
             Model year                       Bin            and  medium/        PM  (mg/hp-hr)            HC  (mg/hp-hr)             CO  (g/hp-hr)
                                                               high load
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
2027 and later.....................  Idle.................            15.0  No Standard.............  No Standard.............  No Standard.
                                     Low load.............             150  8.......................  90......................  9.
                                     Medium/high load.....              30  ........................  15.
--------------------------------------------------------------------------------------------------------------------------------------------------------

5. Compliance and Flexibilities for Off-Cycle Standards
    Given the similarities of the proposed off-cycle standards and test 
procedures to the current NTE requirements that we are proposing they 
would replace starting in MY 2027, we have evaluated the 
appropriateness of applying the current NTE compliance provisions for 
the proposed Options 1 and 2 off-cycle standards, as discussed below. 
We are also requesting comment on a possible broadening of our in-use 
compliance strategy to cover more engines and more operation.
i. Relation of Off-Cycle Standards to Defeat Devices
    CAA section 203 prohibits bypassing or rendering inoperative a 
certified engine's emission controls. When the engine is designed or 
modified to do this, the engine is said to have a defeat device. With 
today's engines, the greatest risks with respect to defeat devices 
involve manipulation of the electronic controls of the engine. EPA 
refers to an element of design that manipulates emission controls as an 
Auxiliary Emission Control Device (AECD).\350\ Unless explicitly 
permitted by EPA, AECDs that reduce the effectiveness of emission 
control systems under conditions which may reasonably be expected to be 
encountered in normal vehicle operation and use are prohibited as 
defeat devices under current 40 CFR 86.004-2.
---------------------------------------------------------------------------

    \350\ 40 CFR 86.082-2 defines Auxiliary Emission Control Device 
(AECD) to mean ``any element of design which senses temperature, 
vehicle speed, engine RPM, transmission gear, manifold vacuum, or 
any other parameter for the purpose of activating, modulating, 
delaying, or deactivating the operation of any part of the emission 
control system.''

---------------------------------------------------------------------------

[[Page 17477]]

    For certification, EPA requires manufacturers to identify and 
describe all AECDs.\351\ For any AECD that reduces the effectiveness of 
the emission control system under conditions which may reasonably be 
expected to be encountered in normal vehicle operation and use, 
manufacturers must provide a detailed justification.\352\ We are 
proposing to migrate the definition of defeat device from 40 CFR 
86.004-2 to 40 CFR 1036.115(h) and clarify that an AECD is not a defeat 
device if such conditions are substantially included in the applicable 
procedure for duty-cycle testing as described in 40 CFR 1036, subpart 
F. ``Duty-cycle testing'' in 40 CFR 1036.115(h)(1)(i) would not include 
the proposed off-cycle test procedure in 40 CFR 1036.515, since it is 
an off-cycle test procedure and not a duty-cycle test procedure for the 
purposes of this provision.
---------------------------------------------------------------------------

    \351\ See 40 CFR 86.094-21(b)(1)(i)(A).
    \352\ See definition of ``defeat device'' in 40 CFR 86.004-2.
---------------------------------------------------------------------------

ii. Heavy-Duty In-Use Testing Program
    Under the current manufacturer-run heavy-duty in-use testing 
(HDIUT) program, EPA annually selects engine families to evaluate 
whether engines are meeting current emissions standards. Once we submit 
a test order to the manufacturer to initiate testing, it must contact 
customers to recruit vehicles that use an engine from the selected 
engine family. The manufacturer generally selects five unique vehicles 
that have a good maintenance history, no malfunction indicators on, and 
are within the engine's regulatory useful life for the requested engine 
family. The tests require use of portable emissions measurement systems 
(PEMS) that meet the requirements of 40 CFR 1065, subpart J. 
Manufacturers collect data from the selected vehicles over the course 
of a day while they are used for their normal work and operated by a 
regular driver, and then submit the data to EPA. Compliance is 
evaluated with respect to the NTE standards.
    We are proposing to continue the HDIUT program, with compliance 
with respect to the new off-cycle standards and test procedures that 
would be added to the program beginning with MY 2027 engines. We are 
also proposing to not carry forward the Phase 2 HDIUT requirements in 
40 CFR 86.1915 beginning with MY 2027. Under the current NTE based off-
cycle test program, if you are required to test ten engines under Phase 
1 testing and less than 8 fully comply with the vehicle pass criteria 
in 40 CFR 86.1912, then we could require you to initiate Phase 2 HDIUT 
testing which would require you to test an additional 10 engines. We 
are proposing that compliance with the off-cycle standards would be 
determined by testing a maximum of 10 engines, which was the original 
limit under Phase 1 HDIUT testing in 40 CFR 86.1915. Similar to the 
current Phase 1 HDIUT requirements in 40 CFR 86.1912, the proposed 40 
CFR 1036.425 requires initially testing five engines. If all five 
engines pass, you are done testing and your engine family is in 
compliance. If one of those engines does not comply fully with the off-
cycle bin standards, you would then test a sixth engine. If five of the 
six engines tested pass, you are done testing and your engine family is 
in compliance. If two of the six engines tested do not comply fully 
with the off-cycle bin standards, you would then test four more for a 
total of 10 engines. The engine family would fail off-cycle standards 
if the arithmetic mean of the sum-over-sum emissions from the ten 
engines for any of the 3 bins for any of the pollutants is above the 
off-cycle bin standards. In regard to the averaging of data from the 
ten engines, we are proposing to take the arithmetic mean of the 
results by bin for each of the 10 engines determined in 40 CFR 
1036.515(h) for each of the pollutants, thus creating mean bin results 
of each pollutant for each bin for the 10 engines. We request comment 
on determining this value by using all of the windows in a given bin 
for a given pollutant over all 10 of the engines tested.
    We are also proposing to allow manufacturers to test a minimum of 2 
engines using PEMS, in response to a test order program, provided they 
measure and report in-use data collected from the engine's on-board 
NOX measurement system. This proposed option would be 
available only where a manufacturer receives approval based on the 
requirements in 40 CFR 1036.405(g).
    We are proposing to not carry forward the provision in 40 CFR 
86.1908(a)(6) that considers an engine misfueled if operated on a 
biodiesel fuel blend that is either not listed as allowed or otherwise 
indicated to be an unacceptable fuel in the vehicle's owner or operator 
manual. We are proposing in 40 CFR 1036.415(c)(1) to allow vehicles to 
be tested for compliance with the new off-cycle standards on any 
commercially available biodiesel fuel blend that meets the 
specifications for ASTM D975 or ASTM D7467. The proposal to make this 
change is based on the availability of biodiesel blends up to B20 
throughout the United States and thus its use as a motor fuel in the 
heavy-duty fleet and the fact that engines must comply with the 
emission standards when operated on both neat ultra-low sulfur diesel 
(ULSD) and these biodiesel fuel blends.
    Finally, we request comment on the need to measure PM emissions 
during in-use testing of new or existing engines subject to in-use 
testing if they are equipped with DPF. PEMS measurement is more 
complicated and time-consuming for PM measurements than for gaseous 
pollutants such as NOX and eliminating it for some or all of 
in-use testing would provide significant cost savings. Commenters are 
encouraged to address whether there are less expensive alternatives for 
ensuring that engines meet the PM standards in use.
iii. PEMS Accuracy Margin
    EPA worked with engine manufacturers on a joint test program to 
establish measurement allowance values to account for the measurement 
uncertainty associated with in-use testing in the 2008-time frame for 
gaseous emissions and the 2010-time frame for PM emissions to support 
NTE in-use testing.\353\ \354\ \355\ PEMS measurement allowance values 
in 40 CFR 86.1912 are 0.01 g/hp-hr for HC, 0.25 g/hp-hr for CO, 0.15 g/
hp-hr for NOX, and 0.006 g/hp-hr for PM. We are proposing to 
maintain the same values for HC, CO, and PM in this rulemaking. For 
NOX we are proposing off-cycle NOX accuracy 
margin (formerly known as measurement allowance) that is 10 percent of 
the off-cycle standard for a given bin. This accuracy margin was based 
on the Joint Research Council Real Driving Emissions (RDE): 2020 
Assessment of Portable Emissions Measurement Systems (PEMS) Measurement 
Uncertainty. In this study, JRC arrived at an accuracy margin of 23 
percent. They note that their Real Driving Emissions (RDE) program does 
not include linear drift correction of the emission measurements over 
the course of the shift-day. They have analytically determined that if 
they implement a

[[Page 17478]]

linear zero drift correction over the course of the shift-day, the 
NOX accuracy margin would be reduced to 10 percent. It 
should be noted that our off-cycle test procedures already include a 
linear zero and span drift correction over at least the shift day, and 
we are proposing to require at least hourly zero drift checks over the 
course of the shift day on purified air that, we believe, will result 
in measurement error that is on par with the analytically derived JRC 
value of 10 percent.\356\
---------------------------------------------------------------------------

    \353\ Feist, M.D.; Sharp, C.A; Mason, R.L.; and Buckingham, J.P. 
Determination of PEMS Measurement Allowances for Gaseous Emissions 
Regulated Under the Heavy-Duty Diesel Engine In-Use Testing Program. 
SwRI 12024, April 2007.
    \354\ Feist, M.D.; Mason, R.L.; and Buckingham, J.P. Additional 
Analyses of the Monte Carlo Model Developed for the Determination of 
PEMS Measurement Allowances for Gaseous Emissions Regulated Under 
the Heavy-Duty Diesel Engine In-Use Testing Program. SwRI[supreg] 
12859. July 2007.
    \355\ Khalek, I.A.; Bougher, T.L.; Mason, R.L.; and Buckingham, 
J.P. PM- PEMS Measurement Allowance Determination. SwRI Project 
03.14936.12. June 2010.
    \356\ Giechaskiel B., Valverde V., Clairotte M. 2020 Assessment 
of Portable Emissions Measurement Systems (PEMS) Measurement 
Uncertainty. JRC124017, EUR 30591 EN. https://publications.europa.eu/en/publications.
---------------------------------------------------------------------------

    We are also in the process of further assessing the gaseous PEMS 
accuracy margin values for NOX. There have been improvements 
made to the PEMS NOX analyzers that were used in the 
emission original measurement allowance value determinations and some 
of these improvements were implemented in the testing that resulted in 
the 10 percent value derived by JRC and some were implemented after. 
Based on information from the on-going PEMS test program using the most 
current PEMS NOX analyzers, we may make further revisions to 
the PEMS accuracy margin for NOX for the off-cycle 
NOX standards. This may result in finalizing a different 
accuracy margin or separate accuracy margins for each off-cycle bin 
NOX standard that could be higher or lower than what we have 
proposed. As results become available from this study, we will add them 
to the docket.
    These accuracy margins can be found in the proposed 40 CFR 
1036.420. We request comment on our proposed approach to PEMS accuracy 
margins for assessing in-use compliance with NOX and other 
pollutant standards.
    As part of the PEMS measurement uncertainty analysis we will be 
continuing to evaluate proposed test procedure options that could 
further reduce the uncertainty of PEMS measurements. This evaluation 
includes the test procedures that define the drift check and drift 
correction, linearity requirements for the analyzers, and the 
requirements that define how the analyzer is zeroed and spanned 
throughout the test. We have proposed updates to 40 CFR 1065.935 to 
require hourly zeroing of the PEMS analyzers using purified air for all 
analyzers. We are also proposing to update the drift limits for 
NOX analyzers to improve data quality. Specifically, for 
NOX analyzers, we are proposing an hourly or more frequent 
zero verification limit of 2.5 ppm, a zero-drift limit over the entire 
shift day of 10 ppm, and a span drift limit between the beginning and 
end of the shift-day or more frequent span verification(s) of 4 percent of the measured span value. We request comment on the 
proposed test procedure updates in 40 CFR 1065.935 and any changes that 
would reduce the PEMS measurement uncertainty.
iv. Demonstrating Off-Cycle Standards for Certification
    Consistent with current certification requirements in 40 CFR 
86.007-21(p)(1), we are proposing a new paragraph in 40 CFR 1036.205(p) 
that would require manufacturers to provide a statement in their 
application for certification that their engine complies with the off-
cycle standards. Our proposal would require manufacturers to maintain 
record of any test data or engineering analysis they used as a basis 
for their statement but would not require manufactures to submit that 
information as part of their application. We request comment on our 
proposal to continue the practice of manufacturers submitting a 
statement without test data as a means of demonstrating compliance with 
off-cycle standards at certification.
    For commenters suggesting manufacturers submit test data, we 
request comment on defining a specific test for manufacturers to 
demonstrate that they meet off-cycle standards at certification. The 
proposed off-cycle standards were designed to apply in-use when engines 
may not be operating on EPA's defined duty cycles. We are proposing 
that manufacturers use the off-cycle test procedure of 40 CFR 1036.515 
when evaluating their in-use emission performance relative to the off-
cycle standards. We request comment on demonstrating compliance with 
off-cycle standards by applying the off-cycle test procedure proposed 
in 40 CFR 1036.515 to one or more test cycles performed on an engine 
dynamometer. We solicit comment on alternatively demonstrating 
compliance with a field test using 40 CFR 1036.515.
6. Summary of Requests for Comment on the Stringency of the Off-Cycle 
Standards
    The effective stringency of the proposed off-cycle standards is 
inherently tied to the way in which these standards are applied. To 
assist commenters in considering the stringency of the standards in the 
full context of the test procedures and compliance provisions, we have 
summarized these factors in Table III-20 below.

 Table III-20--Summary of Off-Cycle Test Procedure Values and Compliance
                               Provisions
------------------------------------------------------------------------
                                      Increasing          Decreasing
              Issue                    effective           effective
                                      stringency          stringency
------------------------------------------------------------------------
Numerical value.................  Lower value.......  Higher value.
Window length...................  Shorter windows...  Longer windows.
Test conditions.................  Broader conditions  Narrower
                                                       conditions.
Operation type..................  Broader operation.  Narrower
                                                       operation.
------------------------------------------------------------------------

    These factors can be considered individually, but commenters are 
encouraged to consider the tradeoffs between them. For example, 
commenters supporting a broader range of test conditions, could address 
the potential need for provisions to offset the stringency impact, such 
as higher standards.
    We are proposing to sum the total mass of emissions for a given 
pollutant and divide by the sum of CO2 mass emissions per 
bin once all the data has been separated into bins. This ``sum-over-
sum'' approach would account for all emissions; however, it would 
require the measurement system (PEMS or a NOX sensor) to 
provide accurate measurements across the complete range of emissions 
concentrations. We specifically request comments on the numeric values 
for the bin cut-points, the number of bins, the definition of the bin 
cut-point and the reference cycle for each bin. The importance of each 
of these values that define the proposed test procedure can be seen 
from the NOX emissions achieved on the EPA Stage 3 engine 
which is summarized in Section III.B.3. This data shows that the 
emissions from this engine are relatively flat as a function of engine 
power. This data could suggest that either fewer bins

[[Page 17479]]

are needed, for example combining the idle and low-load bin or that a 
different bin definition other than window average power should be used 
to bin the data.
    We also request comment on the advantages and disadvantages of 
other statistical approaches that evaluate a percentile window(s) 
within each of the bins instead of the full data set as discussed in 
Chapter 3.2.3 in the draft RIA.

D. Summary of Spark-Ignition Heavy-Duty Engine Exhaust Emission 
Standards and Test Procedures

    This section summarizes current exhaust emission standards and test 
procedures for certain spark-ignition (SI) heavy-duty engines and our 
proposed updates, as well as the feasibility demonstration and data 
that support our proposed changes.
    Heavy-duty SI engines are largely produced by integrated vehicle 
manufacturers. These vehicle manufacturers sell most of their engines 
as part of complete vehicles but may also sell incomplete vehicles 
(i.e., an engine and unassembled chassis components) to secondary 
vehicle manufacturers.\357\ In the latter case, secondary 
manufacturers, sometimes referred to as ``finished vehicle builders,'' 
complete the body and sell the final commercial vehicle product to the 
customer. Under current industry practice, the incomplete vehicle 
manufacturer (i.e., chassis manufacturer) certifies both the engine and 
incomplete vehicle pursuant to all exhaust and evaporative emission 
requirements, performs testing to demonstrate compliance with the 
standards and provides the secondary manufacturer with build 
instructions to maintain compliance with the standards and to prevent 
the secondary manufacturer from performing modifications that would 
result in an un-certified configuration. Original chassis manufacturers 
and secondary manufacturers share responsibility for ensuring that the 
exhaust and evaporative emission control equipment is maintained in the 
final product delivered to the end customer.\358\
---------------------------------------------------------------------------

    \357\ See e.g., the definitions of ``vehicle'' and ``secondary 
vehicle manufacturer'' in 40 CFR 1037.801.
    \358\ Responsibilities for multiple manufacturers are described 
in 40 CFR 1037.620(b).
---------------------------------------------------------------------------

1. Current Exhaust Emission Standards and Test Procedures
    Current Otto-cycle (spark-ignition) heavy-duty engine exhaust 
emission standards in 40 CFR 86.008-10 apply to engines as provided in 
40 CFR 86.016-1.\359\ The test procedure for these exhaust standards is 
the heavy-duty Federal Test Procedure (FTP), which includes an engine 
dynamometer schedule that represents urban driving. This test procedure 
is used for certification, SEA, and in-use emissions testing.\360\ 
Similar to the FTP duty cycle for CI engines, SI engine manufacturers 
evaluate their HD engines for exhaust emission standards by performing 
the FTP duty cycle under cold-start and hot-start conditions and 
determine a composite emission value by weighting the cold-start 
emission results and the hot-start emission results as specified in 40 
CFR 86.008-10(a)(2)(v). This test cycle and cold/hot-start weighting 
was developed based on the typical operation of spark-ignition engines 
and differs from its compression-ignition counterpart in the normalized 
speed and torque setpoints, as well as the length of the cycle. The 
current SI engine exhaust emission standards for this duty cycle are 
identical to those for CI engines, as shown in Table III-21, consistent 
with the principle of fuel neutrality applied in recent light-duty 
vehicle criteria pollutant standards rulemakings.\361\
---------------------------------------------------------------------------

    \359\ These engines include SI engines installed in vehicles 
above 14,000 lb GVWR or incomplete vehicles at or below 14,000 lb 
GVWR, but do not include engines installed in incomplete vehicles at 
or below 14,000 lb GVWR that are voluntarily certified under 40 CFR 
86, subpart S.
    \360\ This duty cycle is summarized in Chapter 2.1.3 of the 
draft RIA. The driving schedule can be found in paragraph (f)(1) of 
Appendix I to 40 CFR part 86.
    \361\ See 65 FR 6728 (February 10, 2000) and 79 FR 23454 (April 
28, 2014).

           Table III-21--Current Otto-Cycle Engine Exhaust Emission Standards Over the FTP Duty-Cycle
----------------------------------------------------------------------------------------------------------------
                                                                                 HC \b\ (g/hp-
                      NOX \a\ (g/hp-hr)                          PM (g/hp-hr)         hr)          CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
0.20.........................................................            0.01             0.14             14.4
----------------------------------------------------------------------------------------------------------------
\a\ Engine families participating in the ABT program are subject to a FEL cap of 0.50 g/hp-hr for NOX.
\b\ Engine families participating in the ABT program are subject to a FEL cap of 0.30 g/hp-hr for HC.

    To generate specific duty cycles for each engine configuration, 
engine manufacturers identify the maximum brake torque versus engine 
speed using the engine mapping procedures of 40 CFR 1065.510. The 
measured torque values are intended to represent the maximum torque the 
engine can achieve under fully warmed-up operation when using the fuel 
grade recommended by the manufacturer (e.g., regular unleaded, 87 
octane fuel) across the range of engine speeds expected in real-world 
conditions. The mapping procedure is intended to stabilize the engine 
at discrete engine speed points ranging from idle to the 
electronically-limited highest RPM before recording the peak engine 
torque values at any given speed. The provision in 40 CFR 
1065.510(b)(5)(ii) allows manufacturers to perform a transient sweep 
from idle to maximum rated speed, which requires less time than 
stabilizing at each measurement point.
    The HD Technical Amendments rulemaking migrated some heavy-duty 
highway engine test procedures from 40 CFR part 86 to part 1036.\362\ 
In addition to migrating the heavy-duty FTP drive schedule for SI 
engines from paragraph (f) of appendix I to part 86 to paragraph (b) of 
appendix II to part 1036, we added vehicle speed and road grade to the 
duty-cycle, which are needed to facilitate powertrain testing of SI 
engines for compliance with the HD Phase 2 GHG standards. As part of 
the drive schedule migration, negative normalized vehicle torque values 
over the HD FTP SI duty-cycle were removed.
---------------------------------------------------------------------------

    \362\ 86 FR 34311, June 29, 2021.
---------------------------------------------------------------------------

2. Proposed Exhaust Emission Standards and Test Procedures
    We are proposing to migrate the existing provisions for heavy-duty 
Otto-cycle engines from 40 CFR part 86, subpart A, into part 1036, with 
the migrated part 1036 provisions applying to heavy-duty SI engines 
starting in MY 2027.\363\ We are also proposing additional revisions as 
noted in this section.
---------------------------------------------------------------------------

    \363\ Under the proposed migration into part 1036, Spark-
ignition HDE produced before model year 2027 would remain subject to 
existing part 86 requirements, including the exhaust and crankcase 
emission standards specified in 40 CFR 86.008-10(a) and (c).

---------------------------------------------------------------------------

[[Page 17480]]

    Our proposed revisions to 40 CFR 1036.1 include migrating and 
updating the applicability provisions of 40 CFR 86.016-1. The 
provisions proposed in this section would apply for SI engines 
installed in vehicles above 14,000 lb GVWR and incomplete vehicles at 
or below 14,000 lb GVWR, but do not include engines voluntarily 
certified to or installed in vehicles subject to 40 CFR part 86, 
subpart S. We propose to update the primary intended service classes 
currently defined in 40 CFR 1036.140 to refer to new acronyms such that 
the proposed requirements in this section apply to the ``Spark-ignition 
HDE'' primary intended service class. Additionally, we are proposing 
updated Spark-ignition HDE exhaust emission standards in a new 40 CFR 
1036.104. The proposal includes two sets of options for these 
standards: Proposed Option 1 and proposed Option 2. Proposed Option 1 
would apply in two steps, with a first step in MY 2027 and a second 
step in MY 2031. Proposed Option 2 would apply in a single step 
starting in MY 2027. The two proposed options generally represent the 
range of lead time, standards, regulatory useful life periods, and 
emission-related warranty periods we are currently considering in this 
rule for HD SI engines.
    As described in the following sections, Spark-ignition HDE 
certification would continue to be based on emission performance in 
lab-based engine dynamometer testing, with a proposed new SET duty 
cycle to address high load operation and idle emission control 
requirements to supplement our current FTP duty cycle.\364\ We are 
proposing two options to lengthen useful life and emissions warranty 
periods for all heavy-duty engines, including Spark-ignition HDE, as 
summarized in the following sections and detailed in Sections IV.A and 
IV.B.1 of this preamble.\365\ Engine manufacturers would continue to 
have the flexibility to participate in EPA's ABT program. We are 
proposing to update our ABT provisions in part 1036, subparts B and H, 
to reflect our proposed standards and useful life periods (see Section 
IV.G of this preamble). We are also proposing family emission limit 
(FEL) caps for NOX in our proposed ABT program as described 
in the following sections.
---------------------------------------------------------------------------

    \364\ CARB's HD Omnibus rulemaking included ``in-use 
thresholds'' (i.e., ``off-cycle standards'' in this proposal) for 
heavy-duty Otto-cycle engines. We request comment on setting off-
cycle standards for Spark-ignition HDE. We are not proposing a 
manufacturer-run in-use testing program for Spark-ignition HDE at 
this time, though we may consider it in future rulemakings. See 
California Air Resources Board. Staff Report: Initial Statement of 
Reasons-Public Hearing to Consider the Proposed Heavy-Duty Engine 
and Vehicle Omnibus Regulation and Associated Amendments. June 23, 
2020. page III-33. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \365\ We are proposing to migrate the current alternate 
standards for engines used in certain specialty vehicles from 40 CFR 
86.007-11 and 86.008-10 into 40 CFR 1036.605 without modification. 
See Section XII.B of this preamble for a discussion of these 
standards and options for which we are requesting comment.
---------------------------------------------------------------------------

i. Proposed Updates to the Federal Test Procedure and Standards
    We propose to update 40 CFR part 1036, including the test procedure 
provisions of part 1036, subpart F, to apply for criteria pollutant 
testing. We propose that manufacturers would use the current FTP drive 
schedule of Appendix II of part 1036.\366\ As part of migrating the FTP 
drive schedule from part 86 to part 1036 in the recent HD Technical 
Amendment rulemaking,\367\ negative torque values were replaced with 
closed throttle motoring but there was no change to the weighting 
factors or drive schedule speed values. As shown in Table III-22, we 
are co-proposing two options to update our Spark-ignition HDE exhaust 
standards for the FTP duty cycle. The proposed Spark-ignition HDE 
exhaust standards maintain our fuel-neutral approach with standards 
that are numerically identical to the two steps of the proposed 
compression-ignition engine standards over our proposed lengthened 
Spark-ignition HDE useful life periods.\368\
---------------------------------------------------------------------------

    \366\ Note that we are proposing to rename this appendix to 
Appendix B to part 1036.
    \367\ 86 FR 34311, June 29, 2021.
    \368\ Our proposed useful life periods are based on the 
operational life of the engines and differ by primary intended 
service class. See Section IV.A of this preamble for a discussion of 
our proposed useful life periods.

                              Table III-22--Proposed Spark-Ignition HDE Exhaust Emission Standards Over the FTP Duty Cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       NOX\a\ (mg/hp-                                                     Useful life
                Scenario                           Model year                hr)        PM (mg/hp-hr)   HC (mg/hp-hr)   CO (g/hp-hr)     (miles/years)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1.......................  2027-2030..................              35               5              60             6.0         155,000/12
                                          2031 and later.............              20               5              40             6.0         200,000/15
Proposed Option 2.......................  2027 and later.............              50               5              40             6.0         150,000/10
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Engine families participating in the ABT program would be subject to a NOX FEL cap of 150 mg/hp-hr for MYs 2027-2030 under proposed Option 1 or for
  MYs 2027 and later under proposed Option 2, and 50 mg/hp-hr for MYs 2031 and later under proposed Option 1.

    Our analysis of recent SI HDE certification data suggests that the 
proposed Options 1 and 2 standards are already nearly achievable for 
the existing useful life mileage values using emission control 
technologies available today. All SI heavy-duty engines currently on 
the market use a three-way catalyst (TWC) to simultaneously control 
NOX, HC, and CO emissions.\369\ We project manufacturers 
would continue to use TWC technology and would adopt advanced catalyst 
washcoat technologies and refine their existing catalyst thermal 
protection (fuel enrichment) strategies to prevent damage to engine and 
catalyst components over our proposed longer useful life. Our 
feasibility analysis in Section III.D.3 describes the derivation of the 
proposed standards, including results from our SI technology 
demonstration program showing the feasibility of meeting these 
standards up to and beyond our proposed Options 1 and 2 useful life 
mileage values.
---------------------------------------------------------------------------

    \369\ See Chapter 1.2 of the draft RIA for a detailed 
description of the TWC technology and other strategies HD SI 
manufacturers use to control criteria emissions.
---------------------------------------------------------------------------

ii. Proposed Updates to Engine Mapping Test Procedure
    As noted in Section III.D.1, manufacturers use the engine fuel 
mapping procedures of 40 CFR 1065.510 for certification. In Chapter 
2.3.2 of our draft RIA, we describe torque variability that can result 
from the electronic controls used in SI engines. We are proposing 
updates to the engine mapping test procedure for heavy-duty engines to 
require that the torque curve established during the mapping procedure 
for highway heavy-duty engines be representative of the highest

[[Page 17481]]

torque level possible when using the manufacturer's recommended fuel 
grade (e.g., regular unleaded, 87 octane). Specifically, our proposed 
update to 40 CFR 1065.510(b)(5)(ii) would require manufacturers to 
disable any electronic controls that they report to EPA as an auxiliary 
emission control device (AECD) that would impact peak torque during the 
engine mapping procedure.\370\ We are proposing these updates to apply 
broadly for all engines covered under part 1065 (see 40 CFR 1065.1). 
Section XII.I of this preamble includes a discussion of proposed 
revisions to part 1065.
---------------------------------------------------------------------------

    \370\ AECDs are defined in 40 CFR 1036.801 and described in our 
proposed, migrated new paragraph 1036.115(h). Manufacturers report 
AECDs in their application for certification as specified in our 
proposed, migrated and updated Sec.  1036.205(b).
---------------------------------------------------------------------------

iii. Proposed Supplemental Emission Test and Standards
    As discussed in Chapter 1 of the draft RIA, SI engines maintain 
stoichiometric air-fuel ratio control for a majority of the points 
represented on a fuel map. However, engine manufacturers program power 
enrichment and catalyst protection enrichment commands to trigger 
additional fuel to be delivered to the engine when either the engine 
requires a power boost to meet a load demand or high exhaust 
temperatures activate thermal protection for the catalyst. Generally, 
these strategies temporarily allow the engine to deviate from its 
``closed loop'' control of the air-fuel ratio to increase the fraction 
of fuel (i.e., fuel enrichment) and lower exhaust temperatures or 
increase engine power. Fuel enrichment is an effective means to protect 
the catalyst and increase engine power, but frequent enrichment events 
can lead to high criteria pollutant emissions and excessive fuel 
consumption not captured in existing test cycles. In Chapter 2.2 of the 
draft RIA, we highlight the opportunities to reduce emissions in high-
load operating conditions where engines often experience enrichment for 
either catalyst protection or a power boost. Our feasibility discussion 
in Section III.D.3 presents thermal management, catalyst design, and 
engine control strategies engine manufacturers can implement to reduce 
enrichment frequency and associated emissions to meet our proposed 
standards.
    Manufacturers implement enrichment strategies in real world 
operation when engines are above about 90 percent throttle for a 
duration that exceeds certain thresholds determined by the 
manufacturer. The FTP duty cycle currently used for engine 
certification does not capture prolonged operation in those regions of 
the engine map. Historically, in light of the limited range of 
applications and sales volumes of SI heavy-duty engines, especially 
compared to CI engines, we believed the FTP duty cycle was sufficient 
to represent the high-load and high-speed operation of SI engine-
powered heavy-duty vehicles. As the market for SI engines increases for 
use in larger vehicle classes, these engines are more likely to operate 
under extended high-load conditions, causing us to more closely examine 
the adequacy of the test cycle in ensuring emissions control under real 
world operating conditions.
    The existing supplemental emission test (SET) duty cycle, currently 
only applicable to CI engines, is a ramped modal cycle covering 13 
steady-state torque and engine speed points that is intended to 
exercise the engine over sustained higher load and higher speed 
operation. We believe the SET procedure, including updates proposed in 
this rule, could be applied to SI engines and we are proposing to add 
the SET duty cycle and co-proposing two options for new SET emission 
standards for the Spark-ignition HDE primary intended service 
class.\371\ This new cycle would ensure that emission controls are 
properly functioning in the high load and speed conditions covered by 
that duty cycle. The proposed SET standards for Spark-ignition HDE are 
based on the same SET procedure, with the same proposed updates, as for 
heavy-duty CI engines, and we request comment on the need for any SI-
specific provisions. Specifically, we request comment on the 
appropriateness of the CI-based weighting factors that determine the 
time spent (i.e., dwell period) at each cycle mode. We encourage 
commenters to submit data to support any alternative dwell periods we 
should consider for SI engines.
---------------------------------------------------------------------------

    \371\ See our proposed updates to the SET test procedure in 40 
CFR 1036.505.
---------------------------------------------------------------------------

    We received comments in response to our ANPR discussion of the 
potential addition of an SET test cycle for HD SI engines.\372\ The 
commenter suggested that additional test cycles to capture sustained 
high load operation are not necessary and deviations from the FTP 
emission control strategies are addressed through the case-by-case AECD 
review process. While we agree that this process is available during 
the certification of an engine or vehicle, we believe it is more 
effective to evaluate the emission control system over measured test 
cycles with defined standards, where such test cycles are available, 
rather than relying solely on case-by-case identification by the 
manufacturer and review by EPA of the AECDs for each engine family. The 
commenter describes a high load enrichment AECD, which potentially 
increases CO, NMHC and PM emissions (see RIA Ch 3.2). However, the 
agency is also concerned about the potential for increased 
NOX emissions during high load stoichiometric operation, 
where the enrichment AECD is not active. The current FTP transient 
cycle does not sufficiently represent these high load conditions, and 
we believe that the SET cycle is appropriate for evaluating this type 
of operation.
---------------------------------------------------------------------------

    \372\ See comments from Roush CleanTech (EPA-HQ-OAR-2019-0055-
0303) in our docket.
---------------------------------------------------------------------------

    Similar to our fuel-neutral approach for FTP, we are proposing to 
align the SET standards for CI and SI engines, as shown in Table III-
23. Specifically, we propose to adopt the SI HDE SET standards for 
NOX and PM emissions based on the demonstrated ability of CI 
engines to control these emissions under high load conditions. The 
proposed Options 1 and 2 Spark-ignition HDE standards for HC and CO 
emissions on the SET cycle are numerically equivalent to the respective 
proposed FTP standards and are intended to ensure that SI engine 
manufacturers utilize emission control hardware and calibration 
strategies that maintain effective control of emissions during high 
load operation.\373\ We believe the proposed SET duty cycle and 
standards would accomplish this goal, and the level of our proposed 
Options 1 and 2 HC and CO standards are feasible over our proposed 
Options 1 and 2 useful life mileages based on our HD SI technology 
demonstration program summarized in Section III.D.3.ii.b. We request 
comment on the proposed SET test cycle and standards for Spark-ignition 
HDE, and any modifications we should consider to adapt the current CI-
based SET duty cycle to SI HDEs.
---------------------------------------------------------------------------

    \373\ Test results presented in Chapter 3.2.3 of the draft RIA 
and summarized in Section III.D.3 indicate that these standards are 
achievable when the engine controls limit fuel enrichment and 
maintain closed loop control of the fuel-air ratio.

[[Page 17482]]



                              Table III-23--Proposed Spark-Ignition HDE Exhaust Emission Standards Over the SET Duty-Cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       NOX (mg/hp-hr)                                                     Useful life
                Scenario                           Model year                           PM (mg/hp-hr)   HC (mg/hp-hr)   CO (g/hp-hr)     (miles/years)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Option 1.......................  2027-2030..................              35               5              60             6.0         155,000/12
                                          2031 and later.............              20               5              40             6.0         200,000/15
Proposed Option 2.......................  2027 and later.............              50               5              40             6.0         150,000/10
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We are also considering other approaches to address emissions from 
enrichment events during high load operation. Our current provisions in 
40 CFR 86.004-28(j) require engine manufacturers to account for 
emission increases that are associated with aftertreatment systems that 
infrequently regenerate.\374\ Compression-ignition engine manufacturers 
currently apply these infrequent regeneration adjustment factor (IRAF) 
provisions to account for emission increases that may occur when the 
DPFs used for PM control on their engines require regenerations. These 
infrequent regeneration events use additional fuel to temporarily heat 
the DPF and clean the filter. Similar to the approach for infrequent 
regeneration events, the agency seeks comment on whether to require 
manufacturers to apply adjustment factors to SI FTP and/or SET emission 
test results to quantify the HC, CO, NOX, and PM emission 
increases that occur due to enrichment AECDs. These factors would be 
quantified in a manner similar to that used in developing IRAFs, where 
they are based on the estimated real-world frequency and the measured 
emissions impact of these events.
---------------------------------------------------------------------------

    \374\ We are proposing to migrate the current IRAF provisions 
into a new section 40 CFR 1036.522.
---------------------------------------------------------------------------

iv. Proposed Idle Control for Spark-Ignition HDE
    As described in Chapter 3.2 of the draft RIA, an idle test would 
assess whether the main component of the SI engine emission control 
system, the catalyst, remains effective during prolonged idle events. 
Heavy-duty SI engines can idle for long periods during loading or 
unloading of the vehicle cargo or to maintain cabin comfort (i.e., 
heating or cooling) when the vehicle is parked.
    Our primary concern for extended idle operation is that prolonged 
idling events may allow the catalyst to cool and reduce its efficiency 
resulting in emission increases including large emission increases on 
the driveaway until the catalyst temperatures increase. As discussed in 
the draft RIA, our recent HD SI test program showed idle events that 
extend beyond four minutes allow the catalyst to cool below the light-
off temperature of 350 [deg]C. The current heavy-duty FTP and proposed 
SET duty cycles do not include sufficiently long idle periods to 
represent these real-world conditions where the exhaust system cools 
below the catalyst's light-off temperature. We are proposing in a new 
paragraph at 40 CFR 1036.115(j)(1) to require the catalyst bed used in 
SI HDEs to maintain a minimum temperature of 350 [deg]C to ensure 
emission control during prolonged idle; manufacturers would also be 
able to request approval of alternative strategies to prevent increased 
emissions during idling. We believe this minimum temperature 
requirement would sufficiently ensure emission control is maintained 
during idle, while addressing ANPR commenter concerns that our proposed 
idle requirements should not require significant additional test and 
certification costs.\375\ We request comment on this proposal, as well 
as additional or alternative strategies, such an idle test cycle and 
standard, that are capable of representing real-world operation and 
would address idle emissions not observed or measured on the current 
and proposed duty cycles. Commenters are encouraged to include data 
that represents engines expected to be available in the MY 2027 and 
later timeframe.
---------------------------------------------------------------------------

    \375\ Roush comments (EPA-HQ-OAR-2019-0055-0303).
---------------------------------------------------------------------------

    We recognize that over the next decade there may be an added 
incentive to generally reduce idling as a compliance strategy to meet 
EPA's heavy-duty greenhouse gas standards. Widespread adoption of idle 
reduction technologies, such as engine stop-start, may reduce the 
frequency and duration of prolonged idle and reduce the need for 
exhaust temperature thresholds. However, these idle reduction 
strategies may also cause emission increases when the engine is 
restarted, where the catalyst and oxygen sensors may have cooled and 
require a warm-up period. We request comment, including relevant data, 
on the expected adoption rate of idle reduction technologies (e.g., 
stop-start) in the heavy-duty sector and the impact on criteria 
pollutant emissions when these technologies are in use.
v. Proposed Powertrain Testing Option for Hybrids
    As summarized in Section III.B, we are proposing to expand the 
existing powertrain test procedures in 40 CFR 1037.550 to allow hybrid 
manufacturers to certify their products as meeting EPA's criteria 
pollutant standards.\376\ The procedure updates are intended to apply 
to both CI and SI-based hybrid systems, but many of the default vehicle 
parameters are based on CI systems. We request comment on the need for 
SI-specific vehicle parameters such as vehicle mass, drag coefficients, 
and rolling resistance coefficients.
---------------------------------------------------------------------------

    \376\ See Chapter 2 of the draft RIA for a detailed description 
of the powertrain test procedure.
---------------------------------------------------------------------------

vi. Proposed Thermal Protection Temperature Modeling Validation
    Manufacturers utilize some form of catalyst or critical exhaust 
component temperature modeling within the ECM to determine when to 
activate fuel enrichment strategies to protect engine and catalyst 
hardware from excessive temperatures that may compromise durability. 
Manufacturers typically design these models during the engine 
development process by monitoring the actual temperatures of exhaust 
system components that have been instrumented with thermocouples during 
dynamometer testing. In these controlled testing conditions, 
manufacturers can monitor temperatures and stop the test to protect 
components from damage from any malfunctions and resulting excessive 
temperatures. The accuracy of these models used by manufacturers is 
critical in both ensuring the durability of the emission control 
equipment and preventing excessive emissions that could result from 
unnecessary or premature activation of thermal protection strategies.
    The existing regulations require any catalyst protection strategies 
adopted by HD SI engine manufacturers to be reported to EPA in the 
application for certification as an AECD.\377\ The engine

[[Page 17483]]

controls used to implement these strategies often rely on a modeling 
algorithm to predict high exhaust temperatures and to disable the 
catalyst, which can change the emission control strategy and directly 
impact real world emissions. During the certification process, 
manufacturers typically disclose the temperature thresholds of the 
critical components that need thermal protection and the parameter 
values (e.g., time and temperature) at which the model activates the 
protection strategy. The agency has historically determined the 
appropriateness of these temperature limits based on information from 
engine manufacturers and component suppliers. We are proposing to 
standardize the process during certification of how a manufacturer 
discloses and validates a thermal protection model's performance.
---------------------------------------------------------------------------

    \377\ See 40 CFR 86.094-21(b)(1)(i) and our proposed migration 
of those provisions to 40 CFR 1036.205(b).
---------------------------------------------------------------------------

    In order to ensure that a manufacturer's model accurately estimates 
the temperatures at which thermal protection modes are engaged, the 
agency is proposing a validation process in a new paragraph 40 CFR 
1036.115(j)(2) that would document the model performance during 
certification testing. The proposed validation process would require 
manufacturers to record component temperatures during engine mapping 
and the FTP and proposed SET duty cycles and a second-by-second 
comparison of the modeled temperature and the actual component 
temperature applications and submit as part of their certification. We 
propose that manufacturers must show that the measured component 
temperatures and the software-derived temperature model estimates are 
within 5 [deg]C. This limitation on temperature differential is 
proposed to prevent model-based AECDs from being overly conservative in 
their design such that catalyst protection and resulting emissions 
increases due to fuel enrichment is triggered at lower temperatures 
than necessary. Manufacturers would be exempt from this model 
validation requirement for all engines that continuously monitor 
component temperatures via temperature sensors in lieu of thermal 
protection modeling.
    As described in Section IV.C, we are proposing to expand the list 
of OBD parameters accessible using a generic scan tool. We are 
proposing that SI engine manufacturers monitoring component 
temperatures to engage thermal protection modes would make the 
component temperature parameters (measured and modeled, if applicable) 
publicly available, as specified in a new 40 CFR 1036.110(c)(4).
    The agency seeks comment on this model validation proposal, 
including data that shows the frequency of preventable enrichment 
occurrences. We request comment on our proposed temperature allowance 
of 5 [deg]C and whether we should require a specific type of 
thermocouple to measure the component temperatures. We also request 
comment on whether we should specify a method to filter temperature 
data to account for transient engine speed conditions. The agency also 
seeks comment on requiring manufacturers to incorporate temperature 
sensors on all production engines to continuously measure the 
temperature of any exhaust component that is currently protected by use 
of an enrichment strategy instead of relying on software models to 
estimate temperature. Currently, temperature sensors are used in 
production compression-ignition emission control systems and some 
light-duty SI applications.
vii. Proposed OBD Flexibilities
    We recognize that there can be some significant overlap in the 
technologies and control systems adopted for products in the chassis-
certified and engine-certified markets. These vehicles may share common 
engine designs and components, and their emission control systems may 
differ only in catalyst sizing and packaging and the calibration 
strategies used to meet the chassis- or engine-based emission 
standards.
    We are proposing to further incentivize HD SI engine manufacturers 
to adopt their chassis-certified technologies and approaches in their 
engine-certified products so that the emission control strategies of 
their two product lines are more closely aligned. Specifically, we are 
proposing to limit the need for duplicate OBD certification testing if 
a manufacturer's chassis- and engine-certified technology packages are 
sufficiently similar. The current regulations in 40 CFR part 86 
distinctly separate the OBD requirements based on GVWR. Under 40 CFR 
86.007-17, engines used in vehicles at or below 14,000 lb GVWR are 
subject to the chassis-based OBD provisions of 40 CFR 86.1806. Engines 
in vehicles above 14,000 lb GVWR are subject to the engine-based 
provisions of 40 CFR 86.010-18 and there is no pathway for these larger 
vehicles to certify using the chassis-based OBD provisions.
    In addition to the general heavy-duty OBD provisions proposed in 
new section 40 CFR 1036.110, we are proposing to allow vehicle 
manufacturers the option to request approval to certify the OBD of 
their spark-ignition, engine-certified products using data from similar 
chassis-certified Class 2b and Class 3 vehicles that meet the 
provisions of 40 CFR 86.1806-17. As part of the approval request, 
manufacturers would show that the engine- and chassis-certified 
products use the same engines and generally share similar emission 
controls (i.e., are ``sister vehicles''). Under this proposal, 
manufacturers would still be required to submit a separate application 
for certification for their engine-certified products, but EPA may 
approve the use of OBD testing data from sister vehicles at or below 
14,000 lb GVWR class for the engine-certified products. We request 
comment on any additional provisions or limitations we should consider 
adopting related to aftertreatment characteristics, chassis 
configurations, or vehicle classes when evaluating a manufacturer's 
request to share OBD data between engine- and chassis-certified product 
lines. Specifically, we request comment, including data, on the impact 
of varying vehicle components such as transmissions, axle ratios, and 
fuel tank sizes on the OBD system. Finally, we request comment on 
additional compliance provisions, beyond OBD, that could be streamlined 
for these sister vehicles.
viii. Potential Off-Cycle Standards for Spark-Ignition HDE
    As described in Section III.C, CI engines have been subject to not-
to-exceed (NTE) standards and in-use testing requirements for many 
years. In Section III.C.2, we propose new off-cycle standards and 
updated in-use test procedures for CI engines. The proposed in-use test 
procedures in 40 CFR part 1036, subpart E, include the steps to perform 
the manufacturer-run field testing program for CI engines as migrated 
and updated from 40 CFR part 86, subpart T. The in-use procedures are 
based on a new moving average window (MAW) procedure in 40 CFR 1036.515 
that separates in-use operation into idle, low load and medium/high 
load bins.
    For SI engines, we request comment on setting off-cycle standards 
that would be based on an approach similar to the one taken by CARB in 
their HD Omnibus rulemaking.\378\ The Omnibus rule includes ``in-use 
thresholds'' (i.e., off-cycle standards) for HD Otto cycle engines 
based on the laboratory-run FTP and SET duty cycles, and manufacturers

[[Page 17484]]

may comply by attesting to meeting the in-use thresholds in their 
application for CARB certification. The CARB in-use thresholds apply to 
emissions measured over a shift day and processed into a single bin of 
operation. The thresholds from the single HD Otto cycle engine bin 
match CARB's standards in the medium/high load in-use bin for CI 
engines.
---------------------------------------------------------------------------

    \378\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. page III-33. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
---------------------------------------------------------------------------

    We are not proposing to include Spark-ignition HDE in our 
manufacturer-run field testing program at this time, and we currently 
lack in-use data to assess the feasibility of doing so, but we may 
consider it in a future rulemaking. We request comment on adopting in-
use provisions similar to those for HD Otto cycle engines in CARB's 
program. Specifically, we request comment on allowing SI HDE 
manufacturers to attest to compliance with off-cycle standards in the 
application for certification and on not including SI HDE in our 
manufacturer-run field testing program. We request comment, including 
data, on the appropriate level of off-cycle standards we should 
consider for Spark-ignition HDE. Table III-24 presents a potential set 
of single bin off-cycle standards for Spark-ignition HDE that match the 
medium/high load in-use bin standards of proposed Options 1 and 2 for 
CI engines and similarly apply conformity factors to the proposed FTP 
and SET duty cycle standards for each pollutant (i.e., 2.0 for MY 2027 
through 2030 and 1.5 for MY 2031 and later under Option 1, and 1.5 for 
MY 2027 and later under Option 2). We request comment on these or other 
off-cycle standards we should consider for Spark-ignition HDE, 
including whether we should include additional in-use bins if we 
finalize LLC or other duty cycles in the future.

               Table III-24--Potential Off-Cycle Exhaust Emission Standards for Spark-Ignition HDE
----------------------------------------------------------------------------------------------------------------
                                                  NOX (mg/hp-hr)
           Scenario                Model year                      PM (mg/hp-hr)   HC (mg/hp-hr)   CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1.............  2027-2030.......              70              10             120            12.0
                                2031 and later..              30               8              60             9.0
Proposed Option 2.............  2027 and later..              75               8              60             9.0
----------------------------------------------------------------------------------------------------------------

    While we are not proposing off-cycle standards or a manufacturer-
run in-use testing program for Spark-ignition HDE, we are soliciting 
comment on draft regulatory text that could be included in 40 CFR 
1036.104 and 1036.515 and in 40 part CFR 1036, subpart E, with 
potential in-use provisions for Spark-ignition HDE.\379\ Even without a 
regulatory requirement for manufacturers to perform field testing, 
these test procedures would be valuable for Spark-ignition HDE 
manufacturers or EPA to compare in-use emissions to the duty cycle 
standards. Manufacturers could also use the procedures to verify their 
DF under the proposed PEMS testing option in 40 CFR 1036.246. We 
request comment on adopting in-use test procedures and setting off-
cycle standards for Spark-ignition HDE, including data to support the 
appropriate level of the standards.
---------------------------------------------------------------------------

    \379\ Brakora, Jessica. Memorandum to Docket EPA-HQ-OAR-2019-
0055. ``Draft regulatory text for potential off-cycle standards and 
in-use test procedures for Spark-ignition HDE'' July 21, 2021.
---------------------------------------------------------------------------

ix. Potential Low Load Cycle and Standards
    Heavy-duty gasoline engines are currently subject to FTP testing, 
and we are proposing a SET procedure to evaluate emissions performance 
of HD SI engines under the sustained high speeds and loads that can 
produce high emissions. We are also considering whether a low-load 
cycle could address the potential for high emissions from SI engines 
when catalysts may not maintain sufficient internal temperature to 
remain effective.
    Section III.B of this preamble describes the LLC duty cycle and 
standards we are proposing for HD compression-ignition engines.\380\ In 
our ANPR, we requested comment on the need for a low-load or idle cycle 
in general, and suitability of CARB's diesel-targeted low-load and 
clean idle cycles for evaluating the emissions performance of heavy-
duty gasoline engines. One commenter suggested the higher exhaust 
temperatures of SI engines made catalyst deactivation less of a concern 
so that a low load cycle was not warranted.\381\
---------------------------------------------------------------------------

    \380\ See 40 CFR 1036.104 for the proposed LLC standards and 
Sec.  1036.512 for the proposed test procedure.
    \381\ Roush comments (EPA-HQ-OAR-2019-0055-0303).
---------------------------------------------------------------------------

    As described in Section III.D.2.iv, we believe the proposed 
catalyst temperature control would effectively address idle emissions, 
but we recognize the value of demonstrating catalyst effectiveness 
during periods of prolonged idle and at low load, including when the 
vehicle accelerates from a stopped idle condition to higher speeds. We 
are soliciting comment on adopting a LLC duty cycle and standards for 
HD SI engines in addition to or in place of the idle control proposed 
in Section III.D.2.iv. We currently do not have test results 
demonstrating HD SI engine performance over the LLC duty cycle.
    In considering Spark-ignition HDE standards over the LLC duty 
cycle, we solicit comment on applying LLC standards over the useful 
life periods of proposed Options 1 and 2 for the other Spark-ignition 
HDE standards. We also solicit comment on adopting the same numeric 
level of the standards for the same pollutants under proposed Options 1 
and 2 for CI engines over the proposed Spark-ignition HDE useful life 
periods. We request comment on the benefits and challenges of an LLC 
standard for HD SI compliance, and encourage commenters to include 
emission performance data over the LLC duty cycle or other cycles that 
they believe would cause manufacturers to improve the emissions 
performance of their heavy-duty SI engines under lower load operating 
conditions.
3. Feasibility Analysis for the Proposed Exhaust Emission Standards
    This section describes the effectiveness and projected costs of the 
control technologies that we analyzed in developing our proposed Spark-
ignition HDE exhaust emission standards. In evaluating technology 
feasibility, we considered impacts on energy by monitoring 
CO2 emissions, the lead time manufacturers need to develop 
and apply control strategies and implement performance demonstrations, 
and the need to maintain utility and safety of the engines and 
vehicles.
    Our feasibility analyses for the proposed Options 1 and 2 FTP and 
SET exhaust emission standards are based on the HD SI technology 
demonstration program summarized in this section and detailed in 
Chapter 3.2.2.3 of the draft RIA. Feasibility of the proposed FTP 
standards is further supported by compliance data submitted by 
manufacturers for the 2019 model year.

[[Page 17485]]

We also support the feasibility of the proposed Options 1 and 2 SET 
standards using engine fuel mapping data from a test program performed 
by the agency as part of the HD GHG Phase 2 rulemaking. See Chapter 3.2 
of the draft RIA for more details related to these datasets.
i. Summary of Exhaust Emission Technologies Considered
    This section summarizes the specific technologies and emission 
control strategies we considered as the basis for our proposed exhaust 
emission standards. The technologies presented in this section are 
described in greater detail in Chapters 1 and 3 of the draft RIA.
    Our proposed Options 1 and 2 Spark-ignition HDE exhaust emission 
standards are based on the performance of the technology packages 
widely adopted for SI engines in chassis-certified vehicles today. We 
project manufacturers would meet our proposed standards by building on 
their existing TWC-based emission control strategies. Our technology 
demonstration evaluated advanced catalyst formulations, catalyst design 
changes including light-off catalysts located closer to the engine, 
engine down-speeding, and engine calibration strategies that can 
minimize enrichment during high-load and accelerate light-off for lower 
load and idle operations.
    The catalyst system and related exhaust components have progressed 
in recent light-duty applications and are currently able to tolerate 
significantly higher exhaust gas temperatures while still maintaining 
emission control over the current useful life. We expect that improved 
materials, such as the advanced catalyst formulations evaluated in our 
technology demonstration, along with more robust temperature management 
would result in significant emission reductions and engines that are 
able to meet the proposed standards. The advanced catalyst formulations 
we evaluated were aged to 250,000 miles, which is longer than the 
useful life mileages that would apply under proposed Options 1 and 2 
for Spark-ignition HDE.\382\
---------------------------------------------------------------------------

    \382\ Proposed Option 1 includes a useful life of 155,000 miles 
or 12 years for model years 2027 through 2030 and 200,000 miles or 
15 years for model years 2031 and later. Proposed Option 2 includes 
a useful life of 150,000 miles or 10 years for model years 2027 and 
later. See Section IV.A. for the development of our proposed useful 
life periods.
---------------------------------------------------------------------------

    Engine down speeding can help avoid the high speed, high exhaust 
gas temperature conditions that typically result in fuel enrichment due 
to engine component durability and catalyst thermal concerns. With the 
integration of modern multi-speed electronically controlled 
transmissions, this down speeding approach is extremely feasible and 
likely to also reduce engine wear and improve fuel consumption with 
little perceptible effect on performance for commercial vehicle 
operation. In our demonstration program, we reduced the base engine's 
manufacturer-stated maximum test speed of 4715 RPM to 4000 RPM to 
evaluate the impact of engine down-speeding.
ii. Projected Exhaust Emission Technology Package Effectiveness
a. Technology Effectiveness Over the FTP Duty Cycle
    Our HD SI technology demonstration program evaluated several 
pathways manufacturers could use to achieve the proposed Options 1 and 
2 standards. As shown in Table III-25, use of advanced catalysts 
provided substantial NOX emission reductions over the FTP 
duty cycle beyond the performance demonstrated by technologies on 
recently certified engines.\383\ Engine down-speeding further decreased 
CO emissions while maintaining NOX, NMHC, and PM control. 
Engine down-speeding also resulted in a small improvement in brake 
specific fuel consumption over the FTP duty cycle reducing from 0.46 to 
0.45 lb/hp-hr. See Chapter 3.2.3 of the draft RIA for an expanded 
description of the test program and results.
---------------------------------------------------------------------------

    \383\ As presented later in this section, MY 2019 gasoline-
fueled HD SI engine certification results included NOX 
levels ranging from 29 to 160 mg/hp-hr at a useful life of 110,000 
miles.

    Table III-25--Exhaust Emission Results From FTP Duty Cycle Testing in the HD SI Technology Demonstration
----------------------------------------------------------------------------------------------------------------
                                                  NOX (mg/hp-hr)                   NMHC (mg/hp-
                                                                   PM (mg/hp-hr)        hr)        CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1 Standards (MY 2027-2030)......              35               5              60             6.0
Proposed Option 1 Standards (MY 2031 and later).              20               5              40             6.0
Proposed Option 2 Standards (MY 2027 and later).              50               5              40             6.0
Base Engine with Advanced Catalyst \a\..........              19             4.8              32             4.9
Down-sped Engine with Advanced Catalyst \b\.....              18             4.5              35            0.25
----------------------------------------------------------------------------------------------------------------
\a\ Base engine's manufacturer-stated maximum test speed is 4,715 RPM; advanced catalyst aged to 250,000 miles.
\b\ Down-sped engine's maximum test speed lowered to 4,000 RPM; advanced catalyst aged to 250,000 miles.

    We expect manufacturers could achieve similar emission performance 
by adopting other approaches, including a combination of calibration 
changes, optimized catalyst location, and fuel control strategies that 
EPA was unable to evaluate in our demonstration program due to limited 
access to proprietary engine controls.
    In addition to our demonstration program, we evaluated the 
feasibility of the proposed Options 1 and 2 FTP standards by 
considering the performance of recently-certified engines. As detailed 
in Chapter 3.2.3.1 of the draft RIA, MY 2019 compliance data over the 
FTP duty cycle included the performance of six HD SI engine families 
from four manufacturers, representing the emission performance of all 
gasoline-fueled HD SI engines certified in MY 2019 as incomplete 
vehicles (i.e., engine certified).
    Table III-26 presents the manufacturer-reported MY 2019 levels for 
the three pollutants addressed by TWCs: NOX, NMHC and 
CO.\384\ PM emissions for most of these SI engines were undetectable 
and reported as zero for certification. In the table, we identify the 
six certified engines by descending NOX level and note that 
three of the six engines, representing over 70 percent of the MY 2019 
engine-certified, gasoline-fueled HD SI engines, achieve a 
NOX level that is less than half the current standard of 
0.20 g/hp-hr (i.e., 200 mg/hp-hr). When calibrating their engines, SI 
manufacturers experience tradeoffs in

[[Page 17486]]

TWC performance for the three pollutants and each manufacturer may 
optimize their emission controls differently while complying with 
applicable emission standards. As expected, the certification results 
show no clear relationship between NMHC or CO emissions and the level 
of reduced NOX among the various engine calibrations.
---------------------------------------------------------------------------

    \384\ U.S. EPA. ``Heavy-Duty Highway Gasoline and Diesel 
Certification Data (Model Years: 2015-Present)''. Available online: 
https://www.epa.gov/sites/production/files/2020-01/heavy-duty-gas-and-diesel-engines-2015-present.xlsx. Accessed June 2020.

                Table III-26--FTP Duty Cycle Emission Levels Reported for Six Engine-Certified, Gasoline-Fueled HD SI Engines in MY 2019
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Cert Engine 1   Cert Engine 2   Cert Engine 3   Cert Engine 4   Cert Engine 5   Cert Engine 6
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr) \a\......................................             160             120             104              89              70              29
NMHC (mg/hp-hr) \a\.....................................              50              60              80              42              80              42
CO (g/hp-hr)............................................             3.7             6.6             8.6             1.5            12.7             2.3
Fraction of MY 2019 HD SI Gasoline-Fueled Engine Sales..              2%             20%              4%             20%             48%              5%
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ NOX and NMHC values are converted from g/hp-hr to mg/hp-hr to match the units of our proposed standards for NOX and HC, respectively.

    To evaluate the NMHC and CO emissions, we calculated an overall 
average for each pollutant that includes all engines, and separately 
averaged a smaller subset of the three engines (i.e., Cert Engines 4-6) 
with the lowest NOX levels. Table III-27 compares these two 
averages with the EPA 2010 standards and results from the engine family 
with the best NOX emission performance of the MY 2019 
compliance data.

    Table III-27--Average Emission Performance for Engine-Certified, Gasoline-Fueled HD SI Engines in MY 2019
----------------------------------------------------------------------------------------------------------------
                                                     EPA 2010         Overall         Subset         Best NOX
                    Pollutant                        standard         average         average       performance
----------------------------------------------------------------------------------------------------------------
NOX (mg/hp-hr) \a\..............................             200              95              63              29
NMHC (mg/hp-hr) \a\.............................             140              59              55              42
CO (g/hp-hr)....................................            14.4             5.9             5.5             2.3
----------------------------------------------------------------------------------------------------------------
\a\ NOX and NMHC values are converted from g/hp-hr to mg/hp-hr to match the units of our proposed standards for
  NOX and HC, respectively.

    Comparing the results in Table III-26 to the averages in Table III-
27, we see that the overall average NMHC level of 59 mg/hp-hr and CO 
level of 5.9 g/hp-hr for the six engines are met by three engine 
families today. We expect at least one additional family could achieve 
the overall average NMHC and CO levels with calibration changes to 
adjust cold start catalyst light-off timing and refine the catalyst 
protection fuel enrichment levels. The NMHC and CO emissions averages 
for these MY 2019 engines align with our MY 2027 proposed Options 1 and 
2 standards for those pollutants. The emission levels of the engine 
with the best NOX performance are approaching the levels we 
are proposing for our Option 1 MY 2031 standards. While these recent 
certification results suggest it may be feasible for some manufacturers 
to meet the proposed Option 1 standards with current engine technology, 
it is less clear if the same emission levels could be maintained at the 
proposed useful life periods. We believe the combination of our 
proposed Option 1 standards and lengthened useful life would force some 
level of improved component durability or increased catalyst volumes 
beyond what is available on current HD SI engines and it will take 
additional time for manufacturers to develop their approach to 
complying.
b. Technology Effectiveness Over the SET Duty Cycle
    As noted in Section III.D.2.iii, we are proposing Spark-ignition 
HDE standards for the SET duty cycle to ensure emissions are controlled 
under high load and speed conditions. Our HD SI technology 
demonstration program evaluated emission performance over the SET duty 
cycle. As shown in Table III-28, the NOX and NMHC emissions 
over the SET duty cycle were substantially lower than the emissions 
from the FTP duty cycle (see Table III-25). Engine down-speeding 
improved CO emissions significantly, while NOX, NMHC, and PM 
remained low. Engine down-speeding also resulted in a small improvement 
in brake specific fuel consumption over the SET duty cycle reducing 
from 0.46 to 0.44 lb/hp-hr. See Chapter 3.2.3 of the draft RIA for an 
expanded description of the test program and results.

    Table III-28--Exhaust Emission Results From SET Duty Cycle Testing in the HD SI Technology Demonstration
----------------------------------------------------------------------------------------------------------------
                                                  NOX (mg/hp-hr)                   NMHC (mg/hp-
                                                                   PM (mg/hp-hr)        hr)        CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1 Standards (MY 2027-2030)......              35               5              60             6.0
Proposed Option 1 Standards (MY 2031 and later).              20               5              40             6.0
Proposed Option 2 Standards (MY 2027 and later).              50               5              40             6.0
Base Engine with Advanced Catalyst \a\..........               8               7               6            36.7
Down-sped Engine with Advanced Catalyst \b\.....               5               3               1            7.21
----------------------------------------------------------------------------------------------------------------
\a\ Base engine's manufacturer-stated maximum test speed is 4,715 RPM; advanced catalyst aged to 250,000 miles.
\b\ Down-sped engine's maximum test speed lowered to 4,000 RPM; advanced catalyst aged to 250,000 miles.


[[Page 17487]]

    Similar to our discussion related to the FTP standards, we expect 
manufacturers could achieve similar emission performance over the SET 
duty cycle by adopting other approaches, including a combination of 
calibration changes, optimized catalyst location, and fuel control 
strategies that EPA was unable to evaluate due to limited access to 
proprietary engine controls.
    To evaluate the impact of fuel enrichment and supplement our SET 
feasibility analysis, we created a surrogate array of SET test points 
using HD SI engine fuel mapping data from a HD GHG Phase 2 test program 
(see Chapter 3.2.3 of the draft RIA). The test program tested a V10 
gasoline engine on an early version of EPA's steady-state fuel mapping 
procedure that requires the engine to be run for 90 seconds at each of 
nearly 100 speed and torque points.\385\ The first 60 seconds at each 
point allowed the engine and fuel consumption to stabilize and the last 
30 seconds were averaged to create the fuel map point.
---------------------------------------------------------------------------

    \385\ The final version of this test procedure is outlined in 40 
CFR 1036.535.
---------------------------------------------------------------------------

    For this analysis, we evaluated three subsets of the emissions data 
(NOX, NMHC, and CO) over the range of engine speeds and 
torque values. The first subset of data included conditions where the 
engine went into power enrichment, as indicated by the air-fuel ratio. 
The second subset of data included conditions where the engine 
controller activated a catalyst protection fuel enrichment strategy 
before a power enrichment strategy was enabled. The third subset 
included only conditions where the engine maintained stoichiometric 
air-fuel ratio.
    Peak torque points for each of these data subsets were used to 
calculate the A, B and C speeds and create three unique sets of 
surrogate SET test points. Emission rates for NOX, NMHC, and 
CO shown in Table III-29 were calculated by interpolating the data 
subsets at each of the SET test points. Finally, the results were 
weighted according to the existing CI-based weighting factors outlined 
in 40 CFR 86.1362.

           Table III-29--Emission Rates Calculated for Surrogate SET Test Points for Each Data Subset
----------------------------------------------------------------------------------------------------------------
                                                                  NOX (mg/hp-hr)   NMHC (mg/hp-
                                                                                        hr)        CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1 Standards (MY 2027-2030)......................              35              60             6.0
Proposed Option 1 Standards (MY 2031 and later).................              20              40             6.0
Proposed Option 2 Standards (MY 2027 and later).................              50              40             6.0
Power Enrichment Allowed........................................              11             110            45.2
Catalyst Protection with No Power Enrichment....................              19              30            11.4
Stoichiometric Operation........................................              28              10            0.97
----------------------------------------------------------------------------------------------------------------

    As observed in the surrogate SET test data, any enrichment mode, 
whether for power or catalyst protection purposes, resulted in 
substantial NMHC and CO emission increases from stoichiometric 
operation. When the engine was commanded into power enrichment mode and 
no longer maintained stoichiometric operation, NMHC and CO emissions 
rose 10 and 50 times higher, respectively. These results suggest that 
it is feasible for manufacturers to achieve low emission levels over 
the 13 modes of an SET duty cycle if their engines maintain 
stoichiometric operation. This can be accomplished with engine 
calibrations to optimize the TWC tradeoffs and fuel-air control 
strategies to limit preventable fuel enrichment.
iii. Derivation of the Proposed Standards
    We are maintaining fuel neutrality of the proposed standards by 
applying the same numerical standards across all primary intended 
service classes. The proposed Options 1 and 2 NOX and PM 
levels for the FTP and SET duty cycles are based on the emission 
performance of technologies evaluated in our HD CI engine technology 
demonstration program.\386\ We are basing the proposed Options 1 and 2 
FTP and SET standards for HC and CO on HD SI engine performance as 
described in Section III.D.3.ii and summarized in this section.
---------------------------------------------------------------------------

    \386\ Our assessment of the projected technology package for 
compression-ignition engines is based on both CARB's and EPA's 
technology demonstration programs. See Section III.B for a 
description of those technologies and test programs.
---------------------------------------------------------------------------

    Results from our HD SI technology demonstration program (see Table 
III-25 and Table III-28) show that the proposed NOX 
standards based on our CI engine feasibility analysis are also feasible 
for HD SI engines over the FTP and SET duty cycles for both options. 
The proposed Option 1 MY 2031 NOX standard was achieved by 
implementing an advanced catalyst with minor catalyst system design 
changes, and NOX levels were further improved with engine 
down-speeding. The emission control strategies that we evaluated did 
not specifically target PM emissions, but we note that PM emissions 
remained low in our demonstration. We project HD SI engine 
manufacturers would be able to maintain near-zero PM levels with 
limited effort. We request comment on challenges manufacturers may 
experience to maintain effective PM control, including duty cycles 
other than FTP.
    For proposed Option 1, starting in model year 2027, we are 
proposing to lower the HC and CO FTP standards consistent with the 
overall average NMHC and CO levels achieved by engine-certified, 
gasoline-fueled HD SI engines over the FTP cycle today (see Table III-
27). We note that the MY 2019 engine certified with the lowest 
NOX (i.e., Cert Engine #6) is below our proposed MY 2027 
NOX standard (35 mg/hp-hr) and maintains NMHC and CO 
emissions below those average levels on the FTP cycle. We are proposing 
the same standards of 60 mg HC/hp-hr and 6.0 g CO/hp-hr would apply 
over the new SET duty cycle starting in MY 2027. We believe emission 
levels based on average engine performance today would be a low cost 
step to update and improve emission performance across all certified 
Spark-ignition HDE, and serve as anti-backsliding standards as 
manufacturers optimize their TWCs, implement a new duty cycle, and 
improve component durability in response to the proposed longer useful 
life periods. CO levels in our SET demonstration were above the 
proposed standard, but manufacturers have opportunities to reduce CO 
below our proposed standard by optimizing their TWC calibrations and 
maintaining stoichiometric conditions over more of their high load 
operation (see Table III-29).
    Proposed Option 2 (MY 2027 and later) and step 2 of proposed Option 
1 (MY 2031 and later) include the same proposed numeric HC standards of 
40

[[Page 17488]]

mg HC/hp-hr and 6.0 g CO/hp-hr for the FTP and SET duty cycles. For the 
FTP duty cycle, results of our demonstration program show that the 
proposed HC standard would be achievable without compromising 
NOX or CO emission control (see Table III-25). For the SET 
duty cycle, lower levels of NMHC were demonstrated, but at the expense 
of increased CO emissions in those higher load operating conditions 
(see Table III-28). The considerably lower NOX and HC in our 
SET duty cycle demonstration results leave enough room for 
manufacturers to calibrate the tradeoff in TWC emission control of 
NOX, HC, and CO to reduce CO below our proposed CO standard. 
For these reasons, we are proposing the FTP standard of 40 mg HC/hp-hr 
standard apply over the SET duty cycle. Proposed Options 1 and 2 
generally represent the range of lead time, standards, and useful life 
periods we are currently considering in this rule for HD SI engines.
    We request comment on the proposed Spark-ignition HDE FTP and SET 
standards, including the appropriateness of applying the same numeric 
emission levels for both duty cycles. Commenters suggesting more 
stringent standards are encouraged to provide data showing lower 
standards are achievable at their suggested useful life periods. We 
also request comment on our approaches to maintain fuel neutrality by 
proposing numerically identical standards for heavy-duty CI and SI 
engines.
iv. Summary of Costs To Meet the Proposed Exhaust Emission Standards
    To project costs for HD SI technology packages manufacturers could 
adopt to meet the proposed standards, we combined manufacturers' HD SI 
MY 2019 compliance data into sales-weighted averages by vehicle 
category to account for aftertreatment system differences by engine. 
The discussion below summarizes our estimate of the technology costs to 
meet our proposed Spark-ignition HDE standards. See Chapter 3.2.3 of 
the draft RIA for an expanded description of the projected sales-
weighted average catalyst volumes, PGM loadings, and other factors used 
to calculate our costs for HD SI engines and Section V of this preamble 
for a summary of how these technology costs are included in the overall 
cost of this proposal.
    We calculated aftertreatment system costs for four categories of SI 
engines. The largest category, liquid-fueled SI engines, includes 
engines fueled by gasoline, ethanol, and ethanol blends, and represents 
the majority of HD SI engines on the market today. The second category, 
gaseous-fueled SI engines, includes engines fueled by compressed 
natural gas (CNG) or liquified petroleum gas (LPG). In addition to the 
general gaseous-fueled SI engines, we separately analyzed two subsets 
of gaseous-fueled SI engines (HHD and urban bus) that have unique 
market shares and distinct aftertreatment demands.
    Table III-30 summarizes the projected technology costs for HD SI 
engines to meet our proposed standards. Chapter 3.2.3 of the draft RIA 
contains a more detailed breakdown of the costs. Our projected costs 
for the liquid-fueled SI engines are based on the aftertreatment system 
used in our HD SI technology demonstration program (see Section 
III.D.3). As shown in our demonstration program, liquid-fueled SI 
engine manufacturers could use the same catalyst systems in both 
proposed Options, including both steps (MY 2027 and 2031) of Option 1 
to meet the proposed exhaust emission standards, so we projected a 
single cost. We request comment, including data, regarding calibration 
costs for manufacturers to optimize their Option 1 MY 2027 systems to 
meet the proposed Option 1 MY 2031 standards and costs for 
manufacturers to reprogram the existing electronics and software to 
down-speed their multi-speed transmissions. For this analysis, we 
assumed these costs would be part of the general research and 
development costs for the rule and did not separately quantify them. We 
did not make any additional cost adjustments to account for the 
proposed lengthened useful life, since the aftertreatment system used 
in the demonstration program represented catalysts aged to 250,000 
miles.
    We projected that most of the gaseous-fueled SI engines would 
include similar aftertreatment system upgrades as the liquid-fueled SI 
engines to meet the proposed standards and those costs are also 
summarized in Table III-30 and detailed in the draft RIA. The HHD and 
urban bus gaseous-fueled SI engine categories in our analysis had lower 
projected technology costs to meet the proposed standards. These two 
subsets include engines that were certified in MY 2019 to California's 
optional and more stringent 0.02 g/hp-hr NOX standard. We 
assumed no additional technology would be needed for these engines to 
meet the proposed standards in future model years. Our projected costs 
for these engines were limited to durability improvements to the 
catalyst substrate support structure (can material, mat, seals, etc.) 
to meet the requirements of our proposed lengthened useful life 
mileages.

                 Table III-30--Summary of Spark-Ignition HDE Direct Manufacturing Package Costs
----------------------------------------------------------------------------------------------------------------
                                                                                  Gaseous fueled
              Cost packages (2019$)                Liquid fueled -----------------------------------------------
                                                     SI engine       SI engine        SI HHD       SI urban bus
----------------------------------------------------------------------------------------------------------------
Baseline Technology.............................            $322            $365          $3,348          $2,511
Projected Technology............................             732             646           3,376           2,531
Projected Technology Incremental................             410             281              28              20
----------------------------------------------------------------------------------------------------------------

4. Potential Alternative
    We also considered the emissions impact of an alternative (the 
Alternative) that is more stringent than our proposed Option 1 MY 2031 
standards when considering the combination of numeric level of the 
standards, length of useful life, and lead time (see Table III-31 
through Table III-33). The Alternative matches our proposed Option 1 MY 
2031 FTP and SET standards for NOX, PM, and CO, but has 
lower (more stringent) HC standards, and starts four years earlier for 
all pollutant standards, in MY 2027. The useful life and warranty 
mileages for the Alternative are also longer than those of proposed 
Option 1 for MYs 2031 and later SI engines. As shown in Table III-25 
and Table III-28, available data indicate that the combination of 
NOX, HC, and CO emission levels over the longer useful life 
period reflected in the Alternative standards would be very challenging 
to meet in the MY 2027 timeframe.
    We believe the additional lead time provided by the second step of 
the proposed Option 1 MY 2031 standards, combined with the higher 
numeric standard for HC and the shorter useful life mileage, results in 
the proposed

[[Page 17489]]

Option 1 standards being both feasible and technology forcing. Proposed 
Option 1 represents the most stringent range of lead time, standards, 
regulatory useful life periods, and emission-related warranty periods 
we are currently considering in this rule for HD SI engines unless we 
receive additional data to support a conclusion that the Alternative 
standards are feasible in the MY 2027 timeframe.

         Table III-31--Comparison of FTP Standards in the HD SI Engine Proposed Options and Alternative
----------------------------------------------------------------------------------------------------------------
                                                  NOX (mg/hp-hr)
           Scenario                Model years                     PM (mg/hp-hr)   HC (mg/hp-hr)   CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1.............  2027-2030.......              35               5              60             6.0
                                2031 and later..              20               5              40             6.0
Proposed Option 2.............  2027 and later..              50               5              40             6.0
Alternative...................  2027 and later..              20               5              10             6.0
----------------------------------------------------------------------------------------------------------------


         Table III-32--Comparison of SET Standards in the HD SI Engine Proposed Options and Alternative
----------------------------------------------------------------------------------------------------------------
                                                  NOX (mg/hp-hr)
           Scenario                Model years                     PM (mg/hp-hr)   HC (mg/hp-hr)   CO (g/hp-hr)
----------------------------------------------------------------------------------------------------------------
Proposed Option 1.............  2027-2030.......              35               5              60             6.0
                                2031 and later..              20               5              40             6.0
Proposed Option 2.............  2027 and later..              50               5              40             6.0
Alternative...................  2027 and later..              20               5              10             6.0
----------------------------------------------------------------------------------------------------------------


Table III-33--Comparison of Useful Life and Emissions Warranty Mileages in the HD SI Engine Proposed Options and
                                                   Alternative
----------------------------------------------------------------------------------------------------------------
                                                                                    Useful life      Warranty
                   Scenario                                Model years                mileage         mileage
----------------------------------------------------------------------------------------------------------------
Proposed Option 1.............................  2027-2030.......................         155,000         110,000
                                                2031 and later..................         200,000         160,000
Proposed Option 2.............................  2027 and later..................         150,000         110,000
Alternative...................................  2027 and later..................         250,000         200,000
----------------------------------------------------------------------------------------------------------------

    See Section 5.2.2. for more details on how we used MOVES to model 
our proposed options and alternative scenarios for the inventory 
analysis. We projected the same HD SI technology costs would apply for 
proposed Options 1 and 2. We believe the range of the proposed Options 
1 and 2 standards could be achieved with the same advanced catalyst 
system from our demonstration program with complete access to 
calibration controls. That same catalyst system was aged to cover the 
range of useful life mileages included in the proposed options. See 
Section V of this preamble and Chapter 7 of the draft RIA for a 
description of the overall costs of the proposed options. Since we do 
not currently have information to indicate that the Alternative 
standards are feasible in the MY 2027 timeframe with the emission 
control technologies we evaluated, we are not presenting an analysis of 
the costs of the Alternative.
5. Summary of Requests for Comment
    For heavy-duty SI engines, we are requesting comment regarding the 
cost, feasibility, and appropriateness of our proposed Options 1 and 2 
standards, duty cycles, and test procedure updates. See the previous 
sections for specific requests for comment on each of those topics. 
When submitting comments, we request that commenters provide data, 
where possible, or additional references to support their positions.
    We request comment on the implementation years of the program, the 
numeric levels of our proposed standards for FTP and SET duty cycles, 
and our approach to propose the same numeric standards for the two duty 
cycles and for both CI and SI engines.
    We request comment on the proposed changes to test procedures, 
including the addition of the SET duty cycle and the disabling of AECDs 
that impact peak torque during engine mapping. We request commenters to 
include data to support recommended modifications to the CI-based SET 
duty cycle or powertrain test procedures for SI engine testing. We also 
seek comment on whether adjustment factors, similar to IRAFs used for 
CI engines, should be applied to SI duty cycle results to account for 
the HC, CO, NOX, and PM emission increases that may occur 
due to enrichment AECDs.
    We introduced several proposals in this section intended to achieve 
emission reductions without the need for manufacturers to perform 
additional tests. We are not proposing HD SI standards over the low 
load cycle or an idle test, but request comment on the need for these 
emission performance demonstrations in addition to or to replace our 
proposed procedures. We request comment on our proposed requirement 
that manufacturers maintain a catalyst temperature above 350 [deg]C to 
ensure effective idle emission control or if an idle test procedure 
would be a better approach. Our proposed process to validate the 
accuracy of catalyst protection models is based on a 5 [deg]C 
temperature allowance. We request comment on that allowance, the need 
for more specific procedures or technology specifications, and whether 
we should require continuous monitoring using temperature sensors 
instead of allowing the use of models. We are proposing flexibilities 
in OBD certifications for integrated engine manufacturers and request 
comment on additional flexibilities or restrictions we should consider.

E. Summary of Spark-Ignition Heavy-Duty Vehicle Refueling Emission 
Standards and Test Procedures

    Compliance with evaporative and refueling emission standards is

[[Page 17490]]

demonstrated at the vehicle level. The vehicle manufacturers that 
produce HD SI engines sell complete vehicles and, in some instances, 
sell incomplete vehicles to secondary manufacturers. As noted in the 
following section, we are proposing refueling emission standards for 
incomplete vehicles above 14,000 lb GVWR under both proposed Options 1 
and 2. These proposed standards would apply over a useful life of 15 
years or 150,000 miles, whichever occurs first, consistent with 
existing evaporative emission standards for these vehicles. Evaporative 
and refueling emission standards currently apply for complete vehicles 
and we are not reopening or proposing to change those requirements in 
this rulemaking.
1. Current Refueling Emission Standard and Test Procedures
    Spark-ignition engines generally operate with volatile liquid fuel 
(such as gasoline or ethanol) or gaseous fuel (such as natural gas or 
LPG) that have the potential to release high levels of evaporative and 
refueling HC emissions. As a result, EPA has issued evaporative 
emission standards that apply to vehicles powered by these 
engines.\387\ Refueling emissions are evaporative emissions that result 
when the pumped liquid fuel displaces the vapor in the vehicle tank. 
Without refueling emission controls, most of those vapors are released 
into the ambient air. The HC emissions emitted are a function of 
temperature and the Reid Vapor Pressure (RVP).\388\ The emissions 
control technology which collects and stores the vapor generated during 
refueling events is the Onboard Refueling Vapor Recovery (ORVR) system.
---------------------------------------------------------------------------

    \387\ 40 CFR 1037.103.
    \388\ E.M. Liston, American Petroleum Institute, and Stanford 
Research Institute. A Study of Variables that Effect the Amount of 
Vapor Emitted During the Refueling of Automobiles. Available online: 
https://books.google.com/books/about/A_Study_of_Variables_that_Effect_the_Amo.html?id=KW2IGwAACAAJ.
---------------------------------------------------------------------------

    Light-duty vehicles and chassis-certified complete heavy-duty 
vehicles that are 14,000 lbs GVWR and under have been meeting 
evaporative and refueling requirements for many years. ORVR 
requirements for light-duty vehicles started phasing in as part of 
EPA's National Low Emission Vehicle (NLEV) and Clean Fuel Vehicle (CFV) 
programs in 1998.\389\ In EPA's Tier 2 vehicle program, all complete 
vehicles with a GVWR of 8,500 to 14,000 lbs were required to phase-in 
ORVR requirements between 2004 and 2006 model years.\390\ In the Tier 3 
rulemaking, all complete vehicles were required to meet a more-
stringent standard of 0.20 grams of HC per gallon of gasoline dispensed 
by MY 2022 (see 40 CFR 86.1813-17(b)).\391\ Engine-certified incomplete 
heavy-duty vehicles that run on volatile liquid fuels have evaporative 
emission standards that phase in over model years 2018 through 2022, 
but the refueling standards were optional for incomplete vehicles.\392\
---------------------------------------------------------------------------

    \389\ 62 FR 31192 (June 6, 1997) and 63 FR 926 (January 7, 
1998).
    \390\ 65 FR 6698 (February 10, 2000).
    \391\ 79 FR 23414 (April 28, 2014) and 80 FR 0978 (February 19, 
2015).
    \392\ Complete heavy-duty vehicles above 14,000 lb GVWR are 
subject to refueling standards starting in model year 2022. EPA has 
not yet received any certification applications for complete 
vehicles over 14,000 lb GVWR.
---------------------------------------------------------------------------

    The current evaporative and refueling emissions test procedures in 
40 CFR part 1066, subpart J, require that testing occur in a sealed 
housing evaporative determination (SHED) enclosure containing the 
complete vehicle. This procedure is used by all light-duty and heavy-
duty complete vehicles subject to the refueling standards, and 
manufacturers have designed and built the SHEDs at their test 
facilities for these vehicles. Since evaporative and refueling emission 
control systems in heavy-duty vehicles are often larger versions of 
those used in light-duty vehicles, EPA's regulations allow 
manufacturers to certify their vehicles above 14,000 lb GVWR using an 
engineering analysis in lieu of providing test data.\393\
---------------------------------------------------------------------------

    \393\ 40 CFR 1037.103(c).
---------------------------------------------------------------------------

    During a recent test program, EPA learned that very few SHEDs are 
available that could fit vehicles over 14,000 lb GVWR, as the length 
and height of these vehicles exceed the dimensions of most 
SHEDs.394 395 Additionally, the limited number of large-
volume SHEDs available at third-party laboratories have challenges in 
accurately measuring refueling emissions because of the very large 
volume inside the enclosures.\396\ These measurement challenges do not 
currently impact manufacturers' ability to demonstrate compliance for 
current evaporative emissions standards because the regulations allow 
manufacturers to submit an engineering analysis to demonstrate 
compliance in lieu of testing their heavier vehicles, and currently no 
HD SI engine manufacturers certify complete vehicles in the over-14,000 
lb GVWR vehicle class where testing is required.
---------------------------------------------------------------------------

    \394\ SGS-Aurora, Eastern Research Group, ``Light Heavy-Duty 
Gasoline Vehicle Evaporative Emissions Testing.'' EPA-420-R-19-017. 
December 2019.
    \395\ U.S. Environmental Protection Agency. ``Summary of ``Light 
Heavy-Duty Gasoline Vehicle Evaporative Emissions Test Program'' '' 
EPA-420-S-19-002. December 2019.
    \396\ See Chapter 2.3 of the draft RIA for a summary of this 
test program and the challenges of applying a test procedure 
originally developed for light-duty vehicles to much larger chassis 
that are certified as incomplete vehicles.
---------------------------------------------------------------------------

2. Proposed Updates to Refueling Requirements
    As HD SI engines continue to improve in their ability to reduce 
exhaust emissions, evaporative emissions become an increasingly 
significant contributor to overall HC emissions. In response to our 
ANPR, ORVR suppliers commented in support of refueling requirements for 
incomplete heavy-duty vehicles, noting the industry's experience 
improving, testing, and implementing the technology.\397\ We are 
proposing refueling emission standards for incomplete vehicles above 
14,000 lb GVWR starting in model year 2027 (see 40 CFR 1037.103). We 
propose that these standards apply for a useful life of 15 years or 
150,000 miles, whichever occurs first, consistent with the current 
useful life for evaporative emission standards in 40 CFR 86.1805. We 
are not proposing any change to the evaporative emission standards or 
the useful life for the evaporative standards. Since the refueling and 
evaporative emission standards are based on the use of similar fuel 
system-based technologies, it is appropriate that the useful life for 
the refueling standards be the same as the useful life for evaporative 
standards. This approach to useful life for our proposed refueling 
standards is consistent with the ORVR suppliers' comments.
---------------------------------------------------------------------------

    \397\ See comments from the Manufacturers of Emission Controls 
Association (EPA-HQ-OAR-2019-0055-0365) and Ingevity Corporation 
(EPA-HQ-OAR-2019-0055-0271).
---------------------------------------------------------------------------

    Current refueling requirements are limited to complete vehicles, 
and all current heavy-duty SI engines for the over-14,000 lb GVWR 
vehicle classes are being certified as part of incomplete vehicles. As 
a result, hydrocarbon vapors from the largest HD SI engines are 
uncontrolled each time these vehicles are refueled. Results from a 
recent EPA test program found refueling emissions of more than 10 times 
the current light-duty ORVR standard for the two uncontrolled HD 
gasoline-fueled vehicles tested.398 399 ORVR

[[Page 17491]]

systems include mature technologies that have been widely adopted in 
vehicles below 8,500 lb GVWR since model year 2000.\400\ As we present 
in our feasibility discussion in Section III.E.3.ii, the fuel systems 
of these larger heavy-duty engines are similar to their chassis-
certified counterparts and we expect manufacturers would generally be 
able to scale their existing light-duty systems to meet the needs of 
the larger fuel tanks in their heavy-duty engine products.
---------------------------------------------------------------------------

    \398\ SGS-Aurora, Eastern Research Group, ``Light Heavy-Duty 
Gasoline Vehicle Evaporative Emissions Testing.'' EPA-420-R-19-017. 
December 2019.
    \399\ U.S. Environmental Protection Agency. ``Summary of ``Light 
Heavy-Duty Gasoline Vehicle Evaporative Emissions Test Program'' '' 
EPA-420-S-19-002. December 2019.
    \400\ 65 FR 6698 (February 10, 2000).
---------------------------------------------------------------------------

i. Proposed ORVR Test Procedure and HC Standard
    We are proposing a refueling emission standard of 0.20 grams HC per 
gallon of liquid fuel for incomplete vehicles above 14,000 lb GVWR, 
which is the same as the existing refueling standard for complete 
vehicles.\401\ We note that this proposed refueling emission standard 
would apply to all liquid-fueled Spark-ignition HDE, including gasoline 
and ethanol blends.\402\ As described in Section III.D.3, we believe it 
is feasible for manufacturers to achieve this standard by adopting 
large-scale versions of the technology in use on complete vehicles. We 
request comment on our proposed standard.
---------------------------------------------------------------------------

    \401\ See our proposed updates to 40 CFR 1037.103.
    \402\ We are not proposing changes to the current refueling 
requirements that apply for gaseous-fueled Spark-ignition HDE. 
Vehicles above 14,000 lb GVWR that are fueled by CNG or LNG would 
continue to meet the fueling connection requirements (see 40 CFR 
1037.103(d)) and fuel tank hold-time requirements (see 40 CFR 
1037.103(e)), respectively, and would be deemed to comply with the 
newly applicable proposed refueling standard.
---------------------------------------------------------------------------

    The current provision in 40 CFR 1037.103(c) allows vehicles above 
14,000 lb GVWR to demonstrate they meet evaporative and optional 
refueling standards using an engineering analysis that compares the 
system to one certified in a full-scale SHED demonstration. We propose 
to continue to allow manufacturers to demonstrate they meet the 
proposed refueling standards using an engineering analysis, and 
manufacturers would continue to use this provision in light of the SHED 
testing challenges summarized in Section III.E.1 and in Chapter 2.3 of 
the draft RIA. Nonetheless, in general we continue to view full-scale, 
vehicle SHED testing as the most accurate representation of real world 
evaporative and refueling emissions and consider it the preferred means 
of demonstrating refueling emission control performance for 
certification.
    We are considering updates to adapt the current test procedures to 
accommodate vehicles in the greater than 14,000 lb GVWR classes and to 
address the challenges highlighted in EPA's test program.\403\ The 
light-duty procedures require full-scale vehicle testing using complete 
vehicles in SHED enclosures. The current test procedures and most 
existing SHED facilities were designed to test passenger vehicles and 
heavy-duty complete vehicles that are much smaller than commercial 
vehicles in the over-14,000 lb GVWR classes. While a limited number of 
third-party laboratories are available with larger SHED facilities, we 
identified two key updates needed to accurately adapt the current 
refueling procedures to larger SHEDs that would fit vehicles above 
14,000 lb GVWR. As discussed in Chapter 2.3 of the draft RIA, we need 
to extend the mixing time for the larger volume of ambient air to reach 
a homogeneous distribution and identify a means to accurately calculate 
the diverse vehicle volumes that displace air in the enclosure. We 
currently have limited data to inform these updates and request 
comment, including data, on appropriate mixing times and approaches to 
calculating air displacement in larger SHED enclosures. Additionally, 
we request comment on other aspects of the current test procedures that 
could be improved for evaluating vehicles above 14,000 lb GVWR.
---------------------------------------------------------------------------

    \403\ Chapter 2.3 of the draft RIA summarizes this test program.
---------------------------------------------------------------------------

    We also request comment on the conditioning procedure to prepare 
the canister for testing. The current preparatory cycle used by 
complete HD vehicles is modeled after light-duty vehicle driving 
patterns and vehicles typically with much smaller fuel tanks and 
canisters.\404\ The current conditioning procedure is designed to 
challenge the purge system in scenarios such as heavy traffic, slow 
speeds and start-stop events over shorter drive distances and time. 
Heavy-duty vehicles, with larger fuel tanks and canisters, may drive 
more miles and longer time periods and have greater power demands that 
may help purge the larger canisters more easily than allowed in the 
current light duty vehicle test. Commercial vehicles typically 
experience more daily operation in traffic and on roads delivering 
goods but generally drive more miles and hours daily and operate under 
higher loads, which can accelerate the removal of vapors stored in the 
canister system from a diurnal or prior refueling event. We request 
comment on a specific canister conditioning cycle or adjustments to the 
current conditioning cycle that would better represent real world 
loading for heavy-duty vehicles entering a refueling event.
---------------------------------------------------------------------------

    \404\ 40 CFR 86.132-00.
---------------------------------------------------------------------------

    We also request comment on additional ORVR performance 
demonstrations EPA should consider adopting. One option would be to 
allow manufacturers to evaluate the entire ORVR system of an incomplete 
vehicle (e.g., fuel tank, filler pipe, canister, control valves) 
separate from the vehicle body and chassis. Using an approach of only 
testing refueling components, manufacturers could use existing, widely-
available chassis testing SHED enclosures, since there would no longer 
be a need to design expanded test cell volumes to accommodate the 
larger and more diverse vehicle configurations produced as incomplete 
vehicles. Similarly, an ORVR components test could also be performed in 
a smaller scale SHED (sometimes referred to as a ``mini-SHED'' or ``rig 
SHED''), which is allowed by CARB for certain evaporative tests and was 
incorporated by reference as a phase-in option for evaporative 
emissions testing in our Tier 3 light-duty rulemaking.\405\ A smaller 
SHED enclosure provides a simpler test methodology with further reduced 
variability. Since testing the refueling-related components independent 
of the vehicle eliminates the challenge of minimizing other hydrocarbon 
sources not associated with fuel or the fuel system (e.g., tires, 
plastics, paints), we request comment on the appropriate numeric level 
for the standard if evaluated using this simpler testing option, as the 
proposed standard is currently based on a full-vehicle test procedure. 
We request comment on these component-focused options or other 
alternatives, including specific test procedures, numeric standards, 
and appropriate canister conditioning cycles that we should consider to 
represent real world operation for these heavy-duty vehicles.
---------------------------------------------------------------------------

    \405\ 40 CFR 86.1813-17(g)(3).
---------------------------------------------------------------------------

ii. Impact on Secondary Manufacturers
    For incomplete vehicles above 14,000 lb GVWR, the chassis 
manufacturer performs the evaporative emissions testing and obtains the 
vehicle certificate from EPA. When the chassis manufacturer sells the 
incomplete vehicle to a secondary vehicle manufacturer, the chassis 
manufacturer provides specific instructions to the secondary 
manufacturer indicating what they must do to maintain the certified 
configuration, how to properly install components, and what, if any, 
modifications may be performed. For the evaporative emission system, a

[[Page 17492]]

chassis manufacturer may require specific tube lengths and locations of 
certain hardware, and modifications to the fuel tank, fuel lines, 
evaporative canister, filler tube, gas cap and any other certified 
hardware would likely be limited.
    We expect that the addition of any ORVR hardware and all ORVR-
related aspects of the certified configuration would continue to be 
managed and controlled by the chassis manufacturer that holds the 
vehicle certificate. The engineering associated with all aspects of the 
fuel system design, which would include the ORVR system, is closely 
tied to the engine design, and the chassis manufacturer is the most 
qualified party to ensure its performance and compliance with 
applicable standards. Example fuel system changes the OEM may implement 
include larger canisters bracketed to the chassis frame close to the 
fuel tanks. Additional valves may be necessary to route the vapors to 
the canister(s) during refueling. Most other evaporative and fuel lines 
would remain in the same locations to meet existing evaporative 
requirements. There may be slightly different filler neck tube designs 
(smaller fuel transfer tube) as well as some additional tubes and 
valves to allow proper fuel nozzle turn-off (click off) at the pump, 
but this is not expected to include relocating the filler neck. Based 
on the comments received on the ANPR, we believe these changes would 
not adversely impact the secondary manufacturers finishing the 
vehicles.\406\
---------------------------------------------------------------------------

    \406\ See comments from the Manufacturers of Emission Controls 
Association (EPA-HQ-OAR-2019-0055-0365) and Ingevity Corporation 
(EPA-HQ-OAR-2019-0055-0271).
---------------------------------------------------------------------------

    The instructions provided by the chassis manufacturer to the 
secondary manufacturer to meet our proposed refueling standards should 
include new guidelines to maintain the certified ORVR configuration. We 
do not expect the new ORVR system to require significant changes to the 
vehicle build process, since chassis manufacturers would have a 
business incentive to ensure that the ORVR system integrates smoothly 
in a wide range of commercial vehicle bodies. Accordingly, we do not 
expect that addition of the ORVR hardware would result in any 
appreciable change in the secondary manufacturer's obligations or 
require secondary builders to perform significant modifications to 
their products.
3. Feasibility Analysis for the Proposed Refueling Emission Standards
    This section describes the effectiveness and projected costs of the 
emissions technologies that we analyzed for our proposed refueling 
standards. Feasibility of the proposed refueling standard of 0.20 grams 
of HC per gallon is based on the widespread adoption of ORVR systems 
used in the light-duty and complete heavy-duty vehicle sectors. As 
described in this section, we believe manufacturers can effectively 
scale the technologies to larger engine applications to meet the 
proposed standard. For our inventory analysis, we assumed all heavy-
duty gasoline-fueled vehicles that are identified as LHD, MHD and HHD 
regulatory subcategories in MOVES would implement ORVR systems starting 
in MY 2027 and we adjusted the refueling emission rates for those 
subcategories to reflect 100 percent implementation of a 0.20 grams of 
HC per gallon of gasoline rate in MY 2027. See Chapter 5.2.2 of the 
draft RIA for a discussion of our inventory model updates. The proposed 
refueling controls would lower refueling VOC and benzene emissions by 
88.5 percent by 2045 for heavy duty gasoline vehicles over 14,000 lb 
GVWR. See the discussion and table in Chapter 5.3.3 of the draft RIA.
i. Summary of Refueling Emission Technologies Considered
    This section summarizes the specific technologies we considered as 
the basis for our analysis of the proposed refueling emission 
standards. The technologies presented in this section are described in 
greater detail in Chapter 1.2.3 of the draft RIA.
    Instead of releasing HC vapors into the ambient air, ORVR systems 
capture HC emissions during refueling events when liquid fuel displaces 
HC vapors present in the vehicle fuel tank as the tank is filled. These 
systems recover the HC vapors and store them for later purging from the 
system and use as fuel to operate the engine. An ORVR system consists 
of four main components that are incorporated into the existing fuel 
system: Filler pipe and seal, flow control valve, carbon canister, and 
purge system.
    The filler pipe is the section of line from the fuel tank to where 
fuel enters the fuel system from the fuel nozzle. The filler pipe is 
typically sized to handle the maximum fill rate of liquid fuel allowed 
by law and integrates either a mechanical or liquid seal to prevent 
fuel vapors from exiting through the filler pipe to the atmosphere. The 
flow control valve senses that the fuel tank is getting filled and 
triggers a unique low-restriction flow path to the canister. The carbon 
canister is a container of activated charcoal designed to effectively 
capture and store fuel vapors. Carbon canisters are already a part of 
HD SI fuel systems to control evaporative emissions. Fuel systems with 
ORVR would require additional capacity, by increasing either the 
canister volume or the effectiveness of the carbon material. The purge 
system is an electro-mechanical valve used to redirect fuel vapors from 
the fuel tank and canister to the running engine where they are burned 
in the combustion chamber.\407\
---------------------------------------------------------------------------

    \407\ This process displaces some amount of the liquid fuel that 
would otherwise be used from the fuel tank and results in a small 
fuel savings. See Chapter 7.2.2 of the draft RIA for our estimate of 
the fuel savings from our proposed refueling standards.
---------------------------------------------------------------------------

    The fuel systems on over-14,000 lb GVWR incomplete heavy-duty 
vehicles are similar to those on complete heavy-duty vehicles that are 
currently subject to refueling standards. These incomplete vehicles may 
have slightly larger fuel tanks than most chassis-certified (complete) 
heavy-duty vehicles and are somewhat more likely to have dual fuel 
tanks. These differences may necessitate greater ORVR system storage 
capacity and possibly some unique accommodations for dual tanks (e.g., 
separate fuel filler locations), as commented by ORVR suppliers in 
response to our ANPR.\408\
---------------------------------------------------------------------------

    \408\ See comments from the Manufacturers of Emission Controls 
Association (EPA-HQ-OAR-2019-0055-0365) and Ingevity Corporation 
(EPA-HQ-OAR-2019-0055-0271).
---------------------------------------------------------------------------

ii. Projected Refueling Emission Technology Packages
    The ORVR emission controls we projected in our feasibility analysis 
build upon four components currently installed on incomplete vehicles 
above 14,000 lb GVWR to meet the Tier 3 evaporative emission standards: 
The carbon canister, flow control valves, filler pipe and seal, and the 
purge system. For our feasibility analysis, we assumed a 70-gallon fuel 
tank to represent an average tank size of HD SI incomplete vehicles 
above 14,000 lb GVWR. A summary of the projected technology updates and 
costs are presented below. See Chapter 3.2 of the draft RIA for 
additional details.
    In order to capture the vapor volume of fuel tanks during 
refueling, we project manufacturers would increase canister vapor or 
``working'' capacity of their liquid-sealed canisters by 15 to 40 
percent depending on the individual vehicle systems. If a manufacturer 
chooses to increase the canister volume using conventional carbon, we 
project a canister meeting Tier 3 evaporative emission requirements 
with approximately 5.1 liters of conventional carbon would need up to 
an additional

[[Page 17493]]

1.8 liters of carbon to capture refueling emissions from a 70-gallon 
fuel tank. A change in canister volume to accommodate additional carbon 
would result in increased costs for retooling and additional canister 
plastic, as well as design considerations to fit the larger canister on 
the vehicle. Alternatively, a manufacturer could choose to add a second 
canister for the extra carbon volume to avoid the re-tooling costs. We 
estimate projected costs for both a single larger canister and two 
canisters in series. Another approach, based on discussions with 
canister and carbon manufacturers, could be for manufacturers to use a 
higher adsorption carbon and modify compartmentalization within the 
existing shell to increase the canister working capacity. We do not 
have data to estimate the performance or cost of higher adsorption 
carbon and so did not include this additional approach in our analysis.
    The projected increase in canister volumes assume manufacturers 
would use a liquid seal in the filler pipe, which is less effective 
than a mechanical seal. For a manufacturer that replaces their liquid 
seal with a mechanical seal, we assumed an approximate 20 percent 
reduction in the necessary canister volume. Despite the greater 
effectiveness of a mechanical seal, manufacturers in the past have not 
preferred this approach because it introduces another wearable part 
that can deteriorate, introduces safety concerns, and may require 
replacement during the useful life of the vehicle. To meet the proposed 
ORVR standards, manufacturers may choose the mechanical seal design to 
avoid retooling charges and we included it in our cost analysis. We 
assumed a cost of $10.00 per seal for a manufacturer to convert from a 
liquid seal to a mechanical seal. We assumed zero cost in our analysis 
for manufacturers to maintain their current liquid seal approach for 
filler pipes. While some of the largest vehicle applications with 
unique tank locations or designs without filler necks may need 
additional hardware modifications to provide enough back pressure to 
stop the nozzle flow and avoid spitback, we believe the cost is similar 
to converting to a mechanical seal, and we did not differentiate these 
low volume applications in our cost analysis.
    In order to manage the large volume of vapors during refueling, 
manufacturers' ORVR updates would include flow control valves 
integrated into the roll-over/vapor lines. We assumed manufacturers 
would, on average, install one flow control valve per vehicle that 
would cost $6.50 per valve. And lastly, we project manufacturers would 
update their purge strategy to account for the additional fuel vapors 
from refueling. Manufacturers may add hardware and optimize 
calibrations to ensure adequate purge in the time allotted over the 
preconditioning drive cycle of the demonstration test.
    Table III-34 presents the ORVR system specifications and 
assumptions used in our cost analysis, including key characteristics of 
the baseline incomplete vehicle's evaporative emission control system. 
Currently manufacturers size the canisters of their Tier 3 evaporative 
emission control systems based on the diurnal test and the Bleed 
Emission Test Procedure (BETP).\409\ During the diurnal test, the 
canister is loaded with hydrocarbons over two or three days, allowing 
the hydrocarbons to load a conventional carbon canister (1500 GWC, 
gasoline working capacity) at a 70 percent efficiency. In contrast, a 
refueling event takes place over a few minutes, and the ORVR directs 
the vapor from the gas tank onto the carbon in the canister at a 
canister loading efficiency of 50 percent. For our analysis, we added a 
design safety margin of 10 percent extra carbon to our ORVR systems. 
While less overall vapor mass may be vented into the canister from the 
fuel tank during a refueling event compared to the three-day diurnal 
test period, a higher amount of carbon is needed to contain the faster 
rate of vapor loaded at a lower efficiency during a refueling event. 
These factors were used to calculate the canister volumes for the two 
filler neck options in our cost analysis.
---------------------------------------------------------------------------

    \409\ 40 CFR 86.1813-17(a).
---------------------------------------------------------------------------

    The assumed purge system updates are also shown in Table III-34. 
The diurnal drive cycle duration is 30 minutes and targets 200 bed 
volumes of purge to clean the canister before the evaporative emissions 
test. The bed volumes of purge are multiplied by the canister volume to 
calculate the total target purge volume. The total purge volume divided 
by the number of minutes driving gives us the average purge rate. An 
ORVR demonstration would also require conditioning of the canister in 
preparation for the ORVR test. The current conditioning cycle used by 
complete vehicles consists of a 97-minute drive cycle to prepare the 
canister.\410\ However, as indicated in the table, a larger target bed 
volume may be needed to purge the larger canister capacity required for 
ORVR.
---------------------------------------------------------------------------

    \410\ Trucks with larger fuel tanks typically will drive more 
miles in a day and between refueling events. As noted in Section 
III.E.2, we are requesting comment on updating our canister 
preconditioning driving procedure in order to better represent the 
operation of these larger vehicles.

 Table III-34--ORVR Specifications and Assumptions Used in the Cost Analysis for HD SI Incomplete Vehicles Above
                                                 14,000 lb GVWR
----------------------------------------------------------------------------------------------------------------
                                                                      Tier 3         ORVR Filler Neck Options
                                                                     Baseline    -------------------------------
                                                                 ----------------              ORVR
                                                                                 -------------------------------
                                                                      Diurnal       Mechanical
                                                                                       seal         Liquid seal
----------------------------------------------------------------------------------------------------------------
Diurnal Heat Build..............................................    72-96 [deg]F       80 [deg]F  ..............
RVP.............................................................           9 psi  ..............  ..............
Nominal Tank Volume.............................................      70 gallons  ..............  ..............
Fill Volume.....................................................             40%     10% to 100%  ..............
Air Ingestion Rate..............................................  ..............              0%          13.50%
Mass Vented per heat build, g/d.................................             120  ..............  ..............
Mass Vented per refueling event.................................  ..............             255             315
Hot Soak Vapor Load.............................................               5  ..............  ..............
Mass vented over 48-hour test...................................           227.2  ..............  ..............
Mass vented over 72-hour test...................................           323.3  ..............  ..............
1500 GWC, g/L (Efficiency) \a\..................................              70              50              50

[[Page 17494]]

 
Excess Capacity.................................................             10%             10%             10%
Estimated Canister Volume Requirement, liters \b\
    48-hour Evaporative only....................................             3.6
    72-hour Evaporative only....................................             5.1
    Total of 72-hour + ORVR \c\.................................  ..............             5.6             6.9
Limiting Drive Cycle, minutes...................................              30              97              97
Target Bed Volumes of Purge \d\.................................             200             646             646
Total Purge Volume, liters \e\..................................            1020            3618            4457
Average Purge Rate, LPM \f\.....................................              34              37              46
BETP Purge......................................................  ..............              37              46
----------------------------------------------------------------------------------------------------------------
\a\ Efficiency of conventional carbon.
\b\ Canister Volume = 1.1(mass vented)/1500 GWC (Efficiency).
\c\ ORVR adds .5 liters and 1.8 liters for Mechanical Seal and Liquid Seal respectively.
\d\ ORVR estimated volumes based on ratio of increased driving distance in ORVR procedure and not necessarily
  reflective of necessary volumes to sufficiently purge canister.
\e\ Total Purge Volume, Liters = canister volume, liters * Bed Volumes Purge.
\f\ Average Purge Rate, LPM = Total Purge Volume, liters/Limiting Drive Cycle, minutes.

    The ORVR components described in this section represent 
technologies that we think most manufacturers would adopt to meet our 
proposed refueling requirements. It is possible that manufacturers may 
choose a different approach, or that unique fuel system characteristics 
may require additional hardware modifications not described here, but 
we do not have reason to believe costs would be significantly higher 
than presented here. We request comment, including data, on our 
assumptions related to the increased canister working capacity demands, 
the appropriateness of our average fuel tank size, the technology costs 
for the specific ORVR components considered and any additional 
information that can improve our cost projections in the final rule 
analysis.
iii. Summary of Costs To Meet the Proposed Refueling Emission Standards
    Table III-35 shows cost estimations for the different approaches 
evaluated. In calculating the overall cost of our proposed program, we 
used $25, the average of both approaches, to represent the cost for 
manufacturers to adopt the additional canister capacity and hardware to 
meet our proposed refueling emission standards for incomplete vehicles 
above 14,000 lb GVWR. See Section V of this preamble for a summary of 
our overall program cost and Chapter 7 of the draft RIA for more 
details.

     Table III-35--Summary of Projected Per-Vehicle Costs To Meet the Proposed Refueling Emission Standards
----------------------------------------------------------------------------------------------------------------
                                                            Liquid seal                   Mechanical seal
                                                 ---------------------------------------------------------------
                                                                   Dual existing                   Dual existing
                                                   New canister    canisters in    New canister    canisters in
                                                                      series                          series
----------------------------------------------------------------------------------------------------------------
Additional Canister Costs.......................             $20             $15              $8              $8
                                                 ---------------------------------------------------------------
Additional Tooling \a\..........................               0.50
                                                               0.50
Flow Control Valves.............................               6.50
                                                               6.50
                                                 ---------------------------------------------------------------
Seal............................................               0               0              10
                                                 ---------------------------------------------------------------
    Total \b\...................................              27              22              25
----------------------------------------------------------------------------------------------------------------
\a\ Assumes the retooling costs are spread over a five-year period.
\b\ Possible additional hardware for spitback requirements.

    Incomplete vehicles above 14,000 lb GVWR with dual fuel tanks may 
require some unique accommodations to adopt ORVR systems. A chassis 
configuration with dual fuel tanks would need separate canisters and 
separate filler pipes and seals for each fuel tank. Depending on the 
design, a dual fuel tank chassis configuration may require a separate 
purge valve for each fuel tank. We assume manufacturers would install 
one additional purge valve for dual fuel tank applications that also 
incorporate independent canisters for the second fuel tank/canister 
configuration and manufacturers adopting a mechanical seal in their 
filler pipe would install an anti-spitback valve for each filler pipe. 
See Chapter 1.2.4.5 of the draft RIA for a summary of the design 
considerations for these fuel tank configurations. We did not include 
an estimate of the population or impact of dual fuel tank vehicles in 
our cost analysis of our proposed refueling emission standards.

[[Page 17495]]

4. Summary of Requests for Comment
    We are requesting comment regarding the cost, feasibility, and 
appropriateness of our proposed refueling emission standard for 
incomplete vehicles above 14,000 lb GVWR. The proposed standard is 
based on the current refueling standard that applies to complete heavy-
duty gasoline-fueled vehicles. We are proposing that compliance with 
these standards may be demonstrated under an existing regulatory 
provision by using an engineering analysis due to uncertainties related 
to testing these larger vehicles. We request comment on approaches to 
adapt the current test procedures used by lower GVWR vehicles for 
vehicles above 14,000 lb GVWR. Specifically, we are interested in 
comments including data or established procedures to calculate 
appropriate mixing times and air displacement in larger SHED 
enclosures. We also request comment on the appropriate conditioning 
procedure for these larger vehicles. Finally, we request comment on 
other testing options we should consider for manufacturers to 
demonstrate the effectiveness of their ORVR systems on incomplete 
vehicles above 14,000 lb GVWR.

IV. Compliance Provisions and Flexibilities

    EPA certification is a fundamental requirement of the Clean Air Act 
for manufacturers of heavy-duty highway engines. EPA has employed 
significant discretion over the past several decades in designing and 
updating many aspects of our heavy-duty engine and vehicle 
certification and compliance programs. In the following sections, we 
discuss several proposed provisions that we believe would increase the 
effectiveness of our regulations, including some opportunities to 
streamline existing requirements. Unless explicitly stated otherwise, 
the proposed provisions in this Section IV would apply to proposed 
Options 1 and 2, as well as the full range of options in between them.
    As noted in Section I, we are proposing to migrate our criteria 
pollutant regulations for model years 2027 and later heavy-duty highway 
engines from their current location in 40 CFR part 86, subpart A, to 40 
CFR part 1036.\411\ Consistent with this migration, the proposed 
compliance provisions discussed in this section refer to the proposed 
regulations in their new location in part 1036. In general, this 
migration is not intended to change the compliance program previously 
specified in part 86, except as specifically proposed in this 
rulemaking. See our memorandum to the docket for a detailed description 
of the proposed migration.\412\
---------------------------------------------------------------------------

    \411\ As noted in the following sections, we are proposing some 
updates to 40 CFR parts 1037, 1065, and 1068 to apply to other 
sectors in addition to heavy-duty highway engines.
    \412\ Stout, Alan; Brakora, Jessica. Memorandum to docket EPA-
HQ-OAR-2019-0055. ``Technical Issues Related to Migrating Heavy-Duty 
Highway Engine Certification Requirements from 40 CFR part 86, 
subpart A, to 40 CFR part 1036''. October 1, 2021.
---------------------------------------------------------------------------

A. Regulatory Useful Life

    In addition to emission standards and test procedures discussed in 
Section III, appropriate regulatory useful life periods are critical to 
assure emission performance of heavy-duty highway engines. Our 
regulations require manufacturers to perform durability testing to 
demonstrate that engines will meet emission standards not only at 
certification but also over the full useful life periods specified by 
EPA. Useful life represents the period over which emission standards 
apply for certified engines, and, practically, any difference between 
the regulatory useful life and the generally longer operational life of 
in-use engines represents miles and years of operation without an 
assurance that emission standards will continue to be met.
    In this section, we describe our estimates of the length of 
operational lives of heavy-duty highway engines, which are almost 
double the current useful life mileages in EPA's regulations for all 
primary intended service classes. EPA is proposing to increase the 
regulatory useful life mileage values for new heavy-duty engines to 
better reflect real-world usage, extend the emissions durability 
requirement for heavy-duty engines, and improve long-term emission 
performance. Our proposed longer useful life periods for heavy-duty 
engines vary by engine class to reflect the different lengths of their 
estimated operational lives. As described in Section III, the proposed 
numeric levels of the standards are the same across engine classes and 
are based on the feasibility of achieving those standards at the 
proposed useful life mileages. Proposed Option 1 useful life periods 
would apply in two steps in MY 2027 and MY 2031 and proposed Option 2 
useful life periods would apply in a single step in MY 2027.
    For CI engines, the proposed Option 1 useful life mileage values 
for MY 2031 and later are based on data on the average periods to the 
first out-of-frame rebuild for these engines. Our CI engine 
demonstration, which is based on the emission performance of an engine 
in the Heavy HDE class, projects the engine can achieve the proposed 
standards for MY 2031 at the proposed useful life mileage.\413\ Our 
demonstration data does not currently show that it is feasible to 
achieve the proposed Option 1 MY 2027 standards at the MY 2031 useful 
life mileages, and the proposed Option 1 useful life mileage values for 
MY 2027 through 2030 are approximately a midpoint between the current 
useful life mileages and our proposed Option 1 MY 2031 and later 
mileages.
---------------------------------------------------------------------------

    \413\ Demonstrating feasibility for the Heavy HDE class 
indicates feasibility for the smaller CI engine classes, Medium HDE, 
and Light HDE, which could adopt similar technologies to meet the 
standards and have shorter proposed useful life periods over which 
to demonstrate the performance.
---------------------------------------------------------------------------

    Similarly, the proposed Option 1 would increase useful life 
mileages in two steps for the proposed standards for heavy-duty SI 
engines that are not chassis-certified. Our proposed Option 1 first 
step for these SI engines in MY 2027 through 2030 would better align 
with the current useful life mileages for GHG emission standards 
applicable to these engines and for chassis-certified complete vehicles 
containing these engines. The proposed Option 1 second step for these 
SI engines in MY 2031 and later would be based on the expected engine 
service life for heavy-duty gasoline engines in the market today. The 
SI demonstration program showed that the proposed Option 1 standards 
are feasible over the proposed Option 1 useful life mileages.
    In our ANPR, we presented CI engine rebuild data and noted that we 
intended to propose useful life mileage values for all categories of 
heavy-duty engines that are more reflective of real-world usage. 
Comments received on the ANPR included varied support for increasing 
engine useful life values. Environmental organizations and state, 
local, and Tribal air agencies largely supported lengthened useful 
life, and many supported aligning with CARB's HD Omnibus rulemaking. 
Among the sixteen state, local, and Tribal governments and related 
associations that expressed support, the National Tribal Air 
Association stated that longer useful life requirements would lead to 
longer design life targets for emissions systems commensurate with 
actual vehicle service lengths.\414\ The International Council on Clean 
Transportation (ICCT) commented that EPA should harmonize useful life 
requirements with California and stated that it could be possible to 
double the

[[Page 17496]]

useful life of the emission control systems with available 
technologies.\415\
---------------------------------------------------------------------------

    \414\ See comments from NTAA, Docket ID EPA-HQ-OAR-2019-0055-
0282.
    \415\ See comments from ICCT, Docket ID EPA-HQ-OAR-2019-0055-
0304.
---------------------------------------------------------------------------

    Other commenters expressed cautious support. The Manufacturers of 
Emission Controls Association (MECA) and Motor and Equipment 
Manufacturers Association (MEMA) supported extending useful life with a 
phased approach that allows suppliers time to design, test, and address 
issues with their components' durability beyond today's 
requirements.416 417 Several commenters expressed concern 
related to the cost of extending longer useful life periods. The 
American Truck Dealers Division of the National Automobile Dealers 
Association (NADA) stated that longer useful life periods may be 
warranted given the increasing number of miles heavy-duty engines 
accumulate prior to engine rebuild.\418\ NADA asked EPA to carefully 
assess higher up-front engine costs associated with longer useful life 
periods and the potential for reduced maintenance and repair costs 
resulting from increased useful life. Volvo stated that more durable 
components are not available ``to pull from the shelf'' and costs to 
extend the life of those components could result in significant costs 
either to improve the components or incorporate a replacement as part 
of the manufacturer's scheduled maintenance.\419\ Volvo also expressed 
concern that second and third owners may use the vehicles for 
applications that could stress the engine and its systems and threaten 
emissions compliance within a lengthened useful life. The Truck and 
Engine Manufacturers Association (EMA) and Cummins commented that EPA 
should carefully evaluate the benefits of extending the useful life 
period.420 421 EMA stated a longer useful life could require 
the replacement of aftertreatment systems during the lengthened period.
---------------------------------------------------------------------------

    \416\ See comments from MECA, Docket ID EPA-HQ-OAR-2019-0055-
0365.
    \417\ See comments from MEMA, Docket ID EPA-HQ-OAR-2019-0055-
0462.
    \418\ See comments from NADA, Docket ID EPA-HQ-OAR-2019-0055-
0369.
    \419\ See comments from Volvo, Docket ID EPA-HQ-OAR-2019-0055-
0463.
    \420\ See comments from EMA, Docket ID EPA-HQ-OAR-2019-0055-
0273.
    \421\ See comments from Cummins, Docket ID EPA-HQ-OAR-2019-0055-
0359.
---------------------------------------------------------------------------

    We note that as manufacturers develop compliance strategies to meet 
our proposed emission standards and lengthened useful life periods, 
they have the ability to design for increased durability of their 
engine and emission controls and to create maintenance instructions 
describing how to clean, repair, or replace emission components at 
specified intervals subject to the limitations in our proposed 
maintenance provisions.\422\ To address the feasibility of meeting the 
proposed standards over the proposed useful life periods, the 
technology demonstration projects described in Section III of this 
preamble include demonstrating the durability and emissions performance 
of CI and SI engines over mileages that cover the range of useful life 
mileages being considered. We believe our proposed useful life periods 
are feasible and would not require manufacturers to adopt component 
replacement as part of their critical emission-related maintenance 
strategies.
---------------------------------------------------------------------------

    \422\ See Section IV.B.5 of this preamble and proposed 40 CFR 
1036.125.
---------------------------------------------------------------------------

1. History of Regulatory Useful Life
    The Clean Air Act specifies that emission standards under section 
202(a) ``shall be applicable to such vehicles and engines for their 
useful life . . . whether such vehicles and engines are designed as 
complete systems or incorporate devices to prevent or control such 
pollution.'' Practically, this means that to receive an EPA certificate 
of conformity under the CAA, a manufacturer must demonstrate that an 
engine or vehicle, including the aftertreatment system, will meet each 
applicable emission standard, including accounting for deterioration, 
over the useful life period specified in EPA's regulations. In 
addition, CAA section 207(c) requires manufacturers to recall and 
repair vehicles or engines if the Administrator determines that ``a 
substantial number of any class or category of vehicles or engines, 
although properly maintained and used, do not conform to the 
regulations prescribed under [section 202(a)], when in actual use 
throughout their useful life (as determined under [section 202(d)]).'' 
Taken together, these sections define two critical aspects of 
regulatory useful life: (1) The period over which the manufacturer must 
demonstrate compliance with emissions standards to obtain EPA 
certification, and (2) the period for which the manufacturer is subject 
to in-use emissions compliance liability, e.g., for purposes of recall. 
Manufacturers perform durability testing to demonstrate that engines 
will meet emission standards over the full useful life. Manufacturers 
may perform scheduled maintenance on their test engines only as 
specified in the owner's manual. As part of the certification process, 
EPA approves such scheduled maintenance, which is also subject to 
minimum maintenance intervals as described in the regulation. See 
Section IV.F for a description of the current and proposed durability 
requirements and Section IV.B.5 for more information on our current and 
proposed maintenance provisions. Manufacturer obligations under recall 
are specified in 40 CFR 1068, subpart F, and we are not proposing to 
update our recall provisions.
    EPA prescribes regulations under CAA section 202(d) for determining 
the useful life of vehicles and engines. CAA section 202(d) provides 
that the minimum useful life for heavy-duty vehicles and engines is a 
period of 10 years or 100,000 miles, whichever occurs first. This 
section authorizes EPA to adopt longer useful life periods that we 
determine to be appropriate. Under this authority, we established 
useful life periods for heavy-duty engines by primary intended service 
class. As introduced in Section I, heavy-duty highway engine 
manufacturers identify the primary intended service class for each 
engine family by considering the vehicles for which they design and 
market their engines.\423\ Heavy-duty compression-ignition engines are 
distinguished by their potential for rebuild and the weight class of 
the final vehicles in which the engines are expected to be 
installed.\424\ Heavy-duty spark-ignition engines are generally 
classified as a single ``spark-ignition'' service class unless they are 
designed or intended for use in the largest heavy-duty vehicles and are 
thereby considered heavy heavy-duty engines.\425\
---------------------------------------------------------------------------

    \423\ See 40 CFR 1036.140 as referenced in the definition of 
``primary intended service class'' in 40 CFR 86.090-2.
    \424\ As specified in the current 40 CFR 1036.140(a), light 
heavy-duty engines are not designed for rebuild and are normally 
installed in vehicles at or below 19,5000 pounds GVWR; medium heavy-
duty engines may be designed for rebuild and are normally installed 
in vehicles from 19,501 to 33,000 lbs GVWR; heavy heavy-duty engines 
are designed for multiple rebuilds and are normally installed in 
vehicles above 33,000 pounds GVWR.
    \425\ See 40 CFR 1036.140(b).

---------------------------------------------------------------------------

[[Page 17497]]

The following useful life periods currently apply to the criteria 
pollutant emission standards for heavy-duty highway engines: 
426 427
---------------------------------------------------------------------------

    \426\ See 40 CFR 86.004-2. EPA adopted useful life values of 
110,000, 185,000, and 290,000 miles for light, medium, and heavy 
heavy-duty engines, respectively, in 1983 (48 FR 52170, November 16, 
1983). The useful life for heavy heavy-duty engines was subsequently 
increased to 435,000 miles for 2004 and later model years (62 FR 
54694, October 21, 1997).
    \427\ The same useful life periods apply for heavy-duty engines 
certifying to the greenhouse gas emission standards, except that the 
spark-ignition standards and the standards for model year 2021 and 
later light heavy-duty engines apply over a useful life of 15 years 
or 150,000 miles, whichever comes first. See 40 CFR 1036.108(d).
---------------------------------------------------------------------------

     110,000 miles or 10 years for heavy-duty spark-ignition 
engines and light heavy-duty compression-ignition engines
     185,000 miles or 10 years for medium heavy-duty 
compression-ignition engines
     435,000 miles, 10 years, or 22,000 hours for heavy heavy-
duty compression-ignition engines
    In our 1983 rulemaking, which first established class-specific 
useful life values for heavy-duty engines and vehicles, EPA adopted the 
principle that useful life mileage values should reflect the typical 
mileage to the first rebuild of the engine (or scrappage of the engine 
if that occurs without rebuilding).\428\ Significantly, this approach 
was adopted at a time when diesel engine emission control strategies 
relied mainly on in-cylinder engine combustion controls.
---------------------------------------------------------------------------

    \428\ U.S. EPA, ``Summary and Analysis of Comments on the Notice 
of Proposed Rulemaking for Revised Gaseous Emission Regulations for 
1984 and Later Model Year Light-Duty Trucks and Heavy-Duty 
Engines'', July 1983, p 43.
---------------------------------------------------------------------------

    Over time, mileage values became the primary metric for useful life 
duration. This is because, due to advancements in general engine 
durability, nearly all heavy-duty engines reach the mileage value in-
use long before 10 years have elapsed. The age (years) value has 
meaning for only a small number of low-annual-mileage applications, 
such as refuse trucks. Also, manufacturer durability demonstrations 
generally target the mileage values, since deterioration is a function 
of engine work and hours rather than years in service and a time-based 
demonstration would be significantly longer in duration than one based 
on applicable mileage value.
    In the 1997 rulemaking that most recently increased heavy-duty 
engine useful life, EPA included an hours-based useful life of 22,000 
hours for the heavy heavy-duty engine intended service class. This 
unique criterion was added to address the concern that urban vehicles, 
particularly urban buses, equipped with heavy heavy-duty engines had 
distinctly different driving patterns compared to the line-haul trucks 
from which the agency based its useful life value of 435,000 
miles.\429\ Commenters in that rulemaking indicated that urban bus 
average speed was near 13 miles per hour. Considering that speed, many 
of these bus engines would reach the end of their operational life or 
be candidates for rebuild before the applicable mileage value or the 
10-year criterion is reached. The 22,000 hours value was adopted in 
lieu of a proposed minimum useful life value of 290,000 miles for heavy 
heavy-duty engines. Considering the current 435,000 useful life mileage 
for heavy heavy-duty engines, the 22,000-hour useful life value only 
has significance for the small subset of vehicles equipped with heavy 
heavy-duty engines with an average speed of less than 20 miles per 
hour.
---------------------------------------------------------------------------

    \429\ U.S. EPA, ``Summary and Analysis of Comments: Control of 
Emissions of Air Pollution from Highway Heavy-Duty Engines'', EPA-
420-R-97-102, September 1997, pp 43-47.
---------------------------------------------------------------------------

    In the Phase 1 GHG rulemaking, we promulgated useful life periods 
for the GHG emission standards for heavy-duty highway engines and their 
corresponding heavy-duty vehicles that aligned with the current useful 
life periods for criteria pollutant emission standards.\430\ In the HD 
Phase 2 GHG rulemaking, we extended the useful life for Light HDV, 
light heavy-duty engines, and spark-ignition engines for the GHG 
emission standards to 15 years or 150,000 miles to align with the 
useful life of chassis-certified heavy-duty vehicles subject to the 
Tier 3 standards.\431\ See 40 CFR 1036.108 and 40 CFR 1037, subpart B, 
for the GHG useful life periods that apply for heavy-duty highway 
engines and vehicles, respectively. We are not proposing changes to the 
useful life periods for GHG emission standards in this rulemaking.
---------------------------------------------------------------------------

    \430\ 76 FR 57181, September 15, 2011.
    \431\ See 79 FR 23414, April 28, 2014 and 81 FR 73496, October 
25, 2016.
---------------------------------------------------------------------------

2. Identifying Appropriate Useful Life Periods
    Emission standards apply for the engine's useful life and 
manufacturers must demonstrate the durability of engines to maintain 
certified emission performance over their useful life. Thus, the 
proposed emission standard options presented in Section III must be 
considered together with their associated proposed useful life periods. 
Larger useful life mileage values would require manufacturers to 
demonstrate emission performance over a longer period and should result 
in effective emission control over a greater proportion of an engine's 
operational (sometimes referred to as ``service'') life. Consistent 
with our approach to adopting useful life mileages in the 1983 
rulemaking, we continue to consider a comprehensive out-of-frame 
rebuild to represent the end of a heavy-duty CI engine's ``first life'' 
of operation. For SI engines that are less commonly rebuilt, engine 
replacement would be a more appropriate measure of an engine's 
operational life. Our proposed Option 1 useful life values are based on 
the expected operational life of the engine or, for CI engines, an 
estimate of the point at which an engine is typically rebuilt. We 
expand on this approach in the following sections. We discuss the basis 
of proposed Option 2 useful life values in Section IV.A.3.
i. Compression-Ignition Engine Rebuild Data
    In 2013, EPA commissioned an industry characterization report on 
heavy-duty diesel engine rebuilds.\432\ The report relied on existing 
data from MacKay & Company surveys of heavy-duty vehicle operators. In 
this report, an engine rebuild was categorized as either an in-frame 
overhaul (where the rebuild occurred while the engine remained in the 
vehicle) or an out-of-frame overhaul (where the engine was removed from 
the vehicle for more extensive service).\433\ The study showed that the 
mileage varied depending on the type of rebuild. Rebuilding an engine 
while the block remained in the frame was typically done at lower 
mileage than rebuilding an engine removed from the vehicle. The results 
of the study by vehicle weight class are presented in Table IV-1.
---------------------------------------------------------------------------

    \432\ ICF International, ``Industry Characterization of Heavy 
Duty Diesel Engine Rebuilds'' EPA Contract No. EP-C-12-011, 
September 2013.
    \433\ Note that these mileage values reflect replacement of 
engine components, but do not include aftertreatment components. At 
the time of the report, the population of engines equipped with DPF 
and SCR technologies was limited to relatively new engines that were 
not candidates for rebuild.

[[Page 17498]]



  Table IV-1--Average Mileage and Age at First Rebuild for Heavy-Duty CI Engines From 2013 EPA Rebuild Industry
                                             Characterization Report
----------------------------------------------------------------------------------------------------------------
                                                         In-frame rebuild              Out-of-frame rebuild
              Vehicle weight class               ---------------------------------------------------------------
                                                      Mileage          Years          Mileage          Years
----------------------------------------------------------------------------------------------------------------
Class 3.........................................         216,900             9.5         256,000             9.5
Class 4.........................................         236,800            11.6         346,300            10.3
Class 5.........................................         298,300            10.9         344,200            11.9
Class 6.........................................         332,200            13.0         407,700            10.6
Class 7.........................................         427,500            15.8         509,100            13.2
Class 8.........................................         680,200            11.9         909,900             8.9
----------------------------------------------------------------------------------------------------------------

    McKay & Company does not collect information on aftertreatment 
systems (e.g., diesel oxidation catalysts, SCR systems, or three-way 
catalysts), so neither EPA's 2013 report nor CARB's more recent report 
for their HD Omnibus rulemaking include aftertreatment system age 
information.\434\ We consider the mileage at rebuild or replacement of 
an engine to represent the operational life of that engine, including 
any aftertreatment components that were part of its original certified 
configuration. We have no data to indicate aftertreatment systems lose 
functionality before engines are rebuilt or replaced, and our 
technology demonstrations in Section III show aftertreatment catalysts 
are able to maintain performance when bench-aged to beyond the 
equivalent of current useful life mileages.\435\
---------------------------------------------------------------------------

    \434\ See Section IV.A.2.iii for a summary of the CARB report 
that reflects engine rebuilds and replacements occurring between 
calendar years 2012 and 2018.
    \435\ See Section IV.F for a summary of catalyst bench-aging 
procedures we are considering in this proposal.
---------------------------------------------------------------------------

    We averaged the mileages for these vehicle classes according to 
EPA's primary intended service classes for heavy-duty CI engines as 
defined in 40 CFR 1036.140. Specifically, we averaged Classes 3, 4, and 
5 to represent Light HDE, Classes 6 and 7 to represent Medium HDE, and 
Class 8 to represent Heavy HDE. These values are shown in Table IV-2 
with the current useful life mileages that apply to each intended 
service class. As seen in the tables, the study reported typical engine 
rebuild mileages that are more than double the current useful life 
mileages for those classes.

  Table IV-2--Average Mileage at First Rebuild for Heavy-Duty CI Engines Based on EPA Intended Service Classes
----------------------------------------------------------------------------------------------------------------
                                                                    Mileage at      Mileage at
                 Primary intended service class                   first in-frame   first out-of-  Current useful
                                                                      rebuild     frame  rebuild   life mileage
----------------------------------------------------------------------------------------------------------------
Light HDE (Vehicle Classes 3-5).................................         250,667         315,500      \a\110,000
Medium HDE (Vehicle Classes 6-7)................................         379,850         458,400         185,000
Heavy HDE (Vehicle Class 8).....................................         680,200         909,900         435,000
----------------------------------------------------------------------------------------------------------------
\a\ The useful life mileage that applies for Light HDE for GHG emission standards is 150,000 miles. See 40 CFR
  1036.108(d).

    We note that Light HDE intended for smaller vehicle classes are not 
designed with cylinder liners to facilitate rebuilding, suggesting they 
are more likely to be scrapped at the end of their operational life. 
The rebuilding report notes that seven percent of the diesel-fueled 
engines in the 2012 Class 3 vehicle population were removed from the 
vehicle to be rebuilt, but does not include data on the corresponding 
number of engines or vehicles scrapped in that year. We assume the 
mileage at which an engine has deteriorated enough to consider 
rebuilding would be similar to the mileage of an engine eligible for 
scrappage and both similarly represent the operational life of an 
engine for the purpose of this analysis.
ii. Spark-Ignition Engine Service Life Data
    The useful life mileage that applies for GHG emission standards for 
Spark-ignition HDE is 150,000 miles, which is longer than the current 
useful life of 110,000 miles for criteria pollutant emission standards 
for those same engines.\436\ For our proposed Option 1 updates to the 
useful life for Spark-ignition HDE criteria pollutant emission 
standards, we considered available data to represent the operational 
life of recent heavy-duty SI engines. A review of market literature for 
heavy-duty gasoline engines showed that at least one line of engine-
certified products is advertised with a service life of 200,000 
miles.\437\ Compliance data for MY 2019 indicate that the advertised 
engine model represents 20 percent of the Spark-ignition HDE certified 
for MY 2019. Additionally, CARB's HD Omnibus rulemaking cited heavy-
duty Otto-cycle engines (i.e., Spark-ignition HDE) for vehicles above 
14,000 lb GVWR that were replaced during calendar years 2012 through 
2018 as reaching more than 217,000 miles on
---------------------------------------------------------------------------

    \436\ See 40 CFR 1036.108(d) for the GHG useful life, and the 
definition of ``useful life'' in 40 CFR 86.004-2 for the criteria 
pollutant useful life.
    \437\ See, e.g., Isuzu Truck web page. ``Isuzu Commercial 
Vehicles: N-Series Gas Trucks.'' Available online: www.isuzucv.com/en/nseries/nseries_gas. Accessed February 28, 2020.

---------------------------------------------------------------------------

[[Page 17499]]

average.\438\ The mileages in these two examples are almost double the 
current useful life for Spark-ignition HDE, indicating many miles of 
operation beyond the current useful life.
---------------------------------------------------------------------------

    \438\ California Air Resources Board/MacKay & Company, ``CARB 
Summary Report on the Analysis of the MacKay & Company Data on 
Heavy-Duty Engine Rebuilds and Replacements'', March 2019.
---------------------------------------------------------------------------

iii. CARB HD Omnibus Useful Life Values
    The CARB HD Omnibus rulemaking, finalized in August 2020, lengthens 
useful life for heavy-duty CI and SI engines in two steps.\439\ As part 
of their rule, CARB analyzed recent MacKay & Company survey data from 
calendar years 2012 through 2018 and reported rebuild mileages for CI 
engine categories that were similar to those described in the Section 
IV.A.2.i. CARB also included average replacement mileage information 
for heavy-duty Otto-cycle (HD SI) engines.\440\ The CARB/MacKay & 
Company data is summarized in Table IV-3.
---------------------------------------------------------------------------

    \439\ California Air Resources Board. Heavy-Duty Omnibus 
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \440\ California Air Resources Board/MacKay & Company, ``CARB 
Summary Report on the Analysis of the MacKay & Company Data on 
Heavy-Duty Engine Rebuilds and Replacements'', March 2019.

     Table IV-3--Summary of CARB/MacKay & Company Engine Rebuild and
         Replacement Mileages for the HD Omnibus Regulation \a\
------------------------------------------------------------------------
                                                        Average  mileage
                     Engine class                        at  rebuild or
                                                           replacement
------------------------------------------------------------------------
HD Otto (Spark-ignition HDE) (All Vehicle Classes                217,283
 above 14,000 lb GVWR)................................
LHDD (Light HDE) (Vehicle Classes 4-5)................           326,444
MHDD (Medium HDE) (Vehicle Classes 6-7)...............           432,652
HHDD (Heavy HDE) (Vehicle Class 8)....................           854,616
------------------------------------------------------------------------
\a\ CARB's naming conventions for HD engines differ from the those in
  this proposal; corresponding EPA names are noted in parentheses

    Although the CARB HD Omnibus program begins in MY 2024, the program 
maintains the current useful life values through MY 2026. Table IV-4 
summarizes the useful life values finalized in the HD Omnibus rule for 
heavy-duty Otto-cycle engines (HDO), and light heavy-duty diesel 
(LHDD), medium heavy-duty diesel (MHDD), and heavy heavy-duty diesel 
(HHDD) engines.

          Table IV-4--CARB Useful Life Mileages for Heavy-Duty Engines in the HD Omnibus Rulemaking \a\
----------------------------------------------------------------------------------------------------------------
                                     HDO  (spark-                                              HHDD  (heavy HDE)
           Model year                ignition HDE)     LHDD  (light HDE)  MHDD  (medium HDE)          \b\
----------------------------------------------------------------------------------------------------------------
2024-2026.......................  110,000 miles.....  110,000 miles.....  185,000 miles.....  435,000 miles.
                                  10 years..........  10 years..........  10 years..........  10 years.
                                                                                              22,000 hours.
2027-2030.......................  155,000 miles.....  190,000 miles.....  270,000 miles.....  600,000 miles.
                                  12 years..........  12 years..........  11 years..........  11 years.
                                                                                              30,000 hours.
2031 and later..................  200,000 miles.....  270,000 miles.....  350,000 miles.....  800,000 miles.
                                  15 years..........  15 years..........  12 years..........  12 years.
                                                                                              40,000 hours.
----------------------------------------------------------------------------------------------------------------
\a\ CARB's naming conventions for HD engines differ from the those in this proposal; corresponding EPA names are
  noted in parentheses.
\b\ CARB adopted an intermediate useful life mileage of 435,000 miles for MY 2027 and later HHDD engines. See
  Section III.B for a discussion of the standards at the intermediate and full useful life mileages.

    As seen in the table, CARB's Omnibus increases useful life first in 
MY 2027 with a second step in MY 2031. The final useful life mileages 
in the CARB regulation are the result of stakeholder engagement 
throughout the development of CARB's HD Omnibus rulemaking. In two 2019 
public workshops, CARB staff presented useful life mileage values under 
consideration that were longer than these final mileages and, in their 
September 2019 presentation, very close to the engine rebuild 
mileages.\441\ In response to feedback from stakeholders indicating 
concerns with availability of data for engines and emission controls at 
those mileages, CARB shortened their final useful life mileages for MY 
2031 and later engines from the values presented in 2019, and the MY 
2027 values were chosen to be approximately the mid-point between the 
current and final useful life mileages.\442\ Additionally, CARB 
finalized an intermediate useful life mileage for MY 2027 and later 
HHDD engines that correspond to the current useful life of 435,000 
miles. See Section III.B for a discussion of the standards at the 
intermediate and full useful life mileages. Consistent with current 
useful life periods, CARB finalized hours values for the HHDD engine 
class based on the useful life mileage and an average vehicle speed of 
20 miles per hour.
---------------------------------------------------------------------------

    \441\ Brakora, Jessica. Memorandum to Docket: EPA-HQ-OAR-2019-
0055. CARB 2019 Public Workshop Presentations Related to Regulatory 
Useful Life and Emissions Warranty. March 19, 2021.
    \442\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons--Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. Page III-57.
---------------------------------------------------------------------------

    Similar to the useful life mileage values, CARB's useful life 
values in years were also adjusted from the values presented in their 
public workshops based on stakeholder feedback. In particular, emission 
controls

[[Page 17500]]

manufacturers recommended CARB consider replacing the 18-year useful 
life presented in their September 2019 workshop with a useful life of 
12 years for heavy-duty engines.\443\ CARB agreed that 12 years was 
reasonable for MHDD and HHDD, but adopted a 15 year useful life for HDO 
and LHDD based on the useful life in years that applies to chassis-
certified engines.
---------------------------------------------------------------------------

    \443\ Manufacturers of Emission Controls Association. 
``Preliminary Suggestions for Future Warranty and FUL 
Requirements.'' Presentation to CARB. September 5, 2019.
---------------------------------------------------------------------------

3. Proposed Regulatory Useful Life Periods
    In this section, we introduce our proposed regulatory useful life 
periods for heavy-duty highway engines as specified in the new 40 CFR 
1036.104(e). Our CI and SI engine technology demonstrations in Section 
III support our conclusion that it is feasible for manufacturers to 
meet our proposed standards for the proposed useful life periods of 
Options 1 and 2. We note that our technology demonstrations rely on an 
accelerated aging process for the catalyst-based aftertreatment systems 
and we are proposing to update our durability demonstration provisions 
to allow manufacturers to similarly accelerate the aging of their 
catalysts for certification. See Section IV.F for a description of our 
durability demonstration proposal.
    We are proposing useful life mileage and years values for all 
primary intended service classes that are based on our current estimate 
of the operational lives of the engines in those classes. The useful 
life values described in this section apply for exhaust emission 
standards for criteria pollutants, as well as evaporative and refueling 
emission standards, OBD, and requirements related to crankcase 
emissions. Proposed Option 1 includes an hours specification for the 
Heavy HDE class, which has the longest useful life mileages, to address 
vehicles that frequently operate at idle or lower speeds. The proposed 
Option 1 useful life periods generally align with those in the CARB HD 
Omnibus regulation. We request comment on our proposal, including 
whether it is appropriate to fully harmonize the federal and CARB 
regulatory useful life periods in light of the authority and 
requirements of section 202, and any concerns if EPA were to finalize 
values that are or are not aligned with CARB for a given engine class 
or range of model years.
i. Proposed Useful Life by Primary Intended Service Class
    Data indicate heavy-duty highway engines remain on the road well 
beyond the current regulatory useful life periods and compliance with 
emission standards is uncertain for a large portion of engine 
operational lives today. We are proposing to lengthen the useful life 
periods to cover a larger fraction of the operational life of these 
engines. Our proposed useful life periods for Spark-ignition HDE, Light 
HDE, Medium HDE, and Heavy HDE classes are presented in Table IV-5 and 
specified in a proposed new 40 CFR 1036.104(e).\444\ In Section III, we 
discuss the feasibility of meeting the emission standards at the useful 
life values of proposed Options 1 and 2. In Section IV.A.4, we 
introduce an alternative set of useful life periods we considered in 
addition to our proposed values as part of our feasibility analysis.
---------------------------------------------------------------------------

    \444\ We are proposing to migrate the current alternate 
standards for engines used in certain specialty vehicles from 40 CFR 
86.007-11 and 86.008-10 into 40 CFR 1036.605 without modification. 
See Section XII.B of this preamble for a discussion of these 
standards and options for which we are requesting comment.

                                                  Table IV-5--Proposed Options 1 and 2 Useful Life Periods by Primary Intended Service Classes
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Current                                    Proposed Option 1                               Proposed Option 2
                                                                 -------------------------------------------------------------------------------------------------------------------------------
                 Primary intended service class                                                            MY 2027-2030                      MY 2031+
                                                                       Miles           Years     ----------------------------------------------------------------      Miles           Years
                                                                                                       Miles           Years           Miles           Years
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spark-ignition HDE \a\..........................................         110,000              10         155,000              12         200,000              15         150,000              10
Light HDE \a\...................................................         110,000              10         190,000              12         270,000              15         250,000              10
Medium HDE......................................................         185,000              10         270,000              11         350,000              12         325,000              10
Heavy HDE \b\...................................................         435,000              10         600,000              11     \c\ 800,000              12         650,000              10
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Current useful life period for Spark-ignition HDE and Light HDE for GHG emission standards is 15 years or 150,000 miles. See 40 CFR 1036.108(d).
\b\ Proposed Option 1 includes an hours-based useful life for Heavy HDE of 32,000 operating hours for model year 2027 through 2030, and 40,000 operating hours for model year 2031 and later.
\c\ For MY 2031 and later Heavy HDE under proposed Option 1, we are proposing intermediate useful life periods of 435,000 miles, 10 years, or 22,000 hours, whichever comes first. See Section
  III for a discussion of the Option 1 standards we propose to apply for the intermediate and full useful life periods.

    We consider a comprehensive out-of-frame rebuild to represent the 
end of a heavy-duty CI engine's ``first life'' of operation. The 
proposed Option 1 useful life periods for all engine classes align with 
the final values adopted by CARB in their HD Omnibus regulation and 
cover a larger fraction of the expected operational lives of these 
engines. Consistent with previous rulemakings, we believe we could 
justify proposing useful life requirements equivalent to the 
operational life data presented in Section IV.A.2, but are proposing 
somewhat shorter (less stringent) values in proposed Option 1 
considering the effect of useful life on the feasibility of meeting the 
proposed Option 1 standards.\445\ The useful life mileages of proposed 
Option 2 generally correspond to the average mileages at which CI 
engines undergo the first in-frame rebuild as described in Section 
IV.A.2.i. At these mileages, CI engine owners could be expected to 
replace some critical components, but would be able to accrue many 
additional miles before a comprehensive rebuild. The out-of-frame 
rebuild data indicates that these engines can last well beyond the in-
frame rebuild mileages, and we are unlikely to finalize a single step 
program with useful life mileages that are lower than proposed Option 
2.\446\
---------------------------------------------------------------------------

    \445\ 61 FR 33446 (June 27, 1996).
    \446\ If our CI demonstration program is unable to achieve the 
proposed standards beyond 600,000 miles, we expect to adjust the 
numeric value of the standards to address feasibility concerns 
before lowering useful life below in-frame rebuild mileages.
---------------------------------------------------------------------------

    For SI engines that are less commonly rebuilt, engine replacement 
more appropriately marks the end of its operational life. The estimated 
operational life data presented in Section IV.A.2 indicate that heavy-
duty highway engines can operate for nearly double their current 
regulatory useful lives. As described in Section III, our SI engine 
demonstration program evaluated emission performance at an equivalent 
250,000 miles (beyond the SI HDE service life and replacement mileage 
information presented in Section IV.A.2). Emission results from

[[Page 17501]]

our demonstration program were lower than the proposed Option 1 MY 2031 
standards for all pollutants on the FTP duty cycle, and for all but CO 
on the SET duty cycle. We project the proposed Option 1 MY 2031 CO 
standard would be met by optimizing emission control calibrations. For 
Option 1, we are proposing a MY 2031 useful life of 200,000 miles 
(50,000 miles shorter than the equivalent mileage of the engine in our 
demonstration program), which we believe would ensure the proposed 
Option 1 MY 2031 standards are feasible for Spark-ignition HDE. For 
Option 1, we are proposing shorter useful life mileages along with the 
less stringent proposed Option 1 standards for MY 2027 to allow 
manufacturers appropriate time to prepare their engines to meet 
standards on the proposed new SET cycle, adopt our proposed idle 
controls, and address other proposed compliance requirements. For SI 
engines, the useful life mileage in proposed Option 2 aligns with the 
current useful life mileage that applies for these engines for GHG 
standards and represents the lowest useful life mileage we are 
currently considering for Spark-ignition HDE. Commenters supporting the 
SI engine useful life mileages for proposed Option 2 are encouraged to 
provide data, since proposed Option 2 useful life mileages currently 
apply for GHG standards and our SI engine test program has demonstrated 
most of the proposed standards are achievable well beyond the proposed 
Option 2 mileage.
    Our CI engine demonstration evaluated emissions at mileages that 
correspond to the Light HDE and Medium HDE operational life mileages 
presented, and we continue to evaluate higher mileages that would cover 
a greater portion of the operational life of Heavy HDE. The uncertainty 
of emission performance at mileages close to Heavy HDE rebuild 
mileages, coupled with the lack of aftertreatment performance 
information in the rebuild data, has led us to propose Option 1 MY 2031 
useful life mileages that cover a majority of the estimated operational 
life mileages, but less than the full rebuild mileages presented in 
Section IV.A.2. Since the EPA rebuild mileages are similar to the 
rebuild mileages in CARB's recent rebuild analysis, we are proposing CI 
HDE useful life mileages that align with CARB.
    We request comment on the proposed approach to base these mileages 
on the data presented. We request additional data to inform our 
consideration of appropriate useful life mileages, including 
rebuilding, replacement, and scrappage data, or other data that may 
represent the operational life of a heavy-duty highway engine. We also 
request comment on what portion of an engine's operational life should 
be covered by the regulatory useful life and whether it should depend 
on specific characteristics of the engine (e.g., primary intended 
service class).
    As seen in Table IV-5, our proposed Option 1 would increase the 
years-based useful life values intended to address engines that 
accumulate fewer miles annually. Our proposed increased useful life in 
years for Option 1 would also occur in two steps that align with the 
values finalized in CARB's HD Omnibus regulation.\447\ Proposed Option 
1 would increase Heavy HDE and Medium HDE useful life years to 11 years 
in MY 2027 and 12 years in MY 2031. The 12-year useful life value is 
consistent with the recommendation by MECA.\448\ Proposed Option 1 
would also increase Spark-ignition and Light HDE useful life years to 
12 years in MY 2027 and 15 years in MY 2031. A 15-year useful life 
value would be consistent with the existing useful life in years for 
these engines for GHG emission standards. We propose to maintain the 
existing years-based useful life of 10 years for all primary intended 
service classes under proposed Option 2.
---------------------------------------------------------------------------

    \447\ See Section IV.A.2.iii.
    \448\ Manufacturers of Emission Controls Association. 
``Preliminary Suggestions for Future Warranty and FUL 
Requirements''. September 5, 2019.
---------------------------------------------------------------------------

    Proposed Option 1 also includes updates to the hours-based useful 
life criteria for the Heavy HDE class to align with the proposed 
mileage steps.\449\ Historically, EPA included a unique hours 
specification for the Heavy HDE class to account for engines that 
operated frequently, but accumulated relatively few miles due to lower 
vehicle speeds.\450\ The 22,000-hour useful life value that currently 
applies for Heavy HDE corresponds to an average vehicle speed of 20 
miles per hour.
---------------------------------------------------------------------------

    \449\ Table 4 of proposed 40 CFR 1036.104(e) includes a 
statement migrated from the current definition of ``useful life'' in 
40 CFR 86.004-2 that the useful life for an individual engine is no 
shorter than 10 years or 100,000 miles, whichever occurs first, 
regardless of operating hours, as required by CAA section 202(d).
    \450\ See background in Section IV.A.1.
---------------------------------------------------------------------------

    Consistent with our original approach to defining an hour-based 
useful life value, we are proposing to update the useful life hours of 
operation value for the Heavy HDE primary intended service class based 
on a 20 mile per hour speed threshold and the proposed useful life 
mileages.\451\ For model year 2027 through 2030 Heavy HDE in Option 1, 
we propose a useful life period of 11 years, 600,000 miles, or 32,000 
hours, whichever comes first. Similarly, for model year 2031 and later 
Heavy HDE in Option 1, we propose 12 years, 800,000 miles, or 40,000 
miles, whichever comes first.
---------------------------------------------------------------------------

    \451\ This approach for the hours criterion is consistent with 
the approach adopted in our 1997 rulemaking where we last increased 
HHD engine useful life. See Section IV.A.1.
---------------------------------------------------------------------------

    We request comment on the need for a useful life hours criterion 
for Heavy HDE and whether we should include one for other primary 
intended service classes. If we were to include a useful life hours 
criterion for other or all heavy-duty highway engines, we request 
comment whether to use a speed other than 20 miles per hour for engines 
intended for lower GVWR class vehicles.
    We are proposing not to migrate paragraph (4)(iv) from the existing 
definition of ``useful life'' in 40 CFR 86.004-2 to proposed 40 CFR 
1036.104. It is our understanding that all modern ECMs contain time 
counters, so it is reasonable to assume that manufacturers can reliably 
access that information to document an engine's hours of operation and 
the requirement for an ``accurate hours meter'' is unnecessary. We 
request comment on the need to include an accurate hours meter 
requirement as part of a useful life hours criterion in part 1036.
    As introduced in Section III.A.1, we are proposing to clarify how 
hybrid engines and powertrains can certify they meet criteria pollutant 
regulations, which includes demonstrating that they meet emission 
standards throughout the regulatory useful life.\452\ We propose that 
manufacturers certifying hybrid engines and powertrains declare the 
primary intended service class of their engine family using 40 CFR 
1036.140, which is partially based on the GVWR of the vehicle in which 
the engine configuration is intended to be used. Once a primary 
intended service class is declared the engine configuration would be 
subject to the corresponding emission standards and useful life values 
from 40 CFR 1036.104(e). Our proposed approach to clarify that hybrid 
components could be part of an engine configuration provides truck 
owners and operators with consistent assurance

[[Page 17502]]

of durability based on the intended vehicle application. Our proposed 
approach is similar to the CARB Omnibus rule requirements for hybrid 
powertrains to meet useful life based on primary intended service 
class, though we are proposing flexibility for manufacturers to 
identify the appropriate service class for their engine 
configurations.\453\
---------------------------------------------------------------------------

    \452\ As outlined in Section III.A, we are proposing to clarify 
in 40 CFR 1036.101(b) that regulatory references to engines in part 
1036 generally apply to hybrid powertrains. We also propose to 
update the definition of ``engine configuration'' in 40 CFR 1036.801 
to clarify that an engine configuration would include hybrid 
components if it is certified as a hybrid engine or hybrid 
powertrain.
    \453\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons--Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. Page III-60. Available at: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/isor.pdf.
---------------------------------------------------------------------------

    Our proposal does not mean that a specific component of the 
certified configuration, such as a hybrid battery, is required to last 
the full useful life indicated by its primary intended service class. 
Manufacturers continue to have options to address the repair or 
replacement of components within the useful life, both in the 
durability demonstration for certification and in-use, as specified in 
the maintenance provisions of 40 CFR 1036.125. See Section IV.B.5 for a 
discussion of our proposals related to maintenance. We request comment 
on our proposed approach for manufacturers certifying hybrid engines 
and powertrains to declare a primary intended service class and meet 
the corresponding emission standards and useful life periods.
ii. Proposed Useful Life for Heavy-Duty Electric Vehicles
    As discussed in Section III.A, we are proposing clarifications and 
updates to our regulations for heavy-duty electric vehicles, including 
battery electric vehicles (BEVs) and fuel cell electric vehicles 
(FCEVs). Our proposal clarifies how the proposed useful life provisions 
for criteria pollutant emission standards would apply to each of these 
types of electric vehicles. Immediately below, we discuss the specifics 
and rationale of our proposed approach to useful life periods for BEVs 
and FCEVs. Additional information on our proposal and requests for 
comment are included in the following subsections: IV.B.1.iv.b (BEV and 
FCEV warranty requirements), IV.B.3.iii (request for comment on 
maintenance and operational information to improve electric vehicle 
serviceability), and IV.I (compliance options for generating 
NOX emission credits from electric vehicles).
    As noted in Section III.A and discussed in Section IV.I, we are 
proposing a change from our current approach under 40 CFR 86.016-
1(d)(4) that would allow manufacturers to generate NOX 
emission credits from BEVs and FCEVs starting in MY 2024, as specified 
in the proposed 40 CFR 1037.616, if they conduct testing and meet 
durability requirements in the proposed 40 CFR 1037.102(b).\454\ We 
propose that manufacturers who choose to generate NOX 
emission credits from BEVs or FCEVs would certify to the emission 
standards and useful life values of an engine-based primary intended 
service class, as specified in proposed 40 CFR 1037.102(b). Proposed 40 
CFR 1037.102(b) specifies that for MYs 2024 through 2026, manufacturers 
choosing to generate NOX emission credits from BEVs or FCEVs 
would apply the useful life periods in current 40 CFR 86.001-2; 
starting in MY 2027 manufacturers would apply the useful life periods 
in proposed 40 CFR 1036.104. We also propose that starting in MY 2027, 
manufacturers who choose not to generate NOX emission 
credits from BEVs or FCEVs could alternatively choose to certify to a 
shorter useful life period that is the same as those for GHG emissions 
standards for the appropriate service class in the current 40 CFR 
1037.105(e).\455\
---------------------------------------------------------------------------

    \454\ See Section III.A.1 for discussion on the current approach 
under 40 CFR part 86 for BEV and FCEV certification requirements. 
Briefly, no testing is required and neither BEVs nor FCEVs may 
generate NOX or PM emission credits.
    \455\ We are not proposing any changes to the current useful 
life periods for GHG emissions. As specified in the current 40 CFR 
1037.150(f), all BEV and FCEV manufacturers would continue to use 
good engineering judgment to apply useful life requirements for GHG 
standards.
---------------------------------------------------------------------------

    Manufacturers who choose not to generate NOX emission 
credits from BEVs or FCEVs may choose to attest that their vehicle 
complies with the standards in proposed 40 CFR 1037.102 instead of 
submitting test data for MY 2027 and later, as specified in the 
proposed 40 CFR 1037.205(q)(1).\456\ Manufacturers who choose to 
generate NOX emission credits from BEVs or FCEVs as early as 
MY 2024 may also attest that their BEV or FCEV meets the durability 
requirements described in proposed 40 CFR 1037.102(b)(3) based on an 
engineering analysis of measured values and other information, 
consistent with good engineering judgment, instead of testing at the 
end of the useful life; however they would also be required to submit 
additional information as specified in the proposed 40 CFR 
1037.205(q)(2) and discussed in Section IV.I.
---------------------------------------------------------------------------

    \456\ Prior to MY 2027, manufacturers who chose not to generate 
NOX emission credits would apply the useful life periods 
specified in the current 40 CFR 86.001-2; however, EPA would 
continue the current approach of deeming these vehicles to have zero 
emissions and allow manufacturers to apply good engineering judgment 
to comply with requirements of the current 40 CFR 86 subpart A.
---------------------------------------------------------------------------

    The purpose of requiring BEV and FCEV manufacturers who choose to 
generate NOX emission credits to meet durability 
requirements is to ensure that manufacturers design the BEV and FCEV 
products to be at least as durable as the engine products that would 
rely on the NOX emission credits to comply with applicable 
NOX standards. Since manufacturers would be able to use 
NOX emissions credits from BEVs or FCEVs to produce other 
engines with NOX emissions above the proposed standards for 
MYs 2027 and later, we believe it is imperative that these technologies 
provide zero-tailpipe emission performance throughout the useful life 
period to which they certify and for which they generate NOX 
emission credits.\457\ This approach would help to ensure that these 
zero-tailpipe emission technologies can operate for the same periods as 
the engine products that rely on the NOX emission credits. 
We also note that data from transit buses show BEVs are capable of 
operating more than 10 million miles and over 30 years of normal 
service in a typical transit bus duty-cycle.458 459 460 
Similarly, the DOE has set heavy-duty FCEV durability target at 1 
million miles by 2030.\461\ Both the transit bus data and DOE target 
support BEV and FCEVs technologies being capable of meeting the useful 
life requirements of proposed Options 1 and 2 for CI engines in the 
2027 and beyond timeframe. Nevertheless, we recognize that BEV and FCEV 
technologies, and the batteries and fuel cells that power them, are 
still developing; thus, we propose to allow BEV and FCEV manufacturers 
not participating in the

[[Page 17503]]

NOX engine ABT program to certify to criteria pollutant 
useful life requirements that are equivalent to the current 
requirements for certifying to the GHG emission standards.\462\
---------------------------------------------------------------------------

    \457\ See Section IV.G for discussion on proposed restrictions 
that would limit emissions above the proposed standards when using 
NOX emission credits.
    \458\ (BYD, 2019) ``BYD Receives Largest Battery-Electric Bus 
Order in U.S. History,'' BYD Motors, November 13, 2019, accessed 
February 10, 2022. https://en.byd.com/news/byd-receives-largest-
battery-electric-bus-order-in-u-s-history/
#:~:text=BYD%20(Build%20Your%20Dreams)%20announced,date%20in%20the%20
United%20States.
    \459\ (Mass Transit, 2015) ``BYD Announces 12 year Battery 
Warranty,'' Mass Transit Magazine, March 26, 2015, accessed August 
3, 2021. https://www.masstransitmag.com/home/press-release/12058920/byd-motors-llcbyd-announces-12-year-battery-warranty.
    \460\ (Metro, 2019) ``Idaho's YRT to add Proterra battery-
electric buses, charging infrastructure,'' Metro Magazine, October 
25, 2019, accessed August 3, 2021. https://www.metro-magazine.com/zero-emissions/news/736104/idaho-s-yrt-toproterra-battery-electric-buses-charging-infrastructure.
    \461\ DOE. 2020. FC135: FC-PAD: Fuel Cell Performance and 
Durability Consortium; https://www.hydrogen.energy.gov/pdfs/review20/fc135_borup_weber_2020_o.pdf.
    \462\ 40 CFR 1037, subpart B.
---------------------------------------------------------------------------

    We request comment on our proposal to align BEV and FCEV useful 
life periods with those for an engine-based service class for 
manufacturers who choose to generate NOX emission credits. 
We further request comment on allowing manufacturers who choose not to 
generate NOX emission credits from BEVs or FCEVs to certify 
to criteria pollutant useful life periods that are equivalent to the 
current useful life periods for the GHG emission standards. We are also 
interested in other approaches identified or recommended by commenters. 
Commenters are encouraged to provide data on current BEV and FCEV 
durability, as well as any additional information EPA should consider 
when setting useful life periods and related requirements for BEVs and 
FCEVs in the final rulemaking.
iii. Proposed Useful Life for Incomplete Vehicle Refueling Emission 
Standards
    As described in Section III.E., proposed Options 1 and 2 include 
refueling standards for incomplete vehicles above 14,000 lb GVWR. 
Manufacturers would meet the proposed refueling emission standards by 
installing onboard refueling vapor recovery (ORVR) systems. ORVR 
systems are based on the same carbon canister technology that 
manufacturers currently use to control evaporative emissions on these 
incomplete vehicles. Since both the evaporative and refueling emission 
control systems are part of the same fuel system, and due to the 
similarity of many of the components, we propose to align the useful 
life periods for the two systems (see our proposed updates to 40 CFR 
1037.103(f)). Specifically, proposed Options 1 and 2 include a useful 
life of 15 years or 150,000 miles, whichever comes first, for refueling 
standards for incomplete vehicles above 14,000 lb GVWR.
    Evaporative emission control systems are currently part of the fuel 
system of incomplete vehicles, and manufacturers are meeting applicable 
standards and useful life requirements for these systems today. ORVR is 
a mature technology that has been installed on complete vehicles for 
many years, and incomplete vehicle manufacturers have experience with 
ORVR systems through their complete vehicle applications. Considering 
the manufacturers' experience with evaporative emission standards for 
incomplete vehicles, and their familiarity with ORVR systems, we 
believe it would be feasible for manufacturers to apply the same 
evaporative emission standard useful life periods to our proposed 
refueling standards.
    We request comment on our proposal to align the useful life for 
refueling standards with the existing useful life periods for 
evaporative emission standards and whether we should instead consider 
aligning with the broader useful life periods proposed for Spark-
ignition HDE (e.g., the proposed Option 1 useful life periods of 12 
years/155,000 miles for MY 2027 through 2030 and 15 years/200,000 miles 
for MY 2031 and later), or whether we should take another approach. We 
also request comment on the need for a transitional useful life step 
for refueling standards for MY 2027 through 2030, including concerns 
with component durability or testing that would require additional lead 
time to address. Commenters are encouraged to include ORVR system data 
at their recommended useful life values. Finally, we request comment on 
any concerns about having different useful life values for refueling 
standards compared to the useful life values for either evaporative 
emission standards or Spark-ignition HDE standards.
4. Potential Alternative Useful Life Mileages
    We considered an alternative set of useful life mileages 
(Alternative), which would each apply in a single step beginning in MY 
2027. Table IV-6 presents a comparison of the current useful life 
mileages and the useful life mileages of the proposed Options and 
Alternative.

                            Table IV-6--Comparison of Useful Life Mileages Considered
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1
 Primary intended service class       Current    --------------------------------    Proposed       Alternative
                                                   MY 2027-2030      MY 2031+        Option 2
----------------------------------------------------------------------------------------------------------------
Spark-ignition HDE..............         110,000         155,000         200,000         150,000         250,000
Light HDE.......................         110,000         190,000         270,000         250,000         350,000
Medium HDE......................         185,000         270,000         350,000         325,000         450,000
Heavy HDE.......................         435,000         600,000         800,000         650,000         850,000
----------------------------------------------------------------------------------------------------------------

    The useful life mileages that we considered in the Alternative are 
longer than the proposed Option 1 MY 2031 useful life mileages. The 
useful life mileages of this alternative match those presented in 
CARB's September 2019 Public Workshop for their Heavy-Duty Low 
NOX program as early CARB staff-level thinking; these draft 
mileages were then lowered in the 2020 Omnibus program approved by CARB 
governing board.\463\ While the CI engine mileages for the Alternative 
are closer to the average mileage at which most CI engines undergo an 
out-of-frame rebuild, currently available data indicate that the 
Alternative standards presented in Section III would be very 
challenging to meet at those useful life mileages for Light HDEs and 
Medium HDEs, and thus data suggest that it may be appropriate for EPA 
to consider providing manufacturers with additional lead time, beyond 
the MY 2027 implementation date of the Alternative. For Heavy HDEs, our 
extrapolation of the data from 435,000 miles through the 850,000 mile 
useful life of the Alternative suggests that the numeric level of the 
NOX emission control in the Alternative could not be 
maintained through the Alternative useful life period (see Section III 
for details).
---------------------------------------------------------------------------

    \463\ Brakora, Jessica. Memorandum to Docket: EPA-HQ-OAR-2019-
0055. CARB 2019 Public Workshop Presentations Related to Regulatory 
Useful Life and Emissions Warranty. March 19, 2021.
---------------------------------------------------------------------------

    The SI mileage for the Alternative represents the equivalent 
mileage of the bench-aged three-way catalyst used in the SI technology 
demonstration for this rulemaking, but currently available data suggest 
it would be very challenging to achieve the standards of this 
alternative for all pollutants in the MY 2027

[[Page 17504]]

timeframe. For both CI and SI engines, we would need additional data to 
be able to conclude that the standards combined with the useful 
mileages included in the Alternative are feasible in the MY 2027 
timeframe, and thereby consider finalizing these useful life mileages 
in this rule. We did not evaluate alternative useful life mileages for 
HD SI refueling standards. As noted in Section IV.A.3.iii, we would 
consider transitional useful life mileages for our refueling standards 
in the early years of the program or longer useful life mileages that 
align with those for the final Spark-ignition HDE class if we receive 
comment and data supporting alignment.
    Our analyses of the emission impacts of the Alternative standards 
and Alternative useful life mileage values are presented in Section VI. 
We do not present an analysis of the costs of the Alternative since we 
currently do not have information to conclude that the Alternative 
standards are feasible in the MY 2027 timeframe with the emission 
control technologies we have evaluated to date. We are also considering 
other approaches that build on the relationship between useful life and 
emissions warranty periods as described in Section IV.B.1.
5. Summary of the Requests for Comment on the Useful Life Proposal
    We request comment on our proposed useful life values, including 
the appropriateness of the data on which we base our proposals, or 
other bases identified in this section or by the commenters. 
Specifically, we request comment on our approaches to base useful life 
mileages for CI engines on data on average mileage to first out-of-
frame rebuild for proposed Option 1 and average mileage to first in-
frame rebuild for proposed Option 2. We also request comment on whether 
to finalize a consistent fraction of the estimated rebuild mileage 
across the three CI service classes. For SI engines, we request comment 
on our proposed Option 1 approach to update the MY 2031 useful life 
mileage based on the advertised service life of a certified SI engine 
in the market today, which is consistent with SI engine mileage from 
recent CARB study, or the proposed Option 2 approach to update the 
criteria pollutant useful life to be closer to the useful life mileage 
that applies for GHG pollutants. As noted in this section and discussed 
in Section III, proposed Options 1 and 2 reflect the general ranges of 
mileages we are currently considering for each engine class, but we 
request comment on a different set of mileages within those ranges that 
may be appropriate. Commenters, especially if suggesting different 
useful life mileages than EPA's proposed values, are encouraged to 
support their comments by addressing feasibility and cost for their 
recommended mileage values.
    We request comment on our proposal to increase the useful life 
years and to update Heavy HDE useful life hours-based values 
proportional to the increased mileages for proposed Option 1. 
Commenters supporting useful life hours for Heavy HDE are encouraged to 
address whether EPA should apply a useful life hours criterion to other 
engine service classes and if a 20 mile per hour average speed is 
appropriate to represent ``low speed'' applications for each engine 
class. As noted in this section, proposed Option 1 is largely aligned 
with useful life periods adopted in the CARB HD Omnibus regulation. We 
request comment our proposal, including whether it is appropriate to 
fully harmonize the federal and CARB regulatory useful life periods in 
light of the authority and requirements of section 202, and any 
concerns if EPA were to finalize aspects of useful life that are or are 
not aligned with CARB for a given engine class or range of model years.

B. Ensuring Long-Term In-Use Emissions Performance

    In the ANPR, we introduced several ideas for an enhanced, 
comprehensive strategy to ensure in-use emissions performance over more 
of an engine's operational life, based on five areas:
     Warranties that cover an appropriate fraction of engine 
operational life.
     Improved, more tamper-resistant electronic controls.
     Serviceability improvements for vehicles and engines.
     Education and potential incentives.
     Engine rebuilding practices that ensure emission controls 
are functional.
     This section discusses proposed provisions for emissions 
warranty, ECM security, and serviceability. Taken together, they are 
intended to increase the likelihood that engine emission controls will 
be maintained properly through more of the service life of heavy-duty 
engines and vehicles, including beyond useful life. Our proposal also 
expands on this suite of measures to include updated maintenance 
provisions, which are described in Section IV.B.5. We are not including 
specific proposals related to education and incentives, but request 
comment on options we could consider in the future. As noted in Section 
IV.B.4, we are also not proposing new or modified rebuilding provisions 
in this rule. However, we intend to continue to monitor rebuilding 
practices and may update our rebuilding regulatory provisions in a 
future rulemaking.
1. Emission-Related Warranty Periods
    EPA is proposing to lengthen the regulatory emission-related 
warranty periods for all primary intended service classes to cover a 
larger portion of the operational lives of new heavy-duty engines. In 
this section we summarize the history of emissions warranty, introduce 
our principles for lengthening the warranty periods, and present our 
proposed values and alternatives considered.
i. EPA Regulatory Emission Warranty Background
    The regulatory emission warranty period is the period over which 
CAA section 207 requires an engine manufacturer to warrant to a 
purchaser that the engine is designed, built, and equipped so as to 
conform with applicable regulations under CAA section 202 and is free 
from defects in materials or workmanship which would cause the engine 
not to conform with applicable regulations for the warranty period. If 
an emission-related component fails during the regulatory emission 
warranty period, the manufacturer is required to pay for the cost of 
repair or replacement. A manufacturer's general emissions warranty 
responsibilities are currently set out in 40 CFR 1068.115. Note that 
while an emission warranty provides protection to the owner against 
emission-related repair costs during the warranty period, the owner is 
responsible for properly maintaining the engine (40 CFR 1068.110(e)), 
and the manufacturer may deny warranty claims for failures that have 
been caused by the owner's or operator's improper maintenance or use 
(40 CFR 1068.115(a)).
    Regulatory warranty provisions were first included in the 1970 
amendments to the Clean Air Act, as a new section 207(a) (``the 
manufacturer of each new motor vehicle and new motor vehicle engine 
shall warrant to the ultimate purchaser and each subsequent purchaser 
that such vehicle or engine is (1) designed, built, and equipped so as 
to conform at the time of sale with applicable regulations under 
section 202, and (2) free from defects in materials and workmanship 
which cause such vehicle or engine to fail to conform with applicable 
regulations for

[[Page 17505]]

its useful life . . .'').\464\ Those amendments also instructed the 
Administrator in section 202(b) to ``prescribe regulations which shall 
require manufacturers to warrant the emission control device or system 
of each new motor vehicle or new motor vehicle engine to which a 
regulation under section 202 applies . . .'' emphasis added). The 1977 
CAA amendments modified the section 207(b) requirements, specifying 
that ``for the period after twenty-four months or twenty-four thousand 
miles (whichever first occurs) the term 'emission control device or 
system' means a catalytic converter, thermal reactor, or other 
component installed on or in a vehicle for the sole or primary purpose 
of reducing vehicle emissions.'' \465\ EPA's first heavy-duty truck 
regulations, promulgated in 1983, set a specific warranty period of 5 
years or 50,000 miles, whichever occurred first, for light-duty trucks, 
gasoline heavy-duty engines, and light heavy-duty diesel engines, and 5 
years or 100,000 miles, whichever occurred first, for all other heavy-
duty diesel engines.\466\ These emission warranty periods were carried 
over in each subsequent revision of the emission control program (see 
40 CFR 86.084-2, 86.085-2, 86.90-2, 86.94-2, 86.096-2, 86.004-2) and 
persist to this day, even as the engine useful life periods were 
increased.\467\ Today, there is a considerable difference between 
useful life and emission warranty periods, as illustrated in Table IV-
7. The proposed changes to the useful life periods described in Section 
IV.A would increase this difference in the absence of an accompanying 
change to emissions warranty periods.
---------------------------------------------------------------------------

    \464\ Public Law 91-604, December 31, 1970.
    \465\ Public Law 95-95, August 7, 1977.
    \466\ 48 FR 52170, November 16, 1983.
    \467\ These same warranty periods apply in our GHG emission 
reduction programs. 76 FR 57106, September 15, 2011 and 81 FR 73672, 
October 25, 2016; see 40 CFR 1037.102(b).

             Table IV-7--Comparison of Current Emissions Warranty and Regulatory Useful Life Periods
----------------------------------------------------------------------------------------------------------------
                                                        Emissions warranty                Useful life \a\
                  Engine class                   ---------------------------------------------------------------
                                                       Miles           Years           Miles           Years
----------------------------------------------------------------------------------------------------------------
Spark-ignition HDE..............................          50,000               5         110,000              10
Light HDE.......................................          50,000               5         110,000              10
Medium HDE......................................         100,000               5         185,000              10
Heavy HDE.......................................         100,000               5         435,000              10
----------------------------------------------------------------------------------------------------------------
\a\ The useful life periods that apply for Spark-ignition HDE and Light HDE for GHG emission standards are
  150,000 miles and 15 years. See 40 CFR 1036.108(d).

    Today, the warranty mileage for Spark-ignition HDE, Light HDE, and 
Medium HDE covers about half of the corresponding useful life for those 
engines; the warranty mileage for Heavy HDE covers about a quarter of 
useful life. The proposal to lengthen engine useful life means that the 
warranty period would cover a smaller portion of useful life unless the 
warranty period is also increased. In the following section, we 
describe ways in which emission warranty periods can impact long-term 
emission performance, which we believe justifies proposing emissions 
warranties that cover more of the operational life of the engine.
ii. Lengthening the Regulatory Emission Warranty Period To Improve 
Long-Term Emission Performance
    As illustrated in Table IV-7, EPA's current emissions-related 
warranty periods range from 22 percent to 54 percent of regulatory 
useful life; the warranty periods have not changed since 1983 even as 
the useful life periods were lengthened.\468\ As EPA is proposing to 
lengthen the useful life periods in this rulemaking, we are also 
proposing to lengthen the emission warranty periods and increase the 
portion of useful life miles covered under warranty. These proposed 
revised warranty periods are expected to result in better engine 
maintenance and less tampering, helping to maintain the benefits of the 
emission controls. In addition, longer regulatory warranty periods may 
lead engine manufacturers to simplify repair processes and make them 
more aware of system defects that need to be tracked and reported to 
EPA.
---------------------------------------------------------------------------

    \468\ The useful life for heavy heavy-duty engines was increased 
from 290,000 miles to 435,000 miles for 2004 and later model years 
(62 FR 54694, October 21, 1997).
---------------------------------------------------------------------------

    Longer regulatory warranty periods that are more consistent with 
EPA's useful life periods are expected to lead owners to better 
maintain their engines and vehicles over a longer period of time so as 
to not void their emission warranty coverage. This is because existing 
warranty provisions specify that owners are responsible for properly 
maintaining their engines (40 CFR 1068.110(e)), and manufacturers may 
deny warranty claims for failures that have been caused by the owner's 
or operator's improper maintenance or use (40 CFR 1068.115(a)).\469\ A 
longer warranty period is expected to lead to better engine emission 
performance overall due to less mal-maintenance (see Chapter 5 of the 
draft RIA for a discussion of mal-maintenance effects in our emission 
inventory estimates). Similarly, longer regulatory emission warranty 
periods are expected to reduce the likelihood of tampering, which would 
also result in better engine emission performance (see Chapter 5 of the 
draft RIA for a discussion of tampering effects in our emission 
inventory estimates). Since emission-related repairs would be covered 
for a longer period of time, the owner will be more likely to have 
systems repaired and, consequently, may be less likely to tamper to 
avoid the cost of a repair that is no longer covered by a warranty. 
Owners may also be less likely to install defeat devices that are 
marketed to boost engine performance since installing such a device 
would void the engine warranty.
---------------------------------------------------------------------------

    \469\ See our proposal in Section IV.B.5 to update our allowable 
maintenance provisions.
---------------------------------------------------------------------------

    Emission-related repair processes may get more attention from 
manufacturers if they are responsible for repairs over a longer period 
of time. As manufacturers try to remain competitive, longer emission 
warranty periods may lead manufacturers to simplify repair processes 
and provide better training to technicians in an effort to reduce their 
warranty repair costs. Simplifying repair processes could include 
modifying emission control components in terms of how systems are 
serviced and how components are replaced. The current, relatively short 
warranty period provides little incentive for manufacturers to specify 
repairs be made at the lowest possible level of complexity, since the 
owner pays for the

[[Page 17506]]

repairs after the warranty period ends. One way to reduce warranty 
repair costs may be to design modular sub-assemblies that could be 
replaced individually, resulting in a quicker, less expensive repair. 
For example, if a DEF level sensor fails, repair practices may call for 
the DEF sensor assembly to be replaced in its entirety (including level 
sensor, quality sensor, lines, and even heaters) instead of only the 
faulty part. Improved technician training may also reduce warranty 
repair costs by improving identification and diagnosing component 
failures more quickly and accurately, thus avoiding repeated failures 
or misdiagnoses of failures and higher costs from repeat repair events 
at service facilities. These improvements may also encourage owners to 
have repairs made because down time is reduced.
    Finally, longer regulatory emission warranty periods would increase 
the period over which the engine manufacturer would be made aware of 
emission-related defects. Manufacturers are currently required to track 
and report defects to the Agency under the defect reporting provisions 
of 40 CFR part 1068. Under 40 CFR 1068.501(b), manufacturers 
investigate possible defects whenever a warranty claim is submitted for 
a component. Therefore, manufacturers can easily monitor defect 
information from dealers and repair shops who are performing those 
warranty repair services, but after the warranty period ends, the 
manufacturer would not necessarily know about these events, since 
repair facilities are less likely to be in contact with the 
manufacturers and they are less likely to use OEM parts. A longer 
warranty period would allow manufacturers to have access to better 
defect information over a period of time more consistent with engine 
useful life.
    The impact of a longer emissions warranty period may be slightly 
different for SI engines. Spark-ignition engine systems rely on mature 
technologies, including evaporative emission systems and three-way 
catalyst-based emission controls, that have been consistently reliable 
for light-duty and heavy-duty vehicle owners.\470\ We expect lengthened 
emission warranty periods to help enhance long-term in-use emissions 
performance of SI engines over time by reducing mal-maintenance and 
tampering. Similar to CI engine owners, we believe a longer warranty 
period would encourage owners of vehicles powered by SI engines to 
follow manufacturer-prescribed maintenance procedures for a longer 
period of time, as failure to do so would void the warranty. From a 
tampering perspective, SI engine owners may not be motivated to tamper 
with their catalyst systems to avoid repairs, but they may be less 
inclined to purchase defeat devices intended to disable emission 
controls to boost the performance of SI engines since installing such a 
device would void the engine warranty.
---------------------------------------------------------------------------

    \470\ The last U.S. EPA enforcement action against a 
manufacturer for three-way catalysts was settled with 
DaimlerChrylser Corporation Settlement on December 21, 2005. 
Available online: https://www.epa.gov/enforcement/daimlerchrysler-corporation-settlement.
---------------------------------------------------------------------------

    EPA seeks comment on all aspects of our proposal to lengthen 
emissions warranty periods for all primary intended service classes. We 
encourage stakeholders to submit any available data on emission control 
system repairs during and after heavy-duty engine emission warranty 
periods, including frequency of incidents, costs of repairs, and 
associated downtime.
iii. CARB's Recent Heavy-Duty Engine Emissions Warranty Updates
    CARB recently finalized two regulatory programs to update emissions 
warranty periods for heavy-duty engines as summarized in this section. 
We considered the warranty updates adopted by CARB when developing the 
proposed warranty periods for this rulemaking.
    CARB's ``Step 1'' warranty program for heavy-duty engines sold in 
California was finalized in 2019 and applied to MY 2022 heavy-duty 
diesel engines.\471\ CARB increased the warranty mileage values for 
heavy-duty diesel engines, but did not update the years-based warranty 
periods during the Step 1 update. The Step 1 program also formally 
linked warranty requirements to the HD OBD system by specifying that 
failures that cause the vehicle's OBD MIL to illuminate are considered 
warrantable conditions. CARB justified this linkage as helping to 
ensure that repairs of malfunctioning emission-related parts would be 
performed in a timelier manner during the lengthened warranty periods.
---------------------------------------------------------------------------

    \471\ California Air Resources Board, ``HD Warranty 2018''. 
Effective date: October 1, 2019. Available online: https://ww2.arb.ca.gov/rulemaking/2018/hd-warranty-2018.
---------------------------------------------------------------------------

    CARB included a second step of warranty updates in their HD Omnibus 
rulemaking that was approved by the Board in 2020.\472\ In the Omnibus 
regulation, CARB lengthened the warranty periods for MY 2027 through MY 
2030 and further lengthened the warranty periods for MY 2031 and later 
heavy-duty diesel engines. The Omnibus regulation also lengthened 
warranty periods for heavy-duty Otto cycle engines, and similarly 
linked HD OBD MIL triggers to warrantable conditions, for the same 
model years. The Omnibus also requires hybrid configurations to meet 
the same warranty periods as the diesel or Otto cycle engine service 
class to which they are certified. In addition, the Omnibus included 
warranty periods for BEVs and FCEVs of 3 years or 50,000 miles. The 
warranty periods adopted in the Omnibus included updated years- and 
hours-based warranty periods. The hours-based values were generally 
based on a 20 miles per hour vehicle speed and the warranty mileage for 
each engine class. Table IV-8 summarizes the emissions warranty periods 
from CARB's recent updates.
---------------------------------------------------------------------------

    \472\ California Air Resources Board, ``Heavy-Duty Omnibus 
Regulation''. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.

                         Table IV-8--Summary of CARB's Emission-Related Warranty Periods
----------------------------------------------------------------------------------------------------------------
                                                       Step 1 (MY 2022-     HD Omnibus (MY      HD Omnibus (MY
      CARB engine class \a\           Pre-MY 2022            2026)            2027-2030)            2031+)
----------------------------------------------------------------------------------------------------------------
HD Otto (Spark-ignition HDE)....  50,000 miles......  50,000 miles......  110,000 miles.....  160,000 miles.
                                  5 years...........  5 years...........  7 years...........  10 years.
                                                                          6,000 hours.......  8,000 hours.
LHDDE (Light HDE)...............  50,000 miles......  110,000 miles.....  150,000 miles.....  210,000 miles.
                                  5 years...........  5 years...........  7 years...........  10 years.
                                                                          7,000 hours.......  10,000 hours.

[[Page 17507]]

 
MHDDE (Medium HDE)..............  100,000 miles.....  150,000 miles.....  220,000 miles.....  280,000 miles.
                                  5 years...........  5 years...........  7 years...........  10 years.
                                                                          11,000 hours......  14,000 hours.
HHDDE...........................  100,000 miles.....  350,000 miles.....  450,000 miles.....  600,000 miles.
(Heavy HDE).....................  5 years...........  5 years...........  7 years...........  10 years.
                                                                          22,000 hours......  30,000 hours.
----------------------------------------------------------------------------------------------------------------
\a\ CARB's naming conventions for HD engines differ from the those in this proposal; corresponding EPA names are
  noted in parentheses.

    CARB's warranty updates were partially motivated by evidence that 
emission-related component failures occur after the end of the current 
emission warranty periods, when manufacturers are no longer responsible 
for repair or replacement costs under the warranty provisions, but 
before the end of the engine's regulatory useful life, through which 
time engines are certified by the manufacturer to meet the emission 
standards. According to the Updated Informative Digest prepared for 
CARB's Amendments to California Emission Control System Warranty 
Regulations and Maintenance Provisions, ``CARB's test programs have 
identified numerous heavy-duty vehicles with mileages within their 
applicable regulatory useful life periods, but beyond their warranty 
period, that have NOX emission levels significantly above 
their applicable certification standards.'' \473\ These incidents may 
not be frequent enough to trigger an emission recall under California's 
program, but CARB noted concern about engine-specific emission 
equipment failures not covered by warranty. In addition, a survey of 
owners and repair shops performed for CARB with respect to downtime for 
repairs found that over half of the owners surveyed experienced 
downtime to address repairs, and more than 60 percent of those repairs 
were not covered by emission warranties.\474\
---------------------------------------------------------------------------

    \473\ California Air Resources Board. ``HD Warranty 2018 Staff 
Report: Initial Statement of Reasons'', May 2018. Available here: 
https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2018/hdwarranty18/isor.pdf. See also the ANPR comments of the California 
Air Resources Board, EPA-HQ-OAR-2019-0055-0471.
    \474\ California Air Resources Board. ``Survey and Analysis of 
Heavy-Duty Vehicle Warranties in California'', December 2017; see 
pages 6-7, Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2018/hdwarranty18/apph.pdf.
---------------------------------------------------------------------------

    The market for extended warranties suggests that some truck 
purchasers are concerned enough about out-of-warranty repairs to be 
willing to purchase additional warranty coverage, either directly from 
the manufacturers or from independent third parties. According to a 
survey conducted on behalf of CARB in support of their heavy-duty 
warranty program, approximately 40 percent of all new heavy-duty 
vehicle buyers ``purchase or receive'' an extended warranty under which 
the coverage is extended to 417,000 miles on average.475 476 
This survey data correlates with information provided to CARB by the 
Truck and Engine Manufacturers Association, which indicated that 50 
percent of new heavy-duty Class 8 vehicles are sold with a 500,000 mile 
extended warranty.\477\
---------------------------------------------------------------------------

    \475\ California Air Resources Board. ``Survey and Analysis of 
Heavy-Duty Vehicle Warranties in California'', December 2017; see 
page 17, Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2018/hdwarranty18/apph.pdf.
    \476\ Some of these extended warranties may be purchased by the 
owners; others may be added by the dealer as part of the sales 
package.
    \477\ California Air Resources Board, ``Staff Report: Initial 
Statement of Reasons'' May 2018, see page II-7. Available here: 
https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2018/hdwarranty18/isor.pdf.
---------------------------------------------------------------------------

iv. Proposed Emissions Warranty Provisions
    This section describes the proposed regulatory emissions warranty 
provisions, including the lengthened warranty periods we are proposing, 
by engine category and the components covered. Our proposed warranty 
provisions are in a new 40 CFR 1036.120. We request comment on the 
proposed warranty mileage values, as well as the corresponding age-
based criteria. Commenters also are encouraged to address whether 
warranty periods should be a consistent fraction of the final useful 
life periods and whether we should align with CARB's Omnibus program 
when considering warranty periods for the final rule.
a. Proposed Warranty Periods by Primary Intended Service Class
    We are proposing to update our emissions warranty periods for 
emission-related components designed to reduce criteria pollutant 
emissions, beginning with model year 2027 and later heavy-duty 
engines.\478\ Following our approach for the proposed useful life 
periods, we are proposing two options (proposed Options 1 and 2) and 
our proposed warranty periods vary by primary intended service class to 
reflect the difference in average operational life of each class.\479\
---------------------------------------------------------------------------

    \478\ We are proposing that components installed to control both 
greenhouse gas (i.e., CO2, N2O, and 
CH4) and criteria pollutant emissions would be subject to 
the proposed warranty periods. See proposed 40 CFR 1036.150(w) and 
Section XII.B for additional warranty considerations related to 
greenhouse gas emissions.
    \479\ All engines covered by a primary intended service class 
would be subject to the corresponding warranty period, regardless of 
fuel used.
---------------------------------------------------------------------------

    When a manufacturer's certified configuration includes hybrid 
system components (e.g., batteries, electric motors, and inverters), 
those components are considered emission-related components, which 
would be covered under the proposed warranty requirements in new 40 CFR 
1036.120.\480\ Similar to the proposed approach for useful life in 
Section IV.A, we are proposing that a manufacturer certifying a hybrid 
engine or hybrid powertrain would declare a primary intended service 
class for the engine family and apply the corresponding warranty 
periods in the proposed 40 CFR 1036.120 when certifying the engine 
configuration.\481\
---------------------------------------------------------------------------

    \480\ See our proposed new definition of ``emission-related 
component'' in 40 CFR 1036.801. Defects or failures of hybrid system 
components can result in the engine operating more, and thus 
increase emissions.
    \481\ See proposed updates to 40 CFR 1036.140 for the primary 
intended service classes that are partially based on the GVWR of the 
vehicle in which the configuration is intended to be used. See also 
the proposed update to definition of ``engine configuration'' in 40 
CFR 1036.801 to clarify that an engine configuration would include 
hybrid components if it is certified as a hybrid engine or hybrid 
powertrain.

---------------------------------------------------------------------------

[[Page 17508]]

Also similar to our proposal for useful life, our proposed approach to 
clarify that hybrid components are part of the broader engine 
configuration provides truck owners and operators with consistent 
warranty coverage based on the intended vehicle application.
    Currently, emission warranties for most HD engine classes (Spark-
ignition HDE, Light HDE, and Medium HDE) cover about half of the 
respective useful life mileages. As mentioned in Section IV.B.1.ii, we 
believe that fewer incidents of mal-maintenance and tampering occur 
during the warranty period, and thus fewer would occur overall if the 
warranty period is lengthened. Consistent with our current 
requirements, we believe it is appropriate to propose to lengthen the 
warranty mileage to continue to cover at least half of the useful life 
mileage for all engine classes.
    More specifically, we are proposing two options that generally 
represent the range of revised emission warranty periods we are 
considering adopting in the final rule. Proposed Option 1 includes 
warranty periods that are aligned with the MY 2027 and MY 2031 periods 
adopted by CARB, which are close to 80 percent of useful life.\482\ At 
this time, we assume most manufacturers would continue to certify 50-
state compliant engines in MY 2027 and later, and it would simplify the 
certification process if there is consistency between CARB and federal 
requirements. The warranty periods of proposed Option 2 would apply in 
a single step beginning in model year 2027, and would match CARB's Step 
1 warranty periods that will already be in effect beginning in model 
year 2022 for engines sold in California.\483\ The proposed Option 2 
mileages cover 40 to 55 percent of the proposed Option 1 MY 2031 useful 
life mileages and represent an appropriate lower end of the range of 
the revised regulatory emission warranty periods we are considering. 
Our proposed emissions warranty periods for heavy-duty engines are 
presented in Table IV-9.\484\ We estimated the emissions impacts of the 
proposed warranty periods in our inventory analysis, which is 
summarized in Section VI and discussed in detail in Chapter 5 of our 
draft RIA. In Section V, we estimated indirect and operating costs 
associated with the proposed warranty periods.
---------------------------------------------------------------------------

    \482\ CARB's Omnibus MY 2031 warranty mileages for the range of 
HD engine classes span 78 percent to 80 percent of the proposed 
Option 1 useful life mileages presented in Section IV.A.
    \483\ For SI engines, the proposed Option 2 warranty mileage 
matches the current useful life for those engines, consistent with 
the approach for Light HDE proposed Option 2 warranty.
    \484\ We are proposing to migrate the current alternate 
standards for engines used in certain specialty vehicles from 40 CFR 
86.007-11 and 86.008-10 into 40 CFR 1036.605 without modification. 
See Section XII.B of this preamble for a discussion of these 
standards and options for which we are requesting comment.

                                             Table IV-9--Proposed Options 1 and 2 Emissions Warranty Periods
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Current \a\                          Proposed Option 1                             Proposed Option 2 \a\
                                         ---------------------------------------------------------------------------------------------------------------
     Primary intended  service class                             MY 2027-2030 \b\                  MY 2031+ \c\
                                         ---------------------------------------------------------------------------------------------------------------
                                               Miles           Miles           Hours           Miles           Hours           Miles           Hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spark-Ignition HDE......................          50,000         110,000           6,000         160,000           8,000         110,000           5,500
Light HDE...............................          50,000         150,000           7,000         210,000          10,000         110,000           5,500
Medium HDE..............................         100,000         220,000          11,000         280,000          14,000         150,000           7,000
Heavy HDE...............................         100,000         450,000          22,000         600,000          30,000         350,000          17,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Current and proposed Option 2 warranty period is the stated miles or 5 years, or hours if applicable, whichever comes first.
\b\ The proposed Option 1 warranty period for model years 2027-2030 is the stated miles, hours, or 7 years, whichever comes first.
\c\ The proposed Option 1 warranty period for model years 2031 and later is the stated miles, hours, or 10 years, whichever comes first.

    While we believe a majority of engines would reach the warranty 
mileage in a reasonable amount of time, some applications may have very 
low annual mileage due to infrequent use or low speed operation; these 
engines may not reach the warranty mileage for many years. To ensure 
manufacturers are not indefinitely responsible for components covered 
under emissions warranty in these situations, we are proposing revised 
years-based warranty periods and new hours-based warranty periods for 
proposed Option 1 and new hours-based warranty periods for proposed 
Option 2. Consistent with current warranty provisions, the warranty 
period would be whichever warranty value (i.e., mileage, hours, or 
years) occurs first.
    For the years-based period, which would likely be reached first by 
engines with lower annual mileage due to infrequent use, proposed 
Option 1 would increase the current period from 5 years to 7 years for 
MY 2027 through 2030, and to 10 years starting with MY 2031. We are 
also proposing to add an hours-based warranty period to both proposed 
options, as shown in Table IV-9, to cover engines that operate at low 
speed and/or are frequently in idle mode. In contrast to infrequent 
use, low speed and idle operation can strain emission control 
components and we believe it is appropriate to factor that gradually-
accumulated work into a manufacturer's warranty obligations. We are 
proposing warranty hours for all primary intended service classes based 
on a 20 mile per hour average vehicle speed threshold to convert from 
the proposed mileage values.\485\ We note that applying a consistent 20 
miles per hour conversion factor to the proposed mileage periods would 
result in a variable number of years of warranty coverage across 
classes and, in some cases, fewer years than the years-based period for 
a given model year. We request comment on applying a different 
conversion speed for all classes or a unique speed to each engine class 
to calculate the hours-based periods.
---------------------------------------------------------------------------

    \485\ As noted in Section IV.A, we are proposing hours-based 
useful life values for the Heavy HDE class in proposed Option 1 
based on the same 20 mile per hour average vehicle speed conversion 
factor.
---------------------------------------------------------------------------

    Consistent with existing regulations, our proposed warranty 
provisions in new 40 CFR 1036.120(c) identify the components covered by 
emission warranty as the general emission-related components listed in 
40 CFR 1068, appendix A, and any other components a manufacturer may 
develop to control emissions. The emission-related components listed in 
Appendix A are broad categories of components and systems that affect 
emissions. We request comment on the completeness of this list and 
whether we should consider adding other or more specific components or 
systems. We also request comment on whether it is appropriate to expand 
the list of components covered

[[Page 17509]]

by emission warranty to include any component whose failure causes the 
vehicle's OBD MIL to illuminate, as adopted by CARB.\486\ While we 
agree that an OBD MIL could be used by an owner or technician to 
identify an underperforming or failed emission-related component that 
should be replaced under warranty, we currently have concerns that not 
all OBD MILs are tied directly to an emission-related component. If we 
were to finalize a link between warranty and OBD MILs, we expect the 
cost of expanding the list of warrantable components to include all 
components that may trigger an OBD MIL, regardless of their direct 
impact on emissions, would be unreasonable.
---------------------------------------------------------------------------

    \486\ California Air Resources Board. ``Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments''. June 23, 2020. Page III-52. Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/isor.pdf.
---------------------------------------------------------------------------

b. Proposed Warranty for Heavy-Duty Electric Vehicles
    Similar to the proposed approach for BEV and FCEV useful life 
periods, described in IV.A, we are proposing in 40 CFR 1037.120(b)(2) 
that BEV and FCEV manufacturers apply the warranty periods 
corresponding to an engine-based primary intended service class, as 
specified in the proposed 40 CFR 1037.120(b).487 488 The 
proposed 40 CFR 1037.120(b)(2) specifies that prior to MY 2027 
manufacturers choosing to generate NOX emission credits in 
MYs 2024 through 2026 would apply the warranty periods in the current 
40 CFR 86.001-2; starting in MY 2027 manufacturers would apply the 
warranty periods specified in the proposed 40 CFR 1036.104. 
Manufacturers choosing not to generate NOX emission credits 
with their BEVs or FCEVs could alternatively choose in MY 2027 or later 
to certify to the existing emission warranty requirements for GHGs, as 
specified in the current 40 CFR 1037.120(b)(1).\489\ As specified in 
the existing 40 CFR 1037.120(e), all manufacturers would continue to 
describe in their owners' manual the warranty provisions that apply to 
the vehicle.
---------------------------------------------------------------------------

    \487\ Manufacturers would identify a primary intended service 
class as specified in proposed 40 CFR 1037.102(b)(1).
    \488\ The warranty periods included in the Alternative would 
similarly apply to BEVs and FCEVs; see Section IV.B.1.vi for more 
discussion on the Alternative warranty periods considered for this 
proposal.
    \489\ Prior to MY 2027, manufacturers who chose not to generate 
NOX emission credits would apply the warranty periods 
specified in the current 40 CFR 86.001-2, which are equivalent to 
those specified in the current 40 CFR 1037.120(b)(1).
---------------------------------------------------------------------------

    As discussed in Section IV.A, data from BEV transit buses and DOE 
research and development work on FCEVs suggest that BEV and FCEV 
technologies will be capable of operating over mileages or time periods 
similar to CI engines in the 2027 and beyond timeframe; thus, we 
believe it is appropriate for the same criteria pollutant warranty 
requirements to apply to BEV and FCEV technologies as those specified 
for CI engines for those manufacturers who choose to generate 
NOX emission credits.
    We further recognize that repeated repair or maintenance issues 
with a BEV or FCEV could increase vehicle operating costs and lead 
owners to purchase a vehicle powered by a CI or SI engine instead, 
which would result in higher emissions than a zero-emission tailpipe 
battery or fuel cell electric vehicle. Our proposed BEV and FCEV 
warranty requirements for manufacturers who choose to generate 
NOX emission credits from BEVs or FCEVs are expected to 
decrease those operating costs in two ways. First, by encouraging 
owners to conduct vehicle maintenance that ensures continued warranty 
coverage and maintains the benefits of the zero-tailpipe emission 
performance. Second, by encouraging manufacturers to simplify repair 
processes and provide better training to technicians in an effort to 
reduce their warranty repair costs.
    As specified in the proposed 40 CFR 1037.120(c), we propose to 
clarify that batteries and fuel cells in BEVs and FCEVs, respectively, 
are considered covered components and would be subject to the proposed 
warranty requirements in 40 CFR 1037.120(b)(2) for manufacturers 
choosing to generate NOX emission credits. Our proposed 
approach for component coverage reflects that defects or failures of 
batteries or fuel cells could render the vehicle inoperable, and thus 
the vehicle would cease to provide zero tailpipe emission performance 
over the full useful life period despite having generated emission 
credits for the full useful life period. We note that our proposed 
approach is less comprehensive than the CARB Zero Emission Powertrain 
(``ZEP'') Certification approach, which defines ``warranted part'' as 
``any powertrain component'' in the case of zero-emission 
powertrains.\490\ At the end of this subsection we request comment on 
our proposed approach for component coverage relative to the CARB ZEP 
Certification approach.
---------------------------------------------------------------------------

    \490\ See Attachment C, ``Proposed, California Standards and 
Test Procedures for New 2020 and Subsequent Model Heavy-Duty Zero-
Emissions Powertrains'', p. 17 for details on warranty requirements. 
Available at: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2019/zepcert/15dayattc.pdf (last accessed August 24, 2021).
---------------------------------------------------------------------------

    In developing our proposal for the duration of the warranty period 
for BEVs and FCEVs, we considered two other options: (1) Align with 
CARB Omnibus emission warranty requirements for BEVs and FCEVs of 3 
years or 50,000 miles, or (2) align criteria pollutant warranty periods 
with the periods specified for GHG emissions in the current 40 CFR 
1037.120 for all manufacturers. The CARB Omnibus warranty requirements 
for BEVs and FCEVs match what manufacturers are already required to 
offer if they participate in the California Heavy-duty Vehicle 
Incentive Program (HVIP), and are less than industry standards for 
warranty periods based on information submitted to CARB through the 
certification process.\491\ The second option we considered, aligning 
criteria pollutant and GHG warranty periods for BEVs and FCEVs would be 
a simplistic approach, but would not recognize the use of these 
technologies to generate NOX emission credits; under the 
proposed ABT program, we would allow these NOX emission 
credits to be used to produce higher-emitting engines with longer 
warranty period requirements.\492\ As such we are proposing that only 
manufacturers who choose not to generate NOX emission 
credits with BEVs or FCEVs could choose to certify to criteria 
pollutant warranty requirements equivalent to the existing GHG emission 
warranty requirements.
---------------------------------------------------------------------------

    \491\ California Air Resources Board, Staff Report: Initial 
Statement of Reasons for Proposed Alternative Certification 
Requirements and Test Procedures for Heavy-Duty Electric and Fuel 
Cell Vehicles and Proposed Standards and Test Procedures for Zero-
Emission Powertrains (Zero-Emission Powertrain Certification 
Regulation), December 31, 2018. Available online: https://ww3.arb.ca.gov/regact/2019/zepcert/isor.pdf.
    \492\ See Section IV.G for details on the proposed ABT program, 
which includes restrictions for the extent to which engines could 
emit emissions above the proposed standards.
---------------------------------------------------------------------------

    We request comment on our proposed approach for BEV and FCEV 
warranty requirements to match those of the engine-based primary 
intended service class for manufacturers who choose to generate 
NOX emission credits from BEVs or FCEVs. Commenters are 
encouraged to provide information and data on whether such requirements 
would help to ensure the zero-emission tailpipe performance of these 
technologies, or if they would hinder the integration of these 
technologies

[[Page 17510]]

into the heavy-duty vehicle market. If commenters suggest that we 
should finalize another alternative to our proposed approach, then we 
request information and data supporting their views on how such an 
alternative would support the environmental benefits of zero-emission 
tailpipe technologies. We further request comment on our proposed 
approach that batteries and fuel cells in BEVs and FCEVs, respectively, 
are covered under warranty for manufacturers choosing to generate 
NOX emission credits. If commenters suggest that we include 
additional components in the final rule, such as the CARB ZEP 
Certification approach, we request that commenters provide a list of 
which specific components should be covered (e.g., electric motor, 
axles), along with a rationale for why those components should be 
covered under emission warranty.
c. Proposed Warranty for Incomplete Vehicle Refueling Emission 
Standards
    As noted in Section III.E, proposed Options 1 and 2 include 
refueling emission standards for Spark-ignition HDE that are certified 
as incomplete vehicles above 14,000 lb GVWR.\493\ Our proposed 
refueling standards are equivalent to the refueling standards that are 
in effect for light- and heavy-duty complete Spark-ignition HDVs. We 
project manufacturers would adapt the existing onboard refueling vapor 
recovery (ORVR) systems from those complete vehicle systems to meet our 
proposed refueling standards.
---------------------------------------------------------------------------

    \493\ See our proposed updates to 40 CFR 1037.103.
---------------------------------------------------------------------------

    As noted in Section III.E, we are not reopening or proposing to 
change evaporative emission requirements that currently apply for all 
SI engines or refueling emission standards that currently apply for 
complete vehicles. Because the onboard refueling vapor recovery systems 
necessary to meet the proposed refueling standards are expected to 
build on existing evaporative systems, proposed Options 1 and 2 would 
require that Spark-ignition HDE manufacturers provide a warranty for 
the ORVR systems of incomplete vehicles above 14,000 lb GVWR for the 
same warranty periods that currently apply for evaporative emission 
control components on these vehicles.\494\ Our proposal to apply the 
existing warranty periods for evaporative emission control systems to 
the ORVR systems is similar to our approach to the regulatory useful 
life periods associated with our proposed refueling standards discussed 
in Section IV.A.
---------------------------------------------------------------------------

    \494\ Warranty periods for refueling emissions components on 
incomplete Light HDV would be 5 years or 50,000 miles, and 5 years 
or 100,000 miles for components on incomplete Medium HDV and Heavy 
HDV. See our proposed updates to 40 CFR 1037.120.
---------------------------------------------------------------------------

v. Additional Considerations for Components Covered and Warranty Claims
    Consistent with existing regulations, our proposed warranty 
provisions in new 40 CFR 1036.120(c) identify the components covered by 
emission warranty as the general emission-related components listed in 
40 CFR 1068, appendix A, and any other components a manufacturer may 
develop to control emissions. The emission-related components listed in 
appendix A are broad categories of components and systems that affect 
emissions. We request comment on the completeness of this list and 
whether we should consider adding other systems or more specific 
components of systems.
    As mentioned in Section IV.B.1.iii, CARB recently expanded their 
list of components covered by emission warranty to include any 
component whose failure causes the vehicle's OBD MIL to illuminate to 
ensure malfunctioning components were repaired in a timely manner.\495\ 
We believe the proposed lengthened warranty periods would effectively 
encourage prompt maintenance without the need to expand the list of 
components covered beyond those specifically identified as emission-
related components. We are also including several other proposed 
updates to improve access to valuable maintenance information for 
certain emission-related components. We are proposing to require 
manufacturers to update their owner's manuals to improve serviceability 
(Section IV.B.3) and to expand the list of OBD parameters available to 
the public (Section IV.C).
---------------------------------------------------------------------------

    \495\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. Page III-52. Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/isor.pdf.
---------------------------------------------------------------------------

    As specified in the current 40 CFR 1068.115 and referenced in 
proposed 40 CFR 1036.120(d), manufacturers may deny warranty claims if 
the engine was improperly maintained or used. In proposed 40 CFR 
1036.125(h)(2), manufacturers would describe the documentation they 
require for owners to demonstrate their engines are properly 
maintained.\496\ ANPR commenters suggest that DEF quality sensor data 
alone is an incomplete indicator of an owner's commitment to 
maintaining high-quality DEF. EPA received comments describing 
incidents where DEF quality faults were triggered repeatedly despite 
flushing the system and filling the tank with new DEF, suggesting a 
fault with a system sensor.\497\ A recent online discussion indicates 
that some OEMs may be denying warranty claims on the basis of using 
poor quality DEF.\498\ While this may be justified for repeated DEF 
quality faults or extremely low urea concentrations (e.g., using 
water), DEF quality sensor readings may also indicate only slightly 
abnormal urea concentrations due to unintentionally long storage 
periods or unpredicted improper storage temperatures. In either case, 
we expect a DEF quality-triggered engine derate would induce a user to 
address the DEF quality issue before it would cause a problem 
downstream.
---------------------------------------------------------------------------

    \496\ See our discussion in Section IV.B.5.
    \497\ See the comments of the National Association of Small 
Trucking Companies (``NASTC''), EPA-HQ-OAR-2019-0055-0456.
    \498\ Wallace, Sam. ``Keep Your Diesel Exhaust Fluid From 
Voiding Your Warranty'', Mitchell1 ShopConnection, August, 2015. 
Available online: https://mitchell1.com/shopconnection/keep-your-diesel-exhaust-fluid-from-voiding-your-warranty/.
---------------------------------------------------------------------------

    We note that current 40 CFR 1068.115 allows manufacturers to deny a 
warranty claim only if they show that a component failure was due to 
improper maintenance or use by the owner or operator, by accidents for 
which the manufacturer has no responsibility, or by acts of God subject 
to certain limitations. For example, 40 CFR 1068.115(b)(3) does not 
allow a manufacturer to deny a warranty claim based on action or 
inaction by the operator unrelated to the warranty claim. In proposed 
40 CFR 1036.120(d), we propose to further clarify that, as described in 
40 CFR 1068.115, for highway heavy-duty engines a manufacturer may deny 
warranty claims if the operator caused the problem through improper 
maintenance or use. In other words, a manufacturer must use more than 
just the presence of a system fault before denying a warranty claim for 
improper maintenance and would have to show that a component failure 
was directly connected to that fault. We request comment on the 
availability of high-quality DEF and whether EPA should explicitly 
state that manufacturers cannot deny warranty claims based on the use 
of commonly available DEF, as is currently specified for fuel in 40 CFR 
1068.115(b)(6). Commenters are encouraged to suggest if a commonly 
available DEF provision should be limited to heavy-duty highway engines 
in 40 CFR 1036.120 or

[[Page 17511]]

if it should be broadly applied to all sectors covered under part 1068.
vi. Analysis of Proposed Emission Warranty Periods and Alternatives
    Consistent with our useful life discussion in Section IV.A.4, we 
considered an alternative set of warranty periods (the Alternative) 
that would apply as a single step beginning in model year 2027. The 
warranty mileages for the Alternative are longer than the proposed 
Option 1 MY 2031 useful life mileages. The Alternative mileages align 
with the warranty mileages presented in CARB's September 2019 Public 
Workshop for their Heavy-Duty Low NOX program and cover up 
to 94 percent of the useful life mileages considered for the 
Alternative.\499\ The warranty mileages of the Alternative would place 
an even greater emphasis on the importance of holding manufacturers 
responsible for emission control defects for a period of time that 
aligns more closely with the operational life of the engine. However, 
we believe it would be inappropriate to consider warranty mileages 
equal to or beyond the proposed Option 1 MY 2031 useful life mileages, 
which are the maximum useful life mileages we consider to be feasible 
given the level of emission standards evaluated in this proposal based 
on available data.
---------------------------------------------------------------------------

    \499\ Brakora, Jessica. Memorandum to Docket: EPA-HQ-OAR-2019-
0055. CARB 2019 Public Workshop Presentations Related to Regulatory 
Useful Life and Emissions Warranty. March 19, 2021.

                             Table IV-10--Comparison of Warranty Mileages Considered
----------------------------------------------------------------------------------------------------------------
                                                        Proposed  Option 1
 Primary intended service class       Current    --------------------------------    Proposed       Alternative
                                                   MY 2027-2030      MY 2031+        Option 1
----------------------------------------------------------------------------------------------------------------
Spark-Ignition HDE..............          50,000         110,000         160,000         110,000         200,000
Light HDE.......................          50,000         150,000         210,000         110,000         280,000
Medium HDE......................         100,000         220,000         280,000         150,000         360,000
Heavy HDE.......................         100,000         450,000         600,000         350,000         800,000
----------------------------------------------------------------------------------------------------------------

    The Alternative warranty mileages are equivalent to or longer than 
the useful life mileages included in the proposed Options 1 and 2. 
Since we do not believe that the emission warranty period should be 
equal to or greater than the useful life period, we focus on the 
warranty values of proposed Options 1 and 2 and the range in between 
them for this proposal. We expect that we would need additional data 
before we could project that the standards and useful life values of 
the Alternative are feasible for the MY 2027 timeframe in order to 
consider adopting them, or the Alternative warranty mileages, in the 
final rule.
    We estimated the emissions impacts of the Alternative warranty 
periods in our inventory analysis, which is summarized in Section VI 
and discussed in detail in Chapter 5 of our draft RIA. We do not 
present an analysis of the costs of the Alternative, since those 
warranty periods are out of the range of mileages we are currently 
considering without additional information to indicate that the 
standards and useful life values of the Alternative are feasible in the 
MY 2027 timeframe.
vii. Other Approaches To Ensure Long-Term In-Use Emission Performance
    Under our current and proposed warranty provisions, parts and labor 
for emission-related components are equally and fully covered over the 
entirety of the warranty period. A graduated warranty coverage 
approach, which was introduced as a topic in the ANPR to this rule and 
is described in more detail below, may provide a similar assurance of 
long-term emission performance with a smaller impact on the purchase 
price.
    Manufacturers are responsible for repairing or replacing emission-
related components that are found to be defective within the specified 
warranty period. Manufacturers include warranty repairs in the price of 
an engine or vehicle, and the Agency considers the warranty cost 
implications of all our emission control rules.\500\ In Section V, we 
provide the cost impacts of the proposed warranty periods. The impact 
that a longer warranty would have on the purchase price of an 
individual engine will vary by factors such as a manufacturer's 
estimate of the risk for an engine, their presumed competition in the 
market, and their relationship with the purchaser.
---------------------------------------------------------------------------

    \500\ A manufacturer estimates the expected costs of warranty 
repairs actuarially, and these costs are added to the purchase price 
of the engine or vehicle, spreading the predicted repair costs over 
the number of engines or vehicles sold.
---------------------------------------------------------------------------

    In the current market, purchasers desiring greater warranty 
protection can buy extended warranties, either from the engine 
manufacturers or third-party companies. The experience with extended 
warranties reveals information about the range of owner preferences 
with respect to bearing the costs of out-of-warranty repairs. Some of 
the estimated 40 percent of purchasers obtaining extended warranties 
may be large companies that purchase extended warranty coverage because 
they have comprehensive in-house service facilities and a business 
relationship with engine manufacturers that allows them to perform 
warranty repairs in-house. Other owners may be reliant on the engine 
manufacturer for warranty repairs but prefer to purchase extended 
warranties for insurance against the cost of out-of-warranty repairs, 
in essence paying for those repairs up-front. Of the 60 percent of 
purchasers that decline to purchase extended warranties, some companies 
may reduce the risk of out-of-warranty repair costs by selling their 
vehicles near the point when the warranty period ends. Others may 
prefer to pay for out-of-warranty repairs when and if they occur. Still 
others may choose to not make out-of-warranty repairs at all. It is 
clear that lengthening the warranty period would remove some of a 
purchaser's flexibility to address out-of-warranty repair costs. We 
request comment on the extent to which emissions warranty period is an 
important aspect of purchasers' business decisions, and the specific 
impacts purchasers anticipate for the range of emissions warranty 
periods we are considering in this rule. For instance, we are 
interested in how a longer regulatory emissions warranty may impact the 
timing of an engine or truck purchase, how long an engine or vehicle is 
kept, and/or how well an engine is maintained.

[[Page 17512]]

    In the ANPR, we described two different potential approaches to 
graduated warranties. Under one approach, there could be longer, 
prorated warranties that provide different levels of warranty coverage 
based on a vehicle's age or mileage. Alternatively, the warranty could 
be limited to include only certain parts during specified warranty 
periods, and/or exclude labor for some, or even all, of the duration of 
coverage. We received feedback from several stakeholders in response to 
the ANPR. Allison Transmission supported EPA considering prorated parts 
and labor as an approach to lengthening warranty periods.\501\ Volvo 
suggested that applying the longer warranty periods to only critical 
components could be a way to reduce manufacturer costs.\502\ NADA 
recommended that longer warranty periods be proposed in a manner that 
varies by class of component or system and include the approaches EPA 
presented in the ANPR such as limited component and/or prorated 
warranties.\503\
---------------------------------------------------------------------------

    \501\ See comments from Allison, Docket ID EPA-HQ-OAR-2019-0055-
0461.
    \502\ See comments from Volvo, Docket ID EPA-HQ-OAR-2019-0055-
0463.
    \503\ See comments from NADA, Docket ID EPA-HQ-OAR-2019-0055-
0369.
---------------------------------------------------------------------------

    We are not proposing and did not analyze a graduated warranty 
approach for this proposal. However, we may consider a graduated 
warranty as a viable alternative to our proposed warranty periods if we 
receive additional information that would support such an approach. A 
graduated warranty approach could extend beyond our proposed warranty 
periods in mileage, hours, and years, to cover more of the operational 
life of the engine, but it could be based on different phases of 
varying coverage. These could include, for example:
     Phase 1: Full parts and labor coverage for all emission-
related components,
     Phase 2: Parts and labor coverage for limited emission-
related components, and
     Phase 3: Parts-only coverage for limited emission-related 
components.
    We request comment on whether EPA should adopt a phased approach 
for a longer emission warranty period. Supporters of such an approach 
should comment on the number of phases, the length of each phase, and 
the components to include in the set of limited emission-related 
components under such an approach. With respect to Phase 1, which would 
be similar to a traditional warranty with full parts and labor 
coverage, EPA may consider the warranty mileages in proposed Option 2 
as the minimum lower bound. For the other phases, commenters are 
encouraged to include data to support their suggested mileage, hours, 
and years of coverage. When considering the set of limited parts to be 
covered in the other phase(s), EPA may consider including components 
that are relatively high-cost components, or components that are labor-
intensive (and thus expensive) to replace. We request data to support 
the set of limited emission-related components that should be included 
in the other phase(s), including failure rates, component costs, and 
labor costs to replace specific components. We note that our proposed 
maintenance provisions in 40 CFR 1036.125 include two categories of 
components we could consider as the set of limited emission-related 
components covered in the graduated warranty approach. As described in 
Section IV.B.5, these two categories of components include a proposed 
list of specific components with minimum maintenance intervals, and 
criteria to identify components that can only be replaced as part of 
scheduled maintenance if the manufacturer covers the cost.
    Finally, we request comment on whether a graduated warranty 
approach would achieve the goals set out in Section IV.B.1.ii: 
Providing an extended period of protection for purchasers, encouraging 
proper maintenance, discouraging tampering, and incentivizing 
manufacturers to design emission control components that are less 
costly to repair.
2. Electronic Control Module Security
    CAA section 203(a)(3)(B) and 40 CFR 1068.101(b)(2) prohibit 
selling, offering to sell, or installing any part or component whose 
principal effect is to bypass, defeat, or render inoperative a motor 
vehicle emission control device or element of design (i.e., a ``defeat 
device''), where the person knows or should know that the part is being 
offered for sale, installed for such use or put to such use. Once 
installed, defeat devices can result in significant tailpipe emissions 
increases, and with the long service life of heavy-duty vehicles, would 
produce a disproportionate amount of lifetime emissions, compared to a 
vehicle with properly functioning emission controls. One of the key 
enablers of defeat devices with modern engines is the unauthorized 
modification, or tampering, with certified calibration parameters and/
or software within the electronic control module (``ECM''). Tampering 
with the ECM can introduce a different calibration that allows the 
engine to produce power at higher emission rates, or it can bypass or 
disable inducement algorithms intended to ensure proper functioning of 
SCR systems. The EPA Office of Enforcement and Compliance Assurance 
(OECA) has found extensive evidence of tampering with the emission 
control systems on heavy-duty engines and vehicles nationwide, although 
EPA lacks robust data on the exact rate of tampering.\504\ Recently, 
OECA announced a new National Compliance Initiative (``NCI'') to 
address the manufacture, sale, and installation of defeat devices on 
vehicles and engines through civil enforcement.\505\
---------------------------------------------------------------------------

    \504\ U.S. EPA. ``Tampered Diesel Pickup Trucks: A Review of 
Aggregated Evidence from EPA Civil Enforcement Investigations'', 
November 20, 2021, Available online: https://www.epa.gov/enforcement/tampered-diesel-pickup-trucks-review-aggregated-evidence-epa-civil-enforcement.
    \505\ U.S. EPA. National Compliance Initiative: Stopping 
Aftermarket Defeat Devices for Vehicles and Engines. Available 
online: https://www.epa.gov/enforcement/national-compliance-initiative-stopping-aftermarket-defeat-devices-vehicles-and-engines.
---------------------------------------------------------------------------

    EPA has for decades had regulations to address the ``physically 
adjustable parameters'' on heavy-duty highway engines that can alter 
emissions performance.\506\ These regulations require the manufacturer, 
subject to review by EPA, to identify the appropriate range of 
adjustment on the operating parameters or physical settings on an 
engine that could potentially increase emissions and the adequacy of 
limits, stops, seals, or other mechanical means of limiting or 
prohibiting adjustment outside of these appropriate ranges. Parameters 
such as injection timing on a diesel engine were once physically 
adjustable with common tools and clearly an adjustable parameter. With 
a modern ECM, many of these parameters are now electronically 
adjustable through changes to software and calibration settings. As 
discussed in Section XII.A.2, we are proposing to revise our 
regulations by adding 40 CFR 1068.50 to specifically address 
electronically adjustable parameters and require that manufacturers 
attest that they are using sufficient measures to secure the ECM, 
thereby limiting adjustment or alteration beyond those used in the 
certified configuration.
---------------------------------------------------------------------------

    \506\ 40 CFR 86.094-22.
---------------------------------------------------------------------------

    ECM tampering is often designed to avoid detection, where the 
software, controls, and onboard diagnostics are intentionally 
manipulated so commonly available scan tools cannot detect the presence 
of a defeat device. This complicates the efforts of state

[[Page 17513]]

inspection and maintenance programs to identify and address tampered 
vehicles. ECM tampering is also a concern for manufacturers, because 
changes to the engine controls can adversely impact the durability of 
the engine and lead to premature failure. If ECM tampering remains 
undetected and a failure occurs within the warranty period, the 
manufacturer would be responsible for the repair costs. Manufacturers 
have been implementing measures to prevent tampering with software in 
the engine's ECM, but manufacturers of defeat devices continue to find 
ways to work around these security measures. Unauthorized access to the 
ECM and other control modules on a vehicle is also a public safety 
concern, as malicious tampering could affect the operation of the 
advanced braking, stability, and cruise control systems found on modern 
heavy-duty vehicles.\507\
---------------------------------------------------------------------------

    \507\ Stachowski, S., Bielawski, R., Weimerskirch, A. 
Cybersecurity Research Considerations for Heavy Vehicles (Report No. 
DOT HS 812 636). Washington, DC: National Highway Traffic Safety 
Administration. December 2018.
---------------------------------------------------------------------------

    To address the safety, financial liability, operational, and 
privacy concerns that can result from tampering, manufacturers, 
industry organizations, and regulators have been working to develop 
standards and design principles that would improve vehicle 
cybersecurity, including ECMs. Three such efforts where cybersecurity 
guidelines and procedures are either under development or already in 
publication are ISO/SAE J21434, UNECE WP29 Cybersecurity Regulation,
and SAE J3061.508 509 \510\ Manufacturers may choose to 
utilize different mixes of technical standards or principles that these 
organizations recommend. A one-size-fits-all approach with detailed 
requirements for ECM security for all engines would be neither 
practical nor prudent. Manufacturers need the flexibility to quickly 
implement measures to address new or emerging threats and 
vulnerabilities. Considering this need for flexibility and noting that 
the security principles in these efforts are constantly evolving as new 
threats are identified, we are not proposing to adopt any of these 
specific guidelines as requirements for manufacturers.
---------------------------------------------------------------------------

    \508\ ``Road vehicles -- Cybersecurity engineering``, ISO/SAE 
FDIS 21434, https://www.iso.org/standard/70918.html.
    \509\ United Nations Economic Commission for Europe, ``UNECE 
WP29 Automotive Cybersecurity Regulation'', Available online: 
https://argus-sec.com/unece-wp29-automotive-cybersecurity-regulation/.
    \510\ Society of Automotive Engineers, ``Cybersecurity Guidebook 
for Cyber-Physical Vehicle Systems``. SAE J3061, Available online: 
https://www.sae.org/standards/content/j3061_201601/.
---------------------------------------------------------------------------

    In 40 CFR 1036.205(s), we propose that manufacturers describe all 
adjustable parameters in their application for certification, which 
would include electronically controlled parameters. Electronically 
controlled parameters may be considered practically adjustable as 
described in proposed 40 CFR 1068.50(d)(2). This would include user-
selectable operating modes and modifications that owners can make with 
available tools. We are proposing that manufacturers describe their 
approach to limiting access to electronic controls in the certification 
application. We retain the right to evaluate a manufacturer's 
determination in their application considering the measures they are 
using (whether proprietary standards, industry technical standards, or 
a combination of both), to prevent access to the ECM. At a minimum, 
this documentation should describe in sufficient detail the measures 
that a manufacturer has used to: prevent unauthorized access; ensure 
that calibration values, software, or diagnostic features cannot be 
modified or disabled; and respond to repeated, unauthorized attempts at 
reprogramming or tampering.\511\ Section XII.A.2 of this preamble 
describes our proposed new section 40 CFR 1068.50 to codify a set of 
provisions that are consistent with current industry best practices 
with respect to adjustable parameters. Additional discussion can be 
found in Chapter 2 of the draft RIA.
---------------------------------------------------------------------------

    \511\ We are proposing that engines are not in the certified 
configuration if they are produced with adjustable parameters set 
outside the range specified in their application for certification 
or produced with other operating parameters that do not conform to 
the certified configuration. See Section XII and proposed 40 CFR 
1068.50(i).
---------------------------------------------------------------------------

3. Serviceability
    Defective designs and tampering can contribute significantly to 
increased in-use emissions. EPA has warranty provisions and tampering 
prohibitions in place to address such issues. Mal-maintenance, which 
includes delayed or improper repairs and delayed or unperformed 
maintenance, also increases in-use emissions and can be intentional 
(e.g., deferring repairs due to costs) or unintentional (e.g., not 
being able to diagnose the actual problem and make the proper repair). 
Mal-maintenance (by owners or repair facilities) can result from:
     Difficulty and high costs to diagnose and repair
     Inadequate troubleshooting guides and maintenance 
instructions
     Limited access to maintenance information and specialized 
tools to make repairs
    Vehicle owners, repair technicians, and manufacturers all play 
important and distinct roles in achieving intended in-use emission 
system performance and preventing mal-maintenance. Vehicle owners are 
expected to properly maintain the engines, which includes performing 
preventative maintenance, scheduled maintenance (e.g., maintaining 
adequate DEF supply for their diesel engines' aftertreatment), and 
completing repairs when components or systems degrade or fail. Repair 
technicians are expected to properly diagnose and repair malfunctioning 
emission systems. Finally, manufacturers play a key role in providing 
both owners and repair technicians with access to the information they 
need to perform such expected maintenance and repairs.
    EPA published several rules between 1993 and 2003 that improved 
service information access and required onboard diagnostic (OBD) 
systems for light-duty vehicles up to 14,000 lb GVWR.\512\ In 2009, EPA 
finalized similar requirements for the heavy-duty industry to ensure 
that manufacturers make diagnostic and service information available to 
any person repairing or servicing heavy-duty vehicles and engines (74 
FR 8309, February 24, 2009).\513\ The service information requirements 
include information necessary to make use of the OBD system and 
instructions for making emission-related diagnoses and repairs, 
training access, technical service bulletins, and other information 
generally available to their franchised dealers or other persons 
engaged in the repair, diagnosing or servicing of motor vehicles. Since 
this time, manufacturers have entered into a service-related agreement 
through trade associations representing the aftertreatment repair 
industry and truck and engine manufacturers, highlighting concerns over 
intellectual property and their continued need for proprietary 
tools.\514\ EPA is not proposing changes to service

[[Page 17514]]

information regulations at this time. While the service information 
regulations were an important first step in improving serviceability, 
as emission control systems have continued to develop, it has become 
necessary to consider other improvements that can be made to support 
in-use maintenance and repair practices. CAA section 207(c)(3)(A) 
requires manufacturers to provide instructions for the proper 
maintenance and use of a vehicle or engine by the ultimate purchaser 
and requires such instructions to correspond to EPA regulations. 
Section 207(c)(3)(A) also requires manufacturers to provide notice in 
those instructions that maintenance, replacement, or repair of emission 
control devices and systems may be performed by any automotive repair 
establishment or individual using any automotive part which has been 
certified as provided in section 207(a)(2). Section 207(c)(3)(B) 
requires that these instructions shall not include any condition on the 
ultimate purchaser's using, in connection with such vehicle or engine, 
any component or service (other than a component or service provided 
without charge under the terms of the purchase agreement) which is 
identified by brand, trade, or corporate name; or directly or 
indirectly distinguishing between service performed by the franchised 
dealers of such manufacturer or any other service establishments with 
which such manufacturer has a commercial relationship, and service 
performed by independent automotive repair facilities with which such 
manufacturer has no commercial relationship; unless EPA finds the 
vehicle or engine will function properly only if the component or 
service so identified is used in connection with such vehicle or 
engine, and that such a waiver is in the public interest.
---------------------------------------------------------------------------

    \512\ See 58 FR 9468 (February 19, 1993); 60 FR 40474 (August 9, 
1995); 65 FR 59896 (Oct 6, 2000); and 68 FR 38428 (June 27, 2003).
    \513\ See 40 CFR 86.010-38(j) for the current service 
information requirements. We are not proposing to migrate the 
service information provisions at this time and these provisions 
will remain in part 86. We are proposing to name the service 
information provisions as an additional requirement in proposed 40 
CFR 1036.601(b). EPA may consider migrating these provisions in a 
future rulemaking.
    \514\ Memorandum of Understanding National Commercial Vehicle 
Service Information. August 2015. Available online: https://www.etools.org/Heavy-Duty-MOU-2015.
---------------------------------------------------------------------------

    Section 207(c)(3)(C) states that manufacturers must affix a 
permanent label indicating that the vehicle or engine is covered by a 
certificate of conformity and containing other information relating to 
control of motor vehicle emissions as prescribed by EPA regulations. 
Finally, section 202(m)(5) clarifies that manufacturers must provide 
this information promptly to anyone engaged in the repairing or 
servicing of motor vehicles or engines, except as specified. This 
section describes proposed regulatory amendments under these statutory 
provisions and are intended to improve serviceability, reduce mal-
maintenance, and ensure owners are able to maintain emission 
performance throughout the entire in-use life of heavy-duty engines.
i. Current Repair and Maintenance Experiences
    Continued maintenance issues can result in, among other things, 
owner dissatisfaction, which may cause some owners to remove or bypass 
emission controls. Any actions we can take to reduce maintenance issues 
could reduce incidents of tampering. In the ANPR, EPA requested comment 
on experiences with serviceability and received comment in three 
general categories: (1) Frustrations related to advanced emission 
control system reliability; (2) misdiagnosis and improper repair by 
professional facilities which lead to repeated trips to repair 
facilities and significant downtime, and (3) limited access to 
maintenance information which leads to the inability to self-diagnose 
problems.
    Serviceability concerns affect all trucking operations, although 
different types of operators may experience these impacts in different 
ways. EPA received comments from trade organizations representing very 
large trucking fleets (e.g., the American Trucking Associations, 
``ATA''), small fleets (e.g., National Association of Small Trucking 
Companies, ``NASTC''), and owner-operators (e.g., Owner-Operator 
Independent Drivers Association, ``OOIDA''), as well as from 
independent commenters, indicating that serviceability issues are one 
of the top concerns when operating trucks with advanced emission 
control systems. ATA commented that current emission control systems 
are still causing concerns for fleets and noted that in a recent study 
by ATA's Truck Maintenance Council, aftertreatment maintenance issues, 
serviceability, and ease of diagnostics were identified as major areas 
of concern by their members.\515\ NASTC submitted comments directly 
from their members indicating a number of concerns related to 
serviceability.\516\ OOIDA commented that their members have 
encountered various problems with emissions systems which have had a 
dramatic impact on their businesses including expensive visits to 
dealers, lost productivity, poor efficiency, and towing costs.\517\ A 
number of other commenters described their experiences and how 
improvements can be made to reduce cost and frustration.\518\ Trucking 
companies participating in a round table discussion in EPA's Region 7 
expressed similar concerns about impacts to business as a result of 
delayed or missed deliveries, including lost customers, and possible 
legal or contract consequences.\519\
---------------------------------------------------------------------------

    \515\ See the comments of the American Trucking Association, 
Docket ID EPA-HQ-OAR-2019-0055-0357.
    \516\ See the comments of the National Association of Small 
Trucking Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
    \517\ See the comments of the Owner-Operator Independent Drivers 
Association, Docket ID EPA-HQ-OAR-2019-0055-0397.
    \518\ For example, see the comments of Swanny's Trucking, Docket 
ID EPA-HQ-OAR-2019-0055-0252.
    \519\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055. 
``EPA Region 7 Heavy-Duty NOX ANPR Roundtable 
Discussion--Serviceability- and Inducement-Related Concerns``. 
October 1, 2021.
---------------------------------------------------------------------------

    In addition to operators, EPA received comments from state and 
local agencies supportive of improving access of maintenance 
information and service tools for fleets and owner-
operators.520 521 For example, NACAA stated that EPA should 
work to increase access to the information and tools needed to repair 
the emission control systems on aging trucks, which is especially 
important for small businesses, small fleets, independent owner/
operators, and rural operations, where access to dealer service 
networks can be a challenge.
---------------------------------------------------------------------------

    \520\ See the comments of the National Association of Clean Air 
Agencies, Docket EPA-HQ-OAR-2019-0055-0283.
    \521\ See the comments of the Northeast States for Coordinated 
Air Use Management, Docket EPA-HQ-OAR-2019-0055-0288.
---------------------------------------------------------------------------

a. Reliability of EPA 2010 Engines
    We are keenly aware of significant discontent expressed by owners 
concerning their experiences with emission systems on engines compliant 
with EPA 2010 standards. EPA has also identified numerous Technical 
Service Bulletins submitted by OEMs to NHTSA's website documenting 
issues such as no trouble found, wiring concerns, or minor corrosion on 
connectors which can lead to inducement.\522\ Although significant 
improvements have been made to these systems since they were first 
introduced into the market, reliability and serviceability continue to 
cause concern. ATA commented that their members are experiencing 
problems with a wide variety of issues such as: Aftertreatment wiring 
harness failures, DEF nozzles plugging or over-injecting, 
NOX sensor failures, defective DEF pumps and level sensors, 
systems being less reliable in rain and cold weather, more frequent 
required cleaning of DPFs, and problems related to DEF

[[Page 17515]]

build-up.\523\ ATA also stated that their members have reported that 
mechanics at dealerships sometimes clear codes with no associated 
repairs being made. Many of these issues can also lead to severe engine 
derate and towing costs (see Section IV.D for further information on 
proposed inducement provisions, including revisions to policy currently 
in guidance). OOIDA commented that some of its members have experienced 
emission technology failures that caused their engines to quickly 
derate, placing truckers and other motorists in unsafe situations.\524\
---------------------------------------------------------------------------

    \522\ See NHTSA Service Bulletins: ID Number 10058856, available 
here: https://static.nhtsa.gov/odi/tsbs/2015/SB-;10058856-6479.pdf 
and ID Number 10154333, available here: https://static.nhtsa.gov/odi/tsbs/2019/MC-10154333-9999.pdf.
    \523\ See the comments of the American Trucking Association, 
Docket ID EPA-HQ-OAR-2019-0055-0357.
    \524\ See the comments of the Owner-Operator Independent Drivers 
Association, Docket ID EPA-HQ-OAR-2019-0055-0397.
---------------------------------------------------------------------------

    In addition to the comments highlighting problems related to wiring 
harness issues and sensor failures, a number of published articles have 
presented similar findings. For example, ``Dealing with Aftertreatment 
Issues'' in Fleet Equipment Magazine discusses how at least one OEM is 
focusing on improving issues with wiring and sensors ``which are often 
the culprits in aftertreatment downtime.'' \525\ A recent article from 
Transport Topics highlights how fleets are experiencing wiring issues 
and sensor failures that are creating problems that even sophisticated 
diagnostic tools cannot solve easily.\526\
---------------------------------------------------------------------------

    \525\ Crissey, Alex. Fleet Equipment Magazine. ``Dealing with 
Aftertreatment Issues''. November 27, 2017. Available online: 
https://www.fleetequipmentmag.com/dealing-aftertreatment-issues/.
    \526\ Frantz, Gary. Transport Topics. ``Diesel Engine Makers 
Tackle Challenges Posed by Stricter Emission Standards''. May 11, 
2020. Available here: https://www.ttnews.com/articles/class-8-engine-makers-tackle-challenges-posed-stricter-emission-standards.
---------------------------------------------------------------------------

b. Misdiagnosis and Improper Repairs
    Misdiagnosis can lead to the unnecessary replacement of parts 
without properly addressing the problem, which can result in additional 
breakdowns and tows with return trips to repair facilities for 
diagnostic service. ATA commented that several fleets are reporting the 
need for 'comeback' repairs and that while emissions-related training 
for diagnosis and repair work has improved, it is still severely 
lagging behind expectations. The NASTC describes problems some owners 
have experienced with repeated emission system component failures.\527\ 
In one example, an owner had to replace four NOX sensors, 
two diesel exhaust fluid (DEF) filters, a DEF pump, a DPF, and a diesel 
oxidation catalyst (DOC) within only 6 months of purchasing a new 
truck. NASTC also described problems other owners experienced due to 
failures of NOX sensors, DPF filters, DOCs, other emission-
related sensors, and wiring harnesses, as well as repeated DEF doser 
injector pumps and valve failures. Other NASTC commenters described 
improper repair experiences resulting in trucks being down for weeks at 
a time. An independent commenter stated that repeated repairs in a 6-
month time period resulted in loss of his truck and the ability to 
continue as an owner-operator.\528\
---------------------------------------------------------------------------

    \527\ See the comments of the National Association of Small 
Trucking Companies (``NASTC''), EPA-HQ-OAR-2019-0055-0456.
    \528\ See the comments of J. Johnson, Docket ID EPA-HQ-OAR-2019-
0055-0265.
---------------------------------------------------------------------------

c. Limited Access to Repair Facilities, Maintenance Information, and 
Service Tools
    In response to the ANPR, EPA received numerous comments on 
difficulties associated with repairs of emission control systems. Many 
commenters indicated there is a substantial wait time to get a vehicle 
into a specialized repair facility, which, in some cases, was more than 
a week in addition to the time required to repair the vehicle.\529\ 
This wait time may be manageable if the vehicle remains operational, 
but can have a significant impact on an owner's ability to generate 
income from a vehicle if the truck is subject to an inducement and they 
are unable to use the vehicle until the repair is made.\530\ EPA 
received comments from the National Tribal Air Association and Keweenaw 
Bay Indian Community suggesting that service information and tools are 
not readily available and affordable for individual owners to diagnose 
and fix their own vehicles, and improved access can be especially 
important for small businesses, Tribes, and those in rural areas with 
less ready access to original equipment manufacturer dealer 
networks.\531\
---------------------------------------------------------------------------

    \529\ See the comments of J. Sibley, Docket ID EPA-HQ-OAR-2019-
0055-0397 and those of the National Association of Small Trucking 
Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
    \530\ See Section IV.D for proposed inducement provisions, which 
include revisions to policy currently in guidance.
    \531\ See the comments of the National Tribal Air Association, 
Docket ID EPA-HQ-OAR-2019-0055-0282.
---------------------------------------------------------------------------

    EPA received a number of comments on difficulties getting the right 
information or tools to repair vehicles outside of specialized repair 
facilities. ATA commented that their members report that in order to 
ensure proprietary tools are used, some manufacturers lock out certain 
diagnostic programs needed to further diagnose and reset systems after 
repairs, which ATA believes is a barrier to owners quickly diagnosing 
emission control system problems. ATA added that while some large 
fleets have added laptops in the field to help troubleshoot issues, 
fleets with more than one brand of truck may face significant expense 
to acquire multiple OEM software/diagnostic packages for these laptops. 
NASTC members noted that there are very few independent repair 
facilities that will repair emission systems problems, and given the 
long lead times at traditional repair facilities, a single fault code 
can remove a truck from service for more than a week. NASTC members 
also commented that diagnostic tools for owners are not affordable but 
are currently the only way to access diagnostic codes outside of a trip 
to a repair facility. OOIDA commented that according to a 2018 survey, 
73 percent of their members perform repairs and maintenance on their 
own trucks.\532\ OOIDA added that being able to diagnose problems and 
repair equipment outside of dealerships is important for owner-
operators and allows them to save time, avoid downtime, and reduce 
operating costs; however, they believe that restrictions built into 
existing trucks are preventing this practice. OOIDA supported an 
emphasis on serviceability improvements so that professional drivers 
can independently identify and repair problems with their engines and 
aftertreatment as much as possible.
---------------------------------------------------------------------------

    \532\ See the comments of the Owner-Operator Independent Drivers 
Association, Docket ID EPA-HQ-OAR-2019-0055-0397.
---------------------------------------------------------------------------

ii. Proposed Maintenance Information for Improved Serviceability
    In addition to labeling, diagnostic, and service information 
requirements, EPA is proposing to require important maintenance 
information be made available in the owner's manual.\533\ The owner's 
manual is a document or collection of documents prepared by the engine 
or vehicle manufacturer for the owner or operator to describe 
appropriate engine maintenance, applicable warranties, and any other 
information related to operating or maintaining the engine or vehicle. 
EPA is proposing to require additional maintenance information in the 
owner's manual as a way to improve factors that may contribute to mal-
maintenance, resulting in better service experiences for independent 
repair technicians,

[[Page 17516]]

specialized repair technicians, owners who repair their own equipment, 
and possibly vehicle inspection and maintenance technicians.\534\ 
Combined with our proposed modifications to onboard diagnostic 
requirements and proposed provisions for inducements, we expect these 
proposed serviceability provisions would improve owner experiences 
operating and maintaining heavy-duty engines and provide greater 
assurance of long-term in-use emission reductions by reducing 
likelihood of occurrences of tampering.\535\
---------------------------------------------------------------------------

    \533\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``Serviceability and Additional Maintenance 
Information''. October 1, 2021.
    \534\ EPA is also proposing changes to existing useful life 
periods to incentivize improved component durability (see Section 
IV.A)), onboard diagnostic requirements intended to make emission 
system faults more easily diagnosed (see Section IV.C), and is 
proposing inducement provisions for DEF replenishment, DEF quality 
and certain SCR-related tamper-resistant design intended to ensure 
manufacturers can meet adjustable parameter and critical emission-
related scheduled maintenance requirements (see Section IV.D).
    \535\ See Section IV.C for discussion on proposed changes to 
onboard diagnostic requirements and Section IV.D for proposed 
inducement provisions.
---------------------------------------------------------------------------

    EPA is proposing changes to owner's manual and label requirements 
that would be mandatory for MY 2027 and later engines. The existing 
proposal would be voluntary for earlier model years, but we are seeking 
comment on making all or parts of this proposal mandatory as soon as MY 
2024. We expect these changes would increase owner understanding of 
emission control systems, improve experiences at repair facilities, 
provide better access to information to help identify concerns, and 
enable owners to self-diagnose problems (especially important for aging 
trucks). Our proposal is intended to ensure consistent access to 
emission systems diagrams and part number information across the range 
of commercial vehicle engines and improve clarity in the information 
presented in those diagrams. Owner's manuals today include very 
detailed descriptions of systems such as radios and infotainment 
centers, fuse box and relay diagrams, and troubleshooting guides for 
phone connectivity features, but generally include limited information 
on emission control system operations. Given the importance and 
complexity of emission control systems and the impact to drivers for 
failing to maintain such systems (e.g., inducements), EPA believes 
including additional information about emission control systems in the 
owner's manual is critical.
    We are proposing to require manufacturers to provide more 
information concerning the emission control system in both the owner's 
manual and the emissions label. Our proposal would require the owner's 
manual to include descriptions of how the emissions systems operate, 
troubleshooting information, and diagrams. The emissions label would 
include an internet link to obtain this additional information. EPA has 
had similar requirements in the past, such as when EPA required vacuum 
hose diagrams to be included on the emission label to improve 
serviceability and help inspection and maintenance facilities identify 
concerns.\536\
---------------------------------------------------------------------------

    \536\ See 53 FR 7675, March 9, 1988 and 55 FR 7177, February 29. 
1990 for more information.
---------------------------------------------------------------------------

    Specifically, as a part of the new 40 CFR 1036.125(h)(3)-(9) and 
(11), we propose that manufacturers provide the following additional 
information in the owner's manual:
     A description of how the owner can use the OBD system to 
troubleshoot problems and access emission-related diagnostic 
information and codes stored in onboard monitoring systems including 
information about the role of the proposed health monitor to help 
owners service their engines before components fail.
     A general description of how the emission control systems 
operate.
     One or more diagrams of the engine and its emission-
related components with the following information:
    [cir] The flow path for intake air and exhaust gas.
    [cir] The flow path of evaporative and refueling emissions for 
spark-ignition engines, and DEF for compression-ignition engines, as 
applicable.
    [cir] The flow path of engine coolant if it is part of the emission 
control system described in the application for certification.
    [cir] The identity, location, and arrangement of relevant sensors, 
wiring, and other emission-related components in the diagram. 
Terminology to identify components would be required to be consistent 
with codes you use for the OBD system.
    [cir] Expected pressures at the particulate filter and exhaust 
temperatures throughout the aftertreatment system.
     Exploded-view drawings to allow the owner to identify the 
part numbers and basic assembly requirements for turbochargers, 
aftercoolers, and all components required for proper functioning of EGR 
and aftertreatment devices including enough detail to allow a mechanic 
to replace any of those components.
     A basic wiring diagram for aftertreatment-related 
components including enough detail to allow a mechanic to detect 
improper functioning of those components.
     Statement instructing owners or service technicians where 
to find emission recall and technical repair information available 
without charge from the National Highway Traffic Safety 
Administration.\537\
---------------------------------------------------------------------------

    \537\ In 2016, NHTSA issued a Federal Register notice (81 FR 
16270, March 25, 2016) stating it would post all Technical Service 
Bulletins and communications to dealers on defects in vehicles, 
regardless of whether the defects were safety related to comply with 
the Congressional mandate in in the ``Moving Ahead for Progress in 
the 21st Century Act'' (MAP-21) enacted on July 6, 2012. More 
information is available here: https://www.autosafety.org/how-to-find-technical-service-bulletins-and-other-manufacturer-communications-via-nhtsas-search-portal/.
---------------------------------------------------------------------------

     Troubleshooting guide to address DEF dosing- and DPF 
regeneration-related warning signals that would be displayed in the cab 
or with a generic scan tool, including a description of the fault 
condition, the potential causes, the remedy, and the consequence of 
continuing to operate without remedy including a list of all codes that 
cause derate or inducement (e.g., list SPN/FMI combinations and 
associated operating restrictions, see proposed requirements in 40 CFR 
1036.110(b)(9)(vi)).
     For the DPF system, instructions on how to remove DPF for 
cleaning, criteria for cleaning the DPF including pressure drop across 
the filter, clean filter weight, pre-installed filter weight, a 
statement that DPF inlet and outlet pressures are available with a 
generic scan tool, and information on maintenance practices to prevent 
damage to DPFs.
    We propose to include these eight additional provisions for all 
engine configurations, including hybrids, where applicable.\538\ EPA is 
seeking comment on these eight proposed additional provisions or other 
approaches to improve the serviceability of heavy-duty engine emission 
control systems. Finally, in 40 CFR 1036.135(c), EPA is proposing that 
manufacturers include a Quick Response Code or ``QR Code'' on the 
emission label that would direct repair technicians, owners, and 
inspection and maintenance facilities to a website which provides 
critical emissions systems information at no cost including: A digital 
copy of the owner's manual (or just the emissions section of the 
manual), engine family information, emission control system 
identification, and fuel and lubricant requirements (see proposed 
revisions in 40 CFR 1036.135). Many manufacturers already make digital 
owner's manuals

[[Page 17517]]

available online.\539\ EPA recognizes that there may be a need to 
accommodate different information formats relating to the QR code link 
and requests comment on whether to include different options to achieve 
the same goals, and if so, what those options should be. The 
maintenance information we are proposing to add to the owner's manual 
is critical to making necessary information available promptly to any 
person performing emissions-related maintenance.
---------------------------------------------------------------------------

    \538\ See Section IV.B.3.iii for discussion on potential 
serviceability requirements for BEV and FCEV technologies on which 
we are seeking comment. Section IV.I also discusses potential 
maintenance requirements for manufacturers who choose to generate 
NOX emission credits from BEVs or FCEVs.
    \539\ Montoya, Ronald, ``How to Find Your Car Owner's Manual 
Online.'' October 18th, 2013. Available online at: https://www.edmunds.com/how-to/how-to-find-your-car-owners-manual-online.html.
---------------------------------------------------------------------------

    Including the proposed additional information in the owner's manual 
and emission label can increase an owner's understanding of emission 
systems operation and fault conditions. Providing owners and repair 
technicians access to diagrams describing system layout and operation 
can help reduce confusion where manufacturers may have different system 
configurations. For example, some configurations may have the DPF in 
front of the SCR catalyst, while others may have it behind the SCR 
catalyst.\540\ Lack of easily accessible diagrams can lead to mal-
maintenance and improper repair where components that need to be 
replaced are not identified properly. For example, some manufacturers 
label exhaust gas temperature (EGT) sensors generically such as EGT1 
and EGT2 and the positioning of these sensors may differ or be reversed 
for the same engine model installed on vehicles with slightly different 
frame configurations.\541\ If a technician is unfamiliar with this 
change, they may replace the wrong EGT which would likely result in a 
repeat visit to a repair facility. Similarly, a DPF temperature sensor 
may be generically labeled ``Exhaust Temperature Sensor'' and may be 
shown on an EGR parts diagram rather than a DPF parts diagram, making 
it difficult to correctly identify replacement parts. With an easily 
accessible parts diagram, owners, parts counter specialists, and repair 
technicians can more quickly identify the correct parts to replace 
which would save time and eliminate frustration, especially where a 
truck is in an inducement. EPA is also seeking comment on the need to 
require standardization of terminology for certain components in the 
proposed labeling and owner's manual provisions to further reduce 
confusion for owners and technicians performing repairs. For example, 
some manufacturers call the DOC outlet temperature a DPF inlet 
temperature. Lack of standardization, including naming conventions and 
data output parameter scaling (e.g., NOX sensor output 
scaling may vary between manufacturers), may lead to confusion and 
inefficiencies when seeking replacement parts and performing 
troubleshooting and repairs. SAE J2403 ``Medium-Heavy Duty E/E System 
Diagnosis Nomenclature'' is designed to standardize nomenclature of 
components and how systems with multiple sensors (e.g., multiple EGT 
sensors) should be numbered starting from the same place (e.g., 
starting at the engine). CARB requires that, to the extent possible, 
certification documentation shall use SAE J1930 or J2403 terms, 
abbreviations, and acronyms. EPA is seeking comment on whether this 
standard should be incorporated and required for use in naming certain 
emission components such as exhaust temperature sensors as a part of 
certification, maintenance instructions, diagnostic, or other 
serviceability-related requirements.
---------------------------------------------------------------------------

    \540\ Powerstrokehub.com, ``6.7L Power Stroke Emissions Control 
System.'' Available here: https://www.powerstrokehub.com/6.7-power-stroke-emissions.html.
    \541\ Earlywine, Brad,''6.7L Power Stroke EGT Replacement.'' 
Available here: https://www.expertswrite.net/article/67l-powerstroke/changing-egt-sensors/.
---------------------------------------------------------------------------

    EPA seeks comment on other pertinent information that should be 
included in owner's manuals so that owners can more easily understand 
advanced emission control system operation and precautions that should 
be taken in order to maintain them. To the extent EPA can ensure this 
information is harmonized among manufacturers, we believe this could 
improve owner, operators, parts counter specialist, and repair 
technician experiences and reduce frustration which can lead to an 
incentive to tamper.
iii. Request for Comments on Maintenance and Operational Information 
for Improved Serviceability of Electric Vehicles
    EPA is requesting comment on several potential serviceability 
requirements for BEV and FCEV technologies. Many of these potential 
serviceability provisions are similar to those proposed in Section 
IV.B.3.ii for CI and SI engines but are specific to these technologies 
that do not require a combustion engine or emissions aftertreatment 
system. As noted in the introduction of Section III.A, under 40 CFR 
86.016-1(d)(4), heavy-duty BEV and FCEV manufacturers currently use 
good engineering judgment to apply the criteria pollutant requirements 
of part 86, Subpart S, including maintenance provisions.
    We are requesting comment on seven categories of potential 
requirements for BEV and FCEV serviceability: (1) Labeling, (2) 
purchaser guidance, (3) maintenance information, (4) maintenance 
information requirements concerning the use of a standardized connector 
and making malfunction codes and powertrain parameters accessible, (5) 
onboard vehicle signals for service and repair technicians, (6) 
information on battery energy used per trip, and (7) battery 
information to facilitate battery recycling. We request comment on 
whether each of these categories individually or in combination should 
be finalized to support owners and repair technicians in maintaining 
and repairing BEV and FCEV technologies, or if alternative provisions 
suggested by commenters would better support these technologies while 
minimizing burden to manufacturers. Each of these categories of 
potential requirements is based on provisions of the 2019 CARB Zero 
Emissions Powertrain Certification (ZEP Certification), which imposes 
requirements on manufacturers choosing to generate NOX 
emission credits under the CARB Omnibus rule.\542\ We believe that 
adopting an approach based on the CARB ZEP Certification program would 
provide manufacturers with consistency across the country. Consistent 
with the ZEP Certification requirements, EPA believes that the 
maintenance and operational information described in this section could 
help potential BEV and FCEV purchasers to understand the possible 
operational impacts of these technologies on their businesses, as well 
as ensure the vehicles are supported during their use in the field. 
Each of the areas in which we are requesting comment is briefly 
discussed immediately below.
---------------------------------------------------------------------------

    \542\ CARB (2019) ``Final Statement of Reasons for Rulemaking, 
Proposed Alternative Certification Requirements and Test Procedures 
for Heavy-Duty Electric and Fuel Cell Vehicles and Proposed 
Standards and Test Procedures for Zero Emission Powertrains.'' 
https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2019/zepcert/fsor.pdf (accessed August 5, 2021).
---------------------------------------------------------------------------

    For the first area (labeling), as specified in the current 40 CFR 
1037.125, all vehicle manufacturers currently must affix a label to 
each vehicle with information such as manufacturer name, vehicle 
certification family, and build date; however, some of the information 
is specific to vehicles propelled by an engine (e.g., 40 CFR 
1037.125(c)(6) requires manufacturers to specify the emission control 
system).

[[Page 17518]]

We request comment on whether there is additional information specific 
to BEVs and FCEVs that would be useful to include on the vehicle label 
for repair technicians, owners, and inspection and maintenance 
professionals. We also request input from commenters on whether we 
should require a QR code on BEV and FCEV labels, similar to the 
proposed QR code requirement in 40 CFR 1036.135(c). Specifically, the 
BEV or FCEV label could include a QR code to a website which would 
direct repair technicians, owners, or inspection and maintenance 
facilities to a website with information including: A digital copy of 
the owner's manual, vehicle family information, and powertrain 
identification. Commenters are encouraged to provide details on how any 
suggestions for additional information would help vehicle owners with 
the repair and maintenance of BEVs or FCEVs, as well as the potential 
burden to manufacturers to include such information on the vehicle 
label.
    For the second area (purchaser guidance), we request comment on 
whether EPA should require BEV and FCEV manufacturers to provide 
purchaser guidance information to potential owners on aspects of BEV or 
FCEV ownership that may differ from owning a vehicle with a CI or SI 
engine. Immediately below, we provide several examples of the types of 
information that manufacturers could provide in purchaser guidance if 
we were to finalize such a requirement in this rule or another future 
rulemaking. For instance, purchaser guidance could include the range 
the vehicle is capable of driving over a specified duty-cycle, top 
speed, and maximum grade. As another example, manufacturers could 
describe how vehicle load, ambient temperatures, and battery 
degradation impact range, top speed, or maximum grade. Manufacturers 
could also provide potential purchasers estimates of the time required 
for maintenance and repairs of common malfunctions, as well as 
potential vehicle transportation costs. Finally, manufacturers could 
clearly describe any warranty coverage of the battery and other key 
powertrain components that would be covered (see Section IV.B.1.iv.b 
for our proposed warranty requirements).\543\ To minimize manufacturer 
burden, EPA could provide an example statement in 40 CFR part 1037 that 
manufacturers could choose to use if they attest that the statement is 
accurate for their vehicle; the example statement could largely mirror 
the statement that was proposed by CARB under the 2019 CARB ZEP 
Certification and subsequently adopted into current CARB regulations 
for GHG emissions from 2014 and later model vehicles.\544\ While an 
example statement provided by EPA would minimize manufacturer burden, 
it would also, by necessity, be more generic and not reflect parameters 
specific to a given vehicle model (e.g., range). We encourage 
commenters to provide input on the potential benefits of manufacturers 
providing such purchaser guidance relative to the potential burden to 
manufacturers to provide such guidance.
---------------------------------------------------------------------------

    \543\ As noted in Section IV.B.1.iv.b, the existing 40 CFR 
1037.120(e) requires all manufacturers to describe in their owner's 
manuals the warranty provisions that apply to the vehicle; 
manufacturers could also provide the same information in purchaser 
guidance such that it could help inform potential owners prior to 
their purchase (i.e., prior to having an owner's manual for the 
vehicle). Per discussion in IV.B.1.iv.b, the proposed warranty 
requirements differ for manufacturers choosing to generate 
NOX emission credits from BEVs or FCEVs versus 
manufacturers choosing not to generate NOX emission 
credits from these vehicles.
    \544\ See Attachment B, ``California Greenhouse Gas Exhaust 
Emission Standards and Test Procedures for 2014 and Subsequent Model 
Heavy-Duty Vehicles``, 3.17 Sales Disclosures, https://ww2.arb.ca.gov/sites/default/files/classic/regact/2019/zepcert/froattb.pdf (accessed 8/5/2021).
---------------------------------------------------------------------------

    For the third area (maintenance information), we request comment on 
whether EPA should require BEV and FCEV manufacturers to make 
additional maintenance information available to owners and repair 
technicians. Under the current 40 CFR 1037.125(f) manufacturers make 
the service manual and any required service tools available to third-
party repair facilities at reasonable cost; however, we request comment 
on any information specific to BEVs or FCEVs that would be important 
for repair technicians in maintaining and repairing BEV and FCEV 
technologies. In addition, we request comment on whether EPA should 
require manufacturers to describe in their certification application 
the monitoring and diagnostic strategies they use for the BEV or FCEV; 
these strategies would also be included in their service manuals. In 
addition to being similar to existing requirements for vehicles powered 
by an engine, this potential provision would be consistent with the ZEP 
Certification requirements.\545\
---------------------------------------------------------------------------

    \545\ See Attachment C, ``Proposed, California Standards and 
Test Procedures for New 2021 and Subsequent Model Heavy-Duty Zero-
Emissions Powertrains'' for details of CARB serviceability 
provisions available here: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2019/zepcert/froattc.pdf.
---------------------------------------------------------------------------

    For the fourth area (standardized connector and accessible 
malfunction codes and powertrain parameters), we request comment on 
whether EPA should require that BEV and FCEV manufacturers use a 
standardized connector that is compatible with automotive scan tools, 
and further that all malfunction codes and key powertrain parameters 
must be readable by a generic automotive scan tool. Commenters are 
encouraged to provide information on whether the use of a standardized 
connector would facilitate repair of BEVs and FCEVs, and the utility of 
making all malfunction codes and key powertrain parameters readable by 
a generic scan tool. We also request stakeholder input on the potential 
burden to manufacturers to make the standardized connector, malfunction 
codes, and key powertrain parameters accessible.
    For the fifth area (onboard vehicle signals), we request comment on 
whether EPA should require manufacturers to make powertrain monitoring 
or diagnostic signals publicly accessible to repair and service 
technicians to facilitate BEV and FCEV maintenance or repair. In 
Section IV.I we request comment on whether and how manufacturers who 
choose to generate NOX emission credits could make 
information on battery or fuel cell durability readily accessible; here 
we request comment on other potential parameters that may be useful for 
maintaining and repairing BEVs and FCEVs:

 Energy Storage System State of Charge (SOCE)
    [cir] Function: Indicate the remaining energy left in the 
battery(ies). Would allow users to identify battery degradation or 
failure that may require maintenance or repair of the battery or 
powertrain systems.
 Energy Storage System State of Range (SOCR)
    [cir] Function: Indicate the remaining range of the battery(ies). 
Would allow users to identify battery degradation or failure that may 
require maintenance or repair of the battery or powertrain systems.
 Drive Motor System Efficiency
    [cir] Function: Compare the energy use of the drive motor from the 
current state to the as manufactured state to see degradation over time 
(e.g., 100 percent being as manufactured and decreasing as the 
performance of the drive motor decreases), or failure. Would allow 
first owner and secondhand buyers to identify degradation in the 
electric motor.
 Battery Temperature
    [cir] Function: Identify battery temperature. Would inform repair 
technicians about when battery

[[Page 17519]]

thermal management system may need repair (e.g., identify when battery 
thermal management system degradation impacts range or charge rate).
 Percent Regenerative Braking
    [cir] Function: Measure the amount of regenerative braking relative 
to total capacity for capturing energy from regenerative braking. 
Information could provide insight on when potential maintenance or 
repair is needed for systems related to regenerative braking, as well 
as feedback to users on driving behavior that results in greater energy 
capture from regenerative braking.
 Charging Rate
    [cir] Function: Check performance of the inverter/converter and 
batteries. Would allow service repair technicians to identify when 
inverter/converter, batteries or other components may need repair.
 Charging System Performance
    [cir] Function: Identify current charge rate at optimal battery 
temperature relative to charge rate at the time of manufacture. Would 
allow service technicians to identify degradation or failure in key 
components of the charging system.

Commenters are encouraged to provide input on whether each of the 
listed parameters would be useful, or if there are additional 
parameters that would be informative. We request that commenters 
provide any additional specifics of why each signal would be useful for 
EPA to include in the final rule, or as part of other future 
rulemakings. We also invite stakeholder input on whether EPA should 
recommend a common language for BEV and FCEV communication protocols 
(e.g., J1979-2). Note that we are not requesting comment on whether and 
how manufacturers would utilize signals or a common communication 
protocol to monitor or diagnose problems. Commenters are encouraged to 
provide information on why additional onboard vehicle information would 
be important for BEV and FCEV repairs, and how EPA suggesting a common 
communication protocol would, or would not, be useful for the industry.
    For the sixth area (battery energy used per trip), we request 
comment on whether manufacturers already utilize onboard vehicle 
sensors that could provide estimates of energy consumption per trip, 
and whether manufacturers could readily provide energy consumption per 
trip information through a dashboard display. We further request 
comment on whether battery energy used per trip would support users 
understanding normal variance in battery performance due to factors 
such as terrain, driving behavior, and temperature, versus battery 
performance degradation that would necessitate maintenance or repair of 
the powertrain. EPA will consider information provided by commenters to 
evaluate the potential benefits of users understanding when a battery 
may need repair relative to the potential burden to manufactures to 
make such information available to users.
    For the seventh area, we request comment (battery information) on 
the utility and feasibility of adding a battery information requirement 
for BEVs and FCEVs. If we were to include a battery information 
requirement in the final rule, then manufacturers would: (1) Briefly 
describe in their owner's manual how to handle the battery after it is 
no longer capable of providing sufficient energy or power to the 
vehicle (e.g., identify alternative uses and safe disposal methods for 
the battery), and (2) affix a label on the battery, and include in the 
owner's manual, information necessary to recycle the battery (e.g., 
manufacturer, chemistry, voltage, hazard statement, QR code to a 
website for additional details). We believe such battery information 
would be important for users to appropriately re-purpose, recycle, or 
otherwise dispose of the battery, and thereby minimize total 
environmental impact of the BEV or FCEV. Commenters are encouraged to 
provide information on whether such battery information would 
facilitate users identifying alternative uses for the battery or 
otherwise recycling the battery. We are also interested in information 
on the feasibility of vehicle manufacturers having sufficient 
information from battery suppliers to provide information on battery 
handling at the end of its life in a vehicle. EPA will consider 
information provided in comments and weigh the potential environmental 
benefits of users having battery information with the potential burden 
to manufacturers to provide such information.
iv. Other Emission Controls Education Options
    In addition to our proposals to provide more easily accessible 
service information for users, we are seeking comment on whether 
educational programs and voluntary incentives could lead to better 
maintenance and real-world emission benefits. We received comments in 
response to the ANPR supportive of improving such educational 
opportunities to promote an understanding of how advanced emission 
control technologies function and the importance of emissions controls 
as they relate to the broader economy and the environment. Some 
commenters were generally supportive of using educational programs and 
incentives to improve maintenance practices. Commenters generally 
agreed that there are actions EPA could take to reduce the 
misinformation surrounding advanced emission control systems and that 
any action that EPA could take to improve access to easily-
understandable maintenance information would be helpful.\546\ NADA 
commented that they would ``welcome new emission control outreach and 
incentives to combat misperceptions that can lead to emissions 
tampering or mal-maintenance.'' \547\ The Motor and Equipment 
Manufacturers Association (MEMA) commented that priority should be 
given to improving education and training offered to service facilities 
and technicians to reduce the misdiagnoses of faulty emission 
components where ``it is a common diagnostic technique in service 
repair shops to continually swap out emissions components until the 
problem goes away.'' \548\ Lubrizol suggested that EPA provide 
education to ensure fleets understand the proper lubricants required to 
maintain engines.\549\
---------------------------------------------------------------------------

    \546\ See the comments of the Oregon Department of Environmental 
Quality, Docket ID EPA-HQ-OAR-2019-0055-0464; Georgia Department of 
Natural Resources, Docket ID EPA-HQ-OAR-2019-0055-0267; and the 
anonymous comments in Docket ID EPA-HQ-OAR-2019-0055-0306.
    \547\ See the comments of the National Automobile Dealers 
Association, Docket ID EPA-HQ-OAR-2019-0055-0369.
    \548\ See the comments of the Motor & Equipment Manufacturers 
Association, Docket ID EPA-HQ-OAR-2019-0055-0462.
    \549\ See the comments of Lubrizol, Docket ID EPA-HQ-OAR-2019-
0055-0454.
---------------------------------------------------------------------------

    We seek comment on the potential benefits of educational and/or 
voluntary, incentive-based programs such as EPA's SmartWay program and 
how such a program could be designed and implemented.\550\
---------------------------------------------------------------------------

    \550\ Learn about SmartWay. Available online at: https://www.epa.gov/smartway/learn-about-smartway. Accessed October 3, 2019.
---------------------------------------------------------------------------

4. Rebuilding
    Clean Air Act section 203(a)(3) prohibits removing or rendering 
inoperative a certified engine's emission controls which typically 
includes being paired with properly functioning aftertreatment devices. 
The regulation at 40 CFR 1068.120 describes how this tampering 
prohibition applies for engine rebuilding and other types of engine 
maintenance. The regulation generally

[[Page 17520]]

requires that rebuilders return a certified engine to its original 
configuration and keep records to document that the rebuilder had a 
reasonable technical basis for believing that the rebuilt engine's 
emission control system performs at least as well as the original 
design.
    Since the rebuilding provisions in 40 CFR 1068.120 broadly apply to 
everyone involved in restoring a rebuilt engine to its certified 
configuration, to the extent that vehicle owners or others remove an 
engine from and install a rebuilt engine in a heavy-duty highway 
vehicle, we consider those steps to be part of the rebuilding process.
    We are not proposing new or modified rebuilding provisions in this 
rule. However, we intend to continue to monitor rebuilding practices 
and may develop updated regulatory provisions in a future rulemaking.
5. Maintenance
    Consistent with the CAA and existing regulations, our proposed 
standards would apply over the applicable useful life. Manufacturers 
perform testing to demonstrate that engines will meet emission 
standards over the full useful life. Manufacturers may perform 
scheduled maintenance on their test engines only as specified in the 
owner's manual. As part of the certification process, manufacturers 
must get EPA approval for such scheduled maintenance, which is also 
subject to minimum maintenance intervals as described in the 
regulations. In this section, we describe the updated maintenance 
provisions we are proposing for heavy-duty highway engines. Section 
IV.F of this preamble summarizes the current the durability 
demonstration requirements and our proposed updates.
    Our proposed maintenance provisions, in a new section 40 CFR 
1036.125, combine and amend the existing criteria pollutant maintenance 
provisions from 40 CFR 86.004-25 and 86.010-38. Similar to other part 
1036 sections we are adding in this proposal, the structure of the new 
40 CFR 1036.125 is consistent with the maintenance sections in the 
standard-setting parts of other sectors (e.g., nonroad compression-
ignition engines in 40 CFR 1039.125).\551\ In 40 CFR 1036.205(i), we 
are proposing to codify the current manufacturer practice of including 
maintenance instructions in their application for certification such 
that approval of those instructions would be part of a manufacturer's 
certification process.\552\ We are also proposing a new paragraph 40 
CFR 1036.125(h) outlining several owner's manual requirements, 
including migrated and updated provisions from 40 CFR 86.010-38(a). For 
example, proposed 40 CFR 1036.125(h)(2) expands on the current 
requirement for manufacturers to describe the documentation owners need 
to provide to show maintenance occurred, by specifying that maintenance 
instructions must clearly state how to ``properly maintain and use'' 
the engine. The new paragraph (h)(2) provides a clearer connection to 
the regulatory requirements for warranty and defect reporting.
---------------------------------------------------------------------------

    \551\ Stout, Alan; Brakora, Jessica. Memorandum to docket EPA-
HQ-OAR-2019-0055. ``Technical Issues Related to Migrating Heavy-Duty 
Highway Engine Certification Requirements from 40 CFR part 86, 
subpart A, to 40 CFR part 1036``. October 1, 2021.
    \552\ See the current submission of maintenance instructions 
provisions in 40 CFR 86.079-39.
---------------------------------------------------------------------------

    This section summarizes maintenance updates recently adopted by 
CARB and introduces our proposed provisions to clarify the types of 
maintenance, update the options for demonstrating critical emission-
related maintenance will occur and the minimum scheduled maintenance 
intervals for certain components, and outline specific requirements for 
maintenance instructions.
i. Recent Updates to CARB Maintenance Regulations
    In two recent rulemakings, CARB updated their maintenance 
regulations and we considered CARB's approach when designing our 
maintenance provisions for this proposal. In its Step 1 warranty 
program, CARB lengthened the minimum allowable maintenance intervals 
for heavy-duty diesel engines to reflect current industry norms for 
scheduling replacement of emissions-related parts.\553\ CARB stated 
that this change limits manufacturers' ability to transfer the 
liability for part replacements to vehicle owners for emissions-related 
parts during the lengthened warranty periods, further strengthening 
warranty coverage.
---------------------------------------------------------------------------

    \553\ California Air Resources Board. HD Warranty 2018 Staff 
Report: Initial Statement of Reasons. May 8, 2018. p III-9. 
Available online: https://ww2.arb.ca.gov/rulemaking/2018/hd-warranty-2018.
---------------------------------------------------------------------------

    CARB staff surveyed owner's manuals for all 2016 California-
certified on-road heavy-duty diesel engines and compiled the intervals 
manufacturers published for specific emission-related components. The 
maintenance intervals published in the owner's manuals were at or above 
the minimum intervals that currently apply for emission-related 
components. For MY 2022 and later HD diesel engines, CARB updated their 
minimum scheduled maintenance intervals to match the shortest (i.e., 
most frequent) interval from those published values for each component. 
If no manufacturer published an interval for a given component, CARB 
set the minimum maintenance interval for that component to match the 
current useful life mileage (i.e., 435,000 miles for HHDD engines). 
CARB's Step 1 program also provides that manufacturers cannot schedule 
replacements for turbochargers, DPF elements, catalyst beds, or exhaust 
gas recirculation systems during the useful life of the engine unless 
the manufacturer agrees to pay for the replacements. These four 
emission-related components were chosen due to their direct emissions 
impact or high cost to replace. Furthermore, CARB clarified that there 
shall be no scheduled maintenance interval throughout the applicable 
useful life for sensors or actuators that are integrated with the 
turbocharger or exhaust gas recirculation (EGR) valve/cooler 
components, as these parts cannot easily be replaced without removing 
the larger systems from the engine. Other sensors and actuators that 
are necessary for the proper function of other emissions-critical 
systems or are not integrated with the turbocharger or EGR systems can 
be included on a maintenance schedule at a minimum interval of 150,000 
miles.
    CARB's HD Omnibus rulemaking did not include further updates to the 
maintenance provisions for diesel engines but addressed HD Otto-cycle 
engines and hybrid vehicles.\554\ Similar to their strategy to identify 
maintenance intervals for diesel engines, CARB surveyed owner's manuals 
for 2018 California-certified HD Otto-cycle engines and updated the 
minimum maintenance intervals for MY 2024 and later HD Otto-cycle 
engines based on the shortest intervals published. For gasoline 
vehicles, EGR systems and catalyst beds were designated ``not 
replaceable'' components. CARB further clarified that the same minimum 
intervals apply to diesel- and Otto-cycle engines used in hybrid 
vehicles.
---------------------------------------------------------------------------

    \554\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. Page III--49.
---------------------------------------------------------------------------

ii. Types of Maintenance
    Our proposed new 40 CFR 1036.125 clarifies that maintenance 
includes any inspection, adjustment, cleaning, repair, or replacement 
of components and, consistent with 40 CFR 86.004-25(a)(2), broadly 
classifies maintenance as

[[Page 17521]]

emission-related or non-emission-related and scheduled or unscheduled. 
We propose to define the following five types of maintenance that 
manufacturers may choose to schedule:

 Critical emission-related maintenance
 Recommended additional maintenance
 Special maintenance
 Noncritical emission-related maintenance
 Non-emission-related maintenance

    We are proposing to define these maintenance categories to 
distinguish between the types of maintenance manufacturers may choose 
to recommend to owners in maintenance instructions, identify the 
requirements that apply to maintenance performed during certification 
durability demonstrations, and clarify the relationship between the 
different types of maintenance, emissions warranty requirements, and 
in-use testing requirements. The proposed provisions described in this 
section specify the conditions for scheduling each of these five 
maintenance categories. Unscheduled maintenance (i.e., repair of failed 
components) is unpredictable and would not be included in a 
manufacturer's maintenance instructions or durability 
demonstration.\555\
---------------------------------------------------------------------------

    \555\ The current provisions of 40 CFR part 1068 describe a 
manufacturer's requirements relating to failed emission-related 
components with respect to emission-related warranty (40 CFR 
1068.110(e)) and defect and recall (1068, subpart F). We are 
proposing to note in a new paragraph 40 CFR 1036.125(h)(2) that 
manufacturers may identify failure to repair critical emission-
related components as improper maintenance if the repairs are 
related to an observed defect.
---------------------------------------------------------------------------

    A primary focus of the current and proposed maintenance provisions 
is critical emission-related maintenance. Critical emission-related 
maintenance includes any adjustment, cleaning, repair, or replacement 
of emission-related components that manufacturers identify as having a 
critical role in the emission control of their engines.\556\ Consistent 
with the current 40 CFR 86.004-25(b)(6)(ii), our proposed 40 CFR 
1036.125(a)(1) allows manufacturers to schedule critical emission-
related maintenance in their maintenance instructions based on the 
manufacturer meeting two conditions: The manufacturer demonstrates the 
maintenance is reasonably likely to occur on in-use engines, and the 
recommended intervals are at least as long as the minimum intervals set 
by EPA. We describe our proposed conditions for demonstrating critical 
emission-related maintenance will occur in Section IV.B.5.iii. In 
Section IV.B.5.iv, we describe our proposal to update the minimum 
maintenance intervals currently specified in 40 CFR 86.004-25(b)(3) and 
(4) for certain critical emission-related components. For new 
technology, not included in the list of proposed components with 
specified minimum maintenance intervals, we are proposing to migrate 
and update the process specified in 40 CFR 86.094-25(b)(7), as 
described in Section IV.B.5.v.
---------------------------------------------------------------------------

    \556\ See Section IV.B.5.iv for our proposed definition of 
critical emission-related components and a list of common critical 
emission-related components for which we are proposing to specify 
minimum scheduled maintenance intervals.
---------------------------------------------------------------------------

    The four other types of maintenance would require varying levels of 
EPA approval. In 40 CFR 1036.125(b), we propose to define recommended 
additional maintenance as maintenance that manufacturers recommend 
owners perform for critical emission-related components in addition to 
what is approved for those components under 40 CFR 1036.125(a). A 
manufacturer may recommend that owners replace a critical emission-
related component at a shorter interval than the manufacturer received 
approval to schedule for critical emission-related maintenance; 
however, the manufacturer would have to clearly distinguish their 
recommended intervals from the critical emission-related scheduled 
maintenance in their maintenance instructions. As described below, 
recommended additional maintenance is not performed in the durability 
demonstration and cannot be used to deny a warranty claim, so 
manufacturers would not be limited by the minimum maintenance intervals 
or need the same approval from EPA by demonstrating the maintenance 
would occur. Special maintenance, proposed in 40 CFR 1036.125(c), would 
be more frequent maintenance approved at shorter intervals to address 
special situations, such as atypical engine operation. Manufacturers 
would clearly state that the maintenance is associated with a special 
situation in the maintenance instructions provided to EPA and owners. 
Our proposed definition of noncritical emission-related maintenance, 
which is based on 40 CFR 86.010-38(d), includes inspections and 
maintenance that is performed on emission-related components but is 
considered ``noncritical'' because emission control will be unaffected. 
As specified in proposed 40 CFR 1036.125(d), manufacturers may 
recommend noncritical emission-related inspections and maintenance in 
their maintenance instructions if they clearly state that it is not 
required to maintain the emissions warranty. Finally, we define ``non-
emission-related maintenance'' as maintenance unrelated to emission 
controls (e.g., oil changes) in proposed 40 CFR 1036.125(e). We propose 
that manufacturers' maintenance instructions can include any amount of 
nonemission-related maintenance that is needed for proper functioning 
of the engine.
    Maintenance instructions play an important role in the service 
accumulation portion of a manufacturer's durability demonstration. We 
currently require that all emission-related scheduled maintenance 
during durability testing occur on the same schedule as specified in 
the maintenance instructions for the purchaser.\557\ When accumulating 
equivalent miles on an engine, manufacturers are currently allowed to 
perform maintenance according to their maintenance instructions. In 
this proposal, we clarify how this relates to the specific types of 
maintenance in proposed 40 CFR 1036.125. Consistent with current 
maintenance provisions, we propose that manufacturers can perform 
critical emission-related maintenance at their approved schedules 
during a durability demonstration. Since the proposed recommended 
additional maintenance provisions do not include the same requirement 
to demonstrate the maintenance will occur in-use, manufacturers could 
not perform recommended additional maintenance during their durability 
demonstration. Special maintenance would also not be performed during a 
durability demonstration, since laboratory-based testing does not 
reflect atypical operation. We propose that manufacturers may perform 
noncritical emission-related inspections on their engines during their 
durability demonstration at any frequency, but could only adjust, 
clean, repair, or replace a component in response to an inspection if 
scheduled maintenance is approved for that component. We propose 
manufacturers can perform any amount of nonemission-related maintenance 
that is needed for proper functioning of the engine during durability 
testing.
---------------------------------------------------------------------------

    \557\ See 40 CFR 86.094-25(b).
---------------------------------------------------------------------------

    The current general warranty requirements of 40 CFR 1068.115(a) 
allow a manufacturer to deny warranty claims for failures resulting 
from improper maintenance or use. We are proposing a new owner's manual 
requirement for manufacturers to specifically identify the steps an 
owner

[[Page 17522]]

must take to properly maintain the engine, including documentation a 
manufacturer may require for an owner to demonstrate the maintenance 
occurred. In 40 CFR 1036.125, we propose to clarify the relationship 
between the different types of maintenance and emissions warranty 
requirements, and specify when manufacturers must note in their 
maintenance instructions (i.e., owner's manual) if a maintenance type 
cannot be used as the basis to deny a warranty claim. We expect 
manufacturers would only schedule critical emission-related maintenance 
and make the effort to demonstrate the maintenance is likely to occur 
in-use for components that they recognize are strongly connected to 
emission performance. As a result, our current maintenance provisions 
allow, and our proposed provisions would continue to allow, 
manufacturers to deny warranty claims if owners do not perform critical 
emission-related maintenance at the recommended schedule, as specified 
in 40 CFR 1068.115. Failure to perform recommended additional 
maintenance could potentially impact emissions, but manufacturers would 
not be able to deny a warranty claim if owners do not perform it, 
because manufacturers would not have taken the extra steps to have it 
approved as critical Manufacturers would be able to deny warranty 
claims if an owner did not perform the special maintenance after it was 
determined that the engine was operated in conditions that meet the 
special situation described in the maintenance instructions. In 
contrast, manufacturers would not be able to deny a warranty claim 
citing ``improper maintenance or use'' for atypical operation if an 
owner follows the corresponding special maintenance instructions. We 
propose that failure to perform noncritical emission-related 
maintenance and nonemission-related maintenance cannot be used to deny 
emissions warranties.
    Since failure to perform maintenance may also impact emissions when 
the engine is in use, we have also identified the relationship between 
the maintenance types and in-use testing. Compression-ignition engine 
manufacturers are subject to off-cycle standards for in-use engines. As 
part of the proposed manufacturer-run testing program in subpart E, we 
specify that manufacturers can select vehicles and engines for testing 
based on proper maintenance and use (see 40 CFR 1036.410(b)(2)). In 40 
CFR 1036.125, we propose that if recommended additional maintenance or 
noncritical emission-related maintenance is not performed on an engine, 
it does not disqualify the engine from in-use testing. Manufacturers 
may reject an engine for in-use testing if the other types of 
maintenance (i.e., critical emission-related maintenance, special 
maintenance, or nonemission-related maintenance) were not performed, 
consistent with current provisions in 40 CFR 86.1908.
iii. Critical Emission-related Maintenance Demonstration
    One of the current conditions for allowing scheduled maintenance to 
be performed during the durability demonstration is that manufacturers 
demonstrate the maintenance is reasonably likely to be performed in-
use.\558\ For critical emission-related scheduled maintenance, we are 
generally including these same requirements in our proposed new 
paragraph 40 CFR 1036.125(a)(1), with clarifications noted below.
---------------------------------------------------------------------------

    \558\ See 40 CFR 86.004-25 and 86.094-25.
---------------------------------------------------------------------------

    Under proposed 40 CFR 1036.125(a)(1)(i), manufacturers could 
demonstrate that the critical maintenance is reasonably likely to occur 
in-use on the recommended schedule by providing data showing that the 
engine's performance unacceptably degrades if the maintenance is not 
performed, consistent with 40 CFR 86.004-25(a)(6)(ii)(A). In this 
proposal, we clarify that this paragraph is intended to cover emission 
control technologies that have an inherent performance degradation that 
coincides with emission increases, such as back pressure resulting from 
a clogged DPF, and is not intended to apply to inducements where a 
manufacturer-specified performance derate is triggered in response to a 
detected or predicted emission increase. We are proposing a separate 
statement in 40 CFR 1036.125(a)(1) that points to the new proposed 
inducement provisions noting that we would accept DEF replenishment as 
reasonably likely to occur if an engine meets the specifications in 
proposed 40 CFR 1036.111.
    Under proposed 40 CFR 1036.125 (a)(1)(ii) and consistent with 40 
CFR 86.004-25(a)(6)(ii)(C), manufacturers could demonstrate a 
reasonable likelihood that the critical maintenance will be performed 
in-use by including a system that displays a visible signal to alert 
drivers that maintenance is due. We are proposing additional criteria 
for use of this visible signal, including that it be continuously 
displayed while the engine is operating and not easily eliminated 
without performing the specified maintenance. We request comment on 
this proposal and any additional criteria we should consider before 
approving a visible signal as a method to ensure critical emission-
related scheduled maintenance is performed.
    Under proposed 40 CFR 1036.125(a)(1)(iii), manufacturers could 
present survey data showing that 80 percent of engines in the field 
receive the specified maintenance. We are maintaining this existing 
option (see paragraphs (B) and (D) of 40 CFR 86.004-25(a)(6)(ii)) in 
our proposal but note that manufacturers have not presented survey data 
related to scheduled maintenance in recent years. We request comment on 
this option and any updates we should consider, including how telematic 
data could be applied and if 80 percent continues to be an appropriate 
threshold.
    We are also proposing in 40 CFR 1036.125(a)(1)(iv) to continue an 
existing provision in 40 CFR 86.004-25(a)(6)(ii)(E) that a manufacturer 
may rely on a clear statement in their maintenance instructions for 
owners that it will provide the critical maintenance free of charge. 
Finally, we propose to continue to allow manufacturers to present other 
options for approval by EPA to demonstrate that critical emission-
related maintenance is reasonably likely to occur (see proposed 40 CFR 
1036.125(a)(1)(v) and current 40 CFR 86.004-25(a)(6)(ii)(F)).
iv. Emission-Related Components and Minimum Maintenance Intervals
    Manufacturers, with EPA approval, may define scheduled maintenance 
for emission-related components, which would be included in maintenance 
instructions directing owners to adjust, clean, or replace components 
at specified intervals. The current regulations in 40 CFR 86.004-25(b) 
specify minimum maintenance intervals for emission-related components, 
such that manufacturers may not specify more frequent maintenance than 
we allow. We propose to migrate and update the minimum maintenance 
intervals from part 86, subpart A to 40 CFR 1036.125(a). These proposed 
minimum intervals would apply for the scheduled adjustment, cleaning, 
or replacement of many common critical emission-related components, as 
described in this section. We are proposing not to migrate the list of 
critical emission-related components currently specified in 40 CFR 
86.004-25, and instead are proposing a new definition of ``critical 
emission-related

[[Page 17523]]

component'' in 40 CFR 1068.30 that refers to 40 CFR part 1068, appendix 
A.
    As part of the migration to part 1036, we are proposing to update 
the lists of components with minimum maintenance intervals to more 
accurately reflect components in use today. We are not including 
carburetors, idle mixture, and particulate trap oxidizers in the 
proposed 40 CFR 1036.125 as these components are obsolete. Our proposed 
language replaces the part 86 diesel particulate trap intervals with a 
more general ``particulate filtration system'' that can apply to 
particulate filters intended for SI or CI engines. We also no longer 
specify an interval for electronic engine control units as we are 
unaware of any scheduled maintenance for those components. Our proposed 
minimum maintenance intervals for each emission-related component or 
system continue to apply to any associated sensors or actuators. We are 
further proposing that these intervals also apply to any hoses, valves, 
and wiring connected to the component or system, such that 
manufacturers would ensure that all parts necessary to keep the 
component functional, including wires and wiring harnesses, remain 
durable throughout useful life or schedule appropriate maintenance to 
address any durability concerns.
    We propose not to migrate the 100,000-mile minimum interval for 
Spark-ignition HDE evaporative emission canister to 40 CFR 1036.125, 
since evaporative emission control systems are covered under the 
vehicle provisions of part 1037. Similarly, we propose that components 
in the refueling emission control system that would be used to meet the 
proposed refueling standards for certain SI HDE, including the carbon 
canisters, filler pipes and seals, refueling flow controls, purge 
systems, and related wiring, actuators, and sensors, would also be 
covered under the maintenance provisions of part 1037.
    We are proposing to add minimum scheduled replacement intervals for 
other components and systems that correspond to technologies we expect 
to be considered by manufacturers for meeting our proposed standards. 
In general, the proposed minimum replacement intervals are set at the 
current useful life for each engine class, since we do not have data 
indicating that manufacturers are scheduling maintenance for these 
components within the current useful life. We are proposing 
NOX sensor minimum intervals at the current useful life 
mileages for the Light, Medium, and Heavy HDE classes. We also propose 
to add minimum intervals for replacing a rechargeable energy storage 
system (RESS) in hybrid vehicles. Our proposed minimum intervals for 
RESS equal the current useful life for the primary intended service 
classes of the engines that these electric power systems are intended 
to supplement or replace. We are not specifying distinct minimum 
intervals for the electric power system components of BEVs and FCEVs; 
instead, manufacturers could request approval for an interval using 40 
CFR 1037.125(a).
    Considering our proposed lengthened useful life periods, we 
reevaluated the current minimum maintenance intervals for replacing 
components and are proposing to extend the replacement intervals such 
that they reflect the scheduled maintenance of components today. Table 
IV-11 summarizes the minimum replacement interval mileages we are 
proposing in a new table in 40 CFR 1036.125(a). Similar to the minimum 
maintenance interval approach adopted by CARB in their recent 
rulemakings (see Section IV.B.5.i), we are proposing to base our 
revised minimum replacement intervals on the scheduled maintenance 
submitted by engine manufacturers for certifying recent model year 
engines.\559\ We believe it is appropriate to account for replacement 
intervals that manufacturers have already identified and demonstrated 
will occur for these components and we are proposing replacement 
intervals for these components that align with the shortest mileage 
interval (i.e., most frequent maintenance) of the published values. We 
propose to update the minimum replacement mileages for remaining 
components that currently do not have specified maintenance intervals 
in the current list from the current 100,000 or 150,000 miles to the 
current useful life mileage for each primary intended service class. 
Since manufacturers are not scheduling replacement of these other 
components within the current useful life of their engines today, we do 
not expect manufacturers would have a technical need to do so in the 
future. We are not proposing to update the maintenance intervals for 
adjusting or cleaning critical emission-related components. These 
intervals are proposed to be migrated, with updated component names 
consistent with the proposed replacement intervals, from 40 CFR 86.004-
25 into a proposed new table in 40 CFR 1036.125(a). Consistent with 
current regulations, our proposed 40 CFR 1036.125(a) would continue to 
allow manufacturers to seek advance approval for new emission-related 
maintenance they wish to include in maintenance instructions and 
perform during durability demonstration.
---------------------------------------------------------------------------

    \559\ Brakora, Jessica. Memorandum to docket EPA-HQ-OAR-2019-
055. ``Approved Scheduled Maintenance Intervals for MY 2019 
Certified Heavy-Duty Engines'', April 27, 2021.

Table IV-11--Proposed Minimum Scheduled Maintenance Intervals for Replacing Critical Emission-Related Components
                                                in 40 CR 1036.125
----------------------------------------------------------------------------------------------------------------
                                                       Accumulated miles (hours) for components
                                    ----------------------------------------------------------------------------
             Component                 Spark-ignition
                                            HDE             Light HDE          Medium HDE          Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs........................       25,000 (750)                 NA                 NA                  NA
DEF filters........................                 NA    100,000 (3,000)    120,000 (3,600)     175,000 (5,250)
Crankcase ventilation valves and        60,000 (1,800)     60,000 (1,800)     60,000 (1,800)      60,000 (1,800)
 filters...........................
Oxygen sensors.....................     80,000 (2,400)                 NA                 NA                  NA
Ignition wires.....................    100,000 (3,000)                 NA                 NA                  NA
Air injection system components....    110,000 (3,300)                 NA                 NA                  NA
Particulate filtration system          100,000 (3,000)    100,000 (3,000)    250,000 (7,500)     250,000 (7,500)
 (other than filter elements)......
Catalyst systems (other than           110,000 (3,300)    110,000 (3,300)    185,000 (5,550)    435,000 (13,050)
 catalyst beds); Fuel injectors;
 Electronic control modules;
 Evaporative emission canisters;
 Turbochargers; EGR system
 components (including filters and
 coolers)..........................
----------------------------------------------------------------------------------------------------------------


[[Page 17524]]


   Table IV-12--Proposed Minimum Scheduled Maintenance Intervals for Adjusting and Cleaning Critical Emission-
                                      Related Components in 40 CR 1036.125
----------------------------------------------------------------------------------------------------------------
                                                       Accumulated miles (hours) for components
                                     ---------------------------------------------------------------------------
     Components and systems \a\         Spark-ignition
                                             HDE             Light HDE          Medium HDE         Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs.........................       25,000 (750)                 NA                 NA                 NA
EGR-related filters and coolers;         50,000 (1,500)     50,000 (1,500)     50,000 (1,500)     50,000 (1,500)
 Fuel injectors; Crankcase
 ventilation valves and filters.....
DEF filters.........................                 NA     50,000 (1,500)     50,000 (1,500)     50,000 (1,500)
Ignition wire; Idle mixture.........     50,000 (1,500)                 NA                 NA                 NA
Oxygen sensors......................     80,000 (2,400)                 NA                 NA                 NA
Air injection system components.....    100,000 (3,000)                 NA                 NA                 NA
Catalyst system components; EGR         100,000 (3,000)    100,000 (3,000)    150,000 (4,500)    150,000 (4,500)
 system components (other than
 filters or coolers); Particulate
 filtration system components;
 Turbochargers......................
----------------------------------------------------------------------------------------------------------------

    The minimum maintenance intervals presented in Table IV-11 and 
Table IV-12 are based on mileage, since equivalent mileage accumulation 
is the parameter used for the durability demonstration. Consistent with 
our current maintenance provisions, we are proposing corresponding 
minimum hours values based on a 33 miles per hour vehicle speed (e.g., 
150,000 miles would equate to 4,500 hours). We request comment on the 
conversion factor between mileage and hours, noting that hours would 
not apply to the manufacturers' durability demonstrations, but may 
impact the frequency of scheduled maintenance for owners with lower 
speed vehicle applications.\560\ Consistent with the current 
maintenance intervals specified in part 86, we are not proposing year-
based minimum intervals; OEMs can use good engineering judgment if they 
choose to include a scheduled maintenance interval based on years in 
their owner's manuals, which is expected to only be used by a small 
number of infrequently operated vehicles. We request comment on the 
need to specify a minimum year-based interval, including data on 
average annual mileages to convert the minimum mileage intervals to 
years for each of the primary intended service classes.
---------------------------------------------------------------------------

    \560\ We are proposing a 20 miles per hour average vehicle speed 
to distinguish low speed vehicles in our emissions warranty proposal 
(see Section IV.B.1) and in our inducement proposal (see Section 
IV.D).
---------------------------------------------------------------------------

    We request comment on all components and systems presented in Table 
IV-11 and Table IV-12 and the corresponding minimum scheduled 
maintenance intervals. Specifically, we request data to support 
different interval values or specific components that should have 
intervals distinct from presented systems. We request comment on our 
proposal to update the list of components and systems, whether 
additional components should be considered, and if any of the listed 
components or systems should be more clearly defined. Additionally, if 
a commenter believes there is value in prioritizing or otherwise 
grouping emission control components, we encourage them to suggest 
criteria to classify the components. We request comment on the numeric 
values of the replacement intervals proposed, and our proposal to 
preserve the current minimum intervals for adjusting and cleaning 
components. Manufacturers and suppliers have shown an interest in 
developing modular emission controls that can be serviced more easily. 
We request comment on the specific emission control systems that may 
use modular components, criteria for defining ``modular'', and 
adjustments to the proposed minimum maintenance intervals or 
replacement restrictions we should consider to account for improved 
serviceability of modular components.
v. Critical Emission-Related Maintenance for New Technology
    Current provisions of 40 CFR 86.094-25(b)(7) outline a process for 
manufacturers to seek approval for new scheduled maintenance that 
includes an EPA announcement of the maintenance interval in the Federal 
Register. Regarding new scheduled maintenance on existing technology, 
we are proposing not to migrate the provision in 40 CFR 86.094-
25(b)(7)(i) for maintenance practices that existed before 1980. 
Instead, the maintenance demonstration and minimum maintenance interval 
provisions we are proposing in the new 40 CFR 1036.125(a) would cover 
the current process for new maintenance on critical emission-related 
components currently in use.
    Regarding scheduled maintenance on new technology, the provision 
currently in 40 CFR 86.094-25(b)(7)(ii) provides a process for approval 
of new critical emission-related maintenance associated with new 
technology. We recognize that new emission control technology may be 
developed in the future and it is important to retain a public process 
for approving maintenance associated with new technology. We are 
proposing to migrate and update 40 CFR 86.094-25(b)(7)(ii) into a new 
40 CFR 1036.125(a)(3) for scheduled critical emission-related 
maintenance associated with new technology. We are proposing to use 
model year 2020 as the reference point for considering whether 
technology is new. Manufacturers using new technology would request a 
recommended maintenance interval, including data to support the need 
for the maintenance, and demonstrate that the maintenance is likely to 
occur at the recommended interval using one of the conditions proposed 
in 40 CFR 1036.125(a)(1). We are also proposing to continue our 
responsibility to communicate such a decision on maintenance for new 
technology. As such, we propose to retain EPA's obligation to publish a 
Federal Register notice based on information manufacturers submit and 
any other available information to announce that we have established 
new allowable minimum maintenance intervals.
    Manufacturers would also continue to have the option currently 
specified in 40 CFR 86.094-25(b)(7)(iii) to ask for a hearing if they 
object to our decision. Hearing procedures are specified in 40 CFR 
1036.820 and 40 CFR part 1068, subpart G, including proposed new 
provisions in 40 CFR part 1068. We request comment on our proposed 
maintenance provisions for new technology, including our proposal to

[[Page 17525]]

use model year 2020 to distinguish ``new'' technology.
vi. Payment for Scheduled Maintenance
    The minimum maintenance intervals specified in Table IV-11 would 
apply for replacement of the listed components and systems. While we 
are proposing replacement intervals for other components in the 
catalyst and particulate filtration systems, current maintenance 
provisions in 40 CFR 86.004-25(b)(4)(iii) state that only adjustment 
and cleaning are allowed for catalyst beds and particulate filter 
elements and that replacement is not allowed during the useful life. 
Current 40 CFR 86.004 25(i) clarifies that these components could be 
replaced or repaired if manufacturers demonstrate the maintenance will 
occur and the manufacturer pays for it. We propose to continue to 
restrict replacement of catalyst beds and particulate filter elements, 
requiring that manufacturers pay for the repair or replacement of 
catalyst beds and particulate filter elements, if needed, within the 
regulatory useful life.
    We are proposing to identify these and other components with 
limited replacement using four criteria based on current provisions 
that apply for nonroad compression-ignition engines.\561\ Our proposed 
40 CFR 1036.125(g) states that manufacturers would pay for scheduled 
maintenance, including parts and labor, if all the following criteria 
are met:
---------------------------------------------------------------------------

    \561\ See 40 CFR 1039.125(g).
---------------------------------------------------------------------------

     Each affected component was not in general use on similar 
engines before 1980,
     The primary function of each affected component is to 
reduce emissions,
     The cost of the scheduled maintenance is more than 2 
percent of the price of the engine, and
     Failure to perform the maintenance would not significantly 
degrade the engine's performance.
    Scheduled maintenance for the replacement of catalyst beds and 
particulate filter elements meets the four criteria of 40 CFR 
1036.125(g). We estimate that EGR valves, EGR coolers, and RESS also 
meet the 40 CFR 1036.125(g) criteria and, under this proposal, 
manufacturers would only be able to schedule replacement of these three 
components if the manufacturer pays for it. In the HD Omnibus 
rulemaking, CARB included turbochargers in their list of components 
``not replaceable'' during the regulatory useful life. Under the 
proposed criteria specified in 40 CFR 1036.125(g), scheduled 
turbocharger maintenance would not meet all four criteria of the 40 CFR 
1036.125(g), since a turbocharger's primary function is not to reduce 
emissions and an underperforming or failed turbocharger would degrade 
engine performance. We request comment on including turbochargers as 
components that should have limited replacement irrespective of the 
four 40 CFR 1036.125(g) criteria. We also request comment on other 
components that meet the criteria, or other criteria EPA should 
consider when determining which components should have limited 
replacement during the scheduled maintenance approval process.
vii. Source of Parts and Repairs
    CAA section 207(c)(3) prohibits manufacturers from requiring 
maintenance work be completed only by OEM-authorized dealers. We are 
proposing a new paragraph 40 CFR 1036.125(f) to clarify that 
manufacturers cannot limit the source of parts and repairs for 
maintenance.\562\ This paragraph would require manufacturers to clearly 
state in their maintenance instructions that owners can choose any 
repair shop or person to perform maintenance. Furthermore, the 
manufacturers cannot specify a particular brand, trade, or corporate 
name for components or service and cannot deny a warranty claim due to 
``improper maintenance'' based on owners choosing not to use a 
franchised dealer or service facility or a specific brand of part. The 
existing and proposed provisions allow manufacturers to specify a 
particular service facility and brand of parts only if they are 
providing the service or component to the owner without charge or if 
the manufacturer convinces EPA during the approval process that the 
engine will only work properly with the identified service or 
component.
---------------------------------------------------------------------------

    \562\ This provision has been adopted in the standard-setting 
parts of several other sectors, including heavy-duty vehicles (see 
1037.125(f)).
---------------------------------------------------------------------------

viii. Maintenance Instructions
    Our proposed 40 CFR 1036.125 preserves the requirement that the 
manufacturer provide written instructions for properly maintaining and 
using the engine and emission control system. We are proposing a new 40 
CFR 1036.125(h) to describe the information that would be required in 
an owner's manual. The proposed 40 CFR 1036.125(h) generally migrates 
the existing maintenance instruction provisions specified in 40 CFR 
86.010-38(a) through (i) with updates as described in Sections IV.B.3 
and IV.C of this preamble. As noted in Section IV.B.3, our 
serviceability proposal supplements the current service information 
provisions currently specified in 40 CFR 86.010-38(j). We are not 
proposing to migrate the service information provisions into part 1036; 
rather, we would preserve their current location in 40 CFR 86.010-
38(j), with updated references to any sections migrated to the new part 
1036.
    While 40 CFR 1036.120(d) allows manufacturers to deny warranty 
claims for improper maintenance and use, owners have expressed concern 
that it is unclear what recordkeeping is needed to document proper 
maintenance and use. Consistent with the current 40 CFR 86.010-
38(a)(2), we propose that manufacturers describe in the owner's manual 
the documentation they consider appropriate to demonstrate the engine 
and emission control system are properly maintained (see 40 CFR 
1036.125(h)(2)). Manufacturers should be able to identify specific 
examples of maintenance practices they would consider improper, and to 
identify their expectations for documenting routine maintenance and 
repairs related to warranty claims. If a manufacturer requires a 
maintenance log as part of their process for reviewing warranty claims, 
we expect the owner's manual would provide an example log that includes 
the required maintenance tasks and intervals and clearly states that 
warranty claims require an up-to-date maintenance record. We would be 
able to review the manufacturers information describing the parameters 
and documentation for demonstrating proper maintenance before granting 
certification for an engine family.
ix. Performing Scheduled Maintenance on Test Engines
    Current provisions defining the limits on maintenance that can be 
performed during testing are specified in 40 CFR 86.004-25(e) and (f). 
We are not migrating those provisions into part 1036; instead, we are 
proposing that the general provisions currently in 40 CFR 1065, subpart 
E, would apply for criteria pollutant standards for model year 2027 and 
later engines.\563\
---------------------------------------------------------------------------

    \563\ We believe the idle speed adjustments, currently 40 CFR 
86.004-25(e)(1), are obsolete, since idle is usually set by the ECM 
and it would not need to be adjusted prior to testing.
---------------------------------------------------------------------------

    We are proposing to update 40 CFR 1065.410(c) to clarify that 
inspections performed during testing include electronic monitoring of 
engine parameters, such as prognostic systems. Manufacturers that 
include prognostic

[[Page 17526]]

systems as part of their engine packages to identify or predict 
malfunctioning components may use those systems during durability 
testing and would include any maintenance performed as a result of 
those systems, consistent with 40 CFR 1065.410(d), in their application 
for certification. We note that, in order to apply these electronic 
monitoring systems in testing, the inspection tool (e.g., prognostic 
system) must be available to all customers or accessible at dealerships 
and other service outlets.

C. Onboard Diagnostics

    As used here, the terms ``onboard diagnostics'' and ``OBD'' refer 
to systems of electronic controllers and sensors required by regulation 
to detect malfunctions of engines and emission controls. EPA's existing 
OBD regulations for heavy-duty engines are contained in 40 CFR 86.010-
18, which were initially promulgated February 24, 2009 (74 FR 8310). 
EPA's OBD requirements promulgated in 2009 were harmonized with CARB's 
OBD program then in place. Since 2009, CARB has revised their OBD 
requirements, while EPA's requirements have not changed. EPA's existing 
OBD program allows manufacturers to demonstrate how the OBD system they 
have designed to comply with California OBD requirements for engines 
used in applications greater than 14,000 pounds also complies with the 
intent of existing EPA OBD requirements.\564\ When applying for EPA 50-
state certification, all manufacturers currently seek OBD approval from 
CARB for OBD systems in engine families and then demonstrate compliance 
with EPA's OBD regulations through this provision. Currently all heavy-
duty manufacturers are certifying to the revised CARB OBD regulations 
that took effect in 2019.\565\
---------------------------------------------------------------------------

    \564\ See 40 CFR 86.010-18(a)(5).
    \565\ CARB Final Rulemaking Package took effect on October 3, 
2019, available here: https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
---------------------------------------------------------------------------

    As part of our effort to evaluate EPA compliance programs, we are 
proposing to update our OBD regulations both to better address newer 
diagnostic methods and available technologies and to streamline 
provisions where possible. These revised regulations are being proposed 
in 40 CFR 1036.110.
1. Incorporation of California OBD Regulations by Reference
    CARB OBD regulations for heavy-duty engines are codified in title 
13, California Code of Regulations, sections 1968.2, 1968.5, 1971.1 and 
1971.5. These regulations have been updated by CARB several times since 
EPA initially promulgated HD OBD regulations in 2009. The most recent 
updates were in October of 2019 and start to phase in with MY 
2022.\566\ It is possible that CARB could further update their heavy-
duty OBD regulations prior to the final rulemaking for this program. In 
July 2021, CARB proposed changes to their OBD program.\567\ These 
amendments may include adding the use of Unified Diagnostic Services 
(``UDS'') to address the concern about the limited number of remaining, 
undefined 2-byte diagnostic trouble codes and the need for additional 
codes for hybrid vehicles. These amendments may also modify freeze 
frame requirements, in-use monitoring performance ratio requirements, 
and expand readiness group lists. As discussed below, our proposal 
intends to harmonize with the majority of CARB's existing OBD 
regulations, as appropriate and consistent with the CAA. EPA also seeks 
comment on harmonizing with any future OBD amendments that may result 
from this proposal.
---------------------------------------------------------------------------

    \566\ The most recent updates for 13 CCR 1971.1 and 13 CCR 
1971.5 are available here https://ww2.arb.ca.gov/resources/documents/heavy-duty-obd-regulations-and-rulemaking.
    \567\ CARB 2021 OBD II and Heavy-Duty OBD (HD OBD) Regulatory 
Documents Public Notice for OBD Regulations Update, July 22, 2021. 
Available here: https://ww2.arb.ca.gov/resources/documents/obd-ii-regulations-and-rulemaking.
---------------------------------------------------------------------------

    In response to the ANPR, EPA received a number of comments 
supportive of EPA's adoption of the revised CARB OBD program including 
the 2019 rule amendments.\568\ In particular, many commenters were 
supportive of the new tracking requirements contained in CARB's updated 
OBD program, known as the Real Emissions Assessment Logging (``REAL'') 
program to track real-world emissions systems performance of heavy-duty 
engines. This update requires the collection of onboard data using 
existing OBD sensors and other vehicle performance parameters, which 
would allow the assessment of real-world, in-use emission performance 
relative to laboratory performance beginning in the 2022 model year.
---------------------------------------------------------------------------

    \568\ For example, see comments from Roush, Docket ID EPA-HQ-
OAR-2019-0555-0303; International Council on Climate Change, Docket 
ID EPA-HQ-OAR-2019-0555-0304; and the Metropolitan Washington 
Council of Governments, Docket ID EPA-HQ-OAR-2019-0555-0286.
---------------------------------------------------------------------------

    In developing the ANPR, we considered proposing to update the 
current text in 40 CFR 86.010-18 and migrate it into the new 40 CFR 
1036.110. However, given industry's familiarity with the current CARB 
regulations, we have decided instead to propose incorporating by 
reference in 40 CFR 1036.110 the existing CARB OBD regulations updated 
in 2019 as the starting point for our updated OBD regulations. EPA's 
proposed OBD requirements are closely aligned with CARB's existing 
requirements with a few exceptions. We are proposing to exclude certain 
provisions that are not appropriate for a federal program and to 
include additional elements to improve on the usefulness of OBD systems 
for users.\569\ We are taking comment on whether and to what extent we 
should harmonize with CARB's next expected update to their OBD 
regulations, or whether the proposed language in 40 CFR 1036.110(b) is 
sufficient to accommodate any future divergence in CARB and EPA OBD 
requirements. EPA anticipates that this language would allow for EPA 
approval of OBD systems that meet certain parts of updated CARB 
requirements (e.g., updated communication protocols), as long as such 
provisions meet the intent of EPA OBD requirements.
---------------------------------------------------------------------------

    \569\ The legal effect of incorporation by reference is that the 
material is treated as if it were published in the Federal Register 
and CFR. This material, like any other properly issued rule, has the 
force and effect of law. Congress authorized incorporation by 
reference in the Freedom of Information Act to reduce the volume of 
material published in the Federal Register and CFR. (See 5 U.S.C. 
552(a) and 1 CFR part 51). See https://www.archives.gov/federal-register/cfr/ibr-locations.html for additional information.
---------------------------------------------------------------------------

i. OBD Threshold Requirements
    The most essential component of the OBD program is the threshold 
requirement. Heavy-duty engine emission control components can 
contribute to an increase in emissions if they malfunction and 
therefore, they must be monitored by OBD systems. Existing OBD 
requirements specify how OBD systems must monitor certain components 
and indicate a fault code prior to when emissions would exceed emission 
standards by a certain amount, known as an emission threshold. Emission 
thresholds for these components are generally either an additive value 
above the exhaust emission standard, or a multiple of the standard. 
Reductions to emission standards mean that without additional action, 
OBD thresholds would also be reduced proportionally.
    The CARB Omnibus Amendments to the HD OBD regulation include a 
provision that will not proportionally reduce NOX and PM OBD 
threshold requirements that correspond to the new lower emission 
standards.\570\ This

[[Page 17527]]

means the future numerical values of OBD NOX and PM 
thresholds would remain unchanged from today's numerical thresholds as 
a part of that rulemaking. CARB noted in the Omnibus rule that more 
time is needed to fully evaluate the capability of HD OBD monitors to 
accommodate lower thresholds that would correspond to lower emission 
levels. EPA is proposing to harmonize with this policy and not lower 
OBD NOX and PM threshold levels in our proposed OBD 
regulations at this time. EPA may consider updating threshold 
requirements in a separate action which may align with a future CARB 
action. Specifically, we are proposing that heavy-duty compression-
ignition engines would be subject to NOX and PM thresholds 
of 0.4 g/hp-hr and 0.03 g/hp-hr, respectively, for operation on the FTP 
and SET duty cycles. For spark ignition engines, we are proposing the 
following thresholds to align with CARB: 0.30 g/hp-hr for monitors 
detecting a malfunction before NOX emissions exceed 1.5 
times the applicable standard, 0.35 g/hp-hr for monitors detecting a 
malfunction before NOX emissions exceed 1.75 times the 
applicable standard, and 0.60 g/hp-hr for monitors detecting a 
malfunction before NOX emissions exceed 3.0 times the 
applicable standard. For spark ignition engines, we are also proposing 
a 0.015 g/hp-hr threshold for PM emissions to align with CARB. EPA is 
seeking comment on this proposed action, or whether thresholds should 
be modified as a part of this proposal.\571\
---------------------------------------------------------------------------

    \570\ California Air Resources Board. Heavy-Duty Omnibus 
Regulation. Available online: https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.
    \571\ California Air Resources Board. Staff Report: Initial 
Statement of Reasons-Public Hearing to Consider the Proposed Heavy-
Duty Engine and Vehicle Omnibus Regulation and Associated 
Amendments. June 23, 2020. https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf.
---------------------------------------------------------------------------

ii. CARB OBD Provisions Revised or Not Included in the Proposed Federal 
Program
    EPA is proposing to adopt the majority of the CARB OBD program. 
However, we are proposing that some provisions may not be appropriate 
for the federal regulations.\572\ As part of CARB's development of the 
2019 OBD program, a number of stakeholders submitted comments to 
CARB.\573\ In developing this proposal, we have reviewed the concerns 
raised by stakeholders to CARB to help us determine what provisions may 
not be appropriate in a federal program. In a new 40 CFR 1036.110(b), 
we are proposing clarifications and changes to the 2019 CARB 
regulations we are otherwise incorporating by reference, including 
provisions related to:
---------------------------------------------------------------------------

    \572\ Note that we are making no determination in this proposal 
about the appropriateness of these provisions for CARB regulation.
    \573\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055. 
``Comments submitted to the California Air Resources Board during 
the development of updated heavy-duty OBD requirements.'' October 1, 
2021.
---------------------------------------------------------------------------

    1. Providing flexibilities to delay compliance up to three model 
years for small manufacturers who have not previously certified an 
engine in California,
    2. Allowing good engineering judgment to correlate the CARB OBD 
standards with EPA OBD standards,
    3. Clarifying that engines must comply with OBD requirements 
throughout EPA's useful life as specified in 40 CFR 1036.104, which may 
differ from CARB for some model years,
    4. Clarifying that the purpose and applicability statements in 13 
CCR 1971.1(a) and (b) do not apply,
    5. Specifying NOX and PM threshold requirements,
    6. Not requiring the manufacturer self-testing and reporting 
requirements in 13 CCR 1971.1(i)(2.3) and 1971.1(i)(2.4),
    7. Retaining and migrating our existing deficiency policy into 
proposed 40 CFR 1036.110(d), and specifying that the deficiency 
provisions in 13 CCR 1971.1(k) do not apply,
    8. Requiring additional freeze frame data requirements,
    9. Requiring additional data stream parameters for compression- and 
spark-ignition engines, and
    10. Providing flexibilities to reduce redundant demonstration 
testing requirements for engines certified to CARB OBD requirements.
    Manufacturers indicated concern with the existing manufacturer 
self-testing (``MST'') requirements in 13 CCR 1971.1(i)(2.3 and 2.4). 
This provision requires manufacturers to obtain vehicles that have 
reached their full useful life and remove the engine for extensive 
testing to quantify emission performance and deterioration of the 
system elements in a manner that allows comparison to deterioration and 
performance levels achieved with the manufacturer's accelerated aging 
process. In 2009, when EPA initially promulgated OBD regulations for 
the heavy-duty industry, we were concerned about the difficulty and 
expense of removing an in-use engine from a vehicle for engine 
dynamometer testing, and we did not adopt such a requirement at that 
time.\574\ EPA continues to be concerned that the cost of this testing 
may be significant and is not warranted for the federal program. 
Further, we believe that the information CARB gains from this program 
can be shared with EPA and would help inform us of the ongoing progress 
manufacturers are making with OBD compliance. Therefore, while we are 
proposing to exclude this CARB OBD provision from the EPA OBD 
regulations at this time, we are proposing that manufacturers submit 
the results of any MST testing performed for CARB to EPA.
---------------------------------------------------------------------------

    \574\ 74 FR 8347, February 24, 2009.
---------------------------------------------------------------------------

    EPA requests comments and information on whether there are 
opportunities for further reducing OBD compliance and certification 
costs of the federal program through increasing the use of modeling or 
other calculation-based methods as a part of the certification process 
which could potentially replace certain testing requirements. Examples 
could include test-out provisions or testing required for infrequent 
adjustment factors. CARB's OBD program includes provisions that may 
allow for certain components to meet specific test-out criteria which 
would exempt them from monitoring requirements. For example, 13 CCR 
1971.1(e)(3.2.6)(B) describes how EGR catalysts would be exempt from 
monitoring if manufacturers can show that both of the following 
criteria are satisfied: (1) No malfunction of the EGR catalyst can 
cause emissions to increase by 15 percent or more of the applicable 
NMHC, NOX, CO, or PM standard as measured from an applicable 
emission test cycle; and (2) no malfunction of the EGR catalyst can 
cause emissions to exceed the applicable NMHC, NOX, CO, or 
PM standard as measured from an applicable emission test cycle. EPA is 
seeking comment on whether manufacturers could use modeling or other 
calculation-based methods to determine if such test-out criteria are 
met.
    Another example where the use of modeling or other calculation-
based methods could reduce testing requirements is for the calculation 
of infrequent regeneration adjustment factors for engines equipped with 
emission controls that experience infrequent regeneration events. These 
adjustment factors are used to account for emissions from regeneration 
events when determining compliance with EPA standards. Manufacturers 
must conduct testing to develop these adjustment factors using the same 
deteriorated component(s) used to determine if the test-out criteria 
are being met. EPA is seeking comment on whether it is possible and 
appropriate to consider modeling- or calculation-based methods to 
replace certain hardware-based test methods in these or other

[[Page 17528]]

areas of certification to reduce costs without reducing the 
functionality of the existing OBD requirements.
    EPA is seeking comment on how these or other provisions in the 
existing or any potential upcoming CARB OBD regulation could be 
modified to better suit the federal OBD program.\575\ It is important 
to emphasize that by not incorporating certain existing CARB OBD 
requirements (e.g., the in-use engine test program) into our 
regulations, we are not waiving our authority to require such testing 
on a case-by-case basis. CAA section 208 gives EPA broad authority to 
require manufacturers to perform testing not specified in the 
regulations in such circumstances. Thus, should we determine in the 
future that such testing is needed, we would retain the authority to 
require it pursuant to CAA section 208.
---------------------------------------------------------------------------

    \575\ CARB intends to propose changes to their HD OBD program, 
as mentioned in the CARB Workshop for 2020 OBD Regulations Update, 
February 27, 2020. Available here: https://ww3.arb.ca.gov/msprog/obdprog/obd_feb2020wspresentation.pdf.
---------------------------------------------------------------------------

    EPA is proposing to retain our existing deficiency provisions in 40 
CFR 86.010-18(n) and not harmonize with CARB's deficiency provisions in 
13 CCR 1971.1(k).\576\ In the 2009 OBD rule, EPA stated that having a 
deficiency provision is important ``because it facilitates OBD 
implementation by allowing for certification of an engine despite 
having a relatively minor shortfall,'' and that while the CARB OBD 
regulations have a provision to charge fees associated with OBD 
deficiencies, EPA has ``never had and will continue not to have any 
such fee provisions.'' EPA is requesting comment on retaining our 
existing deficiency requirements in its entirety or if any changes 
should be made. EPA also seeks comment on how and for what reasons OEMs 
have utilized CARB's deficiency policy, how this may impact compliance 
with the new EPA and CARB requirements and how this may be impacted by 
any future changes in OBD emission thresholds.\577\
---------------------------------------------------------------------------

    \576\ We are proposing to migrate the existing deficiency 
provisions of 40 CFR 86.010-18(n) into 40 CFR 1036.110(d).
    \577\ California Code of Regulations, Title 13, section 
1971.1(k)
---------------------------------------------------------------------------

    CARB's 2019 OBD update to 13 CCR 1971.1 also includes significant 
changes applicable to hybrid vehicles. We are aware that current OBD 
requirements necessitate close cooperation between engine and hybrid 
powertrain system manufacturers for certification, which can present a 
significant challenge for introducing heavy-duty hybrids into the 
marketplace. To learn more about this potential challenge, EPA 
requested input in the ANPR. We learned from commenters that no 
manufacturers have pursued a certification flexibility that CARB put in 
place in 2016 through the Innovative Technology Rule (ITR). The ITR 
provided short-term certification flexibilities, such as allowing 
hybrid manufacturers to use Engine Manufacturers Diagnostics (EMD), 
rather than heavy-duty OBD for two to four consecutive model years 
depending on the all-electric range of the 
vehicle.578 579 580 We also heard from at least one hybrid 
manufacturer suggesting that onboard NOX sensors could be 
used in lieu of OBD for heavy-duty hybrids. The potential use of 
onboard sensors to meet some OBD requirements for any heavy-duty 
vehicle, including hybrids, is discussed in Section IV.C.2.ii below. We 
continue to be interested in understanding from commenters and request 
comment on whether and how OBD may present a barrier to the adoption of 
heavy-duty hybrid systems, and any potential opportunities for EPA to 
address such barriers. We have prepared a memorandum that further 
explores these regulatory issues, with a discussion of a range of 
possible options that we are considering for hybrid systems in heavy-
duty specialty vehicles, but which could apply more broadly to all 
heavy-duty hybrid systems.\581\
---------------------------------------------------------------------------

    \578\ Heavy-duty EMD requires diagnostic monitoring of the 
performance and durability of the fuel system, exhaust gas 
recirculation system (if so equipped), particulate trap, and other 
emission-related electronic components.
    \579\ California Code of Regulations, Title 13, section 2208.1
    \580\ See the comments of the California Air Resources Board, 
Docket ID EPA-HQ-OAR-2019-0055-0471.
    \581\ Stout, Alan. Memorandum to Docket EPA-HQ-OAR-2019-0055. 
``Draft Amendments Related to Alternate Engine Standards for 
Specialty Vehicles''. January 31, 2022.
---------------------------------------------------------------------------

    Finally, EPA is seeking comment on whether improvements could be 
made to OBD to monitor inducement conditions. For example, while 
individual components responsible for inducements currently are 
monitored (e.g., DEF level sensors), there is no requirement that 
inducements themselves be monitored to ensure a false inducement did 
not occur or that such events are tracked for remediation. EPA seeks 
comment on whether OBD systems should monitor the inducement process 
and detect system malfunctions prior to a failure (e.g., for 
deterioration of the DEF delivery system) to improve emission system 
performance by providing opportunities for repairs to be made prior to 
complete failures and by preventing inducements that either should not 
have occurred or could have been avoided.
iii. Additional OBD Provisions in the Proposed Federal Program
    EPA received comments on the ANPR from a wide variety of 
stakeholders describing difficulties diagnosing problems with and 
maintaining proper functionality of advanced emission technologies and 
the important role accessible and robust diagnostics play in this 
process. The California Air Pollution Control Officers Association and 
NACAA commented on the need for EPA to develop and maintain a robust 
OBD program with diagnostic specificity that would ensure OBD continues 
to accurately detect system failures for lower emission standards and 
inform the person performing the repair of what the problem is and the 
cause, so it can be promptly, proficiently and cost-effectively 
repaired, as well as to facilitate the development of comprehensive 
enforcement programs.582 583 The Pennsylvania Department of 
Environmental Protection commented that EPA should evaluate how 
advances in OBD technology could be applied to enhance operations, 
monitoring and maintenance capabilities of heavy-duty diesel 
aftertreatment systems and how current and future technologies may use 
OBD technologies to inform operators and repair technicians as to the 
in-use efficacy of those systems across multiple duty cycles.\584\ ATA 
commented that ease of diagnostics for emission component failures is a 
significant concern for their members.\585\ NASTC members expressed 
significant frustration with the inability to use existing diagnostics 
to understand problems with emission components.\586\
---------------------------------------------------------------------------

    \582\ See the comments of the California Air Pollution Control 
Officers Association, Docket ID EPA-HQ-OAR-2019-0555-0275.
    \583\ See the comments of the National Association of Clean Air 
Agencies, Docket ID EPA-HQ-OAR-2019-0055-0283.
    \584\ See the comments of The Pennsylvania Department of 
Environmental Protection, Docket ID EPA-HQ-OAR-2019-0055-0455.
    \585\ See the comments of the American Trucking Association, 
Docket ID EPA-HQ-OAR-2019-0055-0357.
    \586\ See the comments of the National Association of Small 
Trucking Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
---------------------------------------------------------------------------

    As a part of our effort to update our OBD program and respond to 
these concerns, EPA is proposing to include additional requirements as 
well as modify certain CARB OBD requirements to better address newer 
diagnostic methods and technologies and to ensure that OBD can be used 
to properly diagnose and maintain emission control

[[Page 17529]]

systems to avoid increased real-world emissions. EPA intends to 
continue to accept CARB OBD approval where a manufacturer can 
demonstrate that the CARB program meets the intent of EPA OBD 
requirements (see section IV.C.2.i.b. for further discussion), and 
manufacturers would submit documentation as specified in proposed 40 
CFR 1036.110(c)(5) to show that they meet the additional requirements 
proposed here.
    In this section we describe the following proposed additional EPA 
certification requirements in 40 CFR 1036.110 for OBD systems:
    1. Health monitors for the SCR, DPF, and EGR systems
    2. Display health monitor and inducement-related information in the 
cab
    3. Diagnostic testing to measure the effectiveness of DEF dosing 
must be made available for use with either a generic scan tool or an 
equivalent alternative method
    Enhanced OBD systems that provide more information and value to the 
operator can play an important role in ensuring expected in-use 
emission reductions are achieved long-term. For example, in comments to 
the ANPR, CARB stated that their test programs have identified numerous 
heavy-duty vehicles with mileages within their applicable regulatory 
useful life periods, but beyond their warranty periods, that had 
NOX emission levels significantly above the applicable 
certification standards.\587\ CARB also stated that some stakeholders 
such as fleet owners, retrofit installers, and equipment operators have 
communicated to CARB that they are experiencing significant vehicle 
downtime due to parts failures.
---------------------------------------------------------------------------

    \587\ See the comments of the California Air Resources Board, 
Docket ID EPA-HQ-OAR-2019-0055-0471.
---------------------------------------------------------------------------

    Increasing the transparency and usefulness of OBD systems can help 
to improve maintenance and repair experiences and also serve as a 
mechanism to reduce owner frustration (which otherwise could provide 
motivation to tamper). EPA is specifically proposing to improve the 
robustness and usefulness of OBD systems by including emission system 
health monitors, increasing the number of publicly available data 
parameters, increasing the freeze frame data, and enabling certain 
self-testing capabilities for owners. These changes will benefit the 
environment by helping to reduce malfunctioning emission systems in-use 
through access to additional data that may be useful for service 
technicians, state and local inspection and maintenance operations, and 
owners. These capabilities are also important to enable owners to avoid 
potential inducement conditions that can result from certain component 
failures.
a. Emissions Systems Health Monitor
    The purpose of OBD is to reduce motor vehicle and motor vehicle 
engine emissions by monitoring the systems in-use, detecting 
malfunctions, informing the operator, and assisting with diagnosis of 
emission system problems. One concept EPA is proposing to incorporate 
into our updated OBD regulations is the development of ``health 
monitors'' for specific emission control technologies on CI engines to 
provide vehicle owners information on the overall health of important 
emissions systems at a given point in time. While OBD systems are 
highly proficient in monitoring emission systems and components, the 
historic purpose of OBD has been to monitor systems but only notify 
operators generically (e.g., through the Malfunction Indicator Light or 
``MIL'') once there is a failure or malfunction, rather than to use 
monitored data to proactively provide the operator with information on 
the functionality and status of such systems. However, existing OBD 
monitors and data parameters could also be used in a different way to 
generate aftertreatment health monitors. This could be accomplished by 
evaluating data indicating how much a system has been used or how close 
a system is to exceeding an OBD threshold. While most large fleets have 
already begun to use similar measures by using big data and telematics 
to implement predictive maintenance, this concept is different in that 
it would be focused on using a particular vehicle's data to evaluate 
system status as opposed to using data from thousands of trucks to 
predict system status.\588\ Predictive maintenance relies on analytics 
that examine existing data to identify potential risks of failure on 
particular trucks or components prior to the failures occurring in the 
field.\589\ Predictive maintenance can enable operators to replace 
components later than when utilizing a traditional preventative 
maintenance approach and can essentially increase the service life of 
certain emission system components, prevent breakdowns, and reduce 
total operating costs. Predictive maintenance could also result in 
components being changed more frequently to avoid or reduce breakdowns 
and downtime, thereby also reducing total operating costs. An emissions 
system health monitor, while not as comprehensive of a tool as 
predictive maintenance, could provide similar types of benefits 
resulting in more uptime for emission control systems. Health monitors 
could also provide critical insight on the status of a vehicle's 
emissions systems for buyers considering purchasing used trucks. EPA is 
proposing that the health monitors' status would need to be made 
available on the dash or other display for access to the data without 
the use of a scan tool. The purpose of the health monitor is not to 
guarantee the performance of an emissions system in the future, but 
instead to provide status information on the functioning of the 
relevant system at the moment in time. In addition, such a monitor 
could be used to warn users of potential upstream failures that can 
cause damage to aftertreatment components resulting in expensive 
repairs. EPA worked with Environment and Climate Change Canada 
(``ECCC'') to develop this concept. Using an emissions system health 
monitor to improve and make more efficient heavy-duty engine and 
vehicle maintenance practices could provide environmental benefits by 
helping to sustain system performance long-term.
---------------------------------------------------------------------------

    \588\ Park, Jim. September 7, 2018. ``How Data Is Changing 
Predictive Maintenance.'' Available here: https://www.truckinginfo.com/312738/how-data-is-changing-predictive-maintenance.
    \589\ Lockridge, Deborah. May 31, 2019. ``How One Fleet is 
Closing in on Predictive Maintenance.'' Available here: https://www.truckinginfo.com/332946/how-one-truck-fleet-is-closing-in-on-true-predictive-maintenance.
---------------------------------------------------------------------------

    In discussions with ECCC about how to develop a health monitor 
concept, they suggested that a single value representing the 
performance of the vehicle's emission system as a whole would be less 
effective than two or three individual ``health monitors'', and EPA 
agrees. EPA is proposing, and seeking comment on the benefits of, 
specific methods for CI engines to inform a vehicle operator of the 
general health of the DPF, SCR, and EGR systems. There are two main 
approaches EPA could use to achieve this goal: (1) A broad requirement 
that leaves the identification and implementation of the specific 
methodologies up to each manufacturer, or (2) a specific requirement 
that prescribes the methodologies to be used by all manufacturers. EPA 
is proposing the first alternative, and seeks comment on the second 
alternative, or any other alternative that commenters believe would be 
more beneficial or less costly and that would still provide benefits to 
the owner and resulting environmental benefits from better performing

[[Page 17530]]

emissions controls systems. Under any approach, we are interested in 
emissions system health monitors that better enable owners to 
understand emission system functionality, help avoid potential 
breakdowns, and reduce incentives to tamper with emission control 
systems as a result of experiencing unplanned and catastrophic emission 
system failures. A prescriptive approach may be more useful in that it 
would provide consistency between manufacturers which could result in 
more useful and stable data for users, however, a broad requirement 
that allows manufacturers to better capitalize on their existing OBD 
system design may also achieve the goals of this health monitor 
proposal. This proposal focuses on leveraging existing OBD requirements 
in new ways to develop health monitors for DPF, SCR, and EGR systems to 
avoid costs that could be associated with an entirely new monitoring 
requirement. EPA seeks comment on whether additional monitors could be 
developed utilizing existing OBD requirements which can further help 
prevent downtime, such as additional upstream health indicators (e.g., 
preventing excessive internal oil leaks) to proactively prevent damage 
to expensive aftertreatment components.

(1) Proposed DPF Health Monitor

    For the DPF system, EPA has identified essential information that 
users should have access to for ensuring that proper maintenance and 
use can occur. Having continuous access to DPF health information can 
provide important insight on DPF system status. EPA is proposing that 
users have access to the following information available for display in 
the cab, which together would form the DPF health monitor: (1) A value 
that indicates general system wear, for example a counter for the total 
number of passive and active regeneration (``regen'') events that have 
taken place on the existing DPF, (2) a value that indicates the average 
active and passive regen frequency and a method for operators to track 
changes in these values, (3) a value estimating (in miles or hours) 
when the DPF needs to be cleaned to remove accumulated ash, and (4) 
notification when active regens have been disabled by the system (even 
temporarily) if accompanied by a derate, as well as the reason it was 
disabled. While not specifically a part of the DPF health monitor, EPA 
is proposing additional DPF maintenance information be made available 
to users to improve serviceability experiences, see section IV.B.3.ii. 
for more discussion on these proposed requirements.
    Providing users with a general indicator of system wear can help 
users make informed maintenance decisions. EPA would expect that a 
manufacturer would allow this monitor to be reset if a DPF is replaced. 
Manufacturers could in part utilize work that may be done to meet CARB 
OBD requirements to implement this proposal. For example, the 2019 CARB 
OBD program that we are proposing to harmonize with includes a 
provision for MY 2024 that requires a lifetime counter of DPF regens 
(see 13 CCR 1971.1(h)(5.8.2)). EPA is seeking comment on the use of 
CARB's required lifetime counter to meet this proposed requirement, or 
what alternative information manufacturers could use to meet this 
requirement and whether this information should be standardized.
    Providing users with an indication of the total average regen 
frequency (active and passive) and with a method that could be used to 
detect recent changes in system function can allow users to familiarize 
themselves with proper system operation. For example, this could be 
achieved by displaying the average regen frequency per a fixed number 
of miles or hours and providing a resettable counter to show the most 
recent average regen frequency. Such a feature would enable owners to 
monitor the number of regens occurring over a particular route to 
detect changes (e.g., a significant increase in the number of 
regeneration events) which could inform them of the need to address 
failures upstream of the DPF, clean the DPF, or service the DPF system. 
In particular, EPA seeks to alert operators to potential conditions 
that could indicate an upstream problem (e.g., an oil leak) that can 
damage sensitive aftertreatment components prior to a catastrophic 
failure or result in the need for costly repairs to aftertreatment 
systems. Manufacturers may be able to utilize existing work already 
being done to meet the frequent regeneration requirements in 13 CCR 
1971.1(e)(8.2.2) to inform owners when regen frequency exceeds a 
certain level that may indicate an upstream issue. As discussed 
earlier, EPA is proposing that the health monitors' status would need 
to be made available on the dash or other display for access to the 
data without the use of a scan tool. EPA would expect that operators 
would be able to access this information on demand, and that 
manufacturers would not have the health monitor tied to the MIL to 
avoid any confusion. EPA is seeking comment on whether this component 
of the DPF health monitor is important enough to require that it be 
communicated when the frequency of regens reaches a particular level 
that may indicate the need for inspection and possibly repair, what 
this level would be, and what such a warning system should look like.
    Having access to information that indicates an estimate of when the 
DPF needs to be cleaned would allow operators to plan ahead for 
critical maintenance and reduce downtime. We are not proposing a 
specific method manufacturers would use to generate the estimated time 
to perform such a cleaning, rather we would leave it to manufacturers 
to determine the best method of implementation.
    Finally, providing operators with notification of when active 
regens have been disabled by the system (even temporarily) as well as 
the reason it was disabled would provide benefits to operators and 
repair technicians. Manufacturers generally implement severe derates 
when DPF system faults occur that prevent active regens from occurring. 
Providing owners with information on the cause of a DPF-related derate 
would reduce frustration and may reduce downtime by allowing repairs to 
be made more quickly, increasing in-use emission system performance.
    EPA is seeking comment on how manufacturers could lessen the 
effects of duty cycle related regens frequency variability in the 
health monitor (e.g., vehicles that operate more at lower speeds would 
likely experience more active regens than those that operate at higher 
steady-state speeds), through normalizing the reported data or focusing 
on specific regions of operation where regens occur with more 
regularity. For example, this DPF health monitor parameter could 
include only passive regens that occur during certain vehicle 
operation, such as operation that occurs in OBD REAL Bin 14. EPA is 
seeking comment on whether the DPF health monitor should provide this 
information on demand, and if it should also notify users of potential 
concerns.
(2) Proposed SCR Health Monitor
    For the SCR system, EPA has identified essential information that 
users should have access to for ensuring that proper preventive 
maintenance occurs. EPA is proposing that the SCR health monitors' 
status would need to be made available on the dash or other display for 
access to the data without the use of a scan tool. Having access to SCR 
health information on demand can provide important insight on SCR 
system status and help operators prevent inducements from occurring. 
EPA is proposing that users have access to the following information 
for the SCR

[[Page 17531]]

health monitor: (1) Indicator of average DEF consumption and a method 
for operators to track changes in this value, (2) warnings before 
blockages in the DEF line or dosing valve actually occur and an 
inducement would be triggered, and (3) information on when DEF dosing 
has been disabled by the system (even temporarily) if accompanied by a 
derate as well as the reason it was disabled. EPA is not proposing 
specific methods manufacturers would use to meet these requirements and 
would be leaving it up to manufacturers to develop the most appropriate 
method based on their product designs. We are taking comment on this 
approach, or if instead we should specify the way the SCR health 
monitor should be implemented, which would ensure consistency across 
the fleet.
    Providing users with an indication of average DEF consumption and 
with a method that could be used to detect recent changes in that value 
can allow users to familiarize themselves with proper system operation. 
This could be achieved for example by manufacturers providing the 
lifetime average DEF used per gallon of fuel and a recent or resettable 
counter to show the most recent average DEF consumption value. Such a 
feature would enable owners to develop a high-level understanding of 
proper SCR function and operation, can alert the operator to changes 
that may indicate a problem before there is a failure resulting in a 
breakdown and corresponding downtime, and enable owners to monitor the 
data over a particular route (or after a particular repair) to detect 
system changes (or evaluate the effectiveness of a recent repair).
    EPA is seeking comment on how manufacturers could lessen the 
effects of duty cycle related DEF consumption variability in the health 
monitor, through normalizing the reported data or focusing on specific 
regions of operation where DEF consumption should be more stable. For 
example, this SCR health monitor parameter could include provide 
average DEF consumption that occurs during certain vehicle operations, 
such as operation that occurs in OBD REAL Bin 14.
    The SCR health monitor proposal also includes a requirement for 
manufacturers to provide information to the operator regarding 
potential plugging of the DEF line or dosing valve prior to a blockage 
actually occurring. Manufacturers have likely developed strategies to 
monitor such blockages in response to EPA's existing inducement 
guidance.590 591 DEF can crystallize over time and build up 
in SCR components such as the injector, which in some cases could also 
result in a false inducement being triggered for conditions that appear 
to be caused by tampering, which this health monitor can help 
prevent.\592\ Further, it is critical to ensuring that DEF restrictions 
are promptly addressed to maintain proper SCR system function. Finally, 
EPA is proposing that the health monitor provide information on when 
DEF dosing has been disabled by the system (even temporarily) as well 
as the reason it was disabled if accompanied by a derate. Having access 
to this information is critical to ensuring operators can perform 
maintenance timely, and potentially prior to a vehicle going into 
inducement. EPA is seeking comment on whether the SCR health monitor 
should provide this information on demand, and if it should also notify 
users of potential concerns.
---------------------------------------------------------------------------

    \590\ See CISD-09-04 REVISED.
    \591\ See Section IV.D.4. for further discussion on proposed 
inducement-related requirements for blocked DEF lines.
    \592\ For example, see NHTSA Service Bulletin available here: 
https://static.nhtsa.gov/odi/tsbs/2019/MC-10153679-9999.pdf.
---------------------------------------------------------------------------

    Finally, EPA is seeking comment on alternative methods to develop a 
health monitor for SCR systems, for example including one that would 
use DEF dosing trim values (i.e., DEF dosing rates at particular 
operating points such as within NTE operating zones or REAL bins) and 
compare the dosing rate that is occurring in real-time to what the 
dosing rate was when the vehicle was new. The idea is that as 
components wear and SCR performance deteriorates, the system may 
compensate by increasing the DEF dosing rate at a particular operating 
point; using the information contained in the engine controller 
software could help alert operators to such changes and allow them to 
perform repairs or maintenance prior to the vehicle experiencing a 
catastrophic failure. This method, especially if combined with ammonia 
slip information, could offer a better indication of system 
performance.
(3) Proposed EGR Health Monitor
    For the EGR system, EPA has identified essential information that 
users should have access to for ensuing proper maintenance and use can 
occur. In particular, we expect access to information indicating EGR 
valve coking or EGR cooler failure, which are the two main failure 
conditions, may avoid devastating impacts on downstream aftertreatment 
components.593 594 We are proposing to require manufacturers 
to provide an indication of EGR valve health. For example, they could 
use existing OBD signals to provide an indication of the health of an 
EGR valve by looking at the difference between commanded and actual EGR 
valve position to indicate valve coking. The intent of this health 
monitor is to enable operators to understand when the EGR valve is 
becoming plugged and allow them to perform preventative maintenance 
prior to a catastrophic failure.
---------------------------------------------------------------------------

    \593\ Anderson, Jeremy. 2017 presentation at American Public 
Transportation Association 2017 Annual Meeting & EXPO. Titled ``DPF 
Maintenance: Avoid the Five Most Common Mistakes.'' Available here: 
https://www.apta.com/wp-content/uploads/Resources/mc/annual/previous/2017annual/LZpresentations/Learning%20Zone%20Presentations/Anderson,%20Jeremy.pdf.
    \594\ Stanton, Bob. April 4, 2017. ``Aftertreatment System: A 
New System Not to be Overlooked.'' Available here: https://www.worktruckonline.com/157340/aftertreatment-system-a-new-system-not-to-be-overlooked.
---------------------------------------------------------------------------

    In addition, EPA is proposing a health monitor for the EGR cooler. 
Manufacturers could in part utilize work already being done to meet 
existing CARB requirements in 13 CCR 1971.1(e) for EGR cooler 
performance monitoring to satisfy this requirement. These requirements 
specify that manufacturers design their system to monitor the cooler 
system for insufficient cooling malfunctions, including the individual 
electronic components (e.g., actuators, valves, sensors). The OBD 
system must detect a malfunction of the EGR cooler system prior to a 
reduction from the manufacturer's specified cooling performance that 
would cause an engine's NMHC, CO, or NOX emissions to exceed 
2.0 times any of the applicable standards or the engine's PM emissions 
to exceed the applicable standard plus 0.02 g/hp-hr. EPA is seeking 
comment on these or other strategies that can help inform operators of 
the functionality of the EGR system to help prevent breakdowns due to 
EGR system failures, including whether or how to monitor for EGR cooler 
leaks or plugging, such as through the use of pressure or temperature 
sensors, and whether today's engines are equipped with sensors in the 
EGR system that could be used for this purpose. We are also seeking 
comment on whether fault codes related to incidents of engine derate 
due to EGR-related failures should be displayed in the cab as a part of 
this health monitor, similar to what is being proposed for SCR and DPF-
related derate issues.

[[Page 17532]]

b. Expanded List of Public OBD Parameters
    In another area for improvement in the OBD program, EPA proposes to 
harmonize with the revised list of data parameters CARB has developed 
for MY 2024 through our incorporation by reference of CARB's revised 
OBD regulations and to further expand the list of OBD parameters that 
manufacturers are required to make publicly available. 13 CCR 
1971.1(4.2) data stream requirements state that the listed signals be 
made available on demand through the ``standardized data link 
connector'' (OBD port) in accordance with J1979/J1939 specifications. 
The requirements also specify that the actual signal value must be 
used, the default or limp home value cannot be used. Until MY 2024, 
CARB regulations require a list of 91 signals that must be made 
publicly available, of which approximately ten are related to 
aftertreatment and primarily include measures of the pressure and 
temperature of the DPF. CARB updated these requirements in 2019 such 
that additional aftertreatment-related signals will be added in MY 2022 
and MY 2024. EPA is proposing to adopt CARB's parameter list through 
our incorporation by reference of their updated 2019 OBD regulations, 
to add signals to the list, and to specifically require the addition of 
all parameters related to fault conditions that trigger vehicle 
inducement to be made readily available using generic scan tools if the 
engine is so equipped (see Section IV.D for more discussion on 
inducements). EPA would expect that each of these additional 
requirements would need to be addressed even where manufacturers relied 
in part on a CARB OBD approval to meet the intent of our proposed OBD 
regulations. The purpose of including additional parameters is to make 
it easier to identify malfunctions of critical aftertreatment related 
components, especially where failure of such components would trigger 
an inducement. In addition, the proposed additional information can 
make the repairs themselves easier by allowing for immediate access to 
fault codes, which could alleviate the long wait times associated with 
specialized emission repair facilities or where facilities are not 
available when an inducement occurs (such as on the weekend or in a 
remote location). In response to the ANPR, EPA received comments 
supportive of such changes, for example from the National Tribal Air 
Association (``NTAA'') who noted that service information and tools 
should be made easily available and affordable for individual owners to 
diagnose and fix their own vehicles, which can be especially important 
for small businesses, Tribes, and those in rural areas with less ready 
access to original equipment manufacturer dealer networks.\595\
---------------------------------------------------------------------------

    \595\ See comments of the National Tribal Air Association, 
Docket ID EPA-HQ-OAR-2019-0555-0282.
---------------------------------------------------------------------------

    We are proposing a general requirement to make such parameters 
available if they are used as the basis for an inducement response that 
interferes with the operation of the engine or vehicle. For example, if 
the failure of an open-circuit check for a DEF quality sensor leads to 
an engine inducement, the owner/operator would be able to identify this 
fault condition using a generic scan tool. This proposal should be 
enabled in part by a change to the comprehensive component monitoring 
requirements in CARB's 2019 OBD regulations. CARB now specifies that 
for MY 2024 and later, comprehensive component monitoring must include 
any electronic powertrain component/system that either provides input 
to (directly or indirectly) or receives commands from an on-board 
computer or smart device, which is also used as an input to an 
inducement strategy or other engine derate (see 13 CCR 
1971.1(g)(3.1.1)). We are also proposing some new parameters for HD SI 
engines, as mentioned in Section III.D.2. We are proposing that 
manufacturers make additional parameters available for all engines so 
equipped, including:
     For Compression Ignition engines:
    [cir] Inlet DOC and Outlet DOC pressure and temperature
    [cir] DPF Filter Soot Load (for all installed DPFs)
    [cir] DPF Filter Ash Load (for all installed DPFs)
    [cir] Engine Exhaust Gas Recirculation Differential Pressure
    [cir] DEF quality
    [cir] Parking Brake, Neutral Switch, Brake Switch, and Clutch 
Switch Status
    [cir] Aftertreatment Dosing Quantity Commanded and Actual
    [cir] Wastegate Control Solenoid Output
    [cir] Wastegate Position Commanded
    [cir] DEF Tank Temperature
    [cir] Injection Control Pressure Commanded and Actual
    [cir] DEF System Pressure
    [cir] DEF Pump Commanded Percentage
    [cir] DEF Coolant Control Valve Control Position Commanded and 
Actual
    [cir] DEF Line Heater Control Outputs
     For Spark Ignition Engines:
    [cir] A/F Enrichment Enable flags: Throttle based, Load based, 
Catalyst protection based
    [cir] Percent of time not in stoichiometric operation (including 
per trip, and since new)
    [cir] Catalyst or component temperature parameters (measured and 
modeled, if applicable) specifically used for thermal protection 
control strategies as proposed in Section III.D.2.
    EPA is seeking comment on whether any additional signals should be 
included in this list to help ensure in-use emission benefits occur as 
expected, and whether any other signals should be included such as any 
signals related to maintenance derates (outside of inducements). 
Although CARB currently requires a list of signals that must be made 
public, EPA encountered difficulty accessing many of these signals in 
recent testing on in-use trucks. EPA, working closely with Environment 
and Climate Change Canada, used a number of generic scan tools on a 
variety of vehicle makes and models and were unable to see all of the 
publicly required data. While this could indicate a problem with a 
specific generic scan tool design, none of the scan tools from a range 
of price points was able to display the complete set of signals; some 
tools read less than a third of the required signals. Some parameters 
read ``No Response'' or ``Not Available'' or were missing a signal in 
its entirety. This situation can cause frustration for owners who own 
generic scan tools and are unable to access any required data when 
trying to repair vehicles. EPA requests comment on operator experiences 
with obtaining data using generic scan tools from trucks in-use.
c. Expanding Freeze Frame Data Parameters
    One of the more useful features in the CARB OBD program for 
diagnosing and repairing emissions components is the requirement for 
``freeze frame'' data to be stored by the system. To comply with this 
requirement, manufacturers must capture and store certain data 
parameters (e.g., vehicle operating conditions such as the 
NOX sensor output reading) within 10 seconds of the system 
detecting a malfunction. The purpose of storing this data is in part to 
record the likely area of malfunction. CARB has identified a list of 
approximately 63 parameters that must be captured in the freeze frame 
data for gasoline engines and 69 parameters for diesel engines. 
Currently, the freeze frame data does not include additional signals 
for aftertreatment systems. While existing CARB freeze frame data 
requirements include some DPF-related parameters (e.g., inlet and 
outlet pressure and temperature), there is essentially no SCR 
information, which

[[Page 17533]]

EPA believes is essential for proper maintenance. We are therefore 
proposing that EPA's updated OBD requirements include the additional 
parameters proposed in section IV.C(1)(ii)(b) of this preamble and 
those included in the following section of CARB's regulations sections 
13 CCR 1971.1(h)(4.2.1)(D), 1971.1(h)(4.2.2)(H), 1971.1(h)(4.2.3)(F), 
1971.1(h)(4.2.3)(G), 1971.1(h)(4.2.2)(I). We welcome comment on this 
proposal, including whether additional data parameters should be 
included in the freeze frame data to enable those diagnosing and 
repairing vehicles to more effectively identify the source of the 
malfunction and increase the usefulness of freeze frame data, 
especially for conditions that result in inducement.
d. System Commanded Tests To Facilitate Inducement-Related Diagnoses 
and Repairs
    Today's vehicle control systems have built-in tests that can be 
used to command components to perform a particular function in order to 
confirm that they are working properly.\596\ An equally important 
element of an effective OBD program is ensuring owners have the ability 
to run certain engine or vehicle tests and view the results, especially 
where they can be used by owners in diagnosing and repairing problems 
that may result in inducement. If, for example, the problem was caused 
by a faulty DEF pump, this type of repair likely does not require 
specialized training to complete but is difficult to detect without 
access to such a test. More immediate diagnosis and repair of faulty 
components such as this would result in reduced costs for owners and 
increased long-term environmental benefits through improved emission 
control function.
---------------------------------------------------------------------------

    \596\ Morgan, Jason. January 21, 2019. ``What the right data can 
tell you about aftertreatment issues.'' Available here: https://www.fleetequipmentmag.com/heavy-duty-truck-aftertreatment-service-issues-data/.
---------------------------------------------------------------------------

    Today, vehicle software scan tools can be designed to command a DEF 
pump to operate, which allows a person diagnosing a DEF injection issue 
to measure how much DEF is pumped during a certain time interval and 
compare this amount to the specifications to determine whether or not 
the pump and injector are functioning properly. Performing the test 
would allow diagnosis of the vehicle and a quick determination of 
whether the DEF pump is working, the DEF injector is not faulty, there 
are no wiring-related issues, and DEF is being sprayed properly (both 
in terms of amount and spray pattern). Due to the importance of the DEF 
pump in maintaining full functionality of a vehicle (i.e., avoiding 
inducement), EPA is proposing that the DEF dosing test be made 
available for use with either a generic scan tool (be made available on 
demand through the OBD port in accordance with J1979/J1939 
specifications) or an alternative method (e.g., an option commanded 
through a vehicle system menu).
    Another important test that is used today is an SCR performance 
test that some OEMs offer through their proprietary scan tools. This 
type of test causes the diagnostic system to run the engine through a 
specific operating cycle to check certain SCR parameters, providing a 
pass/fail result and indicating what potential problems may exist. In 
particular, this test allows for a repeatable method to be used to 
compare a known set of engine operating parameters and SCR performance 
specifications to verify that SCR performance is as-expected and to 
narrow the scope of any existing problems that need to be fixed. There 
are currently non-OEM scan tools that also can conduct the same test, 
but the engine's diagnostic system may not allow the generic scan tool 
to access the pass/fail results. The results of this test could be 
especially helpful for users or technicians, may help avoid unexpected 
breakdowns, and may improve in-use emissions. Running an SCR 
performance test can enable the owner or technician to monitor system 
parameters during the test (e.g., by watching SCR inlet and outlet 
temperatures during a particular operating cycle) to evaluate if 
certain components are functioning properly during the test and may 
reduce the need for regens to be run instead, which can reduce wear on 
the DPF system. We are requesting comment on whether EPA should make 
SCR performance tests available via generic scan tool or other on-
vehicle method. EPA is also requesting comment on the need to make 
other self-tests accessible with generic scan tools to improve in-use 
emission systems maintenance and performance, for example being able to 
command that the evaporative system on SI engines be sealed to allow 
for leak testing or including the ability to perform manual regens for 
DPF systems.
2. Other OBD Provisions
    In addition to our proposal to update our OBD regulations by 
incorporating much of the CARB OBD program by reference, we are also 
requesting comment on other improvements to our OBD program. The 
improvements would be intended to make the program more effective at 
improving maintenance of in-use engines and vehicles, as well as 
reducing the compliance burdens for manufacturers. We welcome comments 
suggesting other ways to improve our OBD program.
i. OBD Provisions From the Recent HD Technical Amendment Rule
    EPA recently revised our OBD regulations to harmonize with certain 
CARB requirements in our HD Technical Amendments (HDTA) rulemaking (86 
FR 34340, June 29, 2021). This rule finalized four updated OBD 
provisions including: (1) Revising the misfire threshold, (2) adopting 
updated misfire flexibilities, (3) revising our in-use minimum ratios, 
and (4) allowing the use of CARB OBD reporting templates for EPA OBD 
requirements. EPA did not take final action at that time on two 
proposed revisions related to OBD demonstration testing and carry-over 
of OBD certification. The following sections summarize the revisions 
previously proposed and the concerns expressed in 
comments.597 598
---------------------------------------------------------------------------

    \597\ See 85 FR 28152, May 12, 2020.
    \598\ EPA, ``Improvements for Heavy-Duty Engine and Vehicle Test 
Procedures, and other Technical Amendments Response to Comments,'' 
December 2020, Docket EPA-HQ-OAR-2019-0307, Publication Number: EPA-
420-R-20-026 (see discussion starting on page 80).
---------------------------------------------------------------------------

a. Demonstration Testing Requirements
    One of the provisions EPA did not take final action on in the HDTA 
rulemaking was related to determining the number of engines required to 
undergo demonstration testing. The existing requirements of 40 CFR 
86.010-18(l) and 13 CCR 1971.1(l) specify the number of test engines 
for which a manufacturer must submit monitoring system demonstration 
emissions data. Specifically, a manufacturer certifying one to five 
engine families in a given model year must provide emissions test data 
for a single test engine from one engine rating, a manufacturer 
certifying six to ten engine families in a given model year must 
provide emissions test data for a single test engine from two different 
engine ratings, and a manufacturer certifying eleven or more engine 
families in a given model year must provide emissions test data for a 
single test engine from three different engine ratings.
    The HDTA proposed rulemaking (85 FR 28152, May 12, 2020) proposed 
to allow CARB certified configurations to not count as separate engine 
families for the purposes of determining OEM demonstration testing 
requirements for

[[Page 17534]]

EPA OBD approval. EPA received adverse comment on this proposal stating 
that it was inconsistent for EPA to not include CARB-only families when 
determining demonstration testing requirements for 49-state EPA 
families, but to accept demonstration test data from CARB-only families 
to meet 49-state EPA certification. There were additional concerns that 
the proposal did not include the criteria that EPA would use to approve 
or deny the request to not count certain families, and that this 
proposal applied to ``special families'' which were not defined by EPA. 
In the HDTA final rulemaking, EPA explained that this provision 
required additional consideration and did not take final action on it 
at that time.
    We stated in the HDTA final rulemaking that we intended to review 
this issue as a part of the HD 2027 proposal. EPA recently issued 
guidance for certain cases, where an OBD system designed to comply with 
California OBD requirements is being used in both a CARB proposed 
family and a proposed EPA-only family and the two families are also 
identical in all aspects material to expected emission characteristics. 
EPA anticipates that a manufacturer would be able to demonstrate to EPA 
that the intent of 40 CFR 86.010-18(l) is met for the EPA-only family 
by providing proof that CARB has determined the monitoring system 
demonstration requirements for the corresponding CARB proposed family 
have been met.\599\ We are proposing to codify this as a provision in 
40 CFR 1036.110(b)(11). We are requesting comment on this provision, 
including whether additional restrictions should be included to ensure 
engine families are appropriately counted. EPA is also seeking comment 
on allowing a similar provision for cases where equivalent engine 
families differ only in terms of inducement strategies (see section 
IV.D.6 for further discussion). Finally, EPA is seeking comment on 
whether we should include revisions beyond those proposed to address 
this situation.
---------------------------------------------------------------------------

    \599\ EPA Guidance Document CD-2021-04 (HD Highway), April 26, 
2021, ``Information on OBD Monitoring System Demonstration for Pairs 
of EPA and CARB Families Identical in All Aspects Other Than 
Warranty.'' Available here: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=52574&flag=1.
---------------------------------------------------------------------------

b. Use of CARB OBD Approval for EPA OBD Certification
    EPA did not take final action on the proposed reordering of 40 CFR 
86.010-18(a)(5) in the HDTA final rulemaking. These existing EPA OBD 
regulations allow manufacturers seeking an EPA certificate of 
conformity to comply with the federal OBD requirements by demonstrating 
to EPA how the OBD system they have designed to comply with California 
OBD requirements also meets the intent behind federal OBD requirements, 
as long as the manufacturer complies with certain certification 
documentation requirements. EPA has implemented these requirements by 
allowing a manufacturer to submit an OBD approval letter from CARB for 
the equivalent engine family where a manufacturer can demonstrate that 
the CARB OBD program has met the intent of the EPA OBD program. In 
other words, EPA has interpreted these requirements to allow OBD 
approval from CARB to be submitted to EPA for approval.
    We are proposing to migrate the language from 40 CFR 86.010-
18(a)(5) to 40 CFR 1036.110(a) to allow manufacturers to continue to 
use a CARB OBD approval letter to demonstrate compliance with federal 
OBD regulations for an equivalent engine family where manufacturers can 
demonstrate that the CARB OBD program has met the intent of the EPA OBD 
program. In the case where a manufacturer chooses not to include 
information showing compliance with additional EPA OBD requirements in 
their CARB certification package (e.g., not including the additional 
EPA data parameters in their CARB certification documentation), EPA 
would expect manufacturers to provide separate documentation along with 
the CARB OBD approval letter to show they have met all EPA OBD 
requirements. This process would also apply in the case where CARB has 
further modified their OBD requirements such that they are different 
from but meet the intent of existing EPA OBD requirements. For example, 
if CARB finalizes the use of a different communication protocol than 
EPA's requirements call for, as long as it meets the intent of EPA's 
communication protocol requirements (e.g., can still be used with a 
generic scan tool to read certain parameters), the proposed process 
would apply. EPA expects manufacturers to submit all documentation as 
is currently required by 40 CFR 86.010-18(m)(3), detailing how the 
system meets the intent of EPA OBD requirements, why they have chosen 
the system design, and information on any system deficiencies. As a 
part of this update to EPA OBD regulations, we are clarifying in 40 CFR 
1036.110(c)(4) that we can request that manufacturers send us 
information needed for us to evaluate how they meet the intent of our 
OBD program using this pathway. This would most often mean sending EPA 
a copy of documents submitted to CARB during the certification process.
c. Potential Use of the J1979-2 Communications Protocol
    In a February 2020 workshop, CARB indicated their intent to propose 
allowing the use of Unified Diagnostic Services (``UDS'') through the 
SAE J1979-2 communications protocol for heavy-duty OBD with an optional 
implementation as early as MY 2022.600 601 CARB stated that 
engine manufacturers are concerned about the limited number of 
remaining undefined 2-byte diagnostic trouble codes (``DTC'') and the 
need for additional DTCs for hybrid vehicles. J1979-2 provides 3-byte 
DTCs, significantly increasing the number of DTCs that can be defined. 
In addition, this change would provide additional features for data 
access that improve the usefulness of generic scan tools to repair 
vehicles.
---------------------------------------------------------------------------

    \600\ SAE J1979-2 was issued on April 22, 2021 and is available 
here: https://www.sae.org/standards/content/j1979-2_202104/.
    \601\ CARB Workshop for 2020 OBD Regulations Update, February 
27, 2020. Available here: https://ww3.arb.ca.gov/msprog/obdprog/obd_feb2020wspresentation.pdf.
---------------------------------------------------------------------------

    Section IV.C.1. of this preamble asks for comment on whether EPA 
should harmonize with any updated CARB OBD amendments finalized prior 
to the issuing of this final rulemaking; however, it is not clear if 
CARB's amendment including UDS would be finalized in time for EPA to 
include it in this final rule. We will monitor the development of the 
CARB OBD update and are seeking comment on whether we should finalize 
similar provisions if CARB does not finalize their update before we 
complete this final rule. CARB is expected to allow the optional use of 
the J1979-2 protocol as soon as MY 2023. If manufacturers want to 
certify their engine families for nationwide use, we would need to 
establish a process for reviewing and approving manufacturers' requests 
to comply using the alternative communications protocol. While we 
support adoption of J1979-2 and are clarifying and proposing pathways 
to accommodate its use, we are seeking comment on potential challenges 
associated with this change.
    While EPA believes our existing requirements in 40 CFR 86.010-
18(a)(5) allow us to accept OBD systems using J1979-2 that have been 
approved by CARB, there may be additional considerations prior to the 
finalization of this rule for OEMs that want to obtain

[[Page 17535]]

a 49-state certificate for engines that do not have CARB OBD approval. 
For model years prior to MY 2027, since our proposed OBD revisions 
would take effect in MY 2027 if finalized, EPA is proposing to include 
interim provisions in 40 CFR 1036.150(v) to allow the use of J1979-2 
for manufacturers seeking EPA OBD approval. Finally, once EPA's 
proposed updated OBD requirements would be in effect for MY 2027, we 
expect to be able to allow the use of J1979-2 based on the proposed 
language in 40 CFR 1036.110(b). We are seeking comment on these 
pathways to approval and on whether any additional changes need to be 
made to our existing or proposed OBD requirements to accommodate the 
use of J1979-2.
    While there are expected environmental benefits associated with the 
use of this updated protocol, we are seeking comment on whether the use 
of this alternative protocol could have negative impacts on our 
existing OBD program. In addition to potential impacts on EPA's OBD 
program, EPA is seeking comment on any potential impacts this change 
could have on our service information requirements (see Section 
IV.B.3.ii. for more background on these provisions). CAA section 
202(m)(4)(C) requires that the output of the data from the emission 
control diagnostic system through such connectors shall be usable 
without the need for any unique decoding information or device, and it 
is not expected that the use of J1979-2 would conflict with this 
requirement. Further, CAA section 202(m)(5) requires manufacturers to 
provide promptly to any person engaged in the repairing or servicing of 
motor vehicles or motor vehicle engines, and the Administrator for use 
by any such persons, with any and all information needed to make use of 
the emission control diagnostics system prescribed under this 
subsection and such other information including instructions for making 
emission related diagnosis and repairs. Manufacturers who choose to 
voluntarily use J1979-2 as early as MY 2022 would need to provide 
access to systems using this alternative protocol at that time and meet 
all of the relevant requirements in 40 CFR 86.010-18.
    EPA believes that the software and hardware changes needed to 
accommodate J1979-2 are minimal, and that these changes would not 
impact an OEM's ability to make vehicle data available at a fair and 
reasonable cost. We seek comment on how tool vendors would be affected, 
whether they would be able to support the new services and data 
available in J1979-2, and if there are any concerns tool manufacturers 
have regarding access to vehicle data at a fair and reasonable cost.
    While the move to UDS has been discussed by OEMs in the past with 
CARB, a proposal was expected to be released last year, but is now 
expected this year, and while SAE is working on a new standard, J1978-2 
to specify the scan tool requirements to interface with J1979-2, this 
standard is not yet available.602 603 EPA is seeking comment 
on the impact to generic scan tool manufacturers of the timing of the 
voluntary allowance for the use of J1979-2 in MY 2023 and whether scan 
tool manufacturers can provide updated tools for use to diagnose and 
repair vehicles as well as for inspection and maintenance facilities in 
time for MY 2023, or if this protocol should not be allowed for use 
until a later model year and if so what the appropriate timing is. 
Specifically, EPA is seeking comment on the following issues related to 
generic scan tools:
---------------------------------------------------------------------------

    \602\ IM Solutions, IM Solutions OBD Communication Update 
Webinar, June 10, 2020. Available here: https://www.obdclearinghouse.com/Files/viewFile?fileID=2239.
    \603\ SAE, J1978-2 available here: https://www.sae.org/standards/content/j1978-2/.
---------------------------------------------------------------------------

     Will vendors be able to meet the MY 2023 timeframe?
     Can existing tools be updated to accommodate the new 
protocol or do new scan tools need to be developed to utilize J1979-2?
     Will any additional hardware changes be required to 
accommodate J1979-2?
     Do tool vendors expect the price of tools that can utilize 
J1979-2 to be comparable to tools that utilize J1979?
     Do state inspection and maintenance facilities require 
additional time to be able to modify or update equipment to handle 
J1979-2?
     Will generic scan tools be able to read both J1979-2 and 
J1979 or will separate tools be required?
     Will generic scan tool functionality be the same or better 
with the implementation of J1979-2?
     Will users require specialized training to use J1979-2 
tools?
     Is development going to be delayed until the adoption of 
SAE J1978-2?
ii. Use of Tailpipe Emission Sensors
    EPA is seeking comment on whether and how to allow manufacturers to 
use onboard emission sensors to help reduce test burden associated with 
OBD certification. In particular, EPA would like comment on ways to 
reduce test cell time associated with component threshold testing, such 
as ways to use NOX sensor data instead of test cycle 
NOX measurements (provided those sensors meet the proper 
specifications). There are further complications for testing outside of 
a test cell to demonstrate compliance that need careful consideration 
(as it is assumed that testing that relies on onboard NOX 
sensors would happen outside of a test cell), including:
     What alternative testing methods are reasonable and would 
provide assurances that they are creating robust diagnostic systems?
     For what operating conditions and over what time frame 
should this testing occur?
     What NOX values should be considered (e.g., 
average NOX over a certain period of time, or for a 
particular set of operating conditions?)
     What ambient and vehicle operating conditions should be 
considered?
     How can this methodology ensure repeatable results?
     How would EPA verify this methodology for compliance 
assurance?
    This type of strategy could potentially reduce compliance costs 
because it would reduce the amount of emission testing manufacturers 
need to perform in a test cell during OBD development. We request 
comment on this and other aspects of the OBD program that could be 
improved through the use of emissions sensors. EPA is also seeking 
comment on alternative methods to use onboard emission sensors that 
could be used to generate and provide real-world data that may enable 
improved diagnostics, assess the function of emissions critical 
components and assess the implementation of dynamic AECD inputs. Such a 
program could be voluntary and provide additional data that could be 
used in the future to analyze whether changes to the OBD program should 
be made to improve compliance demonstrations and reduce test cell 
burden.
3. Cost Impacts
    Heavy-duty engine manufacturers currently certify their engines to 
meet CARB's OBD regulations before obtaining EPA certification for a 
50-state OBD approval. We anticipate most manufacturers would continue 
to certify with CARB and that they would certify to CARB's 2019 updated 
OBD regulations well in advance of the EPA program taking effect; 
therefore, we anticipate the incorporation by reference of CARB's 2019 
OBD requirements would not result in any additional costs. EPA does not 
believe the additional OBD requirements described here would result in 
any significant costs, as there are no requirements for new monitors, 
new data parameters, new hardware, or new

[[Page 17536]]

testing included in this rule. However, EPA has accounted for possible 
additional costs that may result from the proposed expanded list of 
public OBD parameters and expanded scan tool tests in the ``Research 
and Development Costs'' of our cost analysis in Section V. EPA 
recognizes that there could be cost savings associated with reduced OBD 
testing requirements; however, we did not quantify the costs savings 
associated with proposed changes to the CARB's OBD testing 
requirements. We seek comment on our approach to including costs for 
OBD and the savings associated with each proposed OBD testing 
modification.

D. Inducements

1. Background
    The 2001 final rule that promulgated the criteria pollutant 
standards for MY 2010 and later heavy-duty highway engines included a 
detailed analysis of available technologies for meeting the new 
emission standards.\604\ Manufacturers ultimately deployed urea-based 
SCR systems instead of catalyzed particulate traps and NOX 
absorbers as EPA had projected in 2001. SCR is very different from 
these other emission control technologies in that it requires operators 
to maintain an adequate supply of diesel exhaust fluid (DEF), which is 
generally a water-based solution with 32.5 percent urea. Operating an 
SCR-equipped engine without the DEF would cause NOX 
emissions to increase to levels comparable to having no NOX 
controls at all.
---------------------------------------------------------------------------

    \604\ 66 FR 5002, January 18, 2001; see Section I of the 
preamble for more information on the history of emission regulations 
for this sector.
---------------------------------------------------------------------------

    As manufacturers prepared to certify their SCR-equipped engines to 
the EPA 2010 standards, EPA was concerned that operators might not take 
the necessary steps to maintain a supply of DEF to keep the emission 
controls working properly. To address concerns regarding the design and 
operation of SCR-equipped heavy-duty highway diesel engines and 
vehicles, between 2007 and 2012 EPA published three guidance documents, 
two notices and one request for comment in the Federal Register, and 
participated in a joint public workshop with CARB.\605\ These documents 
focused on the following three main categories of relevant regulatory 
requirements in the context of the use of DEF in SCR-equipped engines: 
(1) Critical emissions-related scheduled maintenance requirements, (2) 
adjustable parameters requirements, and (3) auxiliary emission control 
device (AECD) requirements. The EPA guidance identify possible 
approaches to meeting these regulations for heavy-duty diesel engines 
using SCR systems; however, the approaches were not required to be used 
and EPA explained that no determination was made in the guidance on 
whether the engine and vehicle designs that use the approaches are 
acceptable for certification, since that determination must be made 
based on the design of particular engines or vehicles. We broadly refer 
to this engine derate guidance as an inducement policy and design 
strategy. Throughout this preamble we refer to engine derates that 
derive from DEF-related triggers as ``inducements.'' This section 
discusses the relevant prior development and use of an inducement 
policy and design strategy for heavy-duty highway vehicles and engines, 
including comments we received on operators' experiences with 
inducements under that strategy in our Advanced Notice of Proposed 
Rulemaking, principles for updating inducement approaches for heavy-
duty highway vehicles and engines, and proposed inducement provisions 
for heavy-duty highway vehicles and engines.\606\
---------------------------------------------------------------------------

    \605\ Kopin, Amy. Memorandum to Docket: EPA-HQ-OAR-2019-0055. 
Inducement-Related Guidance Documents and Workshop Presentation, 
October 1, 2021.
    \606\ See 85 FR 3306.
---------------------------------------------------------------------------

i. DEF Replenishment as Critical Emissions-Related Scheduled 
Maintenance
    EPA regulations at 40 CFR 86.004-25 limit the emission-related 
scheduled maintenance that may be performed by manufacturers for 
purposes of durability testing and specify criteria for inclusion in 
manufacturers' maintenance instructions provided to purchasers of new 
motor vehicles and new motor vehicle engines. Of particular relevance 
here, the regulations in 40 CFR 86.004-25(a)(2) specify that 
maintenance performed on vehicles, engines, subsystems, or components 
used in the determination of emission deterioration factors is 
classified as either emission-related or non-emission-related, and 
either scheduled or un-scheduled. Emission-related scheduled 
maintenance must be technologically necessary to assure in-use 
compliance with the emission standards and must meet the specified 
allowable minimum maintenance intervals, as provided in 40 CFR 86.004-
25(b) (including cross-referenced 40 CFR 86.094-25(b)(7)).\607\ 
Additionally, to ensure that emission controls used in the durability 
demonstration do not under-perform in-use as a result of vehicle owners 
failing to perform scheduled maintenance, manufacturers must show that 
all critical emission-related scheduled maintenance have a reasonable 
likelihood of being performed in-use (see 40 CFR 86.004-25(b)(6)(ii)).
---------------------------------------------------------------------------

    \607\ See Section IV.B.5 for our proposal to migrate and update 
the maintenance provisions from 40 CFR 86.004-25 and 86.010-38 to 40 
CFR 1036.125.
---------------------------------------------------------------------------

    In the guidance document CISD-07-07 signed on March 27, 2007, EPA 
stated that the use of DEF is consistent with the definition of 
critical emission-related maintenance and therefore these requirements 
would apply to the replenishment of the DEF tank. EPA stated that 
manufacturers wanting to use SCR technology would likely have to 
request a change to scheduled maintenance requirements per 40 CFR 
86.094-25(b)(7), as the existing minimum maintenance intervals were 
100,000 miles for medium-duty and 150,000 miles for heavy-duty diesel 
engines. Following the completion of the guidance, EPA received several 
requests for new maintenance intervals for SCR-equipped motor vehicles 
and motor vehicle engines. EPA granted these requests for model years 
2009 through 2011 for heavy-duty engines in a notice that was published 
in the Federal Register (74 FR 57671, November 9, 2009). Engine and 
vehicle manufacturers provided additional requests for new maintenance 
intervals for vehicles and engines in model years not covered by the 
November 9, 2009 Federal Register notice.
    In the November 9, 2009 Federal Register notice and the guidance 
document CISD-09-04-REVISED (CISD-09-04R), regarding the requirement 
that manufacturers must show that all critical emission-related 
scheduled maintenance have a reasonable likelihood of being performed 
in-use, the document explained that manufacturers could make such a 
showing by satisfying at least one of the conditions listed in the 
then-applicable 40 CFR 86.094-25(b)(6)(ii)(A-F). In particular, the 
guidance focused on two of the methods in the regulation: (1) 
Presenting information establishing a connection between emissions and 
vehicle performance such that as emissions increase due to lack of 
maintenance the vehicle performance will deteriorate to a point 
unacceptable for typical driving; and (2) installing a clearly 
displayed visible signal system approved by EPA to alert the driver 
that maintenance is due. In the CISD-09-04R guidance, EPA identified 
possible approaches to show a reasonable likelihood that DEF in a 
vehicle's tank will be maintained at acceptable levels.

[[Page 17537]]

    For the first method, CISD-09-04R suggested that performance that 
deteriorates to a point unacceptable for typical driving would be 
sufficiently onerous to discourage operation without DEF. EPA suggested 
in CISD-09-04R that a possible approach could be for the manufacturer 
to include a derate of the engine's maximum available engine torque of 
a sufficient magnitude for the operator to notice decreased operation, 
explaining that a derate of at least 25 percent is likely to be needed 
for such an effect, and a progression to further degradation to 
severely restrict operation. For the second method, CISD-09-04R 
suggested that a clearly displayed visible signal system could include 
a DEF level indicator, messages in the instrument cluster, a DEF 
indicator, engine shutdown lamp, or audible warnings to warn the driver 
that maintenance is due (DEF refill is needed). The CISD-09-04R 
guidance reiterated that these are possible general approaches to meet 
the requirement that the critical maintenance is reasonably likely to 
occur in use, but EPA will evaluate all approaches taken by 
manufacturers at the time of certification, and such evaluation will be 
based on the requirements in the regulations.
    On January 5, 2012 (77 FR 488), EPA updated and extended its 
approval of maintenance intervals for the refill of DEF tanks for 
heavy-duty engines for 2011 and later model years. In a separate 
rulemaking in 2014, EPA added DEF tank size (which dictates DEF 
replenishment rate) to the list of scheduled emission-related 
maintenance for diesel-fueled motor vehicles and motor vehicle engines 
in 40 CFR 86.004-25(b)(4)(v).\608\ We are proposing to migrate this 
provision into new 40 CFR 1036.115(i).
---------------------------------------------------------------------------

    \608\ 79 FR 46356, August 8, 2014. ``Emergency Vehicle Rule--SCR 
Maintenance and Regulatory Flexibility for Nonroad Equipment.''
---------------------------------------------------------------------------

    EPA also added a limitation in 40 CFR 86.004-25(b)(5)(ii) for DEF 
replenishment (a critical emission-related scheduled maintenance item), 
requiring that manufacturers must satisfy paragraph (b)(6)(ii)(A) or 
(F) to be accepted as having a reasonable likelihood of the maintenance 
item being performed in-use. EPA explained that the criteria in 
(b)(6)(ii)(B)-(E) were not sufficiently robust for DEF replenishment, 
and therefore would not be sufficient for demonstrating that DEF 
replenishment is reasonably likely to occur in use. We are proposing 
that the proposed inducement requirements in 40 CFR 1036.111 will 
ensure the reasonable likelihood of DEF replenishment being performed 
in-use. EPA is not proposing any changes to DEF refill intervals. We 
are proposing to exclude the alternative option in (b)(6)(ii)(F) to 
demonstrate DEF replenishment is reasonably likely to be performed in-
use, but are seeking comment on whether this provision should instead 
be preserved. EPA is otherwise proposing to migrate the provisions in 
40 CFR 86.004-25(b)(5)(ii) to 40 CFR 1036.125(a)(1) (section IV.D.3. 
describes the proposal in detail).
ii. DEF as an Adjustable Parameter
    EPA regulations in 40 CFR 86.094-22(e) require that manufacturers 
comply with emission standards over the full adjustable range of 
``adjustable parameters'' and state that we will determine the adequacy 
of the limits, stops, seals or other means used to inhibit 
adjustment.\609\ For any parameter that has not been determined to be 
adequately limited, 40 CFR 86.094-22(e) authorizes the Administrator to 
adjust the parameter to any setting within the physical limits or stops 
during certification and other testing. In determining the parameters 
subject to adjustment, EPA considers the likelihood that settings other 
than the manufacturer's recommended setting will occur in-use, 
considering such factors as, but not limited to, the difficulty and 
cost of getting access to make an adjustment; damage to the vehicle if 
an attempt is made; and the effect of settings other than the 
manufacturer's recommended settings on engine performance. Adjustable 
parameters historically included things like physical settings that are 
controlled by a dial or screw.
---------------------------------------------------------------------------

    \609\ Section XII.A.2 describes how we are proposing to update 
regulatory provisions in 40 CFR 1068.50 related to adjustable 
parameters.
---------------------------------------------------------------------------

    In guidance document CISD-07-07, EPA provided clarification that an 
SCR system utilizing DEF that needs to be periodically replenished 
would meet the definition set forth in paragraphs 40 CFR 86.094-
22(e)(1) and 86.1833-01(a)(1) and could be considered an adjustable 
parameter by the Agency. EPA is confirming that DEF is considered an 
adjustable parameter because it is both physically capable of being 
adjusted and significantly affects emissions. In particular, DEF level 
and quality are parameters that can physically be adjusted and may 
significantly affect emissions. SCR system designs rely on storing DEF 
in a tank located on the vehicle, the operator refilling the tank with 
quality DEF, and quality DEF being available. This design depends on 
the vehicle operator being made aware that DEF needs to be replaced 
through the use of warnings and vehicle performance deterioration. The 
EPA guidance CISD-07-07 described that without a mechanism to inform 
the vehicle operator that the DEF needs to be replaced, there is a high 
likelihood that the adjustable parameter will be circumvented or 
exceeded in-use and therefore EPA would not consider the system to be 
adequately inaccessible or sealed. EPA stated in CISD-07-07 that we 
would not prescribe a specific driver inducement design, but that the 
options identified in the guidance could be utilized to demonstrate 
that the driver inducement design was robust and onerous enough to 
ensure that engines will not be operated without DEF in the vehicle 
(e.g., if the operator ignored or deactivated the warning system). In 
addition, the guidance stated that the driver inducement mechanism 
should not create undue safety concerns, but should make sure vehicle 
operators are adding DEF when appropriate by having the vehicle 
performance degraded in a manner that would be safe but would be 
onerous enough to discourage vehicles from being operated without DEF. 
EPA stated that the key challenge of this approach is to determine what 
would constitute an acceptable performance degradation strategy.
    EPA guidance document CISD-09-04R re-emphasized that under the 
adjustable parameter requirements, EPA makes a determination at 
certification whether the engine is designed to prevent operation 
without quality DEF. The guidance suggested a similar strategy for both 
DEF level and quality could be used, which would alert the operator to 
the problem and then use a gradually more onerous inducement strategy 
to either fill the tank or correct the poor-quality DEF and discourage 
its repeated use. CISD-09-04R also provided more detail on the 
potential use of inducements with tamper resistant designs to reduce 
the likelihood that the adjustable parameters will be circumvented in 
use, noting that in particular, manufacturers should be careful to 
review the tamper resistance of the system to prevent the disconnection 
of certain components (e.g., DEF pump or dosing valve). EPA did not 
determine in CISD-07-07 what specific amount of time or mileage would 
be necessary for an inducement policy. EPA guidance document CD-13-13 
was issued in November 2013 in response to concerns that operators may 
dilute DEF with water to reduce

[[Page 17538]]

costs.\610\ CD-13-13 provides guidance to manufacturers of heavy-duty 
on-highway engines on how EPA expects to determine the physical range 
of adjustment of DEF quality for certification testing. EPA explained 
that we generally would consider the range of adjustment for emission 
testing to span the change in urea concentration from 32.5 percent 
(unadulterated DEF) to the point at which poor DEF quality can be 
detected. This guidance also provides possible measures manufacturers 
may take, such as inducements, to sufficiently restrain the adjustment 
of DEF quality to limit the need for testing outside the manufacturer's 
specified range. EPA is proposing to adopt certain performance 
degradation strategy requirements that must be met for EPA to make a 
determination at certification that the engine is designed to prevent 
operation without quality DEF under the adjustable parameter 
requirements (section IV.D.3. describes the proposal in detail).
---------------------------------------------------------------------------

    \610\ Kopin, Amy. Memorandum to Docket: EPA-HQ-OAR-2019-0055. 
Inducement-Related Guidance Documents, and Workshop Presentation, 
October 1, 2021.
---------------------------------------------------------------------------

iii. DEF Usage and Auxiliary Emission Control Devices (AECDs)
    In CISD-09-04R EPA discussed that under extreme temperature 
conditions DEF may freeze and not immediately flow to the SCR system. 
There are, however, systems and devices that can be utilized to ensure 
the flow of DEF. These systems are evaluated as AECDs (see 40 CFR 
86.082-2) and manufacturers must describe this AECD and show that the 
engine design does not incorporate strategies that reduce emission 
control effectiveness compared to strategies used during the applicable 
Federal emissions test procedures. EPA examines systems during 
certification for ensuring proper dosing during extreme conditions such 
as cold weather operation. CISD-09-04R provided an example of a test 
procedure that could be used for ensuring the SCR system has adequate 
DEF freeze protection. Under this example, SCR systems that are capable 
of fully functional dosing at the conclusion of the test procedure 
might be considered acceptable. EPA is not proposing any changes to 
existing regulatory requirements for AECDs or to supersede guidance 
with our proposed requirements, if finalized, except as explicitly 
identified in section 40 CFR 1036.111.
iv. Tamper-Resistance Design
    The existing EPA guidance and this section discuss inducements as a 
tamper-resistant design strategy in the context of steps manufacturers 
can take to prevent operation without quality DEF. Under the CAA, 
engines must meet emission standards promulgated under section 202(a) 
throughout useful life. Engines that do not meet those standards 
throughout useful life may result in increased emissions that 
fundamentally undermine EPA's emission control program and prevent us 
from realizing the intended improvements in air quality. Tamper-
resistant design in engines can be an important part of a 
manufacturer's compliance strategy to ensure that emissions standards 
are met in-use throughout useful life. In addition to the reasons 
described in the cited guidance documents, an inducement strategy for 
SCR-system tamper-resistance can be part of a manufacturer's 
demonstration at certification that engines will be built to meet 
emission standards in-use throughout useful life.
    The Agency believes that combining detection of open-circuit fault 
conditions for SCR components (i.e., disconnection of SCR components) 
with inducements would decrease the likelihood that the SCR system will 
be circumvented through tampering.
2. ANPR Comments on the EPA's Inducement Guidance
    The ANPR requested comment on EPA's existing guidance related to 
SCR and DEF. A majority of the comments expressed concern that despite 
the use of high-quality DEF and in the absence of tampering, in-use 
vehicles are experiencing inducements for reasons outside of the 
operator's control. Commenters stated that the reasons for these types 
of inducements are often difficult to diagnose and can lead to repeat 
trips to a repair facility and additional costs. Commenters also stated 
that the existing schedule and speeds are not necessary to achieve 
EPA's compliance goals, and instead the severe nature of these concerns 
may be leading to unusual tampering rates. This section summarizes the 
submitted comments.
    Several commenters described problems with repeated occurrences of 
inducements even with the use of a sufficient quantity of high-quality 
DEF and in the absence of tampering (i.e., a ``false inducement''). 
They reported that some of these cases were traceable to incidents 
where the system detected a problem that did not exist and did not 
create emission concerns, for example a vehicle with a full DEF tank 
experienced an inducement due to a faulty DEF level sensor which 
reported an empty tank. Commenters stated that false inducements can 
occur, for example, as a result of software glitches, wiring harness 
problems, minor corrosion of terminals, or faulty sensors, even if 
those problems have no effect on the function of the emission control 
system.\611\
---------------------------------------------------------------------------

    \611\ For example, see the comments of the National Association 
of Small Trucking Companies, Docket ID EPA-HQ-OAR-2019-0055-0456.
---------------------------------------------------------------------------

    Commenters stated that ``no trouble found'' events were common 
where repair technicians were unable to diagnose a system fault after 
the engine triggered an inducement. This condition has also been 
documented by manufacturers who have issued technical service bulletins 
(``TSBs'') discussing such concerns. EPA has identified a significant 
number of TSBs documenting in-use problems that cause erratic fault 
codes which can lead to inducements or engine derate despite operators 
using high-quality DEF and not tampering.\612\ For example, some TSBs 
describe faulty wire harness routing problems that can cause 
inducements and recommend fixes that include adding extra zip ties or 
tape. Commenters noted that erratic system problems can lead to 
``defensive repairs'' as a diagnostic strategy for returning the 
vehicle to service, which could result in repair expenses for replacing 
parts that are not faulty and add risk of future costs if the problem 
reoccurs, repeated tows are required, further diagnosis is done, and 
more repairs are attempted. Commenters expressed a particular concern 
for intermittent fault conditions that make diagnosis especially 
difficult. To alleviate such concerns, ATA commented that EPA should 
eliminate inducements for reasons other than maintaining an adequate 
supply of high-quality DEF. ANPR commenters also expressed a concern 
that technicians might repair a defective part without addressing the 
root problem that caused the part to fail, which again leads to 
repeated experiences of towing and repairing to restore an engine to 
proper functioning.
---------------------------------------------------------------------------

    \612\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``TSB Aftertreatment Faults.'' September 9, 2021.
---------------------------------------------------------------------------

    Commenters stated that, despite their continued diligence to use 
high-quality DEF, they have repeated experiences with inducements 
resulting in very onerous costs. Some commenters noted they were 
subject to the most severe restrictions multiple times per year even 
though DEF tanks were properly filled.

[[Page 17539]]

OOIDA commented that inducement-related costs can severely jeopardize 
owner-operators' ability to stay in business, citing costs that 
included towing and lost income from downtime in addition to diagnosis 
and repair. Commenters were especially concerned with long-distance 
routes, which might involve a vehicle that is several days distant from 
the base of operations. Other commenters highlighted that service 
information and tools should be made easily available and affordable 
for individual owners to diagnose and fix their own vehicles, which can 
be important for small businesses, Tribes, and those in rural areas 
with less ready access to original equipment manufacturer dealer 
networks.\613\ While these comments did not specifically discuss 
inducements, EPA also considers these comments relevant to vehicles 
that are in an inducement condition. Other commenters added that false 
inducements in these situations can necessitate having engines serviced 
at an unfamiliar repair facility that has no information on a given 
vehicle's repair history, which can result in improper repairs and 
increased travel expenses for drivers to return home.\614\
---------------------------------------------------------------------------

    \613\ For example, see the comments of the Keweenaw Bay Indian 
Community, Docket ID AX-20-000-3862.
    \614\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``ANPR Inducement Comment Summary.'' August 5, 2021.
---------------------------------------------------------------------------

    Commenters stated that the four hours of operation before engines 
reach final inducement is poorly matched with typical wait times of 
three or four days before repair technicians can look at and attempt to 
diagnose the problem with their vehicles, plus additional time is 
needed to complete the repairs. Commenters further stated that repair 
technicians are often unable to diagnose the problem, repairs can take 
several days in any case, with additional time lost if there is a need 
to order parts and wait for shipment, and there are frequently ``come-
back'' repairs for vehicles not fixed properly the first time.
    Commenters stated that the money needed for a tow would be better 
spent on repairs.\615\ Some commenters emphasized that a speed 
restriction of 5 mph caused the need for towing, even though a less 
restrictive inducement would accomplish the same purpose without 
incurring towing expenses.
---------------------------------------------------------------------------

    \615\ Commenters suggested the cost of a tow starts at $800, 
which could approximately cover the cost to replace a faulty 
NOX sensor. Others noted that the cost of a tow and 
related repairs is estimated to be around $7500-8000.
---------------------------------------------------------------------------

    Commenters described experiences of sudden inducements restricting 
vehicle speed to 5 mph which they stated caused highway safety problems 
for truck drivers and nearby vehicles.\616\ Others described having 
safety concerns when a vehicle is stranded, such as having buses 
carrying passengers parked along the highway or freeway.\617\
---------------------------------------------------------------------------

    \616\ For example, see the anonymous comments in Docket ID EPA-
HQ-OAR-2019-0055-0426.
    \617\ See the comments of Theilen Bus Lines, Docket ID EPA-HQ-
OAR-2019-0055-0521.
---------------------------------------------------------------------------

    Some commenters stated that in addition to monetary costs, there 
are other business impacts such as missing critical deadlines, loss of 
customer trust and credibility, and loss of future contracts. Other 
comments indicate that EPA's existing inducement policy, especially 
where application of it has resulted in false inducements, may have 
created a strong incentive to either tamper with SCR systems (e.g., 
installing ``delete kits'') and may be leading to owners extending the 
life of older vehicles; they further asserted that these behaviors were 
causing trucks to fail to accomplish the intended emission reduction 
goal. For example, the American Truck Dealers division of National Auto 
Dealers Association commented that in addition to emission-related 
maintenance and repair issues, improperly functioning SCR derate 
maintenance inducements have also led to emissions tampering.\618\
---------------------------------------------------------------------------

    \618\ See the comments of the National Automotive American Truck 
Dealers division of National Auto Dealers Association, Docket ID 
EPA-HQ-OAR-2019-0055-0369.
---------------------------------------------------------------------------

    It is worth noting that in comments on CARB's Omnibus rule both the 
California Trucking Association and ATA member companies requested CARB 
work with EPA to further investigate the efficacy of progressive de-
rate inducements typically associated with low-volume or empty DEF 
tanks or the use of poor-quality DEF. They added that the safety and 
environmental implications of these types of de-rate occurrences need 
additional evaluation and study prior to enacting additional 
NOX controls. Further, they commented that following more 
than a decade of experience, de-rates not related to low DEF levels or 
inferior DEF quality continue to occur, and that among a sampling of 
fleets operating more than 10,000 trucks, nearly 80 percent of de-rates 
in 2019 were attributed to other causes such as sensor failures, 
electrical defects and SCR component issues. ATA stated that many of 
these causes are not associated with the emissions performance of the 
SCR system and yet are initiating operational restrictions. After the 
ANPR was issued, EPA received a letter from charter bus companies 
detailing their concerns and difficulties experienced with existing 
inducements. Specifically, they mentioned the inadequate timeframe for 
which to resolve problems, the safety risk to passengers, the high cost 
of towing, other costs incurred due to breakdowns such as 
reimbursements owed for tickets to missed shows or flights, and the 
cost to their reputation despite their efforts to maintain their fleets 
and keep the emissions systems functioning properly.\619\
---------------------------------------------------------------------------

    \619\ Kopin, Amy. Memorandum to docket EPA-HQ-OAR-2019-0055. 
``Letter to EPA from Bus and Motorcoach Operators Regarding 
Inducement Experiences In-Use.'' November 17, 2021.
---------------------------------------------------------------------------

3. Principles for Updating Inducement Provisions
    In general, emission control technology is integrated into engine 
and vehicle systems in ways that do not require routine operator 
interaction. However, ensuring that on-highway engines using SCR are 
designed, consistent with our regulations, to prevent operation without 
quality DEF through and dependent upon steps performed by operators in-
use presents unique challenges. Crafting an inducement policy includes 
complex technological questions on how manufacturers should demonstrate 
that SCR system standards and related requirements will be met and 
challenging policy decisions on how to appropriately motivate or 
restrict certain types of human behavior that are either necessary for 
or directly impact in-use compliance with emissions standards. EPA 
recognizes and commenters have highlighted that the existing inducement 
policy and its implementation have resulted in a complex mix of 
incentives and behaviors. Policymaking for inducements therefore 
presents itself not as an engineering problem with a single solution.
    EPA is proposing to codify inducement provisions, which include 
adjustments as compared to our existing inducement guidance after 
consideration of manufacturer designs and operator experiences with 
SCR. We recognize that SCR technology has continued to mature, and 
appropriate designs for heavy-duty engines using SCR systems have 
evolved over the past decade. EPA continues to believe that designing 
SCR-equipped engines with power derating is an effective and reasonable 
measure to ensure that operators perform critical emissions-related 
scheduled maintenance on the SCR system and to demonstrate to EPA that 
it is reasonable to anticipate, consistent with requirements for

[[Page 17540]]

adjustable parameters, that the engine would normally be operated using 
quality DEF. We are proposing inducement requirements whose objective 
is to ensure that emission controls function and emission reductions 
occur in-use while reducing potential impacts to operators through the 
consideration of the following key principles.
    EPA's inducement approach should result in:
    1. Operators maintaining an adequate supply of high-quality DEF 
while discouraging tampering of SCR systems,
    2. a speed derating schedule for inducement that balances impacts 
to operators while still achieving required emission control,
    3. unique inducement schedules for different categories of vehicles 
that reflect different primary operating conditions to ensure that the 
final inducement speed is effective while acknowledging operating 
constraints,
    4. ensuring that the inducement condition is warranted,
    5. clear communication of SCR system problems to the operator,
    6. avoiding the need for intervention at a dealer or other 
specialized service center where possible, and
    7. reduced likelihood of in-use tampering based on a more targeted 
inducement approach.
    Development of regulatory inducement requirements that reflect 
these key principles requires consideration of potentially competing 
concerns. A minimally restrictive approach might result in increased 
emissions because of extensive operation without scheduled maintenance 
being performed and circumvention of the limit on the adjustable range 
(i.e., without use of sufficient high-quality DEF). In contrast, an 
overly restrictive approach might impose unnecessary costs and pose a 
threat to operators' livelihoods, as well as leading to potentially 
increased tampering with engines or reduced fleet turnover rates that 
would lead to increased emissions.
    The principles described here are those EPA used to develop the 
proposed inducement provisions in 40 CFR 1036.111 and are discussed 
later in this section for heavy-duty engines certified under 40 CFR 
part 1036 that use SCR systems. These principles are based on our 
existing guidance but include important adjustments. The first 
principle is to develop an effective inducement proposal that ensure 
that all critical emission-related scheduled maintenance has a 
reasonable likelihood of being performed and allows manufacturers to 
demonstrate an acceptable performance degradation strategy at the time 
of certification to meet adjustable parameter requirements. This 
principle should result in a proposal that would ensure operators will 
add high-quality DEF and would help prevent tampering with the SCR 
system by requiring increased levels of inducement to occur in stages 
for reasons related to insufficient quantity of high-quality DEF or 
tampering with the SCR system. This approach creates an immediate and 
increasing incentive to remedy the problem. Operators would keep tanks 
full of high-quality DEF prior to the inducement process starting and 
avoid tampering with the SCR system.
    Our second principle seeks to identify an appropriate speed 
derating schedule for inducements that reflects experience gained over 
the past decade with SCR. This schedule would better balance impacts to 
operators while ensuring that all critical emission-related scheduled 
maintenance has a reasonable likelihood of being performed and allow 
manufacturers to demonstrate an acceptable performance degradation 
strategy at the time of certification to meet adjustable parameter 
requirements. An appropriate inducement speed and schedule should be 
low enough to ensure that operators maintain a supply of high-quality 
DEF, while allowing engines to operate at a limited speed over a 
restricted timeframe that restricts commercial operation (e.g., highway 
operation) but allows for safely operating the vehicle to return home 
for repair and to perform the necessary post-repair diagnostic checks 
to avoid ``come-back'' repairs. Almost all heavy-duty vehicles are 
engaged in commercial activity for which it would be completely 
unacceptable to operate indefinitely at vehicle speeds that do not 
allow for travel on limited-access highways. This principle should 
result in an inducement schedule that would allow a reduced level of 
operation over a sufficient period of time for operators when there is 
a need to get a driver home from a distance, deliver critical freight 
(e.g., passengers, livestock, or concrete) or for scheduling repairs in 
a time or area of limited openings in repair shops. Establishing an 
inducement policy that would be consistent among manufacturers would 
improve operator experiences. For example, today manufacturer 
strategies may differ in ways that potentially may have significant 
effects on operators (e.g., some manufacturers implement a final severe 
inducement only after a vehicle is stopped, others implement it 
immediately while a vehicle is in motion). EPA believes another 
important aspect of this principle is to set an inducement schedule 
that would include additional stages of derated engine power that would 
be tied to drive-time to create a predictable schedule of increasing 
incentive to repair the engine. We also believe that our proposed 
approach, including the proposed inducement speeds and schedules, would 
be the most effective way to minimize operational disruptions due to 
potential supply chain problems such as component or DEF shortages.
    The third principle is to recognize the diversity of the real-world 
fleet and that one inducement schedule may not be appropriate for the 
entire fleet. Instead, separate inducement speeds and schedules should 
apply to vehicles that primarily operate at low- or high-speeds to 
ensure an appropriate final inducement is applied. Certain vocational 
vehicles, such as utility trucks, local delivery vehicles, refuse 
trucks, cement mixers, and urban buses do not operate fast enough to be 
effectively constrained by the same inducement speed that would be 
appropriate for trucks with extended highway driving. Similarly, 
applying a low final inducement speed to the entire fleet would overly 
constrain vehicles that spend the majority of their time at highway 
speeds. Rather than the EPA identifying a different inducement schedule 
for each type of vehicle, vehicles would be subject to an alternative 
inducement schedule based on the average vehicle speed history recorded 
in the onboard computer.
    The fourth principle would not apply an inducement if there is a 
fault code flagged by the system but the SCR system is still 
controlling NOX emissions. Under this principle, putting a 
vehicle into an inducement for a condition that does not result in a 
failure of the engine to comply with emission standards would be 
inconsistent with the goal of an inducement policy. To apply 
inducements consistent with this principle, manufacturers would design 
their diagnostic system to override a detected fault condition if 
NOX sensors confirm that the SCR system is in fact 
appropriately reducing NOX emissions. The diagnostic system 
depends on multiple sensors and complex algorithms to detect fault 
conditions. This override feature could be helpful to reduce false 
inducements that can occur when the fault is not due to tampering or 
the absence of high-quality DEF in the system (e.g., a faulty DEF level 
sensor in a tank full of DEF). An inducement approach that includes a

[[Page 17541]]

backup check would address problems with faulty sensors or part 
shortages that can strand owners.\620\ Under CARB's updated 2019 OBD 
regulations, which apply under CARB's regulations starting with MY 2023 
compliant OBD systems would be able to query data in the most recent 
``active 100-hour array'', which monitors and records the most recent 
engine and emission control parameters at discrete operating conditions 
to confirm that appropriate NOX reductions are occurring. We 
are proposing to incorporate by reference these updated CARB OBD 
requirements and to make them mandatory for MY 2027 and later, while 
manufacturers could voluntarily choose to certify to these requirements 
prior to that (see section IV.C.1. for further discussion on OBD).
---------------------------------------------------------------------------

    \620\ July 10, 2021. De Maris, Russ, ``Will a DEF head problem 
ruin your trip?'' Available here: https://www.rvtravel.com/def-head-problem-ruin-trip/.
---------------------------------------------------------------------------

    The fifth principle seeks to improve the type and amount of 
information operators receive from the truck to help avoid or quickly 
remedy a problem that is causing an inducement. This could include 
manufacturers providing information on the dashboard or other display 
to indicate when the first (and next) stage of derating will start in 
addition to identifying the current (and next) restricted speed. It is 
important for operators to understand what is happening to the truck as 
well as whether or not they can make it back home or to a preferred 
repair facility and reduce anxiety that can occur when an inducement or 
engine derate occurs. The indicator would also show the fault condition 
that caused the inducement. This status information would help to 
prevent an unsafe condition resulting from an unexpected step down in 
speed, and it would give operators important information for planning 
routes to arrange for repairs.
    The sixth principle includes allowing operators to perform an 
inducement reset by using a generic scan tool or allowing for the 
engine to self-heal through the completion of a drive cycle that will 
warm up the SCR system to operating temperature and permit the system 
to automatically reset the inducement condition as appropriate. This 
approach would allow vehicle owners much more discretion to perform 
repairs themselves or select appropriate repair facilities for their 
vehicles. This flexibility becomes increasingly important as vehicles 
get older, especially for second or third owners, who typically depend 
on simpler maintenance procedures to keep operating costs low enough 
for viable operation. Any system reset that does not follow the fault 
condition being addressed would require the engine to immediately 
return to the stage of inducement that applied before the reset, which 
would address the risk of improper resets. Together with allowing more 
time to diagnose and repair a vehicle, this provision would help to 
address comments from Tribal interests stating that Tribes and others 
operating in remote areas often have limited access to dealers or 
specialized repair facilities for repairing engines including vehicles 
that are in an inducement condition. These provisions would increase 
options available to all vehicle owners and small fleets who perform 
their own repair and maintenance and may be unable to service their own 
vehicles if the fault condition occurs any distance from the home base. 
A higher proposed final inducement speed would also allow the OBD 
system to run an internal diagnostic check to confirm that the fault 
condition is no longer active and that the SCR catalyst is again 
reducing NOX emissions. This would be especially important 
for vehicle owners that do their own repair work on older vehicles or 
for operators in remote areas with limited access to dealers and 
specialized tools.
    The seventh principle seeks to develop an inducement schedule that 
will ensure scheduled maintenance has a reasonable likelihood of being 
performed and allow manufacturers to demonstrate they meet adjustable 
parameter requirements at the time of certification while addressing 
operator frustration with false inducements and severe inducement speed 
restrictions that may potentially lead to in-use tampering of the SCR 
system. We are concerned that engine designs that may have been 
intended to be responsive to the existing SCR guidance may have 
resulted in high levels of false inducement and overly restrictive 
speed limitations and may have increased in-use tampering.\621\ For 
example, there are many technical support bulletins that have been 
released by manufacturers that detail inducements occurring for reasons 
outside of operator control, such as minor corrosion on electrical 
connectors.\622\ In addition, we received comments on the ANPR 
regarding false inducements leading to emissions tampering.\623\ EPA is 
aware there are products available in the marketplace to facilitate 
tampering through the removal of SCR systems, which might be being 
unlawfully used by vehicle owners who are adversely affected by false 
inducements. After a decade of experience with SCR-equipped engines and 
existing EPA guidance, several of the initial concerns with the use of 
SCR that formed the basis of some elements of the existing guidance 
have been resolved. DEF is widely available and the cost of DEF at the 
pump is not that different from the cost of distilled water. A less 
restrictive approach could be equally effective at encouraging 
operators to maintain a supply of DEF, without causing problems that 
may be leading to increased in-use tampering. A less restrictive 
inducement schedule would allow operators more flexibility for on-time 
delivery, reduce operator costs by allowing vehicles to be driven to 
repair shops thereby avoiding towing fees, and allow more time for 
proper diagnosis and repair to reduce the need for repeat visits to 
repair shops.
---------------------------------------------------------------------------

    \621\ See section IV.D.1. for further discussion on existing 
inducement guidance documents including: CISD-07-07 and CISD-09-04 
REVISED.
    \622\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``TSB Aftertreatment Faults.'' September 9, 2021.
    \623\ See comments from NADA, Docket ID EPA-HQ-OAR-2019-0055-
0369.
---------------------------------------------------------------------------

    These seven principles, which include improved diagnostic fault 
communication, NOX override checks, and revised inducement 
speeds and schedules that reflect more realistic vehicle operations, 
would result in a program that more effectively maintains in-use 
emission reductions. We believe the proposed provisions described in 
the following section would provide a net benefit to fleet operators, 
small businesses, and the environment.
4. Proposed Inducement Provisions
    Consistent with the seven principles described in Section IV.D.3. 
EPA is proposing to specify in 40 CFR 1036.125(a)(1) that manufacturers 
must meet the specifications in 40 CFR 1036.111 to demonstrate that DEF 
replenishment is reasonably likely to occur at the recommended 
intervals on in-use engines and that adjustable parameter requirements 
will be met. We are proposing to exclude the alternative option in 40 
CFR 86.004-25(b)(6)(ii)(F) to demonstrate DEF replenishment is 
reasonably likely to be performed in use and are seeking comment on 
whether manufacturers should be allowed to ask for approval to use an 
alternative method of compliance to meet these requirements. Consistent 
with the existing guidance, the proposed requirements would codify that 
SCR-equipped engines must meet critical emission-related scheduled 
maintenance requirements and limit the

[[Page 17542]]

physically adjustable range under the adjustable parameter requirements 
by triggering inducements. EPA is proposing to adopt requirements that 
inducements be triggered for fault conditions including: (1) DEF supply 
is low, (2) DEF quality does not meet manufacturer specifications, or 
(3) tampering with the SCR system. EPA is also proposing separate 
inducement schedules for low- and high-speed vehicles. The proposed 
inducement requirements would include a NOX override to 
prevent false inducements. EPA is proposing to require manufacturers to 
improve information provided to operators regarding inducements. The 
proposal also includes a provision to allow operators to remove 
inducement conditions after repairing the engine either through the use 
of a generic scan tool or through a drive cycle to ensure that repairs 
have been properly made. EPA is proposing that if multiple repeat fault 
conditions are detected that the inducement schedule would not restart 
with each new fault.
    The proposed inducement provisions include several aspects. The 
first three described here relate to proposed inducement triggers in 40 
CFR 1036.111. First, EPA is proposing to require inducements related to 
DEF quantity to ensure that high-quality DEF is used, similar to the 
approach described in our existing guidance. Specifically, we propose 
that SCR-equipped engines must trigger the start of an inducement when 
the amount of DEF in the tank has been reduced to a level corresponding 
to three hours of engine operation.
    Second, EPA proposes to require inducements related to DEF quality 
to ensure that high-quality DEF is used, similar to the approach 
described in our existing guidance. There was a concern when SCR was 
first introduced into the market a decade ago that DEF availability may 
be limited and some operators may choose to use poor quality DEF, or, 
for example, dilute DEF with water to reduce operating costs. DEF 
quickly became widely available and today is conveniently available 
even in pump form (e.g., next to diesel pumps at refueling stations) to 
refill DEF tanks while refilling diesel tanks. Modern engines are 
designed with feedback controls to increase or decrease DEF flow as the 
system detects that a greater or lesser quantity of DEF is needed to 
supply the amount of urea needed to keep the SCR catalyst working 
properly or trigger an inducement. This DEF dosing feedback removes any 
practical incentive for diluting DEF, as any such attempt would result 
in more volume of DEF being consumed and trigger an inducement when 
emissions control is no longer possible. Further, OEMs have made clear 
to operators that using water without urea would cause extensive engine 
damage and void the warranty. Today, the per-gallon price of DEF at the 
pump is closer to the price of a gallon of distilled water. Given an 
operator's ability to physically adjust DEF quality and the increase in 
NOX emissions that would result if they do so, EPA maintains 
that DEF quality is an adjustable parameter and is proposing to require 
inducements when DEF quality fails to meet manufacturer concentration 
specifications. Due to widespread DEF availability and familiarity with 
operators, EPA believes operators would readily find and use high-
quality DEF to avoid inducements. As discussed in Section IV.D.1.ii, 
CD-13-13 provides guidance on DEF quality as an adjustable parameter. 
The guidance states that EPA generally considers the range of 
adjustment for emission testing to span the change in urea 
concentration from 32.5 percent (unadulterated DEF) to the point at 
which poor DEF quality can be detected. This point represents the limit 
for DEF quality adjustment because it is the first point at which a 
manufacturer is able to implement inducements to prevent sustained 
engine or vehicle operation with poor quality DEF. EPA is not proposing 
changes to this guidance.
    Third, EPA is proposing to require inducements to ensure that SCR 
systems are designed to be tamper-resistant to reduce the likelihood 
that the SCR system would be circumvented, similar to the approach 
described in our existing guidance. CISD-09-04R discusses tamper-
resistant design with respect to a list of engine components in the SCR 
system and suggests that manufacturers could design these components to 
be physically difficult to access in addition to using warnings and 
inducements if they are disconnected. We are proposing to require 
monitoring for and triggering of an inducement for tampering with the 
components listed in CISD-09-04R, as well as for a limited number of 
other components. Specifically, we are proposing that open-circuit 
fault conditions for the following components trigger inducements if 
detected, to prevent disconnection through tampering: (1) DEF tank 
level sensor, (2) DEF pump, (3) DEF quality sensor, (4) SCR wiring 
harness, (5) NOX sensors, (6) DEF dosing valve, (7) DEF tank 
heater, and (8) aftertreatment control module (ACM). Monitoring the DEF 
tank heater is important to ensure AECD requirements are met. We are 
not proposing to include the language from CISD-09-04R that such 
components should be designed to be physically difficult to access 
because an inducement condition would be triggered upon the unplugging 
of a component (i.e., an open-circuit condition).\624\ Similar to the 
approach described in CISD-09-04R which specified that disconnection of 
the SCR wiring harness could trigger inducements as a tamper-resistant 
design strategy, we are proposing to specify that the ACM also be 
monitored for disconnection. In addition to proposing to require 
detection of open-circuit conditions for certain components to prevent 
tampering, EPA is also proposing to require that manufacturers trigger 
an inducement for blocked DEF lines or dosing valves similar to the 
approach described in CISD-09-04R.\625\ EPA is proposing that all 
inducement-related diagnostic data parameters be made available with 
generic scan tools (see section IV.C.1.iii.b. for further information). 
Finally, EPA is proposing to require that manufacturers monitor for a 
missing catalyst (see OBD requirements for this monitor in 13 CCR 
1971.1(i)(3.1.6)) and trigger an inducement if this condition is found.
---------------------------------------------------------------------------

    \624\ An Open-Circuit is a fault where the resistance of a 
circuit has increased to the point where electrical current will no 
longer flow through it, and is typically caused by a blown fuse, 
broken wire, or removal of circuit components.
    \625\ We are proposing in 40 CFR 1036.110(b)(8)(i) that 
manufacturers notify operators of problems before blockages actually 
occur to allow operators an opportunity to perform repairs and avoid 
an inducement.
---------------------------------------------------------------------------

    As indicated in ANPR comments summarized in Section IV.D.2, many 
operators report experiencing false inducements from faulty hardware 
that are not a result of tampering. These experiences may indicate that 
the existing triggers for inducements in engines may be too aggressive, 
or that OEMs may not be able to clearly distinguish between tampering 
and faulty hardware. EPA reviewed various manufacturer's inducement 
strategies in their certification documents and compared those to our 
existing guidance. Some manufacturers have certified engines with 
nearly 200 different reasons for an engine to go into a derate 
condition, including nearly 50 reasons for an SCR-related inducement. 
Many of the derates are for engine protection, and we are not proposing 
to make any changes to these types of derates. However, we are adopting 
a list of SCR system inducement triggers for

[[Page 17543]]

meeting critical emissions-scheduled maintenance and adjustable 
parameter requirements that focus on specific emission control 
components and conditions that owners can control such as disconnecting 
a DEF pump or other SCR-related emission control hardware. The proposed 
list includes the tamper-resistance inducement triggers included in 
CISD-09-04R as well as additional components. We believe that 
standardizing the list of tampering inducement triggers would aid 
owners, operators, and fleets in the repair of their vehicles by 
reducing the cost and time required to diagnose the reason for 
inducement.
    Fourth, we are proposing separate four-step derate schedules and 
final inducement speeds for vehicles that operate at low and high 
speeds as shown in Table IV-13. We are proposing that the application 
of low-speed inducements (LSI) and high-speed inducements (HSI) be 
based on an individual vehicle's operating profile. In particular, 
vehicles that have a stored average vehicle speed below 20 mph during 
the previous 30 hours of engine operation (not including idle time) 
would be considered low-speed vehicles and be subject to an LSI. 
Excluding idle from the calculation of vehicle speed allows us to more 
effectively evaluate each vehicle's speed profile, not time spent 
idling, which does not impact the effectiveness of a final inducement 
speed. EPA chose this speed based on an analysis of real-world vehicle 
speed activity data from the FleetDNA database maintained by the 
National Renewable Energy Laboratory (NREL).\626\ Our analysis provided 
us with insight into the optimum way to characterize high-speed and 
low-speed vehicles in a way to ensure these categories received 
appropriate inducements that would not be ineffective or overly 
restrictive.
---------------------------------------------------------------------------

    \626\ Miller, Neil; Kopin, Amy. Memorandum to docket EPA-HQ-OAR-
2019-0055. ``Review and analysis of vehicle speed activity data from 
the FleetDNA database.'' October 1, 2021.
---------------------------------------------------------------------------

    EPA is proposing to require specific inducement schedules for low-
speed and high-speed vehicles. We are proposing to codify progressively 
increasing inducement derate schedules that allow the owner to 
efficiently address conditions that trigger inducements. Table IV-13 
shows the proposed default four-step inducement schedules in cumulative 
hours. The time spent in each stage of inducement would include time 
spent idling. The initial inducement of either 50 mph or 65 mph would 
apply immediately when the OBD system detects: (1) There is 
approximately three hours-worth of DEF remaining in the tank, (2) DEF 
quality fails to meet manufacturers' concentration specifications, or 
(3) when certain SCR system tampering events have occurred. The 
inducement schedule would then step down over time to result in a final 
inducement speed of either 35 mph or 50 mph depending on individual 
vehicle operating profiles. In determining the appropriate final 
inducement speeds for this proposal, EPA also relied in part on 
analysis of data in the NREL FleetDNA database. Analyzing potential 
impacts of final inducement speeds based on vehicle applications 
involves a number of different considerations, beyond how much time a 
particular application spent at different speeds. For example, the 
ability to achieve higher speeds may be critical to many different duty 
cycles and logistics necessary for commercial activities. Inducements 
are intended to reduce/eliminate the ability to perform work such that 
operators will replenish the tank with high-quality DEF and not tamper 
with the SCR system. For example, our data show that combination long-
haul vehicles spend nearly almost 40 percent of their driving time over 
65 mph. Based on this operation, an inducement speed of 65 mph will 
cause a significant impact on the ability of the vehicle to be used for 
commercial purposes, which means that any speed restriction below this 
threshold is less likely to further incentivize operators to keep 
emissions systems compliant. In addition, there were other segments 
that may operate at lower average speeds, but when looking at their 
duty cycle, it is clear that they depend on being able to complete 
their work by achieving high rates of speed frequently, although not 
for sustained periods (e.g., delivery vehicles that return to a 
warehouse multiple times throughout the day to reload). These vehicles 
may travel at lower speeds with frequent stop and go operation during 
delivery but may need to travel on the highway to return to the 
warehouse in order to complete a certain number of operations in a day. 
Many vehicle segments in our sample exhibited this type of duty cycle 
with frequent higher speeds, for example, some single short-haul 
vehicles that had average speeds under 20 mph had duty cycles that 
reached 60-70 mph briefly every hour.
    We are proposing that the inducement schedules for low- and high-
speed vehicles include four stages that ramp down speeds to the final 
LSI and HSI. The first stepped decrease in speed would apply six hours 
after the initial inducement, which allows time for operators to fill 
the DEF tank and resume operation in a way that allows the engine to 
confirm a proper DEF supply without starting the next stage of 
inducement. If the fault code is not resolved, the schedule continues 
to reduce the vehicle speed by 5 mph increments in two additional 
stages. One of the considerations in choosing the stepped speed 
decreases is allowing drivers time to safely adjust to operation at a 
lower speed while also adequately incentivizing action by vehicle 
owners and operators, and we are proposing that 5 mph increments 
achieve this balance. Commenters noted that even small changes in 
allowable speeds are sufficient incentive to use high quality DEF. 
Further, we believe the first step of our proposed inducement policy 
would result in the use of high-quality DEF. The proposed additional 
time would also allow for the diagnosis and repair of more extensive 
problems and intermittent conditions.
    The low-speed vehicle schedule and the final LSI speed of 35 mph is 
designed for vehicles such as urban buses, school buses, and refuse 
haulers that have sustained operation at low speeds, but frequently 
travel at high speeds. Further, the final LSI speed would also apply to 
concrete trucks, street sweepers, or other utility vehicles that have 
low average speeds, but depend on higher speed operation to get to a 
job site. In part, because of this high-speed operation, the final LSI 
speed will be effective for compelling operators to properly maintain 
their aftertreatment systems. The high-speed vehicle schedule and the 
final HSI speed of 50 mph is designed for vehicles such as long-haul 
freight trucks that have sustained operation at high speeds. The final 
restricted speed of 50 mph prevents the vehicle from travel on most 
interstate highways with state laws regarding impeding traffic and may 
require the operator to use flashers to warn other vehicles of the 
reduced speed.
    We expect that the proposed derate schedules would be no less 
effective than the current approach under existing guidance for 
ensuring operators properly maintain aftertreatment systems and that it 
would result in lower costs and impacts to operators and ultimately 
result in lower tampering rates. EPA recognizes that the fleet is very 
diverse, and believes that applying two inducement schedules and speeds 
is an effective and reasonable approach that is not too aggressive or 
too inconsequential to ensure operators maintain compliance. Our 
analysis and proposed LSI and HSI schedules are intended to achieve the 
proper balance

[[Page 17544]]

and limit unintended consequences such as increased tampering.

               Table IV-13--Proposed Inducement Schedules
------------------------------------------------------------------------
                                                  Maximum speed (mi/hr)
                                               -------------------------
               Engine hours \a\                  Low-speed    All other
                                                  vehicles     vehicles
------------------------------------------------------------------------
0.............................................           50           65
6.............................................           45           60
12............................................           40           55
60............................................           35           50
------------------------------------------------------------------------
\a\ Hours start counting with the onset of the triggering condition
  specified in paragraph (b) of this section. For DEF supply, you may
  program the engine to reset the timer to three hours when the engine
  detects zero DEF flow.

    Sixth, to reduce occurrences of false inducements, the proposed 
inducement approach would require a warning to be displayed to the 
operator to indicate a fault, but utilize a NOX override 
feature to prevent false inducement. We are proposing that an 
inducement would not be triggered if average data from the 
NOX sensor show that the catalyst is reducing NOX 
emissions consistent with stored OBD REAL Bin data within an estimated 
10 percent margin of error due to limitations of in-use detection and 
measurement. A 10 percent reduction in NOX conversion 
efficiency has been selected because the accuracy of the NOX 
measurement can have errors as much as 10-20 percent based on a study 
conducted by SwRI.\627\ This NOX sensor error increases as 
the NOX concentration is reduced. Using a 10 percent error 
is a reasonable threshold based on the work completed by SwRI and 
considering continuing advances in technology of on-board 
NOX sensors.
---------------------------------------------------------------------------

    \627\ ``Heavy-Duty Engine Low-Load Emission Control Calibration, 
Low Load Test Cycle Development, and Evaluation of Engine Broadcast 
Torque and Fueling Accuracy During Low-Load Operation,'' Low 
NOX Demonstration Program--Stage 2, Christopher A. Sharp, 
Southwest Research Institute, SwRI Project No. 03.22496, Final 
Report, May 6, 2020.
---------------------------------------------------------------------------

    For vehicles subject to a HSI, this data would come from Bin 14 
which holds data taken during operation at vehicle speeds greater than 
40 mph and when the engine power output is greater than 50 percent of 
rated power. For vehicles subject to a Low Speed Inducement (LSI), this 
data would come from Bin 13 which holds data taken during operation at 
vehicle speeds greater than 25 mph and less than or equal to 40 mph and 
when the engine power output is greater than 50 percent of rated power. 
This data would indicate whether DEF is present in the system as zero 
NOX reductions would occur without DEF, and data showing 
reductions consistent with operation prior to the condition would 
indicate that the operator is adding high-quality DEF. We propose that 
the NOX sensor data used to evaluate the need for inducement 
would come from the 100-hour active array, which would be reset at the 
time an initial inducement trigger occurred. Resetting the array at 
that time would ensure that the data used to evaluate whether 
sufficient high-quality DEF is present in the system would be taken 
after the initial inducement was triggered and not rely on historical 
data to make the assessment. The OBD system would continue to monitor 
the fault condition and provide a warning to the operator that an issue 
should be addressed, but an inducement would not be triggered unless 
NOX performance fell below the threshold of a 10 percent 
reduction in NOX conversion efficiency (e.g., indicating 
that the operator has not added DEF).
    Seventh, as discussed in section IV.D.3, EPA is proposing in 40 CFR 
1036.111(f) that manufacturers must display the condition that 
triggered the pending or active derate and a countdown timer to 
estimate the time or distance remaining before the next stage of 
derating. This display requirement would apply even if the engine 
overrides a detected fault condition based on NOX 
measurements, and the display should indicate that the derates will not 
apply as long as NOX sensors continue to show that emission 
controls are functioning properly. It is critical that operators have 
clear and ready access to information regarding inducements to reduce 
potential anxiety over progressive engine derates (which can lead to 
motivations to tamper) as well as to allow operators to make informed 
decisions.
    Eighth, we are proposing that the system would remove the 
inducement and resume unrestricted engine operation once the OBD system 
detects the condition has been remedied. EPA would also expect 
manufacturers to enable the system to reset once the problem was 
repaired. EPA is proposing to require that generic scan tools be able 
to remove an inducement condition. This would allow owners who repair 
vehicles outside of commercial facilities to complete the repair 
without delay (e.g., flushing and refilling a DEF tank where 
contaminated DEF was discovered). However, if the same fault condition 
repeats within 80 hours of engine operation (e.g., in response to a DEF 
quantity fault an owner adds a small but insufficient quantity of DEF), 
we are proposing that the system would treat the reoccurring fault 
condition as the same triggering condition and immediately resume the 
derate at the same point in the derate schedule where it was last 
deactivated. In addition, we are proposing that the Active 100 Hour 
Array would not be reset if an additional fault occurs before the first 
code is resolved. The 80 hour window should be long enough to prevent 
operators from applying temporary remedies, but not so long that 
operators are unfairly held to the schedule for a past fault condition 
when a new fault occurs. This repeat fault provision would prevent 
operators from circumventing requirements by not properly addressing 
the problem.
    As discussed in Section IV.C, EPA is seeking comment on whether 
improvements could be made to OBD to monitor inducement conditions to 
ensure a false inducement did not occur and to track such inducements 
and the conditions that trigger them. Having access to additional OBD 
data for inducement-related conditions can help operators and repair 
technicians pinpoint and respond to conditions that currently are often 
leading to reports of `no trouble found' or false inducements.
    As noted in ANPR comments, vehicle operators have experienced 
inducements that do not seem to be keyed to detected fault conditions, 
and inducements have occurred on a different schedule than 
anticipated.\628\ These problems may be caused by wear conditions, 
malfunctioning components, or inadequate system logic. Successful 
implementation of the proposed inducement provisions depends on 
production of engines that operate according to the engine 
manufacturers' designs over a lifetime of in-use operation.
---------------------------------------------------------------------------

    \628\ See the comments of the American Trucking Associations on 
the CARB Omnibus rulemaking, ``Proposed Heavy-Duty Engine and 
Vehicle Omnibus Regulation and Associated Amendments.'' Available 
here: https://www.arb.ca.gov/lists/com-attach/45-hdomnibus2020-U2EHMQQ3AGNSegZl.pdf.
---------------------------------------------------------------------------

    We believe this proposed approach minimizes potential adverse 
impacts on operators while meeting the fundamental objective that 
manufacturers design engines to ensure that operators maintain an 
adequate supply of DEF to keep the SCR emission control system 
functioning properly.
5. Requests for Comment
    We are open to considering a wide range of adjustments to the 
proposed inducement provisions and request comment on all aspects of 
the proposal described in this section. We ask that commenters 
suggesting alternative approaches or specifications consider the 
principles identified in Section IV.D.3 to inform our development of 
the

[[Page 17545]]

proposed provisions. We are interested in any alternative regulatory 
provisions and any different principles recommended by commenters, as 
well as commenters' views on how EPA applied the identified principles 
in developing the proposed inducement provisions.
    We are also interested in whether commenters support adoption of 
inducement provisions that closely follow existing inducement 
strategies in-use, for example derating to 5 miles per hour within four 
hours of detecting certain fault conditions and, if so, whether such an 
approach would meet the principles we described or whether there are 
other principles that support such an approach.
    While we believe the proposed derate schedule would effectively 
lead every vehicle owner to address certain detected fault conditions 
within the duration of the specified schedule, we invite comment and 
relevant information that would help to assess how vehicle operators in 
a wide variety of vehicle applications would respond to a derate at any 
specific level of operating speed restriction. Toward that end, we ask 
for comments in response to the following questions:
     Is the proposed initial speed restriction of 50 (for low-
speed vehicles) and 65 miles per hour (for high-speed vehicles) 
immediately upon detecting a fault condition meaningful? For example, 
we may consider alternative initial speed restrictions of 40 and 55 mph 
to focus the operator's attention on addressing the fault condition 
since the remedy could be as simple as adding DEF or as extensive as 
making substantial repairs after a thorough diagnosis.
     Is the proposed final speed restriction of 35 (for low-
speed vehicles) and 50 miles per hour (for high-speed vehicles) 
meaningful? For example, we may consider alternative final speed 
restrictions of 25 and 40 mph.
     Is it appropriate to create a fault condition that 
triggers inducement three hours before the DEF supply will be depleted? 
The engine could alternatively be designed to warn the operator when 
DEF supply is running low and start the inducement when the DEF supply 
is depleted.
     Is the proposed six hours of non-idle operation the right 
amount of time for the first stage of inducement to take effect at 50 
or 65 miles per hour before progressing to the next stage of derating? 
A shorter time may be appropriate for simply refilling DEF, but in 
other situations that may frequently occur, the fault condition causing 
the inducement requires diagnosing and repairing a defective component.
     Is the proposed schedule for successive derates after 12 
and 60 hours appropriate? We may consider additional steps. As an 
example, we may also consider a longer schedule involving more time 
between stages such as 20 and 120 hours. Similarly, we may consider a 
shorter schedule reducing the time between stages such as 8 and 40 
hours.
     Is the proposed 80 hours of operation without repeating a 
fault condition the appropriate length of time to distinguish between a 
new fault condition that restarts the inducement schedule at the 
initial derate speed and a repeated fault condition that resumes the 
previous inducement at the same point that the system deactivated the 
derate?
     Is the proposed schedule of derating speeds over time for 
high-speed vehicles from 65 to 50 miles per hour and from 50 to 35 
miles per hour both reasonable and effective? Would a more or less 
aggressive schedule work to prevent operators from being content with 
restricted operation to avoid the cost or inconvenience of maintaining 
SCR systems? We request that commenters also explain whether any 
information provided would support an adjusted schedule consistent with 
the principles described in Section IV.D.3.
     Is the proposed average speed of 20 miles per hour over 
the preceding 30 hours of operation the appropriate threshold speed for 
a more restrictive derate schedule for low-speed vehicles? Is it 
appropriate to exclude idle from the low-speed vehicle determination?
     Should a high-speed vehicle that continues to operate at 
the final inducement speed eventually be treated like a low-speed 
vehicle if its average speed eventually falls to that level (20 miles 
per hour) based on its slower operation during inducement? Using the 
proposed values, this would cause a vehicle to eventually shift from a 
final inducement speed of 50 miles per hour down to a final inducement 
speed of 35 miles per hour. This question is fundamentally about 
whether there are any applications or scenarios for high-speed vehicles 
for which an inducement at 50 miles per hour (or another final 
inducement speed for high-speed vehicles in the final rule) is 
insufficient to compel corrective action.
     Monitoring for tampering due to a blocked DEF line or 
injector is intended to ensure that the line itself is not crimped or 
the injector plugged intentionally. However, EPA is aware that urea 
crystallization can mimic this type of tampering. OEMs can monitor DEF 
line and injector pressures and know at what point they consider 
pressure changes to be indicative of tampering. They should be able to 
use these pressure readings to indicate that the system is plugging 
over time and warn operators well in advance of an inducement (see 
section IV.C.1.iii.2. for more information on this proposal). If 
practical, should we specify the amount of time that manufacturers 
should provide operators with advance notice of a blocked DEF line or 
dosing valve prior to an inducement occurring for those cases where the 
blockage is caused by plugging due to DEF crystallization as opposed to 
direct tampering?
    We request comment on the proposed set of fault conditions for 
triggering inducements intended to address the unique aspect of SCR 
systems that depend on cooperation from vehicle operators. Toward that 
end, we raise the following questions:
     Is it necessary and appropriate to include DEF 
concentration as a fault condition, as proposed? There is an 
established practice of using DEF and engines now have built-in 
features to prevent diluting DEF or filling DEF tanks with water. Also, 
with the proposed warranty provisions, owners may be more likely to 
properly maintain their engines over longer periods, including use of 
DEF that meets the owner's manual specifications. We request comment on 
whether this concern about DEF quality continues to justify the 
additional complexity and the associated risk of false inducements.
     Are the proposed fault conditions of DEF fill level, DEF 
quality, and tampering associated with the SCR system the proper way to 
ensure an adequate supply of quality DEF in-use?
     Does the proposal properly define tampering conditions for 
inducement by identifying conditions that owners can control, such as 
open-circuit faults for disconnected DEF pump, SCR wiring harness, DEF 
dosing valve, DEF quality sensors, DEF tank heaters, DEF level sensors, 
aftertreatment control module, and NOX sensors?
     Is there a risk that the engine will incorrectly detect a 
tampering fault condition based on the specified open-circuit faults? 
For example, how likely is it that maintenance steps that require 
disconnecting or disassembling certain components as part of a repair 
will be identified as tampering? Or, how likely is it that a failing 
sensor will give an incorrect signal indicating that one of the 
specified components has been disconnected? The proposal addresses 
this, at least in part, by including an override feature based on 
measured

[[Page 17546]]

NOX emissions before and after the SCR catalyst.
     Should we allow or require additional fault conditions to 
ensure that SCR systems are working properly? We could identify 
numerous additional fault conditions based on OBD system monitoring 
that detects any number of SCR-related components that need to be 
adjusted or replaced. We have focused the proposal on things that 
owners can actually control consistent with the original focus of the 
existing guidance on ensuring an adequate supply of high-quality DEF 
paired with tamper-resistant SCR systems that focus on open-circuit 
conditions. We request comment on any additional OBD fault conditions 
that would be needed to ensure the functionality of the SCR system.
     Should EPA codify the DEF freeze protection guidance that 
describes how to meet EPA AECD requirements currently described in CD-
13-13?
     Should EPA establish an acceptable range of DEF 
concentration for defining the limits of the inducement fault 
condition? Inducements for DEF quality are based on the change in urea 
concentration from 32.5 percent (unadulterated DEF) to the point at 
which poor DEF quality can be detected and inducements are triggered. 
Manufacturers design some tolerance into their SCR systems to adapt to 
and compensate for in-use DEF quality variances instead of triggering 
an inducement for minor concentration differences. For example, if a 
vehicle with DEF in the tank has not been driven for some time, some of 
the water in the DEF can evaporate, leaving a slightly higher 
concentration of urea in the DEF. We seek comment on the need to 
clarify in the regulations appropriate DEF quality inducement triggers 
to ensure that an acceptable tolerance is being designed into SCR 
systems consistently across manufacturers and that reflects real-world 
conditions. Further we seek comment on what an acceptable tolerance 
would be.
    The proposed approach for overriding inducements based on 
NOX sensors showing that the SCR catalyst is working 
properly is an important feature to reduce the risk of false 
inducements. Operators would see a warning for a fault condition even 
if the override prevents a speed restriction, which should allow the 
operator to take the time necessary to address the fault condition. The 
override should be set at a level of NOX conversion 
efficiency to reliably indicate that an override is appropriate because 
the detected fault condition in fact does not prevent the SCR catalyst 
from working according to design. We request comment on the proposed 
approach that allows for overriding inducement if the average data from 
the NOX sensor show that the catalyst is reducing 
NOX emissions consistent with stored OBD REAL Bin data 
within an estimated 10 percent margin of error due to limitations of 
in-use detection and measurement. Toward that end, we raise the 
following questions:
     Should the margin of error be more or less than 10 
percent? NOX conversion efficiency is more stable at higher 
speed and load conditions and is generally greater than 90 percent, so 
overriding based on a greater margin of error should still be 
effective. Fault conditions such as depleted DEF or disconnected 
aftertreatment would cause NOX conversion efficiency to be 
at or near zero and would quickly impact the NOX conversion 
efficiency value due to the stored data array being reset at the time a 
trigger is detected. In such cases a less rigorous or stringent 
threshold value would be sufficient to evaluate the validity of the 
detected fault condition. Note however that some system defects may 
allow for partial NOX conversion.
     Are the (reset) Active 100 Hour Array and the specified 
Real Bins 13 and 14 the appropriate data to assess the NOX 
override, as proposed? The selected operating conditions are intended 
to be most favorable for a stable and repeatable current assessment of 
NOX conversion efficiency. Would the NOX override 
need to account for a wider range of vehicle operation to work properly 
for the full range of vehicle applications?
     Does the proposed final inducement speed in combination 
with the provision for NOX overrides provide a proper self-
healing path for deactivating derates after correcting a fault 
condition? There are likely times when this may be a preferrable option 
for operators for resolving an inducement instead of relying on scan 
tools.
    EPA is seeking comment on provisions to accommodate equivalent 
engine families that are identical except for the diagnostic system 
adjustments needed to meet the different inducement protocols. If 
finalized, we would count two equivalent engine families as one for the 
purposes of determining the number of engine families that are subject 
to OBD demonstration testing requirements for certification. This would 
be analogous to the way we are proposing to treat engine families that 
have a California-only federal certificate because of differences such 
as warranty provisions (see Section IV.C.2.i.a. for further discussion 
on this provision).
    As described in Section IV.D.1, engine manufacturers have been 
producing engines for many years with inducement strategies that align 
with the potential approaches described in EPA guidance. If we replace 
the guidance documents with regulatory provisions that include new 
derating specifications, those specifications could be understood to 
represent an alternative design strategy for meeting the objectives 
described in guidance relative to requirements for maintenance 
specifications and adjustable parameters. It may accordingly be 
appropriate to allow engine manufacturers to modify earlier model year 
engines to align with the new regulatory specifications. We are not 
proposing to change the regulation to address this concern. We are 
seeking comment on whether and how manufacturers might use field-fix 
practices under EPA's field fix guidance to modify in-use engines with 
algorithms that incorporate some or all of the inducement provisions we 
include in the final rule.\629\ For example, this approach could 
potentially allow engine manufacturers to change the final inducement 
speed from 5 miles per hour to 50 miles per hour over a 60-hour period.
---------------------------------------------------------------------------

    \629\ ``Field Fixes Related to Emission Control-Related 
Components,'' EPA Advisory Circular, March 17, 1975.
---------------------------------------------------------------------------

    Engine manufacturers may similarly be interested in modifying 
engines from the current model year by amending the application for 
certification. See Section XII.B.3 for additional discussion related to 
amending applications for certification.
    Finally, EPA is seeking comment on whether existing manufacturer 
inducement strategies are causing certain vocational segments to 
transition from diesel to gasoline powertrains. For example, one school 
bus manufacturer introduced gasoline-powered buses in late 2016, which 
appear to have quickly come to represent nearly 25 percent of 
sales.\630\ Another school bus manufacturer has indicated growing 
interest in alternative fuel powertrains such as gasoline or propane in 
response to SCR-related maintenance issues and downtime.\631\
---------------------------------------------------------------------------

    \630\ ``Blue Bird delivers its 5,000th gasoline-powered school 
bus'' March 13, 2019. Available here: https://blue-bird.com/about-us/press-releases/146-blue-bird-delivers-its-5-000th-gasoline-powered-school-bus.
    \631\ ``Fleet Managers Rethinking Fuel Choice: Many Choosing New 
Engines That Reduce Budget Pressure and Maintenance Headaches'' 
February 1, 2019. Available here: https://thomasbuiltbuses.com/bus-advisor/articles/fleet-managers-rethinking-fuel-choice/.

---------------------------------------------------------------------------

[[Page 17547]]

E. Certification Updates

    In an effort to better serve the regulated community, EPA has taken 
a number of important steps to streamline the data collection processes 
that manufacturers use to apply for annual certificates of conformity 
from the agency. These streamlining efforts include numerous 
modifications and enhancements to improve the user experience, minimize 
manual data submission processes, and eliminate duplication of effort 
for manufacturers. Beginning with the overall process, EPA has made 
user-centered design a central theme when developing systems for 
manufacturers. Engaging manufacturers before and throughout the 
development process helps reduce incorrect assumptions about their 
business needs and ensures that systems are end-user tested for 
viability. We recently transitioned our compliance information system 
from the Verify System to a new Engines and Vehicles Compliance 
Information System (EV-CIS). This new platform incorporates 
manufacturer feedback and includes updates that help manufacturers work 
more efficiently while minimizing the need for costly fixes which can 
lead to rework. Although we have made significant progress to improve 
the certification process, we welcome comments suggesting additional 
improvements EPA could consider.

F. Durability Testing

    EPA regulations require that a heavy-duty engine manufacturer's 
application for certification include a demonstration that the engines 
will meet applicable emission standards throughout their regulatory 
useful life. This is often called the durability demonstration. 
Manufacturers typically complete this demonstration by following 
regulatory procedures to calculate a deterioration factor (DF). 
Deterioration factors are additive or multiplicative adjustments 
applied to the results from manufacturer testing to quantify the 
emissions deterioration over useful life.\632\
---------------------------------------------------------------------------

    \632\ See proposed 40 CFR 1036.240(c) and the definition of 
``deterioration factor'' in 40 CFR 1036.801, which are proposed to 
be migrated and updated from 40 CFR 86.004-26 and 86.004-28.
---------------------------------------------------------------------------

    Currently, a DF is determined directly by aging an engine and 
exhaust aftertreatment system to useful life on an engine dynamometer. 
This time-consuming service accumulation process requires manufacturers 
to commit to product configurations well ahead of their pre-production 
certification testing to complete the durability testing so EPA can 
review the test results before issuing the certificate of conformity. 
Some manufacturers run multiple, staggered durability tests in parallel 
in case a component failure occurs that may require a complete restart 
of the aging process.\633\
---------------------------------------------------------------------------

    \633\ See 40 CFR 1065.415.
---------------------------------------------------------------------------

    EPA recognizes that durability testing over a regulatory useful 
life is a significant undertaking, which can involve more than a full 
year of continuous engine operation for Heavy HDE to test to the 
equivalent of the current useful life of 435,000 miles. Manufacturers 
have been approved, on a case-by-case basis, to age their systems to 
between 35 and 50 percent of full useful life on an engine dynamometer, 
and then extrapolate the test results to full useful life.\634\ This 
extrapolation reduces the time to complete the aging process, but data 
from a test program shared with EPA show that while engine out 
emissions for SCR-equipped engines were predictable and consistent, 
actual tailpipe emission levels were higher by the end of useful life 
when compared to emission levels extrapolated to useful life from 
service accumulation of 75 or lower percent useful 
life.635 636 In response to the new data indicating DFs 
generated by manufacturers using service accumulation less than useful 
life may not be fully representative of useful life deterioration, EPA 
worked with manufacturers and CARB to address this concern through 
guidance for MY 2020 and later engines.
---------------------------------------------------------------------------

    \634\ See 40 CFR 86.004-26.
    \635\ U.S. EPA. ``Guidance on Deterioration Factor Validation 
Methods for Heavy-Duty Diesel Highway Engines and Nonroad Diesel 
Engines equipped with SCR.'' CD-2020-19 (HD Highway and Nonroad). 
November 17, 2020.
    \636\ Truck and Engine Manufacturers Association. ``EMA DF Test 
Program.'' August 1, 2017.
---------------------------------------------------------------------------

    In this section, we describe our proposal to migrate and update the 
DF provisions for heavy-duty highway engines from their current 
location in 40 CFR 86.004-26(c) and (d) and 86.004-28(c) and (d) to 40 
CFR 1036.245 and 1036.246. While the current DF guidance is specific to 
SCR-equipped engines, we are proposing to update our DF provisions to 
apply certain aspects of the current DF guidance to all engine families 
starting in model year 2027.\637\ We also propose that manufacturers 
could optionally use these provisions to determine and verify their 
deterioration factors for earlier model years. As noted in the 
following section, we propose to continue the option for Spark-ignition 
HDE manufacturers to request approval of an accelerated aging DF 
determination, as is allowed in our current regulations (see 40 CFR 
86.004-26(c)(2)), though our proposed provision would extend this 
option to all primary intended service classes. We are not proposing 
changes to the existing compliance demonstration provision in 40 CFR 
1037.103(c) for evaporative and refueling emission standards. As 
introduced in Section III.E, our proposal would apply refueling 
emission standards to incomplete vehicles above 14,000 lb GVWR. 
Incomplete vehicle manufacturers certifying to the refueling emission 
standards for the first time under this proposal would have the option 
to use engineering analyses to demonstrate durability using the same 
procedures that apply for the evaporative systems on their vehicles 
today.
---------------------------------------------------------------------------

    \637\ As noted in Section III.A, the proposed update to the 
definition of ``engine configuration'' in 40 CFR 1036.801 would 
clarify that hybrid engines and powertrains would be part of a 
certified configuration and subject to all of the criteria pollutant 
emission standards and other requirements; thus the DF provisions 
for heavy-duty engines discussed in this subsection would apply to 
configurations that include hybrid components.
---------------------------------------------------------------------------

    In Section IV.F.1, we propose two methods for determining DFs in a 
new 40 CFR 1036.245, including a new option to bench-age the 
aftertreatment system to limit the burden of generating a DF over the 
lengthened useful life periods proposed in Section IV.A.3. We also 
propose to codify the three DF verification options available to 
manufacturers in the recent DF guidance. As described in Section 
IV.F.2, the verification options in a new 40 CFR 1036.246 would confirm 
the accuracy of the DF values submitted by manufacturers for 
certification. In Section IV.F.3, we introduce a test program to 
evaluate a rapid-aging protocol for diesel catalysts that we may 
consider as an option for CI engine manufacturers to use in their 
durability demonstration.
    We request comment on the proposed options for DF determination and 
verification, including other options we should consider. We further 
request comment on whether DF testing of the engine is sufficient for 
hybrid engines and powertrains, or if we should consider additional 
testing requirements for manufacturers to demonstrate durability of 
other key components included in a hybrid configuration (e.g., battery 
durability testing).
    As described in Section XII.A.8, we are also proposing to allow 
manufacturers of nonroad engines to use the procedures described in 
this section to establish deterioration factors based on bench-aged 
aftertreatment, along with in-use verification testing.

[[Page 17548]]

1. Proposed Options for Determining Deterioration Factor
    Accurate methods to demonstrate emission durability are key to 
ensuring certified emission levels represent real world emissions, and 
the efficiency of those methods is especially important in light of our 
proposal to lengthen useful life periods. To address these needs, we 
are proposing to migrate our existing regulatory options and include a 
new option for heavy-duty highway engine manufacturers to determine DFs 
for certification. We note that manufacturers apply these deterioration 
factors to determine whether their engines meet the duty cycle 
standards. For MY 2031 and later Heavy HDE, we are proposing separate 
duty cycle standards at an intermediate useful life, and are further 
proposing that a separate deterioration factor would apply for the 
intermediate useful life as well.
    Consistent with existing regulations, proposed 40 CFR 1036.245 
would allow manufacturers to continue the current practice of 
determining DFs based on engine dynamometer-based aging of the complete 
engine and aftertreatment system out to regulatory useful life. In 
addition, under our proposed new DF determination option, manufacturers 
would be able to perform dynamometer testing of an engine and 
aftertreatment system to a mileage that is less than regulatory useful 
life. Manufacturers would then bench age the aftertreatment system to 
regulatory useful life and combine the aftertreatment system with an 
engine that represents the engine family. Manufacturers would run the 
combined engine and bench-aged aftertreatment for at least 100 hours 
before collecting emission data for determination of the deterioration 
factor. Under this option, the manufacturer would propose a bench aging 
procedure and obtain prior approval from the Agency, which could be a 
bench aging procedure that is established today (e.g., procedures that 
apply for light-duty vehicles under 40 CFR part 86, subpart S).
    We request comment on the options proposed for DF determination. 
Specifically, we ask commenters to consider if the proposed new bench-
aged aftertreatment option accurately evaluates the durability of the 
emission-related components in a certified configuration. We are 
proposing to allow manufacturers to define and seek approval for a 
less-than-useful life mileage for the dynamometer portion of the bench-
aging option. We request comment on the need to define a minimum number 
of engine hours of dynamometer testing beyond what is required to 
stabilize the engine before bench-aging the aftertreatment.\638\ We 
note that EPA's bench-aging proposal focuses on deterioration of 
emission control components. We request comment on including a more 
comprehensive durability demonstration of the whole engine, such as the 
recent diesel test procedures from CARB's Omnibus regulation that 
includes dynamometer-based service accumulation of 2,100 hours or more 
based on engine class and other factors.\639\ We also request comment 
on whether EPA should prescribe a standardized aging cycle for the 
dynamometer portion, as was done by CARB in the Omnibus rule.\640\ We 
also request cost and time data corresponding to the current DF 
procedures, and projections of cost and time for the options proposed 
in this section at the proposed useful life mileages. As discussed in 
Section IV.F.3, EPA is currently validating an accelerated aging 
protocol for heavy-duty diesel engine aftertreatment systems. We expect 
that if the protocol is validated, manufacturers could choose to use 
that protocol in lieu of developing their own for approval by EPA.
---------------------------------------------------------------------------

    \638\ We are proposing to update the definition of ``low-hour'' 
in 40 CFR 1036.801 to include 300 hours of operation for engines 
with NOX aftertreatment to be considered stabilized.
    \639\ California Air Resources Board, ``Appendix B-1 Proposed 
30-Day Modifications to the Diesel Test Procedures'', May 5, 2021, 
Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/30dayappb1.pdf, page 54.
    \640\ California Air Resources Board, ``Staff Report: Initial 
Statement of Reasons for Proposed Rulemaking, Public Hearing to 
Consider the Proposed Heavy-duty Engine and Vehicle Omnibus 
Regulation and Associated Amendments,'' June 23, 2020. Available 
online: https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf, 
page III-80.
---------------------------------------------------------------------------

2. Proposed Options for Verifying Deterioration Factors
    In proposed new 40 CFR 1036.246, manufacturers would annually 
verify an engine family's deterioration factor for each duty cycle 
until all DFs are verified at 85 percent of useful life. We propose 
that a manufacturer could request to apply an approved DF to a future 
model year for that engine family, using the proposed updates to 
carryover engine data provisions in 40 CFR 1036.235(d), as long as the 
carryover data includes DF verification results for the production year 
of that new model year as specified in proposed 40 CFR 1036.246(b). 
Since emission performance is expected to be stable early in the life 
of the engine, we are proposing not to require DF verification in the 
first two calendar years following a DF determination for an engine 
family. Starting in the third year, manufacturers would verify the DFs 
using an in-use engine with a mileage at or greater than 35 percent of 
the useful life for the original model year of that DF determination. 
Subsequent years after production would increase minimum mileages in 10 
percent increments each year. Table IV-14 presents the minimum age we 
are proposing for each year after a DF is applied. We note that these 
are minimum values and manufacturers could complete the testing earlier 
if they recruit higher-mileage vehicles for verification testing. If a 
manufacturer is unable to find enough test vehicles that meet the 
mileage specifications, we propose that they would perform the testing 
using vehicles with the highest available mileage and describe how they 
would attempt to test properly qualified vehicles for later years. If 
this occurs in the eighth year, they would continue testing in future 
years until all tested vehicles have mileage that is at least 85 
percent of the engine's useful life.

      Table IV-14--Minimum Age for Obtaining In-Use Engines for DF
                          Verification Testing
------------------------------------------------------------------------
                                                         Minimum engine
                                                            service
 Year of production following the initial model year      accumulation
       that relied on the deterioration factors           (percent of
                                                          useful life)
------------------------------------------------------------------------
1....................................................               None
2....................................................               None
3....................................................                 35
4....................................................                 45
5....................................................                 55
6....................................................                 65
7....................................................                 75
8 or later...........................................                 85
------------------------------------------------------------------------

    We include three testing options in our proposed DF verification 
provisions. For each option, manufacturers would select in-use engines 
meeting the criteria proposed in 40 CFR 1036.246(c), including the 
appropriate minimum mileage corresponding to the production year of the 
engine family. We request comment on the proposed number of engines to 
test under each of these three DF verification options, as well as the 
corresponding pass threshold.
    In the first verification option, proposed in new 40 CFR 
1036.246(d)(1), manufacturers would test at least two in-use engines 
over all duty cycles with brake-specific emission standards in 40 CFR 
1036.104(a) by removing each engine from the vehicle to install it on 
an engine dynamometer and measure emissions. Manufacturers would

[[Page 17549]]

determine compliance with the emission standards after applying 
regeneration adjustment factors to their measured results. We propose 
that the engine family passes the DF verification if 70 percent or more 
of the engines tested meet the standards for each pollutant over all 
duty cycles. If a manufacturer chooses to test two engines under this 
option, both engines would have to meet the standards. We are proposing 
that the aftertreatment system, including all the associated wiring, 
sensors, and related hardware or software be installed on the test 
engine. We request comment on whether EPA should require approval for 
hardware or software used in testing that differs from those used for 
production engines and criteria EPA should consider for that approval.
    Under our second proposed verification option in new 40 CFR 
1036.246(d)(2), manufacturers would perform the testing on-board the 
vehicle using a PEMS. Manufacturers would bin and report the emissions 
following the in-use testing provisions in 40 CFR part 1036, subpart E. 
Compliance would be determined by comparing emission results to the 
off-cycle standards for each pollutant for each bin after adjusting for 
regeneration.\641\ We propose the PEMS-based verification would require 
testing of at least five in-use engines to account for the increased 
variability of vehicle-level measurement. We also propose that the same 
70 percent threshold be used to determine a passing result for this 
option, which is at least four engines if the manufacturer tests the 
minimum of five engines. In the event that a DF verification fails 
under the PEMS option, we propose that a manufacturer could reverse a 
fail determination and verify the DF using the engine dynamometer 
option in 40 CFR 1036.246(d)(1).
---------------------------------------------------------------------------

    \641\ For Spark-ignition HDE, we are not proposing off-cycle 
standards; however, for the in-use DF verification options, 
manufacturers would compare to the duty cycle standards applying a 
2.0 multiplier for model years 2027 through 2030, and a 1.5 
multiplier for model years 2031 and later, or multipliers consistent 
with the corresponding medium/high load bin off-cycle standards for 
CI.
---------------------------------------------------------------------------

    Our third proposed option to verify DF is to measure NOX 
emissions using the vehicle's on-board NOX measurement 
system (i.e., a NOX sensor) according to 40 CFR 
1036.246(d)(3). We expect manufacturers would only choose this option 
if they have a well-established infrastructure to access on-board data 
from a large number of vehicles (e.g., telematics). Manufacturers 
choosing this option would verify their NOX measurement 
system meets 40 CFR 1065.920(b), is functional within 100 seconds of 
engine starting, and maintains functionality over the entire shift-day. 
Due to further uncertainty in measurement accuracy, and the fact that 
fewer pollutants would be monitored with a NOX sensor, we 
propose the on-board NOX measurement system option would 
require testing 50 percent of the production for that engine family 
with a 70 percent threshold to pass. Similar to the PEMS option, we 
propose that a manufacturer could reverse a fail determination and 
verify the DF using the engine dynamometer option in 40 CFR 
1036.246(d)(1).
    In the case of a failed result from any of these verification 
options, we proposed that manufacturers could request approval for a 
revised DF or retest to determine a new DF, but the affected engine 
families would not be able to generate emission credits using a DF that 
failed to pass verification. We propose to allow the manufacturer to 
continue to certify the engine family for one additional model year 
using the original deterioration factor to provide time for the 
manufacturer to change the engine and generate new DFs. We may require 
manufacturers to certify with revised family emission limits and apply 
revised DFs to retroactively adjust the family emission limits and 
recalculate emission credits from previous model years that used the 
invalidated DF. We note that a DF verification failure may result in an 
expanded discovery process that could eventually lead to recall under 
our existing provisions in 40 CFR part 1068, subpart F.
    As part of the proposed new DF verification provisions, we include 
a new 40 CFR 1036.246(c) specifying how to select and prepare engines 
for testing. We are proposing to allow manufacturers to exclude 
selected engines from testing if they have not been properly maintained 
or used and require that the engine must be in a certified 
configuration, including its original aftertreatment components. 
Recognizing that manufacturers may schedule maintenance for emission-
related components, we request comment on whether restricting engines 
to those with original components would considerably limit the number 
of candidate engines for testing.
3. Diesel Aftertreatment Rapid Aging Protocol
    As discussed in Section IV.F.1, we are proposing that manufacturers 
could use engine dynamometer testing for less than full useful life in 
combination with an accelerated catalyst aging protocol in their 
demonstration of heavy-duty diesel engine aftertreatment durability 
through full useful life. EPA has approved accelerated aging protocols 
for spark-ignition engine manufacturers to apply in their durability 
demonstrations for many years. While CI engine manufacturers could also 
propose an accelerated aging protocol for EPA approval, CI engine 
manufacturers have largely opted to seek EPA approval to use a service 
accumulation test with reduce mileage and extrapolate to determine 
their DF.
    Other regulatory agencies have promulgated accelerated aging 
protocols,642 643 and we are evaluating how these protocols 
could apply to our heavy-duty highway engine compliance program. EPA is 
in the process of validating a protocol that CI engine manufacturers 
could potentially choose to use in lieu of developing their own 
protocol as proposed in 40 CFR 1036.245. This validation program for a 
diesel aftertreatment rapid-aging protocol (DARAP) builds on existing 
rapid-aging protocols designed for light-duty gasoline vehicles (64 FR 
23906, May 4, 1999) and heavy-duty engines.\644\
---------------------------------------------------------------------------

    \642\ California Air Resources Board. California Evaluation 
Procedure For New Aftermarket Diesel Particulate Filters Intended As 
Modified Parts For 2007 Through 2009 Model Year On-Road Heavy-Duty 
Diesel Engines, March 1, 2017. Available online: https://ww3.arb.ca.gov/regact/2016/aftermarket2016/amprcert.pdf.
    \643\ European Commission. Amending Regulation (EU) No 583/2011, 
20 September 2016. Available online: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R1718&from=HU.
    \644\ Eakle, S and Bartley, G (2014), ``The DAAAC Protocol for 
Diesel Aftertreatment System Accelerated Aging''.
---------------------------------------------------------------------------

    The objective of this validation program is to artificially 
recreate the three primary catalytic deterioration processes observed 
in field-aged aftertreatment components: Thermal aging based on time at 
high temperature, chemical aging that accounts for poisoning due to 
fuel and oil contamination, and deposits. The validation program has 
access to three baseline engines that were field-aged to the current 
useful life of 435,000 miles. For comparison, we are aging engines and 
their corresponding aftertreatment systems using our current, engine 
dynamometer-based durability test procedure. We are also aging the 
catalyst-based aftertreatment systems using a burner \645\ in place of 
an engine. The validation test plan compares emissions at the following 
approximate intervals: 0 percent, 25 percent, 50 percent, 75 percent, 
and 100 percent of the current useful life of 435,000 miles.

[[Page 17550]]

We include more details of our DARAP test program in a memo to the 
docket.\646\
---------------------------------------------------------------------------

    \645\ A burner is a computer controlled multi-fuel reactor 
designed to simulate engine aging conditions.
    \646\ Memorandum to Docket EPA-HQ-OAR-2019-0055: ``Diesel 
Aftertreatment Rapid Aging Program''. George Mitchell. May 5, 2021.
---------------------------------------------------------------------------

    The DARAP validation program is currently underway, and we have 
completed testing of one engine through the current useful life. Our 
memo to the docket includes a summary of the preliminary validation 
results from this engine. We will docket complete results from our 
validation program in a final report for the final rule. If the 
validation is successful, we would likely include an option for 
manufacturers to reference this protocol for DF determination and 
streamline approval under proposed 40 CFR 1036.245(b)(2). We request 
comment on improvements we should consider for the protocol outlined in 
our memo to the docket, including whether EPA should prescribe a 
standardized aging cycle, as was done by CARB in the Omnibus rule, for 
input to the DARAP.\647\ We also request comment on the current 
proposal to require approval to use DARAP or if EPA should codify this 
protocol as a test procedure.
---------------------------------------------------------------------------

    \647\ California Air Resources Board, Staff Report: Initial 
Statement of Reasons for Proposed Rulemaking, ``Public Hearing to 
Consider the Proposed Heavy-duty Engine and Vehicle Omnibus 
Regulation and Associated Amendments,'' June 23, 2020. https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf, page III-80.
---------------------------------------------------------------------------

G. Averaging, Banking, and Trading

    EPA established an averaging, banking, and trading (ABT) program 
for heavy-duty engines in 1990 (55 FR 30584, July 26, 1990). By 
offering the opportunity to use ABT credits and additional 
flexibilities we can design progressively more stringent standards that 
help meet our emission reduction goals at a faster and more cost-
effective pace.\648\ In Section III, we show that the proposed 
standards are feasible without the use of credits. However, we see 
value in maintaining an ABT program to provide flexibility for 
manufacturers to spread out their investment and prioritize technology 
adoption in the applications that make the most sense for their 
businesses during the transition to meeting new standards. An ABT 
program is also an important foundation for targeted incentives that we 
are proposing to encourage manufacturers to adopt advanced technology 
in advance of required compliance dates.\649\
---------------------------------------------------------------------------

    \648\ See NRDC v. Thomas, 805 F. 2d 410, 425 (D.C. Cir. 1986) 
that upheld emissions averaging after concluding that ``EPA's 
argument that averaging will allow manufacturers more flexibility in 
cost allocation while ensuring that a manufacturer's overall fleet 
still meets the emissions reduction standards makes sense''.
    \649\ See Section IV.H for our proposed early adoption 
incentives.
---------------------------------------------------------------------------

    In Section IV.G.1, we introduce our proposal to continue allowing 
averaging, banking, and trading of NOX credits generated 
against applicable heavy-duty engine NOX standards. We also 
propose targeted revisions to the current ABT approach to account for 
specific aspects of the broader proposed program, which include 
discontinuing a credit program for HC and PM and new provisions to 
clarify how FELs apply for additional duty cycles. We recognize that 
ABT allows manufacturers to use generated emission credits (from 
engines produced with emission levels below the standards) to produce 
engines with emission levels above the standards. To limit the 
production of new engines with higher emissions than the standards, we 
are proposing restrictions for using emission credits generated in 
model years 2027 and later that include averaging sets (Section 
IV.G.2), FEL caps (Section IV.G.3), and limited credit life (Section 
IV.G.4). We are also proposing that credits generated as early as MY 
2024 against current criteria pollutant standards could only be used in 
MY 2027 and later if they meet proposed requirements for the generation 
of transitional credits (Sections IV.G.5 and IV.G.6).
    The existing ABT provisions that apply for GHG standards in 40 CFR 
part 1036, subpart H, were adapted for the Phase 1 GHG rulemaking from 
earlier ABT provisions for HD engines (i.e., 40 CFR 86.007-15).\650\ In 
this rulemaking and described in this section, we are proposing to 
revise 40 CFR part 1036, subpart H, to also apply for criteria 
pollutant standards.\651\ We are also proposing a new paragraph at 40 
CFR 1036.104(c) to specify how the ABT provisions would apply for MY 
2027 and later heavy-duty engines subject to the proposed criteria 
pollutant standards in 40 CFR 1036.104(a). The proposed interim 
provision in 40 CFR 1036.150(a)(1) describes how manufacturers could 
generate credits in MY 2024 through 2026 that could be applied in MY 
2027 and later.
---------------------------------------------------------------------------

    \650\ 76 FR 57127 and 57238, September 15, 2011.
    \651\ Our proposal does not include substantive revisions to the 
existing GHG provisions in 40 CFR 1036, subpart H; our proposed 
revisions clarify whether paragraphs apply for criteria pollutant 
standards or GHG standards.
---------------------------------------------------------------------------

    We request comment on our proposed revisions to the ABT program. As 
discussed further below, we are particularly interested in stakeholder 
feedback on alternative approaches to accounting for multiple standards 
and duty cycles, as well as our proposed approaches for restricting the 
use of credits that are generated for use in MY 2027 and later.
1. Multiple Standards and Duty Cycles
    Heavy-duty compression-ignition engine manufacturers currently must 
certify to FTP, SET, and off-cycle standards.\652\ Based on FTP and SET 
test results, CI engine manufacturers participating in the ABT program 
declare FELs in their application for certification. Spark-ignition 
engine manufacturers that are only subject to FTP standards may also 
declare FELs based on the FTP duty cycle testing. An FEL replaces the 
standard and the manufacturer agrees to meet that FEL whenever the 
engine is tested over the FTP or SET duty cycle--whether for 
certification or a selective enforcement audit. The current NTE 
standards apply in-use whenever a CI engine is operating within the NTE 
applicability limits and are equal to 1.5 times the FTP and SET 
standards. The same 1.5 adjustment factor applies to the declared FEL 
for CI engine manufacturers participating in ABT.
---------------------------------------------------------------------------

    \652\ As discussed in Section III, the current standards use the 
same numeric value for the FTP and SET cycles. The Not to Exceed 
(NTE) standard is an off-cycle standard that applies when an engine 
is not on a defined laboratory test cycle.
---------------------------------------------------------------------------

    We are not proposing changes to the following aspects of the ABT 
program currently specified in 40 CFR 86.007-15:
     Allow ABT credits for NOX
     Calculate NOX credits based on a single 
NOX Family Emission Limit (FEL) for an engine family
     Specify FELs to the same number of decimal places as the 
applicable standards
     Apply FEL caps for NOX to constrain maximum 
values for FELs
     Calculate credits based on the work and miles of the FTP 
cycle
     Limit credits to four averaging sets corresponding to the 
four primary intended service classes (detailed in Section IV.G.2)
    As discussed in Section III, we are proposing to revise HC and PM 
standards for heavy-duty engines to levels that are feasible without 
the use of credits. We are proposing not to allow averaging, banking, 
or trading for HC (including NOX+NMHC) or PM for MY 2027 and 
later engines. This includes not allowing HC and PM emissions credits 
from prior model years to be used for MY 2027 and later engines. For 
engines certified to MY 2027 or later standards, manufacturers must 
demonstrate in their application for certification that they meet the 
proposed

[[Page 17551]]

PM, HC, and CO emission standards in 40 CFR 1036.104(a) without using 
emission credits.
    While we continue to consider the FTP duty cycle the appropriate 
reference cycle for generating NOX emission credits, we are 
proposing new provisions to ensure the NOX emission 
performance over the FTP is proportionally reflected in the range of 
cycles that we are proposing for these heavy-duty engines. 
Specifically, we propose that manufacturers would declare an FEL to 
apply for the FTP standards and then they would calculate a 
NOX FEL for the other applicable cycles by applying an 
adjustment factor based on their declared FELFTP.\653\ We 
propose the adjustment factor be a ratio of the declared NOX 
FELFTP to the FTP NOX standard to scale the 
NOX FEL of the other duty cycle or off-cycle standards.\654\ 
For example, if a manufacturer declares an FELFTP of 30 mg 
NOX/hp-hr in MY 2031 for a Heavy HDE, where the proposed 
NOX standard is 40 mg/hp-hr, a ratio of 30/40 or 0.75 would 
be applied to calculate a FEL to replace each NOX standard 
that applies for these engines in the proposed 40 CFR 1036.104(a). 
Specifically, for this example, a Heavy HDE manufacturer would replace 
the intermediate and full useful life standards for SET, LLC, and the 
three off-cycle bins with values that are three-quarters of the 
proposed standards. For an SI engine manufacturer that declares an 
FELFTP of 15 mg NOX/hp-hr compared to the 
proposed MY 2031 of 20 mg/hp-hr, a ratio of 15/20 or 0.75 would be 
applied to the SET duty cycle standard to calculate an 
FELSET. Note that an FELFTP can also be higher 
than the NOX standard in an ABT program if it is offset by 
lower-emitting engines in an engine family that generates equivalent or 
more credits in the averaging set. For an FEL higher than the 
NOX standard, the adjustment factor would proportionally 
increase the emission levels allowed when manufacturers demonstrate 
compliance over the other applicable cycles.\655\
---------------------------------------------------------------------------

    \653\ Our proposed approach for calculating a NOX FEL 
is similar to the current approach for NTE standards; see Section 
III.C.1 for more description of the current NTE standards.
    \654\ We are proposing to require manufacturers to declare the 
NOX FEL for the FTP duty cycle in their application for 
certification. Manufacturers and EPA will calculate FELs for the 
other applicable cycles using the procedures specified in 40 CFR 
1036.104(c)(3) to evaluate compliance with the other cycles; 
manufacturers would not be required to report the calculated FELs 
for the other applicable cycles. As noted previously, manufacturers 
would demonstrate they meet the standards for PM, CO, and HC and 
would not calculate or report FELs for those pollutants.
    \655\ We are proposing in 40 CFR 1036.104(c) that manufacturers 
meet the PM, HC, and CO emission standards without generating or 
using credits; they would not be required to calculate PM, HC, and 
CO FELs as is proposed for NOX.
---------------------------------------------------------------------------

    Under the current and proposed ABT provisions, FELs serve as the 
emission standards for the engine family for the respective testing. In 
our proposal, manufacturers would include test results to demonstrate 
their engines meet the declared and calculated FEL values for all 
applicable cycles (see proposed 40 CFR 1036.240(a)). CI engine 
manufacturers participating in ABT would use the FELs calculated for 
the off-cycle bins to replace the standards in the in-use testing 
provisions proposed in 1036, subpart E and PEMS-based DF verifications 
in the proposed 40 CFR 1036.246(2).\656\ We expect manufacturers would 
base their final FELFTP for credit generation on their 
engine family's emission performance on the most challenging cycle. For 
instance, if a CI engine manufacturer demonstrates NOX 
emissions on the FTP that is 25 percent lower than the standard but can 
only achieve 10 percent lower NOX emissions for the low load 
cycle, the declared FELFTP would be based on that 10 percent 
improvement to ensure the proportional FELLLC would be met. 
For the duty cycle standards at intermediate useful life, we are 
proposing that the DF determination data at the equivalent intermediate 
useful life mileage serve as a demonstration of emission control 
performance for certification. For off-cycle standards, we are 
proposing that manufacturers may attest, rather than demonstrate, that 
all the engines in the engine family comply with the proposed off-cycle 
emission standards for all normal operation and use (see the proposed 
40 CFR 1036.205(p)) in their application for certification.
---------------------------------------------------------------------------

    \656\ We are not proposing off-cycle standards for SI engines; 
SI engine manufacturers opting for PEMS-based DF verification in the 
proposed 40 CFR 1036.246(2) would use their FEL to calculate the 
effective in-use standard for those procedures.
---------------------------------------------------------------------------

    Once FEL values are established, credits are calculated based on 
the FTP duty cycle. We are not proposing substantive revisions to the 
equation that applies for calculating emission credits in 40 CFR 
1036.705, but we are proposing to update the variable names and 
descriptions to apply for both GHG and criteria pollutant 
calculations.\657\ In Equation IV-1, we reproduce the equation of 40 
CFR 1036.705 to emphasize how the FTP duty cycle applies for 
NOX credits. Credits are calculated as megagrams (i.e., 
metric tons) based on the emission rate over the FTP cycle. The 
emission credit calculation represents the emission impact that would 
occur if an engine operated over the FTP cycle for its full useful 
life. The difference between the FTP standard and the family limit 
(i.e., FEL for criteria pollutants) is multiplied by a conversion 
factor that represents the average work performed over the FTP duty 
cycle to get the per-engine emission rate over the cycle. This value is 
then multiplied by the production volume of engines in the engine 
family and the applicable useful life mileage. Credits are calculated 
at the end of the model year using actual production volumes for the 
engine family. The credit calculations are submitted to EPA as part of 
a manufacturer's ABT report (see 40 CFR 1036.730).
---------------------------------------------------------------------------

    \657\ The emission credits equations in the proposed 40 CFR 
1036.705 and the current 40 CFR 86.007-15(c)(1)(i) are functionally 
the same.
[GRAPHIC] [TIFF OMITTED] TP28MR22.001

Where:
StdFTP = the FTP duty cycle NOX emission 
standard, in mg/hp-hr, that applies for engines not participating in 
the ABT program
FEL = the engine family's FEL for NOX, in mg/hp-hr.
WorkFTP = the total integrated horsepower-hour over the 
FTP duty cycle.
MilesFTP = the miles of the FTP duty cycle. For Spark-
ignition HDE, use 6.3 miles. For Light HDE, Medium HDE, and Heavy 
HDE, use 6.5 miles.
Volume = the number of engine eligible to participate in the ABT 
program within the given engine family during the model year, as 
described in 40 CFR 1036.705(c).
UL = the useful life for the standard that applies for a given 
engine family, in miles.
2. Averaging Sets
    EPA has historically allowed averaging, banking, and trading only

[[Page 17552]]

within specified ``averaging sets'' for its heavy-duty engine emission 
standards. This restriction is in place to avoid creating unfair 
competitive advantages or environmental risks due to credit 
inconsistency.\658\ We propose to continue this approach, using engine 
averaging sets that correspond to the four primary intended service 
classes,\659\ namely:
---------------------------------------------------------------------------

    \658\ 66 FR 5002 January 18, 2001 and 81 FR 73478 October 25, 
2016.
    \659\ Primary intended service class is defined in 40 CFR 
1036.140, which is referenced in the current 40 CFR 86.004-2.

 Spark-ignition HDE
 Light HDE
 Medium HDE
 Heavy HDE

    As discussed in Section IV.I, we are proposing that manufacturers 
could certify battery-electric and fuel cell electric vehicles to 
generate NOX emission credits. Manufacturers would include 
battery-electric and fuel cell electric vehicles in an averaging set 
based on a manufacturer-declared primary intended service class 
considering the GVWR of the vehicle.\660\
---------------------------------------------------------------------------

    \660\ As specified in the proposed 40 CFR 1037.102(b)(1), 
battery-electric and fuel cell electric vehicles would certify to 
standards in the following engine categories: Light HDE, Medium HDE 
and Heavy HDE, and as such would only generate NOX 
emission credits in these averaging sets. The same restrictions 
would apply to averaging, banking, or trading these credits only 
within the averaging set in which they are generated (see the 
proposed 40 CFR 1036.741)
---------------------------------------------------------------------------

3. FEL Caps
    EPA has historically capped FELs for a new criteria pollutant 
standard at the level of the previous emission standard to avoid engine 
technologies backsliding. FEL caps limit the amount that an individual 
engine can emit above the level of emission standard when manufacturers 
choose to use emission credits to comply with the standard. Without a 
FEL cap, manufacturers could choose to use emission credits to produce 
engines that emit at any numeric level for which they had sufficient 
credits, whereas, with a FEL cap in place, EPA can constrain the level 
of emissions from engines that are certified with the use of credits. 
By setting the FEL cap at the level of the previous emission standard 
EPA can ensure that all engines must at least maintain the current 
level of emission control performance.
    In this section, we are proposing a new approach to setting FEL 
caps. We believe FEL caps continue to be critical to avoid backsliding 
through use of emission credits. Considering our proposal to allow 
manufacturers to include BEVs or FCEVs in the NOX ABT 
program, we believe FEL cap levels below the previous standard are 
appropriate. The zero-tailpipe emissions performance of BEVs and FCEVs 
inherently provides the opportunity for manufacturers to generate more 
credits from these vehicles relative to conventional engines that 
produce emissions between zero and the level the standard. We believe 
that lower FEL caps would provide a necessary constraint on allowable 
emission levels from CI and SI engines that would use NOX 
credits generated from BEVs or FCEVs. See Section IV.I for more 
discussion on our proposal to allow manufacturers to generate 
NOX emission credits from BEVs and FCEVs.
    As specified in the proposed 40 CFR 1036.104(c)(2), the maximum 
NOX FELFTP values for model year 2027 through 
2030 under proposed Option 1, or model year 2027 and later under 
proposed Option 2, would be 150 mg/hp-hr, which is consistent with the 
average NOX emission levels achieved by recently certified 
CI engines (see Chapter 3.1.2 of the draft RIA). We believe a cap based 
on the average NOX emission levels of recent engines is more 
appropriate than a cap at the current standard of 0.2 g/hp-hr (200 mg/
hp-hr) when considering the potential for manufacturers to apply 
NOX credits generated from electric vehicles for the first 
time. For MY 2031 and later under Option 1, we propose a consistent 30 
mg/hp-hr allowance for each primary intended service class applied to 
each full useful life standard. For Spark-ignition HDE, Light HDE, and 
Medium HDE, this proposed allowance would equate to a NOX 
FELFTP cap of 50 mg/hp-hr compared to the proposed full 
useful life standard of 20 mg/hp-hr. Heavy HDE would have a separate 
NOX FELFTP cap of 70 mg/hp-hr compared to the 
proposed 40 mg/hp-hr full useful life standard. For MY 2031 and later 
FEL caps under Option 1, we are proposing a 30 mg/hp-hr allowance in 
lieu of the proposed Option 1 MY 2027 standard of 35 mg/hp-hr for two 
reasons. First, we do not believe a 15 mg/hp-hr differential between 
the MY 2031 and MY 2027 standards would provide an appropriate 
incentive for Spark-ignition HDE, Light HDE, and Medium HDE 
manufacturers to develop advanced technologies in early model years. 
Second, the MY 2031 standard for Heavy HDE is higher than the MY 2027 
standard to reflect deterioration over the longer useful life.
    We request comment on our proposed FEL caps, including our approach 
to base the cap for MY 2027 through 2030 under Option 1, or MY 2027 and 
later under Option 2, on the recent average NOX emission 
levels. We request comment on whether the NOX 
FELFTP cap in MY 2027 should be set at a different value, 
ranging from the current federal NOX standard of 205 mg/hp-
hr to the 50 mg/hp-hr standard that will be in place for engines 
subject to CARB's HD Omnibus rule starting in MY 
2024.661 662 663 We also request comment on the proposal to 
set the proposed Option 1 MY 2031 NOX FEL caps at 30 mg/hp-
hr above the full useful life standards. We request comment on whether 
different FEL caps should be considered if we finalize standards other 
than those proposed (i.e., within the range between the standards of 
proposed Options 1 and 2 as described  in the feasibility analysis of 
Section III).
---------------------------------------------------------------------------

    \661\ California Air Resources Board, Staff Report: Initial 
Statement of Reasons for Proposed Rulemaking, ``Public Hearing to 
Consider the Proposed Heavy-duty Engine and Vehicle Omnibus 
Regulation and Associated Amendments,'' June 23, 2020. https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/isor.pdf, page III-4.
    \662\ Note that the current g/hp-hr emission standards are 
rounded to two decimal places, which allow emission levels to be 
rounded down by as much as 5 mg/hp-hr.
    \663\ As noted in Section I.D, EPA is reviewing a waiver request 
under CAA section 209(b) from California for the Omnibus rule; we 
may include consideration of engines meeting the Omnibus 
requirements as one of the factors in our determination of an 
appropriate FEL cap level for the final EPA rule.
    \664\ This includes credits generated by BEVs or FCEVs for use 
in MYs 2027 and later, as discussed in Section IV.I.
---------------------------------------------------------------------------

4. Credit Life for Credits Generated for Use in MY 2027 and Later
    In the original heavy-duty criteria pollutant ABT program (55 FR 
30584, July 26, 1990), the recent Phase 2 heavy-duty GHG rulemaking (81 
FR 73638, October 25, 2016), and the current CARB HD Omnibus 
rulemaking, a limited credit life was adopted to help encourage 
continued technology development to meet the proposed standards. We are 
proposing to update the existing credit life provisions in 40 CFR 
1036.740(d) to apply for both CO2 and NOX 
credits. As specified in the proposed 40 CFR 1036.740(d), 
NOX emission credits generated for use in MY 2027 and later 
could be used for five model years after the year in which they are 
generated.\664\ For example, credits generated in model year 2025 could 
be used to demonstrate compliance with emission standards through model 
year 2030.

[[Page 17553]]

    We are not proposing an expiration date for the ABT program, and 
manufacturers could continue to generate credits by adopting 
increasingly advanced technologies. However, we do not see a need for 
manufacturers to bank credits generated in a given model year 
indefinitely. We recognize the need to allow enough time for 
manufacturers to apply credits generated early to cover the transition 
to the more stringent standards of proposed Option 1 for MY 2031. We 
believe a five-year credit life adequately covers a transition period 
for that option, while continuing to encourage technology development 
in later years. We are not proposing to migrate 40 CFR 86.004-
15(c)(1)(ii) that specifies a discount for credits that are banked or 
traded. Discounted credits were originally included to incentivize 
manufacturers to adopt new technology instead of relying on the use of 
older credits (62 FR 54703, October 21, 1997). We believe the proposed 
five-year credit life would provide the same incentive as a credit 
discount. We request comment on our proposed five-year credit life.
5. Existing Credit Balances
    Under the current HDE criteria pollutant ABT program, manufacturers 
have generated NOX emission credits with an unlimited credit 
life but have not used the credits in recent years. While emission 
credits generated prior to MY 2027 could continue to be used to meet 
the existing emission standards through MY 2026 under 40 CFR part 86, 
subpart A, we are proposing that these banked credits could not be used 
to meet the proposed MY 2027 and later standards for two reasons.
    First, the credits were generated without demonstrating emissions 
control under all test conditions of the proposed program, and thus are 
not equivalent to credits that would be generated under the proposed 
program. Specifically, the existing credits were generated without 
demonstrating emission control on the proposed SET duty-cycle standard 
for SI engines, or the proposed low-load duty-cycle standard and 
proposed off-cycle standards and test procedures for CI engines. 
Second, EPA did not rely on the use of existing credit balances to 
demonstrate feasibility of the proposed standards (see Section III).
    Taken together, these two factors lead us to believe that it would 
not be appropriate to allow the unlimited use in the proposed new 
NOX compliance program of credits generated under the 
existing program. We are proposing a new interim provision in 40 CFR 
1036.150(a) that includes the options for manufacturers to bank credits 
for use in MY 2027 and later. In paragraph (a)(1), we are proposing 
provisions to allow manufacturers to generate transitional 
NOX credits prior to MY 2027 that could be applied for MY 
2027 and later based on an approach that combines the current 
NOX standards and the proposed test procedures (see Section 
IV.G.6). Paragraph (a)(2) includes our proposal to allow manufacturers 
to generate early adoption incentive credits by complying with the 
proposed MY 2027 standards (or MY 2031 standards, if applicable) before 
the required compliance date (see Section IV.H).\665\ Paragraph (a)(3) 
would clarify that manufacturers must use one of these two options for 
generating credits prior to MY 2027 for use in MY 2027 and later.
---------------------------------------------------------------------------

    \665\ Also see Section IV.I and the corresponding proposed 
provisions in 40 CFR 1037 for a description of how these options 
apply for manufacturers certifying electric vehicles.
---------------------------------------------------------------------------

6. Transitional Credits Generated in MYs 2024 Through 2026
    We are proposing an option for manufacturers to generate 
transitional credits in MYs 2024 through 2026 that could be applied in 
MYs 2027 and later. We propose these transitional credits as a 
flexibility that accounts for key differences between the current and 
proposed compliance programs, and incentivizes manufacturers to adopt 
the proposed test procedures earlier than required in MY 2027. As 
described below, the proposed approach bases the transitional credit 
calculation on the current NOX standards and useful life 
periods; therefore, manufacturers may not need to adopt new 
technologies or demonstrate durability over longer useful life periods, 
which would otherwise be needed to comply with the proposed more 
stringent emission standards and longer useful life periods.\666\
---------------------------------------------------------------------------

    \666\ In Section IV.H, we propose early adoption incentives with 
credit multipliers for manufacturers who achieve the full proposed 
emission standards and compliance measures for engine families 
before MY 2027.
---------------------------------------------------------------------------

    Specifically, we are proposing a new interim provision in 40 CFR 
1036.150(a)(1) that manufacturers could use to generate transitional 
credits in model years 2024 through 2026. The transitional credits rely 
on the same structure as the general ABT provisions proposed in 40 CFR 
1036.104(c) and subpart H, with differences noted in this section. 
Manufacturers would similarly declare a NOX FEL for 
operation over the FTP duty cycle. The FELFTP would then be 
used to calculate FELs for operation over the other applicable duty 
cycles and off-cycle bins for which there are no current standards. 
Manufacturers would calculate an FEL for each other applicable cycle by 
multiplying the corresponding MY 2027 standard for that cycle by the 
ratio of their declared FELFTP to the MY 2027 FTP standard.
    For an example model year 2025 Light HDE engine family, the 
proposed Option 1 MY 2027 NOX standards are 35 mg/hp-hr for 
FTP and SET, and 90 mg/hp-hr for LLC. If a Light HDE manufacturer 
declares an FELFTP of 0.10 g/hp-hr, then the calculated MY 
2025 FEL for LLC (FELLLC) would equal 0.090 g/hp-hr 
multiplied by the ratio 0.10/0.035, i.e., 0.26 g/hp-hr. The 
manufacturer would have to demonstrate that they can meet an LLC 
NOX emission level of 260 mg/hp-hr for certification. 
Similar to the general ABT program, the FELs calculated for these 
cycles would serve as the emission standards for the engine family for 
the respective testing, and manufacturers would demonstrate that they 
meet those FELs in their application for certification. Compared to the 
current ABT program, CI engine manufacturers opting to generate 
transitional credits under this proposal would have to show that they 
meet a calculated FELLLC on the proposed LLC test procedure 
in 40 CFR 1036.512. SI engine manufacturers would have to show that 
they meet a calculated FELSET on the proposed SET test 
procedure in 40 CFR 1036.505.
    To calculate transitional credits, we propose that manufacturers 
would apply the declared FELFTP in the emission credits 
equation in 40 CFR 1036.705(b)(1) (see Equation IV-1). We propose that 
the credits be calculated relative to the current FTP standard of 0.20 
g/hp-hr and the current useful life that applies for the engine family 
as defined in 40 CFR 86.004-2.
    Since transitional credits would be used in MYs 2027 or later, we 
are proposing that transitional credits would have the same five-year 
credit life as proposed for other credits generated for use in MYs 2027 
and later. See proposed 40 CFR 1036.740(d). Similarly, to generate 
transitional NOX emission credits, manufacturers would be 
required to meet the applicable current PM, HC, and CO emission 
standards in 40 CFR 86.007-11 or 86.008-10 without generating or using 
emission credits. We propose that manufacturers would record the PM, 
HC, and CO emission levels during testing over the proposed new duty 
cycles, but they would not scale PM, HC, and CO as proposed for 
NOX over the other cycles.
    We request comment on our proposed approach to offer transitional 
NOX

[[Page 17554]]

emission credits that incentivize manufacturers to adopt the proposed 
test procedures earlier than required in MY 2027. We request comment on 
if CI engines should be subject to off-cycle standards as proposed in 
40 CFR part 1036, subpart E, to qualify for the transitional credits. 
We are specifically interested in comments on other approaches to 
calculating transitional credits before MY 2027 that would account for 
the differences in our current and proposed compliance programs. We 
also request comment on our proposal to apply a five-year credit life 
for transitional NOX emission credits.

H. Early Adoption Incentives

    We are proposing an early adoption incentive program as an interim 
provision in 40 CFR 1036.150(a)(2). Manufacturers have four or more 
model years of lead time to meet the proposed criteria pollutant 
standards that would begin to apply in MYs 2027 and 2031 for proposed 
Option 1 or MY 2027 for proposed Option 2. However, we recognize that 
manufacturers have opportunities to introduce some technologies earlier 
than required and that public health and the environment would benefit 
from early introduction. Specifically, early introduction of new 
emission control technologies can accelerate the entrance of lower-
emitting engines and vehicles into the heavy-duty vehicle fleet, 
thereby reducing NOX emissions from the heavy-duty sector 
and lowering its contributions to ozone and PM formation.
    Early introduction of engines capable of meeting all of the 
proposed standards and requirements for MY 2027, or MY 2031 if 
applicable, would reduce emissions from heavy-duty trucks across 
operating modes and maintain that degree of emission control throughout 
a longer portion of the engine operational life. For example, our 
analysis shows that without the proposed standards, low-load emissions 
would account for 28 percent of the heavy-duty NOX emission 
inventory in calendar year 2045, which suggests that early introduction 
of technologies capable of reducing low-load emissions could help 
accelerate important reductions of this portion of the inventory. 
Similarly, our analysis shows that emissions attributable to 
deterioration of emission controls after the existing useful life 
periods would account for 25 percent of the heavy-duty emission 
inventory in calendar year 2045, which again suggests that early 
adoption of technologies capable of reducing emissions for longer 
periods of time could have important impacts on this part of the heavy-
duty emission inventory (see Section I.E for more details on Engine 
Operation and Processes Contributing to Heavy-Duty NOX 
Emission Inventory in 2045). As discussed in Section II, many state and 
local agencies have asked the EPA to further reduce NOX 
emissions, specifically from heavy-duty engines, because such 
reductions will be a critical part of many areas' strategies to attain 
and maintain the ozone and PM2.5 NAAQS. Several of these 
areas are working to attain or maintain NAAQS in timeframes leading up 
to and immediately following the required compliance dates of the 
proposed standards, which underscores the importance of the early 
introduction of lower-emitting vehicles.
    We are proposing an early adoption incentive program that would 
recognize the environmental benefits of lower-emitting engines and 
vehicles entering the fleet ahead of required compliance dates for the 
proposed standards. Under the proposed new interim provision in 40 CFR 
1036.150(a)(2), this optional program would allow manufacturers who 
demonstrate early compliance with the proposed MY 2027, or MY 2031 if 
applicable, standards to generate more NOX credits for the 
relevant early compliance model years than under the proposed ABT 
program for the model years for which the standards are applicable 
(described in Section IV.G).
1. Eligibility for Early Adoption Incentives
    In MYs 2024 through 2026, manufacturers may choose to participate 
in the proposed early adoption incentive program by demonstrating 
compliance with all of the proposed MY 2027 (or, alternatively, MY 
2031) standards and other requirements specified in proposed 40 CFR 
1036.205.\667\ Similarly, under proposed Option 1, manufacturers may 
participate in the proposed early adoption incentive program in MYs 
2027 through 2030 by demonstrating compliance with all of the proposed 
Option 1 MY 2031 standards and other requirements. Early adoption 
credits generated under proposed 40 CFR 1036.150(a)(2) could be used to 
comply with the proposed NOX emission standards starting as 
early as MY 2027 as further specified in proposed 40 CFR part 1036, 
subpart H.
---------------------------------------------------------------------------

    \667\ See Section IV.G.1 for discussion on the relationship of 
the FELFTP and demonstrating compliance with all duty-cycle 
standards.
---------------------------------------------------------------------------

2. Calculating Credits Under the Early Adoption Incentive Program
    Our proposed early credit provisions in 40 CFR 1036.150(a)(2) 
recognize the benefits of early adoption of low-NOX 
technologies in two ways. First, we propose to reduce the declared FEL, 
for purpose of calculating credits, to provide appropriate credit for 
the additional years of emissions assurance that come with certifying 
to a longer useful life. Second, we proposed to apply a traditional 
credit multiplier to further incentivize early adoption of technologies 
that will meet our standards. Our proposed multipliers would be based 
on the current model year relative to the model year of the standards 
to which the engine is being certified, with a larger multiplier for 
meeting the MY 2031 requirements before MY 2027.
    To calculate credits under the early adoption incentive program, we 
are proposing a manufacturer would multiply the engine family's 
declared FEL by a ratio of useful life period of the current model year 
relative to the longer useful life period of the model year to which 
the engine family is certified.\668\ For example, a manufacturer 
certifying a MY 2027 Heavy HDE to proposed Option 1 MY 2031 standards 
would multiply the declared FELFTP by the ratio of 600,000 miles to 
800,000 miles (i.e., MY 2027 UL to MY 2031 UL for Heavy HDE under 
proposed Option 1). The manufacturer would then apply a multiplier to 
calculate the total early adoption credit for the engine family. 
Equation IV-2 illustrates how the Eq. 1036.705-1 would be updated to 
calculate early credits as proposed in 40 CFR 1036.150(a)(2). The 
proposed Early Adoption Multiplier (ECM) values are shown in Table IV-
15.
---------------------------------------------------------------------------

    \668\ This approach is similar to the early compliance approach 
adopted by CARB in the 30-Day Modifications to the HD Omnibus 
regulation. See Appendix B-1 and Appendix B-2 available online: 
https://ww2.arb.ca.gov/rulemaking/2020/hdomnibuslownox.

---------------------------------------------------------------------------

[[Page 17555]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.002

Where:
StdFTP = the FTP duty cycle NOX emission 
standard, in mg/hp-hr, that applies for engines not participating in 
the ABT program
FEL = the engine family's FEL for NOX, in mg/hp-hr.
ULMY = the useful life, in miles, that applies for 
engines not participating in the ABT program in that model year.
UL = the useful life, in miles, for the standard that applies for 
the applicable primary intended service class.
WorkFTP = the total integrated horsepower-hour over the 
FTP duty cycle.
MilesFTP = the miles of the FTP duty cycle. For Spark-
ignition HDE, use 6.3 miles. For Light HDE, Medium HDE, and Heavy 
HDE, use 6.5 miles.
Volume = the number of engines eligible to participate in the ABT 
program within the given engine family during the model year, as 
described in the existing 40 CFR 1036.705(c).
EAM = early adoption multiplier based on model year of the engine 
family and the model year of the standard to which the engine family 
is being certified. See Table IV-15.

                                Table IV-15--Proposed Early Adoption Multipliers
----------------------------------------------------------------------------------------------------------------
                                                                 Meet all  requirements       Early adoption
                 Engine family model year \a\                        for model year             multiplier
----------------------------------------------------------------------------------------------------------------
2024 through 2026.............................................                     2027                      1.5
2024 through 2026 \b\.........................................                     2031                      2.0
2027 through 2030 \b\.........................................                     2031                      1.5
----------------------------------------------------------------------------------------------------------------
\a\ BEV and FCEV could generate NOX emission credits as described in Section IV.I.2.ii, but would not be
  eligible for early adoption multipliers.
\b\ Early adoption multipliers for meeting MY 2031 standards would only apply under the two-step proposed Option
  1.

    Our proposal to reduce a manufacturer's declared FELFTP in the 
early credit calculation would increase the number of credits relative 
to the general ABT credit calculation in proposed 40 CFR 1036.705. We 
believe it is appropriate to scale down the FEL using the useful life 
ratio for all primary intended service classes to reflect the 
durability improvements needed to meet the standards when the useful 
life mileages differ. This adjustment is particularly important to 
avoid negative credit values when calculating early credits for Heavy 
HDE in model years 2027 through 2030 under the two-step approach of 
proposed Option 1 when the proposed numeric value of the standard at 
full useful life is lower than the MY 2031 standard.\669\
---------------------------------------------------------------------------

    \669\ For example, without an FEL adjustment, the difference 
between the proposed NOX standard of 35 mg/hp-hr in MY 
2027 through 2030 and an otherwise credit-generating FEL in the 
range of 36 to 40 mg/hp-hr would be negative (i.e., 35 mg/hp-hr - 40 
mg/hp-hr = - 5 mg/hp-hr).
---------------------------------------------------------------------------

    We believe that the proposed 1.5 to 2.0 multipliers in the early 
adoption incentive program appropriately balance providing an incentive 
for manufacturers to develop and introduce lower-emitting technologies 
earlier than required while also considering that the credits could be 
used to produce higher-emitting engines in later model years. Our 
proposed multipliers would encourage early introduction to augment 
manufacturers' longer-term flexibility in product planning to meet the 
proposed standards. As discussed in Section IV.G, we are proposing 
credit life limits and FEL caps to ensure that NOX emission 
credits generated through the early adoption incentive program do not 
compromise the environmental benefits expected from the proposal. 
Specifically, our proposed NOX FEL caps would ensure 
significant emission reductions from all heavy-duty highway engines 
compared to today's products.
    We have aligned both the compliance requirements and numeric value 
of our proposed early adoption multipliers with the Early Compliance 
Credit Multipliers included in the Omnibus for MY 2024 and later. We 
believe that aligning our approach with the CARB program provides 
manufacturers with a common set of requirements and incentives for the 
early introduction of lower emitting vehicles.\670\
---------------------------------------------------------------------------

    \670\ We believe that aligning the proposed EPA early adoption 
incentive program and the CARB Early Compliance Credit Multipliers 
is useful for manufacturers even inf the standards and other 
requirement of the EPA final rule do not fully align with the CARB 
Omnibus provisions.
---------------------------------------------------------------------------

3. Requests for Comment on Early Adoption Incentive Program
    Our proposed approach would incentivize manufacturers to produce 
lower emitting vehicles prior to required compliance dates by offering 
more emission credits for early introduction of these cleaner 
technologies. EPA requests comment on all aspects of our proposed early 
adoption incentive program. Specifically, we are interested in 
stakeholder feedback on our approach that engine families meet all 
proposed MY 2027, or MY 2031 if applicable, requirements in order to 
participate in the early adoption incentive program. The proposed 
eligibility criteria would ensure that products participating in the 
early adoption incentive program not only meet lower numeric levels of 
the standards, but also maintain emission control across a broad range 
of engine operations and over a longer duration of operational life, 
consistent with the proposed requirements. Nevertheless, we are aware 
that there may be aspects of the proposed requirements that are 
challenging to meet ahead of the required compliance dates, and thus 
EPA requests comment on any needed flexibilities that we should include 
in the early adoption incentive program in the final rule.
    We are also interested in stakeholder feedback on the proposed 
numeric values of the credit multipliers in the early adoption 
incentive program; commenters recommending alternative numeric values 
for credit multipliers are encouraged to include data supporting why 
those values are appropriate. In addition, we are interested in whether 
EPA should further restrict the use of NOX credits generated 
under the early adoption incentive program. For instance, we could 
consider finalizing a shorter credit life for NOX emission 
credits generated under the early adoption incentive program. We could 
also consider finalizing a cap on the

[[Page 17556]]

number of engines with which a manufacturer could generate early 
adoption incentive credits, or a cap on the number of credits per model 
year that a manufacturer could generate.
    Finally, we request comment on our approach to align the 
requirements and numeric values of the multipliers with the Early 
Compliance Credit Multipliers included in the Omnibus. In addition, we 
are interested in stakeholder input on whether EPA should adopt 
specific provisions that incentivize manufacturers to certify engine 
families that meet the MY 2024 Omnibus requirements.\671\ As described 
in Section IV.G.6, we are proposing a transitional credit option for MY 
2024 through 2026 that is calculated relative to the current standards. 
We may consider a multiplier or other incentive that reflects the CARB 
MY 2024 requirements being a step more stringent than the current 
standards, but less comprehensive than the proposed MY 2027 
requirements. For instance, in MYs 2024 through 2026, EPA could offer 
an early adoption multiplier of 1.25 for manufacturers certifying 50-
state engine families that meet all of the requirements of the MY 2024 
Omnibus program. We request comment on incentivizing adoption of the MY 
2024 Omnibus requirements, including suggested multipliers or other 
approaches we should consider.
---------------------------------------------------------------------------

    \671\ As noted in Section I.D, EPA is reviewing a waiver request 
under CAA section 209(b) from California for the Omnibus rule; if we 
were to grant the waiver request for the CA Omnibus, then we may 
consider in the final EPA rule ways to incentivize manufacturers to 
produce engines that meet the Omnibus requirements and are available 
for sale outside of CA or other states that may adopt the Omnibus.
---------------------------------------------------------------------------

I. Compliance Options for Generating NOX Emission Credits 
From Electric Vehicles

    The number of heavy-duty electric vehicles (EVs) in the form of 
hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), and 
fuel cell electric vehicles (FCEVs) in the heavy-duty market today is a 
small percentage of the total heavy-duty fleet based on estimates from 
several sources.672 673 674 675 However, growing numbers of 
these EV technologies are in production, in demonstration projects, or 
planned for production in the early 2020s (see Chapter 1.4 of the draft 
RIA for more discussion). Forecasting models and studies generally 
agree that HEV, BEV, and FCEV production volumes will grow, yet the 
predicted rate of growth ranges widely across various forecasts and 
partly depend on the specific market segments and time periods being 
evaluated, study methodologies, as well as underlying 
assumptions.676 677 678 Many ANPR commenters asserted that 
EV technologies would continue to grow as part of the heavy-duty fleet; 
commenters generally focused on projected growth of BEVs based on their 
own production plans and/or customer orders for their products, 
although no specific data was provided by commenters.\679\
---------------------------------------------------------------------------

    \672\ North American Council for Freight Efficiency ``Guidance 
Report: Viable Class \7/8\ Electric, Hybrid and Alternative Fuel 
Tractors``, available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \673\ UCS (2019) ``Ready for Work: Now Is the Time for Heavy-
Duty Electric Vehicles``; www.ucsusa.org/resources/ready-work.
    \674\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers''. American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \675\ Smith, D. et al. (2019) ``Medium- and Heavy-Duty 
Electrification An Assessment of Technology and Knowledge Gaps''. 
Oak Ridge National Laboratory and National Renewable Energy 
Laboratory. ORNL/SPR-2020/7
    \676\ Energy Information Association (2018) ``Annual Energy 
Outlook; Table 50: Freight Transportation Energy Use'', available 
at: https://www.eia.gov/outlooks/aeo/data/browser/#/?id=58-
AEO2018®ion=0-
0&cases=ref2018&start=2016&end=2050&f=A&linechart=ref2018-
d121317a.6-58-AEO2018~ref2018-d121317a.11-58-AEO2018~ref2018-
d121317a.17-58-AEO2018~ref2018-d121317a.22-58-AEO2018~ref2018-
d121317a.28-58-AEO2018~ref2018-d121317a.33-58-
AEO2018&ctype=linechart&sid=ref2018-d121317a.22-58-AEO2018~ref2018-
d121317a.11-58-AEO2018~ref2018-d121317a.33-58-AEO2018&sourcekey=0.
    \677\ Jadun, et al. (2017) ``Electrification Futures Study: End-
Use Electric Technology Cost and Performance Projections through 
2050''. Golden, CO: National Renewable Energy Laboratory. NREL/TP-
6A20-70485. https://www.nrel.gov/docs/fy18osti/70485.pdf.
    \678\ Brooker et al. (2021) ``Vehicle Technologies and Hydrogen 
and Fuel Cell Technologies Research and Development Programs 
Benefits Assessment Report for 2020''. Golden, CO: National 
Renewable Energy Laboratory. NREL/TP-5400-79617. https://www.nrel.gov/docs/fy21osti/79617.pdf.
    \679\ For example, see Comments of Tesla Inc. ``Control of Air 
Pollution from New Motor Vehicles: Heavy-Duty Engine Standards, 
Docket No. EPA-HQ-OAR-2019-0055, 85 Fed. Reg. 3306 (Jan. 21, 
2020).'' Docket EPA-HQ-OAR-2019-0055-0268.; Comments of Rivian. 
``Comments on the Control of Air Pollution From New Motor Vehicles: 
Heavy-Duty Engine Standards Advanced Notice of Proposed Rulemaking 
(EPA-HQ-OAR-2019-0055; FRL-10004-16- OAR).'' Docket EPA-HQ-OAR-2019-
0055-0272.; Comments of Volvo Group. ``Comments of the Volvo Group; 
U.S. EPA Cleaner Trucks Initiative Advanced Notice of Proposed 
Rulemaking.'' Docket EPA-HQ-OAR-2019-0055-0463.
---------------------------------------------------------------------------

    In the ANPR for this action we requested comment on any barriers or 
incentives that EPA should consider to better encourage emission 
reductions from HEVs, BEVs, and FCEVs.\680\ Most but not all ANPR 
commenters were generally supportive of EPA following approaches used 
in the past of offering emission credits and credit multipliers for EV 
technologies.\681\ Commenters also noted that making credits in an ABT 
program available for EV technologies, particularly credits available 
prior to MY 2027, would provide manufacturers with flexibility by 
providing additional time to develop the technologies to comply with 
the proposed emission standards.\682\ However, under the current 
criteria pollutant program, manufacturers do not have a pathway to 
generate NOX emission credits for HEVs, BEVs, or FCEVs. For 
BEVs and FCEVs, current 40 CFR 86.016-1(d)(4) stipulates that these 
technologies may not generate NOX emission credits, and for 
HEVs, there has historically not been a test procedure available to 
demonstrate NOX emission performance of the technologies 
(see Sections III.A and III.B for discussion on the current regulatory 
provisions specific to heavy-duty electric vehicles, and test 
procedures for HEVs, respectively).\683\ We outline in the subsections 
that follow how we propose to address these barriers to generating 
NOX emission credits for HEVs, and, separately, BEVs or 
FCEVs.
---------------------------------------------------------------------------

    \680\ 85 FR 3306, January 21, 2020.
    \681\ For example, see Comments of Tesla Inc. ``Control of Air 
Pollution from New Motor Vehicles: Heavy-Duty Engine Standards, 
Docket No. EPA-HQ-OAR-2019-0055, 85 Fed. Reg. 3306 (Jan. 21, 
2020).'' Docket EPA-HQ-OAR-2019-0055-0268.; Comments of Rivian. 
``Comments on the Control of Air Pollution From New Motor Vehicles: 
Heavy-Duty Engine Standards Advanced Notice of Proposed Rulemaking 
(EPA-HQ-OAR-2019-0055; FRL-10004-16- OAR).'' Docket EPA-HQ-OAR-2019-
0055-0272.; Comments of Volvo Group. '' Comments of the Volvo Group; 
U.S. EPA Cleaner Trucks Initiative Advanced Notice of Proposed 
Rulemaking.'' Docket EPA-HQ-OAR-2019-0055-0463.; Comments of Edison 
Electric Institute. ``Comments of the Edison Electric Institute on 
the U.S. Environmental Protection Agency's Advanced Notice of 
Proposed Rulemaking Control of Air Pollution from New Motor 
Vehicles: Heavy-Duty Engine Standards.'' Docket EPA-HQ-OAR-2019-
0055-0293.; Note that one commenter did not support credit 
multipliers, see Comments of Eaton. ``Eaton Comments to EPA Control 
of Air Pollution from New Motor Vehicles: Heavy-Duty Engine 
Standards Docket No. EPA-HQ-OAR-2019-0055.'' Docket EPA-HQ-OAR-2019-
0055-0452.
    \682\ Tesla Inc. ``Control of Air Pollution from New Motor 
Vehicles: Heavy-Duty Engine Standards, Docket No. EPA-HQ-OAR-2019-
0055, 85 Fed. Reg. 3306 (Jan. 21, 2020).'' Docket EPA-HQ-OAR-2019-
0055-0268.; Rivian. ``Comments on the Control of Air Pollution From 
New Motor Vehicles: Heavy-Duty Engine Standards Advanced Notice of 
Proposed Rulemaking (EPA-HQ-OAR-2019-0055; FRL-10004-16- OAR).'' 
Docket EPA-HQ-OAR-2019-0055-0272.; Volvo Group. ``Comments of the 
Volvo Group; U.S. EPA Cleaner Trucks Initiative Advanced Notice of 
Proposed Rulemaking.'' Docket EPA-HQ-OAR-2019-0055-0463.
    \683\ 40 CFR 86.016-1(d)(4) states: ``Electric heavy-duty 
vehicles may not generate NOX or PM emission credits. 
Heavy-duty vehicles powered solely by electricity are deemed to have 
zero emissions of regulated pollutants.''
---------------------------------------------------------------------------

    EPA is proposing to allow HEVs to generate NOX emission 
credits based on

[[Page 17557]]

their near-zero tailpipe emissions and because they provide an 
opportunity for manufacturers to develop and refine transferable 
technologies to BEVs and FCEVs (e.g., batteries, electric motors). We 
are proposing to allow BEVs and FCEVs to generate NOX 
emission credits because of the zero-tailpipe emissions performance of 
these technologies and after consideration of ANPR comments.\684\ We 
are further proposing to allow manufacturers to generate BEV and FCEV 
NOX emission credits starting in MY 2024 in response to ANPR 
comments concerning the importance of such credits in providing 
manufacturers with flexibility in their product planning. Some ANPR 
comments also supported emission credit multipliers for HEVs, BEVs, and 
FCEVs.\685\ In developing our proposal, we considered whether to 
provide credit multipliers for these technologies in the early years of 
the proposed program; however, we are choosing not to propose 
NOX emission credit multipliers for HEVs, BEVs, or FCEVs due 
to the potential emission impacts of the use of credit multipliers and 
the current state of technology development and implementation (see 
Section IV.I.4 for more details on this topic).\686\ The subsections 
that follow discuss: (1) How manufacturers can certify HEV, BEVs, and 
FCEVs to the proposed criteria pollutant standards, (2) proposed 
requirements for generating NOX emission credits for these 
technologies, (3) potential options for how EPA could approach 
NOX emission credits from BEVs and FCEVs in the long-term 
(e.g., post-MY 2031), and (4) our reasoning for not proposing credit 
multipliers for NOX emission credits generated from HEVs, 
BEVs, or FCEVs.
---------------------------------------------------------------------------

    \684\ As noted in Section III.A, our proposal for how 
manufacturers could generate NOX emissions credits from 
BEVs and FCEVs would be available under any of the regulatory 
options that we are considering for revised NOX 
standards.
    \685\ Rivian. ``Comments on the Control of Air Pollution From 
New Motor Vehicles: Heavy-Duty Engine Standards Advanced Notice of 
Proposed Rulemaking (EPA-HQ-OAR-2019-0055; FRL-10004-16- OAR).'' 
Docket EPA-HQ-OAR-2019-0055-0272.; Volvo Group. ``Comments of the 
Volvo Group; U.S. EPA Cleaner Trucks Initiative Advanced Notice of 
Proposed Rulemaking.'' Docket EPA-HQ-OAR-2019-0055-0463.
    \686\ As noted in Section IV.I.4, BEVs and FCEVs would not be 
eligible for Early Adoption Incentive credit multipliers (see 
Section IV.H for details of Early Adoption Incentives).
---------------------------------------------------------------------------

1. Certification Provisions for Generating NOX Emission 
Credits From Electric Vehicles
    As outlined in Section III.A, we are proposing to clarify in 
proposed 40 CFR 1036.101(b) that manufacturers may optionally test the 
hybrid engine and powertrain together, rather than testing the engine 
alone; this option would allow manufacturers to demonstrate emission 
performance of the hybrid technology that are not apparent when testing 
the engine alone.\687\ To generate NOX emission credits with 
a hybrid engine or hybrid powertrain, manufacturers would conduct the 
emission testing described in Section IV.I.2.i and apply the results as 
specified for the proposed engine ABT program discussed in Section 
IV.G.
---------------------------------------------------------------------------

    \687\ We are also proposing to update the definition of ``engine 
configuration'' in 40 CFR 1036.801 to clarify that an engine 
configuration would include hybrid components if it is certified as 
a hybrid engine or hybrid powertrain.
---------------------------------------------------------------------------

    Similarly, we propose to clarify the procedures for certifying BEVs 
and FCEVs to criteria emission standards. As discussed in Section 
III.A, we are proposing to consolidate criteria pollutant and GHG 
emission certification requirements in 40 CFR part 1037 for BEVs and 
FCEVs with a GVWR over 14,000 pounds, as specified in the current 40 
CFR 1037.1 and proposed 40 CFR 1037.102.\688\ As noted in the 
introduction to this Section IV.I, we are also proposing that BEVs and 
FCEVs may generate NOX emission credits, as specified in 
proposed 40 CFR 1037.616. Manufacturers choosing to participate in the 
NOX ABT program would be required to conduct testing to 
measure work produced over a defined duty-cycle test, and either 
useable battery energy for BEVs or fuel cell voltage for FCEVs (see 
Section IV.I.2 for details). Manufacturers would generate vehicle 
emissions credits, which would then be fungible between vehicle and 
engine ABT programs, such that NOX credits generated through 
the vehicle program could be applied to the proposed engine ABT program 
described in Section IV.G.\689\ See Sections IV.G.2, IV.G.3, IV.G.4, 
and IV.G.6 for details on proposed limitations on the use of 
NOX emission credits, including NOX emission 
credits generated from BEVs or FCEVs, within the engine ABT program, as 
specified in proposed 40 CFR 1036.741. Based on proposed 40 CFR 
1037.102(b)(1) and proposed 40 CFR 1036.741, NOX emission 
credits generated by BEVs or FCEVs would be restricted to use in the CI 
engine averaging set in which those credits are generated; further 
below we request comment on this approach.
---------------------------------------------------------------------------

    \688\ As specified in proposed 40 CFR 1037.102(b)(1), we are 
proposing that manufacturers apply the Light HDE provisions to Light 
HDV, apply the Medium HDE provisions to Medium HDV, and apply the 
Heavy HDE provisions to Heavy HDV.
    \689\ As described in proposed 40 CFR 1036.705 and 1036.741.
---------------------------------------------------------------------------

    In developing our proposed approach of a vehicle certification 
pathway for BEV and FCEV criteria pollutant requirements, we considered 
two options: vehicle certification or powertrain certification. We are 
proposing to allow vehicle manufacturers, rather than powertrain 
manufacturers, to generate vehicle credits for BEVs or FCEVs because 
the vehicle certification pathway is already utilized for certifying 
BEVs and FCEVs to GHG standards, and thus would require fewer resources 
to implement and carryout for both manufacturers and EPA's 
certification program. We recognize that under our proposed approach 
powertrain manufacturers would need to partner with vehicle 
manufacturers in order to obtain an EPA certificate, and that EMA 
commented on the proposed CARB HD NOX Omnibus regulation 
that powertrain manufacturers, not vehicle manufacturers, should 
generate NOX credits generated from zero tailpipe emission 
vehicles.\690\ We further recognize that the final CARB Heavy-Duty 
NOX Omnibus Regulation includes a powertrain certification 
pathway for BEVs and FCEVs, rather than a vehicle certification 
pathway. EPA believes that this incomplete alignment with the CARB 
Omnibus program would be minor and minimally disruptive to 
manufacturers since under the CARB Omnibus program NOX 
credits can be generated from BEVs and FCEVs only through MY 2026.\691\ 
Further, we note that this concern does not apply to vertically 
integrated powertrain manufacturers and that non-vertically integrated 
powertrain manufacturers could develop their business arrangements with 
the vehicle manufacturers such that NOX credits are 
transferred to the powertrain manufacturer.
---------------------------------------------------------------------------

    \690\ California Air Resources Board, Responses to Comments on 
the Environmental Analysis for the Proposed Heavy-Duty Engine and 
Vehicle Omnibus Regulation and Association Amendments. EMA Comment 
on CARB Omnibus (see p. 132 of pdf at https://ww3.arb.ca.gov/regact/2020/hdomnibuslownox/res20-23attbrtc.pdf).
    \691\ Under the Omnibus, at the end of MY 2026 NOX 
credits can no longer be generated from BEVs and FCEVs, and existing 
NOX credits from BEVs and FCEVs can no longer be used, 
and thus the lack of alignment between the CARB and proposed EPA 
certification pathways for these technologies is only for a few 
model years.
---------------------------------------------------------------------------

    On balance, EPA believes that the vehicle certification pathway for 
BEVs and FCEVs leads to a lower burden to manufacturers and EPA's 
certification program, and thus is the preferable option. Immediately 
below we request comment on our proposed approach and broader concepts 
related to NOX

[[Page 17558]]

emission credits for HEVs, BEVs, and FCEVs.
    We request comment on the general proposed approach of allowing 
HEVs, BEVs and FCEVs to generate NOX credits, which can then 
be used in the heavy-duty ABT program. We also specifically request 
comment on our proposal to allow BEV and FCEV vehicle manufacturers to 
generate vehicle emission credits for NOX. We further 
request comment on whether and how EPA could extend the opportunity to 
generate NOX engine emission credits to other manufacturers 
in the BEV and FCEV production process (e.g., non-vertically integrated 
powertrain manufacturers in addition to or in lieu of vehicle 
manufacturers). In addition, we request comment on our proposed 
approach to limit the use of NOX emission credits generated 
from BEV or FCEVs to the Light HDE, Medium HDE and Heavy HDE averaging 
sets in which they are generated. In particular, we are interested in 
stakeholder input on allowing NOX emission credits generated 
by BEVs or FCEVs in the Light HDE or Medium HDE averaging sets to be 
used in SI engine averaging sets.
2. Electric Vehicle Testing and Other Requirements for Generating 
NOX Emission Credits
    Similar to our approach for CI and SI engine manufacturers, EPA is 
proposing that manufacturers of HEVs, BEVs, and FCEVs would submit test 
data at the time of certification to support their calculation of 
NOX emission credits. Manufacturers would calculate the 
value of NOX emission credits generated from HEVs, BEVs, or 
FCEVs using the same equation provided for engine emission credits (see 
Equation IV-1 in Section IV.G.1). This equation relies on three key 
inputs: (1) The engine family's FEL for NOX, in mg/hp-hr, 
(2) work produced over the FTP duty-cycle, and (3) useful life mileage 
of the engine. Immediately below we describe how manufacturers would 
generate these three key inputs for HEVs, BEVs, and FCEVs, 
respectively.
i. Hybrid Electric Vehicle Testing for NOX Emission Credits
    For HEVs, we are proposing that starting in MY 2023 manufacturers 
could use powertrain testing procedures to certify hybrid 
configurations to criteria pollutant standards (see Section III.B.2 for 
more discussion on our proposal to allow powertrain testing for hybrid 
engines and powertrains).\692\ Manufacturers would generate the engine 
family's FEL for NOX, in mg/hp-hr and work produced over the 
FTP duty-cycle using the powertrain test procedure for the FTP duty-
cycle, as specified in the current 40 CFR 1036.510. By using the 
powertrain testing protocol, manufacturers could demonstrate 
NOX emissions performance of their hybrid powertrain 
technology and, where appropriate, generate NOX emission 
credits under the proposed ABT program described in Section IV.G. 
Manufacturers would complete their NOX credit calculation 
using the useful life mileage of the hybrid engine and powertrain 
configuration. As discussed in Section IV.A.3, we are proposing that 
hybrid engine and powertrain configurations certify to the same useful 
life requirements as the conventional engine that would typically be 
installed in the vehicle in order to provide truck owners and operators 
with similar assurance of durability regardless of the powertrain 
configuration they choose.
---------------------------------------------------------------------------

    \692\ As described in Section III.B.2, in a previous rulemaking 
we included an option for manufacturers to use powertrain test 
procedures to certify a hybrid powertrain to the FTP and SET 
greenhouse gas engine standards; under this rulemaking we are 
proposing to allow manufacturers to use powertrain test procedures 
to certify hybrid powertrains to the proposed FTP, SET, and LLC 
criteria emission standards.
---------------------------------------------------------------------------

ii. Battery and Fuel Cell Electric Vehicle Testing Requirements for 
NOX Emission Credits
    We are proposing for the first input into the NOX 
emission credit calculation (NOX FEL for the engine family) 
that BEV and FCEV manufacturers would declare an FEL for 
NOX, in mg/hp-hr that represents the NOX emission 
standards that the vehicle will meet throughout useful life, as stated 
in proposed 40 CFR 1037.616(a)(2). For the second input (work produced 
over the FTP duty-cycle), we are proposing that manufacturers would use 
data generated by a powertrain test procedure for a series of duty-
cycle tests (multicycle test, MCT) (see Section III.B and proposed 40 
CFR 1037.552 and 1037.554 for details on the MCT for BEVs and FCEVs, 
respectively). One of the duty-cycle tests included in each MCT is the 
FTP, which provides the necessary input to the credit calculation (see 
Section IV.I.2.iii for additional information on data generated by the 
MCT). The third input (useful life mileage) is discussed in Section 
IV.A.3 and specified in proposed 40 CFR 1037.102(b)(2). Briefly, we are 
proposing that BEV and FCEV manufacturers meet the useful life period 
of an equivalent engine-based service class. As discussed in Section 
IV.A.3, we believe that current data support BEV and FCEV technologies 
being capable of meeting the same useful life requirements of CI 
engines in the MY 2027 and beyond timeframe.\693\ We further believe 
that this approach provides truck owners and operators with equivalent 
durability expectations regardless of the powertrain they choose.
---------------------------------------------------------------------------

    \693\ As described in Section IV.A and specified in proposed 40 
CFR 1037.102(b)(2), prior to MY 2027, manufacturers choosing to 
generate NOX emission credits with BEVs or FCEVs would 
apply the useful life periods specified in the current 40 CFR 
86.001-2.
---------------------------------------------------------------------------

iii. Battery and Fuel Cell Electric Vehicle Durability Requirements for 
NOX Emission Credits
    The MCTs for BEVs and FCEVs would provide results that include work 
produced over the FTP duty-cycle, as well as initial useable battery 
energy (UBE) for BEVs, and initial fuel cell voltage (FCV) for 
FCEVs.\694\ These additional measures (UBE and FCV) would provide 
information critical to understanding the durability of the BEV or 
FCEV. BEVs and FCEVs must be durable throughout the useful life period 
to which they are certified in order to provide the zero-tailpipe 
emissions performance for which they are generating NOX 
credits. For instance, if the batteries or fuel cells of a BEV or FCEV 
are only capable of propelling the vehicle through one half of the 
certified useful life, and thus the BEV or FCEV can only travel half of 
the miles used to calculate the NOX credits being generated, 
then the remaining half of the NOX emission credits could be 
used by manufacturers to produce higher emitting internal combustion 
engines without actually achieving the real-world emission reductions 
from a BEV or FCEV being used for the full useful life. In other words, 
the zero-tailpipe emission performance of a BEV or FCEV could turn out 
to be illusory if the BEV or FCEV is unable to operate, and is thereby 
unable to achieve zero tailpipe emission performance, for its full 
useful life. Where BEVs or FCEVs are used to generate emission credits 
and thereby enable higher-emitting vehicles to be produced, it is 
especially important for the manufacturer to provide an assurance that 
the BEV or FCEV will be durable for the full useful life period.
---------------------------------------------------------------------------

    \694\ Useable battery energy is defined as the energy capacity 
of the battery less any energy the manufacturer determines is 
necessary for protecting the battery (e.g., thermal management). 
Fuel cell voltage is defined as voltage measured when current is 
between 55 percent-65 percent of rated stack current.

---------------------------------------------------------------------------

[[Page 17559]]

    To ensure that BEV and FCEV NOX credits are calculated 
accurately and reflect the environmental benefit of vehicles with zero 
tailpipe emissions over their full useful life, we are proposing that 
in MY 2024 and beyond, BEVs and FCEVs used to generate NOX 
emission credits must meet certain durability requirements. As 
specified in proposed 40 CFR 1037.102(b)(3), BEV or FCEV manufacturers 
would measure UBE or FCV at the start of useful life using the MCT 
procedures in proposed 40 CFR 1037.552 or 1037.554, respectively. BEV 
manufacturers could then attest, in lieu of demonstrating, that UBE 
remains at 70 percent or greater of the initial value throughout useful 
life. FCEV manufacturers could similarly attest, in lieu of 
demonstrating, that FCV remains at 80 percent or greater of the initial 
value throughout useful life. We recognize that BEV and FCEV 
technologies, and the batteries and fuel cells that power them, are in 
relatively nascent periods of development. Although we are proposing 
that starting in MY 2024 manufacturers must maintain the same 
percentage of UBE or FCV throughout useful life regardless of model 
year, the useful life periods are shorter in the proposed earlier model 
years. Specifically, the useful life period over which manufacturers 
must demonstrate, or attest, that UBE or FCV will be maintained at or 
above the proposed percentages are shorter for MYs 2024 through 2026 
and increase for MYs 2027 through 2030, with a further increase for MYs 
2031 and later (see proposed 40 CFR 1037.102(b)(2); see Section IV.A 
for our proposed useful life periods). We are not proposing a minimum 
requirement for UBE or FCV (i.e., manufacturers can design their 
products with an initial UBE or FCV value of their choosing). Further, 
there are multiple approaches that manufacturers could choose to use to 
meet the proposed requirements for UBE and FCV. For instance, 
manufacturers could choose to design the battery or fuel cell in their 
product to have a larger capacity at the start of the vehicle life and 
limit the extent to which the initial capacity is available for use; as 
the battery or fuel cell ages, the manufacturer could design the 
product to make more of the battery or fuel cell capacity available for 
use, and thereby maintain the same percent of UBE or FCV.\695\ Another 
approach that could be taken is the manufacturer could declare a UBE or 
FCV that is lower than the result from running the respective test 
procedures. This approach would give the user access to the full UBE or 
FCV, but the manufacturer would only be accountable for meeting the 
requirements in 40 CFR 1037.102(b)(3) for the value that they declared. 
Alternatively, a manufacturer could choose to include battery or fuel 
cell maintenance or replacement as part of critical emission-scheduled 
maintenance; manufacturers choosing this option would need to 
demonstrate that the maintenance is reasonably likely to be done on in-
use vehicles, as specified in the current 40 CFR 1037.125(a). As 
described in Section IV.I.2.iv, we are requesting comment on whether we 
should require manufacturers who choose this option to ensure that the 
maintenance is reasonably likely to be done by providing the 
maintenance free of charge and clearly stating so in their maintenance 
instructions, per the current 40 CFR 1037.125(a)(3).
---------------------------------------------------------------------------

    \695\ As specified in 40 CFR 1037.552 and 1037.554, 
manufacturers may declare a UBE or FCV lower than the measured value 
in order to account for degradation over useful life; however, the 
UBE or FCV available for operating the vehicle must be at least the 
value that is declared.
---------------------------------------------------------------------------

    We believe the proposed battery and fuel cell durability 
requirements are necessary to provide assurance that vehicles with 
these technologies would continue to provide the zero-tailpipe 
emissions performance throughout the useful life for which they are 
given credits. Our proposed approach for UBE and FCV as measures of 
durability builds on the ZEP Certification requirements and test 
procedures developed by CARB, work on light-duty vehicle battery 
durability under the United Nations Economic Commission for Europe 
(UNECE) Electric Vehicles and the Environment (EVE) Working Group for 
the Working Party on Pollution and Energy, and work on fuel cell 
durability by DOE.696 697 698 699 EPA believes the proposed 
battery and fuel cell durability requirements for BEVs and FCEVs would 
not only provide necessary assurance of zero-tailpipe emission 
performance for emission credit calculations, but would also help to 
ensure consistency in product quality as these technologies become 
increasingly available in larger portions of the heavy-duty fleet. 
Consistent product quality is critical not only for potential 
purchasers to have confidence in selecting BEVs and FCEVs for use in 
their business, but also for ensuring continued environmental benefits 
from the technologies throughout their use in the field. We further 
believe that basing our proposal on the approach being developed for 
light-duty technologies allows manufacturers to leverage the research 
and experience of the light-duty industry. The proposed percentages for 
UBE durability over useful life are drawn from comparable percentages 
for light-duty battery durability UBE under the UNECE EVE.\700\ 
Similarly, the proposed percentages for FCV durability are drawn from 
DOE targets for fuel cell durability in heavy-duty 
vehicles.701 702 We also note that at least one BEV bus 
manufacturer currently provides warranty coverage for their battery 
degrading below 80 percent of initial capacity.\703\ As discussed at 
the end of this subsection, we request comment on whether these 
percentages are appropriate for MY 2024 and later heavy-duty vehicles, 
and whether we should finalize different percentages for BEVs and FCEVs 
prior to MY 2027.
---------------------------------------------------------------------------

    \696\ California Air Resources Board. ``Attachment C: California 
Standards and Test Procedures for New 2021 and Subsequent Model 
Heavy-Duty Zero-Emissions Powertrains``, available at: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2019/zepcert/froattc.pdf (last accessed September 20, 2021); see Section D for 
details of CARB rated energy capacity test procedure requirements.
    \697\ Informal Working Group (IWG) on Electric Vehicles and the 
Environment (EVE). (July 2021) Proposal for a new UN GTR on In-
vehicle Battery Durability for Electrified Vehicles. Available at: 
https://wiki.unece.org/download/attachments/128420965/Based%20on%20GRPE-83-09%208%209%20July%202021%20EC%20US%20proposal.docx?api=v2 (last 
accessed August 6, 2021).
    \698\ Adams, J. (2020) DOE H2 Heavy Duty Truck Targets. 
Available at: https://www.energy.gov/sites/prod/files/2020/02/f71/fcto-compressed-gas-storage-workshop-2020-adams.pdf (last accessed 
on August 5, 2021).
    \699\ DOE. 2020. FC135: FC-PAD: Fuel Cell Performance and 
Durability Consortium. Available at: https://www.hydrogen.energy.gov/pdfs/review20/fc135_borup_weber_2020_o.pdf 
(last accessed August 20, 2021).
    \700\ See Table 1 (Battery Energy based (SOCE) MPR) of Informal 
Working Group (IWG) on Electric Vehicles and the Environment (EVE). 
(July 2021) Proposal for a new UN GTR on In-vehicle Battery 
Durability for Electrified Vehicles. Available at: https://wiki.unece.org/download/attachments/128420965/Based%20on%20GRPE-83-09%208%209%20July%202021%20EC%20US%20proposal.docx?api=v2 (last 
accessed August 6, 2021).
    \701\ Adams (2020) DOE H2 Heavy Duty Truck Targets. Available 
at: https://www.energy.gov/sites/prod/files/2020/02/f71/fcto-compressed-gas-storage-workshop-2020-adams.pdf (last accessed on 
August 5, 2021).
    \702\ Hydrogen and Fuel Cell Technologies Office (2014) DOE 
Technical Targets for Fuel Cell Transit Buses. Available at: https://www.energy.gov/eere/fuelcells/doe-technical-targets-fuel-cell-transit-buses. (last accessed on August 5, 2021).
    \703\ Blue Bird. (2019) Standard Limited Warranty. Available in 
the docket for this rule EPA-HQ-OAR-2019-0055.

---------------------------------------------------------------------------

[[Page 17560]]

iv. Alternatives Considered and Requests for Comment on Battery 
Electric and Fuel Cell Electric Vehicle Testing and Durability 
Requirements for NOX Emission Credits
    EPA recognizes that requiring BEV and FCEV manufacturers to run the 
MCT to measure work produced over the FTP duty cycle and to measure UBE 
and FCV places an additional burden on manufacturers who choose to 
generate NOX emission credits. We considered two alternative 
data sources for work produced over the FTP duty cycle in order to 
allow BEV and FCEV manufacturers to calculate NOX emission 
credits: (1) EPA could assume FTP work based on BEVs and FCEVs 
performing comparable work to CI and SI heavy-duty engines in the same 
engine service class, or (2) EPA could modify the GEM model to 
calculate work performed by electric motors. EPA believes that both 
alternative options would provide less accurate assessments of FTP-work 
than our proposed approach due to variability between different 
powertrains. We believe the value of the greater accuracy of our 
proposed approach justifies the additional test burden to 
manufacturers.
    Similarly, in addition to the proposed 70 percent UBE and 80 
percent FCV durability provisions, we considered two alternative 
approaches for evaluating battery and fuel cell durability. Under the 
first alternative manufacturers would measure battery energy 
consumption using a battery bench test during which the battery would 
be depleted at a constant rate. While this option would have a lower 
test burden for manufacturers, depleting the battery at a constant rate 
would not provide information on useable battery energy under realistic 
driving conditions. The second alternative durability approach we 
considered was for manufacturers to measure UBE or FCV by driving their 
BEV or FCEV on a chassis dynamometer. While this option would provide 
data that is slightly more reflective of UBE or FCV during realistic 
driving conditions due to the inclusion of the full vehicle, it would 
result in a much higher test burden for manufacturers given the limited 
number of heavy-duty chassis dynamometers available for conducting this 
type of testing. Ultimately, we believe that our proposed powertrain 
test method for measuring UBE (for BEVs) or FCV (for FCEVs) would 
provide assurance when calculating NOX emission credits that 
the environmental benefits of zero tailpipe emission technologies would 
be maintained throughout useful life, without imposing undue 
manufacturer test burden.
    We request comment on our proposed approach, along with the 
suggested alternatives and other possible approaches for demonstrating 
the amount of work performed on the FTP duty-cycle by BEVs and FCEVs, 
as well as measuring UBE or FCV. We also request comment whether EPA 
should adopt different percentages than 70 and 80 percent, 
respectively, for the required percentage of UBE and FCV remaining at 
the end of the useful life period for the NOX emission 
credit calculation. We are also interested in input on whether 
manufacturers who choose to include battery or fuel cell scheduled 
maintenance or replacement as part of critical emission-related 
maintenance during the useful life period should be required to provide 
the maintenance free of charge and clearly state that in their 
maintenance instructions, per the current 40 CFR 1037.125(a)(3) (i.e., 
rather than choosing any of the conditions listed in current 40 CFR 
1037.125(a), manufacturers including battery or fuel cell maintenance 
during the useful life period would be required to satisfy current 40 
CFR 1037.125(a)(3)). We recognize that battery or fuel cell maintenance 
during the useful life period may be costly, and thus it may be 
necessary for manufacturers to provide the maintenance free of charge 
in order to ensure that the maintenance is reasonably likely to occur 
in-use and the vehicle continues to provide the zero-tailpipe emissions 
performance over the useful life period for which it is generating 
NOX credits. We are especially interested in comments and 
data on battery and fuel cell durability, and information on how 
manufacturers providing battery or fuel cell maintenance free of charge 
during the proposed useful life periods could impact the upfront 
purchase price of the vehicles.
    We also request comment on whether to require manufacturers to make 
readily available to the operator onboard the vehicle a reading of the 
percent remaining UBE (for BEVs) or FCV (for FCEVs) relative to the 
value at the time of certification (e.g., 85 percent UBE relative to 
100 percent UBE at the time of certification). Such information could 
support an understanding of UBE and FCV throughout useful life for both 
EPA and users but may be an additional burden for manufacturers. For 
instance, manufacturers could choose to display the remaining 
percentage of UBE or FCV on the dashboard or make the reading available 
through a generic scan tool. Manufacturers choosing to generate 
NOX emission credits would measure initial UBE or initial 
FCV using the same MCT for certification; however, manufacturers could 
then utilize onboard vehicle sensors and an algorithm of their design 
(based on battery or fuel cell durability test data or good engineering 
judgment) to determine UBE (for BEVs) or FCV (for FCEVs) during vehicle 
operation. Under this option, manufacturers at the time of 
certification could choose to demonstrate or attest to the accuracy of 
their onboard vehicle sensor measurements combined with an algorithm, 
and EPA could measure UBE and FCV during any confirmatory testing.\704\ 
As an alternative option, EPA could require manufacturers to provide 
data at the time of certification showing the accuracy of their 
algorithm. We believe that information on the remaining UBE or FCV 
would provide owners an understanding of battery and fuel cell 
durability over time. We further believe that an understanding of 
battery and fuel cell durability would allow users to identify 
unexpected battery or fuel cell degradation and plan for repairs in a 
manner that minimizes downtime. We encourage commenters to provide 
input on utility and feasibility of displaying, or otherwise making 
available to the operator, the percent remaining UBE or FCV, and 
whether such information would support BEV or FCEV maintenance and 
repair in the field.
---------------------------------------------------------------------------

    \704\ As described in Section IV.I.2.iii and specified in the 
proposed 40 CFR 1037.205(q), manufacturers could attest, in lieu of 
demonstrating, that UBE or FCV remains at or above the specified 
percentage of the initial value through useful life, in addition to 
attesting or demonstrating the accuracy of their algorithm for 
calculating UBE or FCV throughout useful life.
---------------------------------------------------------------------------

3. Options for Long-Term Treatment of Emission Credits for Electric 
Vehicles
    We are proposing to recognize the NOX emission benefits 
of HEVs, BEVs, and FCEVs by allowing these technologies to generate 
NOX emission credits. At the same time, we recognize that 
NOX emission credits from HEV, BEV, and FCEV technologies 
would enable manufacturers to use these credits to produce some CI and 
SI engines with higher NOX emissions. We are proposing to 
limit the potential impacts of this approach with revised FEL caps, 
which restrict how much CI and SI engines could exceed the 
NOX emission standard by relying on NOX credits 
(see Section IV.G.3 for details on our proposed FEL caps). Even with 
this restriction, there is the potential for a greater portion of CI 
engines to emit up to the level of the FEL cap due to NOX

[[Page 17561]]

emission credits generated from BEVs or FCEVs relative to HEVs due to 
the zero emissions tailpipe performance of BEVs and FCEVs.\705\ We 
therefore believe it is important to consider what impact 
NOX emission credits generated from BEVs and FCEVs might 
have on the NOX emission reductions expected from the 
proposed rulemaking and to evaluate potential restrictions for 
NOX emission credits from BEVs and FCEVs.
---------------------------------------------------------------------------

    \705\ As noted in Section IV.I.1 and specified in proposed 40 
CFR 1037.102(b)(1) and 40 CFR 1036.741, we are proposing that 
NOX emission credits generated from BEVs and FCEVs may 
only be used within Light HDE, Medium HDE and Heavy HDE averaging 
sets. We are requesting comment on whether to allow NOX 
emission credits generated by BEVs or FCEVs to be used for the SI 
engine service class, but do not expect NOX emission 
credits from BEVs and FCEVs to result in higher-emitting SI engines 
under our proposed approach.
---------------------------------------------------------------------------

    In the final rule or other future rulemakings, it may be 
appropriate to restrict NOX emission credits from BEVs and 
FCEVs in the longer term (e.g., beyond MY 2031).\706\ Long-term 
adjustments to the proposed NOX emission credit provisions 
for BEVs and FCEVs could include any of the following options: (1) 
Sunsetting BEV and FCEV NOX emission credits, (2) setting 
NOX emission standards for engines with consideration of the 
availability of BEV and FCEV technologies, or (3) further restricting 
the use of NOX emission credits from BEVs and FCEVs. We 
discuss each of these options immediately below and request stakeholder 
input on the appropriateness of each for the final rule or future 
rules.
---------------------------------------------------------------------------

    \706\ We use MY 2031 as an example here; we may finalize one or 
more of the options presented in this Section IV.I.3 for an earlier 
or later model year (see Section XI.C for more discussion).
---------------------------------------------------------------------------

    Under the first option, we would sunset, i.e., end, the generation 
and use of NOX emission credits for BEVs and FCEVs after a 
specified period of time (e.g., ten years). Doing so would allow EPA to 
recognize the zero emission tailpipe benefits of BEVs and FCEVs as they 
transition into mainstream technologies in the heavy-duty market, and 
later revert back to a more limited scope of flexibilities for 
manufacturers to meet NOX emission standards within CI 
engine averaging sets. We may adopt BEV and FCEV NOX 
emission credit sunset provisions in the final rule, and we request 
comment on both the broad approach of sunsetting NOX 
emission credits for BEVs and FCEVs, as well as how EPA could determine 
a specific time period or other metric (e.g., percentage of 
manufacturer sales that are BEVs or FCEVs, percentage of U.S. heavy-
duty fleet that are BEVs or FCEVs) for ending NOX emission 
credit generation and use for BEVs and FCEVs.
    Under the second option, we could establish or revise the numeric 
level of the NOX emission standards based in part on the 
availability of EV technology in the baseline fleet or in projected 
compliance options.\707\ If, for example, the BEV and FCEV technologies 
were projected to reach a greater degree of market penetration than our 
current projections, we could incorporate that level of BEV and FCEV 
penetration into a calculation of an appropriate numerical standard to 
represent the combined benefits of achieving NOX control 
from engines along with zero tailpipe NOX emissions from BEV 
and FCEV technologies. Depending on achieved and forecasted future 
penetration rates and EPA decisions in the rulemaking, this option 
could lead to a more stringent NOX emission standard that 
would be achieved only if manufacturers develop and produce a certain 
number of powertrain technologies with zero-tailpipe NOX 
emissions. We request comment on both the broad principle of factoring 
BEV and FCEV penetration into an assessment of the feasibility of 
NOX emission standards in the final rule, or future rules, 
as well as data and methods that EPA could use to appropriately 
forecast market penetration levels and analyze cost and emissions 
impacts.
---------------------------------------------------------------------------

    \707\ See Section III.A.2 for discussion on our decision not to 
rely on BEV or FCEV technologies in the development of our proposed 
standards for NOX emissions, as well as our current 
understanding of market projections for the MY 2027 timeframe and 
the type of information that may lead us to reevaluate our approach 
for the final rule. Section XI presents our analysis of EV market 
projections in the MY 2027 timeframe as they relate to the proposed 
revisions to HD GHG Phase 2 emission standards.
---------------------------------------------------------------------------

    Under the third option, we could further restrict the generation 
and/or use of NOX emission credits from BEVs and FCEVs. Such 
restrictions could take one or more of the following forms. First, we 
could restrict NOX emission credits for BEVs and FCEVs to 
those powertrains that meet certain performance standards (e.g., an 
energy efficiency standard). Alternatively, we could restrict the use 
of NOX emission credits from BEVs and FCEVs to a shorter 
period of time (e.g., a credit life of two years for credits generated 
from BEVs and FCEVs, rather than the currently proposed five-year 
credit life). We request comment on the general concept of further 
restricting NOX emission credits from BEVs and FCEVs, as 
well as specific approaches that EPA could take to further restrict 
credits from these technologies.
4. Emission Credit Multipliers for Electric Vehicles
    In some light-duty and heavy-duty vehicle ABT programs, EPA has 
provided for emission credit multipliers for advanced technologies such 
as HEVs, BEVs, and FCEVs. As discussed in Section XI, the HD GHG Phase 
2 program currently provides multipliers of 3.5, 4.5, and 5.5 for HEVs, 
BEVs, and FCEVs, respectively. Emission credit multipliers are an 
approach to incentivize the investments that manufacturers make to 
develop and produce technologies that are considered ``advanced'' at 
the time of a rulemaking; however, the use of multipliers can result in 
the production of a larger number of higher emitting engines or 
vehicles than the number of lower emitting, advanced technology engines 
or vehicles on which the credits are based, since the multiplier 
inherently pairs one new advanced technology, low-emitting engine or 
vehicle with more than one new less-advanced higher emitting engine or 
vehicle.
    For this proposal, we do not believe that advanced technology 
NOX emission credit multipliers are appropriate for HEVs, 
BEVs, or FCEVs. We are choosing not to propose NOX emission 
credit multipliers for several reasons. First, specific to HEVs, these 
technologies have the potential to generate NOX emissions, 
and those emissions can vary based on the duty-cycle, battery state of 
charge, payload, and other factors. The potential variability in 
NOX emissions, and the likelihood for hybrid technology to 
become a primary technology pathway for meeting heavy-duty emission 
standards leads us to propose that NOX emission credit 
multipliers are not appropriate for HEVs (plug-in or more mild hybrid 
configurations).\708\
---------------------------------------------------------------------------

    \708\ For more discussion on hybrid technology use in the heavy-
duty fleet see MECA 2020, ``Technology Feasibility for Heavy-Duty 
Diesel Trucks in Achieving 90% Lower NOX Standards in 
2027'', available online at: https://www.meca.org/wp-content/uploads/resources/MECA_2027_Low_NOx_White_Paper_FINAL.pdf.
---------------------------------------------------------------------------

    For BEVs and FCEVs, we are not proposing emission credit 
multipliers for two reasons. First, multipliers inherently reduce the 
NOX emission benefits of the proposal to a greater extent 
than credits alone since the production of a single BEV or FCEV may be 
used to offset a greater number of CI engines emitting above the 
standard up to the FEL cap. We believe that the combination of FEL caps 
limiting the extent to which an engine could emit above the standard 
and the zero-tailpipe emission performance of BEVs and FCEVs warrant 
emission credits but not

[[Page 17562]]

credit multipliers. Second, the current state of technology development 
and implementation of HD BEVs and FCEVs leads us to believe that these 
technologies, while still relatively nascent compared to CI and SI 
engines, are mature enough not to warrant emission credit multipliers. 
For instance, numerous reports document growing numbers of BEVs and 
FCEVs entering the market over the next few model years (see draft RIA 
Chapter 1.4). In addition, a recent analysis shows that BEV 
technologies will reach parity in total cost of ownership with CI or SI 
engine technologies in most market segments by 2025 or earlier.\709\ 
The emission credit multipliers in the HD GHG Phase 2 rule were 
calculated based on higher costs of the particular advanced 
technologies they were targeting relative to conventional vehicles. The 
expectations for growing adoption of BEV and FCEV technologies combined 
with expectations that the technologies will reach cost parity in the 
near-term with conventional technologies lead us to propose that 
NOX emission credit multipliers, in the form of advanced 
technology credit multipliers or Early Adoption Incentive credit 
multipliers described in Section IV.H, would not apply for BEVs and 
FCEVs for the proposed criteria pollutant standards.\710\
---------------------------------------------------------------------------

    \709\ MJ Bradley (2021) ``Medium- & Heavy-Duty Vehicles: Market 
structure, Environmental Impact, and EV Readiness. Available online 
at: https://www.edf.org/sites/default/files/documents/EDFMHDVEVFeasibilityReport22jul21.pdf (last accessed August 21, 
2021).
    \710\ See Section XI for discussion on our current thinking for 
emission credit multipliers under the HD GHG Phase 2 program. We are 
requesting comment on potential revisions to the emission credit 
multipliers under the GHG Phase 2 program and are proposing emission 
credit multipliers are not appropriate under the proposed criteria 
program based on current information. We are not proposing any 
changes to advanced technology credit multipliers already 
established for other programs or taking comment on emission credit 
multipliers offered in previous rulemakings.
---------------------------------------------------------------------------

    Although we are not proposing multipliers, we nonetheless request 
comment on whether to include NOX emission credit 
multipliers for HEVs, BEVs, or FCEVs in the final rule. We recognize 
that there may be alternative approaches to our proposal, including the 
alternatives detailed below with our request for comment. Commenters 
are encouraged to submit data supporting their suggested approaches 
(e.g., emissions impacts or manufacturing costs of advanced powertrain 
technologies).
    For instance, EPA is interested in whether emission credit 
multipliers might be appropriate for specific market segments for which 
heavy-duty EV technology development may be more challenging (e.g., 
extended range battery-electric or hydrogen fuel cell). We recognize 
that current heavy-duty EV technologies generally claim to offer a 
range of 250 miles or less prior to needing to recharge.\711\ While 
there are a number of manufacturers with plans to produce or 
demonstrate BEVs or FCEVs with longer-range capabilities in next few 
model years, these longer-range capabilities would likely experience 
more challenges to market entry than shorter-range vehicles (e.g., 
charging/hydrogen refilling infrastructure, battery density, powertrain 
efficiency).\712\ \713\ \714\ Based on these challenges, it could make 
sense to provide interim incentives such as multipliers for BEVs or 
FCEVs capable of driving longer ranges prior to recharging/refilling 
(e.g., 300+ miles). Under this approach, EPA could provide a multiplier 
for longer-range BEVs or FCEVs (e.g., no multiplier for vehicles 
capable of <300 miles, multiplier of 1.5 for vehicles capable of >=300 
to 500 miles, multiplier of 2 for vehicles capable of >500 miles). In 
any case, EPA anticipates that incentives associated with specific 
performance criteria like the capability of driving a certain distance 
prior to recharging or refilling would need to include a requirement 
for manufacturers to demonstrate that capability to ensure the 
performance for which they are generating credits. We encourage 
commenters who support an approach that incentivizes specific 
attributes or performance criteria to comment on what demonstration 
requirement would be appropriate.\715\
---------------------------------------------------------------------------

    \711\ UCS (2019) ``Ready for Work: Now Is the Time for Heavy-
Duty Electric Vehicles''; www.ucsusa.org/resources/ready-work.
    \712\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \713\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers''. American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \714\ Smith, D. et al. (2019) ``Medium- and Heavy-Duty 
Electrification An Assessment of Technology and Knowledge Gaps''. 
Oak Ridge National Laboratory and National Renewable Energy 
Laboratory. ORNL/SPR-2020/7.
    \715\ Similar to the discussion in Section III on in-use testing 
procedures, we encourage commenters to include suggestions for non-
traditional demonstration mechanisms, such as the use of production 
or demonstration vehicle data if it could be supplied in sufficient 
quantity, quality, and representation of certification products.
---------------------------------------------------------------------------

    In addition, EPA solicits comment on whether emission credit 
multipliers for specific model years would be appropriate (e.g., 2 for 
MY 2023-2024; 1.5 for MY 2025-2026). We are also interested in 
commenters' views on whether BEVs and FCEVs should have different 
numeric multiplier values. Both technologies have knowledge and 
performance gaps to overcome in entering the market (e.g., battery 
density, charging/refilling infrastructure, duty cycle requirements 
analyses), and both technologies will likely be used in different 
applications across the heavy-duty market.\716\ \717\ Nevertheless, 
there may be inherent differences that lead to treating BEVs and FCEVs 
differently regarding multipliers.
---------------------------------------------------------------------------

    \716\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \717\ Smith, D. et al. (2019) ``Medium- and Heavy-Duty 
Electrification An Assessment of Technology and Knowledge Gaps''. 
Oak Ridge National Laboratory and National Renewable Energy 
Laboratory. ORNL/SPR-2020/7.
---------------------------------------------------------------------------

    Similarly, we are choosing not to propose advanced technology 
credit multipliers for HEVs, including plug-in HEVs (PHEVs), due to 
inherent differences in tailpipe emission performance relative to BEVs 
and FCEVs; however, we request comment on whether PHEVs should be 
eligible for credit multipliers, and if so, how manufacturers could 
demonstrate real-world NOX emission reductions given 
differences in emissions based on factors such as driving behavior or 
charging rate or frequency.
    We request comment on all of these alternative options (model year 
ranges, multiplier numeric value, common versus specific multiplier(s) 
for BEV and FCEV technologies, and potential PHEV multiplier), or 
additional alternatives commenters identify related to potential 
emission credit multipliers for HEVs, BEVs, and FCEVs. If commenters 
recommend that EPA include emission credit multipliers for HEVs, BEVs, 
and/or FCEVs, then we encourage them to provide input and submit data 
on how EPA should evaluate the potential emission impacts of any credit 
multipliers. Commenters are also encouraged to submit data and analyses 
relevant to BEV and FCEV sales projections, fleet turnover, and other 
relevant information for such an analysis.

J. Fuel Quality

    EPA has long recognized the importance of fuel quality on motor 
vehicle emissions and has regulated fuel quality to enable compliance 
with emission standards. In 1993, EPA limited diesel sulfur content to 
a maximum of 500 ppm and put into

[[Page 17563]]

place a minimum cetane index of 40. Starting in 2006 with the 
establishment of more stringent heavy-duty highway PM, NOX 
and hydrocarbon emission standards, EPA phased-in a 15-ppm maximum 
diesel fuel sulfur standard to enable heavy-duty diesel truck 
compliance with the more stringent emission standards.\718\
---------------------------------------------------------------------------

    \718\ 66 FR 5002 January 18, 2001.
---------------------------------------------------------------------------

    EPA continues to recognize the importance of fuel quality on heavy-
duty vehicle emissions and is not currently aware of any additional 
diesel fuel quality requirements that would be necessary for 
controlling criteria pollutant emissions from these vehicles.
1. Biodiesel Fuel Quality
    As discussed in Chapter 2.3.2 of the draft RIA, metals (e.g., Na, 
K, Ca, Mg) can enter the biodiesel production stream and can adversely 
affect emission control system performance if not sufficiently removed 
during production. Our review of data collected by NREL, EPA, and CARB 
indicates that biodiesel is compliant with the ASTM D6751-18 limits for 
Na, K, Ca, and Mg. As such, we are not proposing to regulate biodiesel 
blend metal content at this time because the available data does not 
indicate that there is widespread off specification biodiesel blend 
stock or biodiesel blends in the marketplace.
    While occasionally there are biodiesel blends with elevated levels 
of these metals, they are the exception. Data in the literature 
indicates that Na, K, Ca, and Mg levels in these fuels are less than 
100 ppb on average. Data further suggest that the low levels measured 
in today's fuels are not enough to adversely affect emission control 
system performance when the engine manufacturer properly sizes the 
catalyst to account for low-level exposure.
    Given the low levels measured in today's fuels, however, the ASTM 
is currently evaluating a possible revision to the measurement method 
for Na, K, Ca, and Mg in D6751-18 from EN14538 to a method that has 
lower detection limits (e.g., UOP-389-15, ASTM D7111-16, or a method 
based on the ICP-MS method used in the 2016 NREL study). We anticipate 
that ASTM will likely specify Na, K, Ca, and Mg limits in ASTM 7467-19 
for B6 to B20 blends that is an extrapolation of the B100 limits (see 
draft RIA Chapter 2.3.2 for additional discussion of ASTM test methods, 
as well as available data on levels of metal in biodiesel and potential 
impacts on emission control systems).
2. Compliance Issues Related to Biodiesel Fuel Quality
    Given the concerns we raised in the ANPR regarding the possibility 
of catalyst poisoning from metals contained in biodiesel blends and 
specifically heavy-duty vehicles fueled on biodiesel blends, EPA 
requests comment on providing a process to receive EPA approval to 
exempt test results from in-use testing compliance and test results 
being considered for potential recall if an engine manufacturer can 
show that the vehicle was historically fueled with biodiesel blends 
whose B100 blend stock did not meet the ASTM D6751-20a limit for Na, K, 
Ca, and/or Mg metal (metals which are a byproduct of biodiesel 
production). The potential approach we are requesting comment on would 
include requiring the engine manufacturer to provide proof of historic 
misfueling with off-specification biodiesel blends, which would include 
an analysis of the level of the poisoning agents on the catalysts in 
the engine's aftertreatment system, to qualify for the test result 
exemption(s).

K. Other Flexibilities Under Consideration

1. Overview of Verification Testing and Request for Comment on Interim 
In-Use Standards
    To verify that heavy-duty engines are meeting emission standards 
and other certification requirements throughout useful life, EPA 
regulations provide for testing engines at various stages in the life 
of an engine. These compliance provisions are confirmatory testing, 
selective enforcement audit (SEA) testing, and in-use testing.\719\ 
First, EPA may conduct confirmatory testing before an engine is 
certified to verify the manufacturer's test results with our own 
results.\720\ If conducted, the EPA confirmatory test results become 
official test results and are compared against the manufacturer's FEL, 
or family certification limit (FCL) for CO2. Second, EPA may require a 
manufacturer to conduct SEA testing of engines that come off the 
production line.\721\ Third, EPA and manufacturers can conduct in-use 
testing of engines that have already entered commerce.\722\ In-use 
testing is used to verify that the engine meets applicable duty cycle 
or off-cycle emission standards throughout useful life.
---------------------------------------------------------------------------

    \719\ In this section the phrase ``in-use testing'' refers to 
duty-cycle and off-cycle testing of field aged engines and does not 
refer solely to manufacturer run in-use testing.
    \720\ Confirmatory testing is addressed in proposed 40 CFR 
1036.235.
    \721\ SEA testing is conducted according to current 40 CFR part 
1068, subpart E.
    \722\ In-use testing is covered in the proposed 40 CFR part 
1036, subpart E.
---------------------------------------------------------------------------

    Typically, EPA sets the same standards for certification testing 
and in-use testing but, in a few cases, we have allowed temporary 
higher numerical in-use standards to give manufacturers time to gain 
experience with the new technology needed to meet the standards and 
reflect uncertainties about potential variabilities in performance 
during the early years of implementing new technology.\723\ \724\ As 
discussed in Section III, we are proposing lower numerical standards 
and longer useful life periods for HD highway engines, which would 
require manufacturers to include additional technology on the engines 
they manufacture. As discussed in Section III.A.3, we are conducting 
extensive analyses on the performance of next-generation SCR systems 
and engine CDA technology that in combination can effectively reduce 
NOX emissions to meet the proposed standards out to at least 
435,000 miles. While we expect the data that we are continuing to 
gather for the final rule would show that these technologies continue 
to be capable of meeting the proposed Option 1 numeric levels of the 
standards for Heavy HDEs out through 800,000 miles, we are considering 
the degree to which there is uncertainty in how the emissions control 
technologies deteriorate when the engine is installed in the wide 
variety of heavy-duty vehicle applications that exist in the 
marketplace and how to address such uncertainty.
---------------------------------------------------------------------------

    \723\ See 81 FR 23479, April 28, 2014.
    \724\ See 66 FR 5002, January 18, 2001.
---------------------------------------------------------------------------

    Given the potential for uncertainty in how the emissions control 
technologies would deteriorate in the field and across different 
vehicle applications, we are soliciting comment on providing engine 
manufacturers with higher (numerical) standards for an interim period 
to gain experience with the additional emission control technologies 
needed to meet the proposed Heavy HDE NOX standards (and 
their rates of deterioration) while those technologies are operating in 
the field. Manufacturers could, for instance, use the interim period to 
collect data from field-aged engines in a range of applications to 
inform how the engines can be designed to meet the standards throughout 
useful life for all applications in which the engine is used.
    In setting the duration of an interim period we would consider how 
long it would take manufacturers to collect

[[Page 17564]]

field data from engines operating out to the useful life mileage 
ultimately finalized in this rule. For example, if we were to finalize 
a useful life mileage of 800,000 for Heavy HDEs and assume that 
vehicles with Heavy HDEs typically travel 100,000 miles per year, then 
we could consider that manufacturers who collect data from pre-
production test fleets starting in 2025 would have field-aged parts out 
to 800,000 miles by 2033 (i.e., an eight-year period for data 
collection and a six-year interim period from the start of the proposed 
MY 2027 standards).
    We understand that manufacturers generally aim to design and build 
vehicles not only with a sufficient margin to ensure the emissions 
control technology is meeting the applicable standards throughout the 
full useful life, but also an additional margin to reflect the fact 
that not every vehicle manufactured and every vehicle application will 
perform identically to the laboratory tests.\725\ This is particularly 
important, and challenging for manufacturers, when new technologies and 
test procedures are being implemented. Thus, if we observe as part of 
EPA's engine demonstration study that the engine just meets the 
proposed standards including accounting for deterioration then we may 
consider adopting higher temporary in-use standards than if we observe 
the engine performing better compared to the proposed Option 1 
standards after being aged to the equivalent of 800,000 miles. In this 
rulemaking, we may consider adopting higher temporary in-use standards 
for all of the proposed duty-cycle and off-cycle NOX 
standards for Heavy HDEs in 40 CFR 1036.104. Table IV-16 and Table IV-
17 present the range of interim in-use standards that we are 
considering for MY 2027 through MY 2033 Heavy HDEs under proposed 
Option 1.
---------------------------------------------------------------------------

    \725\ As discussed in Chapter 3 of the draft RIA, manufacturer 
margins can range from less than 25 percent to 100 percent of the 
FEL.

  Table IV-16--Range of Potential Interim In-Use NOX FTP, SET and LLC Standards for MY 2027 Through 2033 Heavy
                                          HDEs Under Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                                                    In-use FTP
                                                                     standards
             Range \a\                        Model year         ----------------   In-use SET      In-use LLC
                                                                   NOX  (mg/hp-      standards       standards
                                                                        hr)
----------------------------------------------------------------------------------------------------------------
Low End of the Range...............  2027-2030..................              49              49             126
                                     2031 and later through                   28              28              70
                                      intermediate useful life.
                                     2031 and later for full                  56              56             140
                                      useful life.
High End of the Range..............  2027-2030..................              70              70             180
                                     2031 and later through                   40              40             100
                                      intermediate useful life.
                                     2031 and later for full                  80              80             200
                                      useful life.
----------------------------------------------------------------------------------------------------------------
\a\ The table defines the range of in-use standards we are considering for proposed Option 1. We would only
  finalize one standard for each, not a range.


 Table IV-17--Range of Potential Interim In-Use NOX Idle, Low-Load and Medium/High Load Off-cycle Standards for
                             MY 2027 Through 2033 Heavy HDEs under Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                                                                   In-use     In-use
                                                                                 off-cycle  off-cycle    In-use
                                                                                    idle     low load  off-cycle
                Range \a\                               Model year               standards  standards   medium/
                                                                                ---------------------- high load
                                                                                  NOX (g/    NOX (mg/  standards
                                                                                    hr)       hp-hr)
----------------------------------------------------------------------------------------------------------------
Low End of the Range.....................  2027--2030..........................         14        252         98
                                           2031 and later through intermediate          11        105         42
                                            useful life.
                                           2031 and later for full useful life.         11        210         84
High End of the Range....................  2027--2030..........................         20        360        140
                                           2031 and later through intermediate          15        150         60
                                            useful life.
                                           2031 and later for full useful life.         15        300        120
----------------------------------------------------------------------------------------------------------------
\a\ The table defines the range of in-use standards we are considering for proposed Option 1. We would only
  finalize one standard for each, not a range.

    We request comment on whether we should consider including in the 
final rule interim in-use standards to account for uncertainties about 
potential variabilities in performance during the early years of 
implementing new technology. Commenters are encouraged to provide input 
on what types of information we should consider when setting the 
duration and level of any interim in-use standard, and whether the ones 
included in discussion in this section are appropriate, or if there are 
other considerations that would be important for setting an interim in-
use standard. In particular we are seeking comment on whether, and if 
so how, to take into consideration the effects of fuel quality of 
biodiesel blends discussed in Section IV.J.2 in establishing interim 
in-use standards, or whether that is unnecessary if we were to finalize 
both an interim in-use standard for heavy HDE NOX standards 
and an allowance to exempt test results from engines that have been 
historically misfueled with off specification

[[Page 17565]]

biodiesel blends. We also request input on whether any interim in-use 
standard should apply to engine classes other than heavy HDEs under 
proposed Option 1, and whether we should consider including interim in-
use standards for pollutants other than NOX under proposed 
Option 1. Finally, we request that commenters provide any available 
field data on deterioration of next-generation SCR emission controls, 
or other technologies that could achieve the proposed standards 
throughout the proposed useful life periods.
2. Production Volume Allowance for Model Years 2027 Through 2029
    We are considering a flexibility allowing engine manufacturers, for 
model years 2027 through 2029 only, to certify up to 5 percent of their 
total production volume of heavy-duty highway compression-ignition (CI) 
engines in a given model year to the current, pre-MY 2027 engine 
provisions of 40 CFR part 86, subpart A. The allowance we are 
considering would be limited to Medium HDE or Heavy HDE engine families 
that manufacturers show would be used in low volume, specialty 
vocational vehicles. Such an allowance from the MY 2027 criteria 
pollutant standards may be necessary to provide engine and vehicle 
manufacturers additional lead time and flexibility to redesign some low 
sales volume products to accommodate the technologies needed to meet 
the proposed more stringent engine emission standards. One example of a 
low sales volume vocational vehicle type for which this flexibility 
could be appropriate is fire trucks, where the design cycles are 
typically longer than other HD on-highway products and packaging of new 
exhaust aftertreatment components within existing designs may 
potentially present a challenge to engine, chassis, and body 
manufacturers. Under this potential option, we are requesting comment 
on cases where packaging and design challenges are present, allowing 
specialty vocational vehicle manufacturers to install exempt engines, 
as long as the number of exempt engines installed does not exceed 5 
percent of the engine manufacturer's total production volume.
    We request comment on this potential option of a three-year 
allowance from the proposed MY 2027 criteria pollutant standards for 
engines installed in specialty vocational vehicles, including whether 
and why this flexibility is warranted and whether 5 percent of a 
manufacturers engine production volume is an appropriate value for such 
an interim provision. In addition, we request comment on whether this 
flexibility should be limited to specific vocational vehicle regulatory 
subcategories and the engines used in them.

V. Proposed Program Costs

    In Chapter 3 of the draft RIA, we present the direct manufacturing 
costs of the technologies we expect to be used to comply with the 
proposed standards. In this section we build upon those direct 
manufacturing costs to estimate the year-over-year costs going forward 
from the first year of each phase of implementation. We also present 
the indirect costs associated with the expected technologies. Like 
direct costs, indirect costs are expected to increase under the 
proposal, in large part due to the proposed warranty and useful life 
changes. The analysis also includes estimates of the possible operating 
costs associated with the proposed changes. We present total costs 
associated with proposed Options 1 and 2 in Section V.C. All costs are 
presented in 2017 dollars consistent with AEO 2018, unless noted 
otherwise.
    We request comment on all aspects of the cost analysis. In 
particular, we request comment on our estimation of warranty and 
research and development costs via use of scalars applied to indirect 
cost contributors (see Section V.A.2) and our estimates of emission 
repair cost impacts (see Section V.B.3). We also request comments that 
include supporting data and/or alternative approaches that we might 
consider when developing estimates for the final rulemaking.

A. Technology Package Costs

    Technology costs are associated with the two phases of the proposed 
Option 1 standards in MY 2027 and MY 2031, and with the single phase of 
the proposed Option 2 standards in MY 2027 (see Chapter 3 of the draft 
RIA). Individual technology piece costs are presented in Chapter 3 of 
the draft RIA and, in general, consist of the direct manufacturing 
costs (DMC) estimated for the first year of each phase of the proposed 
Option 1, or the first year of Option 2 standards, and are used as a 
starting point in estimating program costs. Following each year of when 
costs are first incurred, we have applied a learning effect to 
represent the cost reductions expected to occur via the ``learning by 
doing'' phenomenon. This provides a year-over-year cost for each 
technology as applied to new engine sales. We then applied industry 
standard ``retail price equivalent'' (RPE) markup factors industry-
wide, with adjustments discussed below, to estimate indirect costs 
associated with each technology. Both the learning effects applied to 
direct costs and the application of markup factors to estimate indirect 
costs are consistent with the cost estimation approaches used in EPA's 
past transportation-related regulatory programs. The sum of the direct 
and indirect costs represents our estimate of technology costs per 
vehicle on a year-over-year basis where MY 2031 and later costs include 
costs associated with MY 2027 and later. These technology costs 
multiplied by estimated sales then represent the total technology costs 
associated with the proposed standards.
    This cost calculation approach presumes that the expected 
technologies would be purchased by original equipment manufacturers 
(OEMs) from their suppliers. So, while the DMC estimates include the 
indirect costs and profits incurred by the supplier, the indirect cost 
markups we apply cover the indirect costs incurred by OEMs to 
incorporate the new technologies into their vehicles and to cover 
profit margins typical of the heavy-duty truck industry. We discuss the 
indirect cost markups in more detail below.
1. Direct Manufacturing Costs
    To produce a unit of output, manufacturers incur direct and 
indirect costs. Direct costs include cost of materials and labor costs. 
Indirect costs are discussed in the following section. The direct 
manufacturing costs presented here include individual technology costs 
for emission-related engine components and exhaust aftertreatment 
systems (EAS).
    Notably, for this analysis we include not only the marginal 
increased costs associated with the proposed Options 1 or 2, but also 
the emission control system costs for the baseline, or no action, 
case.\726\ Throughout this discussion we refer to baseline case costs, 
or baseline costs, which reflect our cost estimate of engine systems--
that portion that is emission-related--and the exhaust aftertreatment 
system absent impacts of this proposed rule. This inclusion of baseline 
system costs contrasts with EPA's approach in recent greenhouse gas 
rules or the light-duty Tier 3 criteria pollutant rule where we 
estimated costs relative to a baseline case, which obviated the need to

[[Page 17566]]

estimate baseline costs. We have included baseline costs in this 
analysis because under both of the proposed options the emissions 
warranty and regulatory useful life provisions are expected to have 
some impact on not only the new technology added to comply with the 
proposed standards, but also on emission control technologies already 
developed and in use.\727\ The baseline direct manufacturing costs 
detailed below are intended to reflect that portion of baseline case 
engine hardware and aftertreatment systems for which new indirect costs 
would be incurred due to the proposed warranty and useful life 
provisions, even apart from changes in the level of emission standards.
---------------------------------------------------------------------------

    \726\ See Section VI for more information about the emission 
inventory baseline and how that baseline is characterized. For this 
cost analysis, the baseline, or no action, case consists of engines 
and emission control systems meeting 2019 era criteria emission 
standards but in 2027 and later model years. Our rationale for 
including costs for the no action case is described in this section.
    \727\ The proposed warranty and useful life provisions would 
increase costs not only for the new technology added in response to 
the proposal, but also for the technology already in place (to which 
the new technology is added) because the proposed warranty and 
useful life provisions would apply to the entire emission-control 
system, not just the new technology added in response to the 
proposed standards.
---------------------------------------------------------------------------

    We have estimated the baseline engine costs based on recently 
completed studies by the International Council on Clean Technology 
(ICCT) as discussed in more detail in Chapter 7 of the draft RIA. As 
discussed there, the baseline engine costs consist of turbocharging, 
fuel system, exhaust gas recirculation, etc. These costs represent 
those for technologies that would be subject to extended warranty and 
useful life provisions under this proposal. For cylinder deactivation 
costs under the proposal, we have used FEV-conducted teardown-based 
cylinder deactivation costs as presented in Chapter 3 of the draft 
RIA.\728\ As for the EAS costs, those are also presented in Chapter 3 
of the draft RIA and, as discussed there, are based on an ICCT 
methodology with extensive revision by EPA. As discussed in draft RIA 
Chapter 3, we also have EAS cost estimates from a recent FEV-conducted 
teardown study.\729\ As discussed in Chapter 3 of the draft RIA, these 
teardown-based estimated EAS costs are similar to the EPA-estimated 
costs and we may use those FEV-study teardown-based cost estimates in 
the final rule. The direct manufacturing costs for the baseline 
engine+aftertreatment and for the proposed Options 1 and 2 are shown 
for diesel engines in Table V-1, gasoline engines in Table V-2 and CNG 
engines in Table V-3. Note that direct manufacturing costs for proposed 
Options 1 and 2 are equivalent because we expect that the same 
technologies would be needed to meet the standards in each option. 
Costs are shown for regulatory classes included in the cost analysis 
and follow the categorization approach used in our MOVES model. Please 
refer to Chapter 6 of the draft RIA for a description of the regulatory 
classes and why the tables that follow include or do not include each 
regulatory class. In short, where MOVES has regulatory class 
populations and associated emission inventories, our cost analysis 
estimates costs. Note also that, throughout this section, LHD = light 
heavy-duty, MHD = medium heavy-duty, HHD = heavy heavy-duty, CDPF = 
catlyzed diesel particulate filter, DOC = diesel oxidation catalyst, 
SCR = selective catalytic reduction, HC = hydrocarbon, and CNG = 
compressed natural gas.
---------------------------------------------------------------------------

    \728\ Mamidanna, S. 2021. Heavy-Duty Engine Valvetrain 
Technology Cost Assessment. U.S. EPA Contract with FEV North 
America, Inc., Contract No. 68HERC19D0008, Task Order No. 
68HERH20F0041. Submitted to the Docket.
    \729\ Mamidanna, S. 2021. Heavy-Duty Vehicles Aftertreatment 
Systems Cost Assessment. Submitted to the Docket.

Table V-1--Diesel Technology and Package Direct Manufacturing Costs per Vehicle by Regulatory Class for Proposed
                                    Options 1 and 2, MY2027, 2017 Dollars \a\
----------------------------------------------------------------------------------------------------------------
                                                                                      Proposed Options 1 and 2
 MOVES regulatory class           Technology                    Baseline                (MY2027 increment to
                                                                                              baseline)
----------------------------------------------------------------------------------------------------------------
LHD2b3.................  LHD2b3 Package.............                        $3,788                        $1,616
                         Engine hardware............                         1,097                             0
                         Closed crankcase...........                             0                             0
                         Cylinder deactivation......                             0                           196
                         CDPF.......................                           504                             0
                         DOC........................                           350                             0
                         SCR........................                         1,837                         1,174
                         Canning....................                             0                            30
                         HC dosing..................                             0                           216
                        ----------------------------------------------------------------------------------------
LHD45..................  LHD45 Package..............                         3,806                         1,653
                         Engine hardware............                         1,097                             0
                         Closed crankcase...........                            18                            37
                         Cylinder deactivation......                             0                           196
                         CDPF.......................                           504                             0
                         DOC........................                           350                             0
                         SCR........................                         1,837                         1,174
                         Canning....................                             0                            30
                         HC dosing..................                             0                           216
                        ----------------------------------------------------------------------------------------
MHD67..................  MHD67 Package..............                         4,032                         1,619
                         Engine hardware............                         1,254                             0
                         Closed crankcase...........                            18                            37
                         Cylinder deactivation......                             0                           147
                         CDPF.......................                           570                             0
                         DOC........................                           316                             0
                         SCR........................                         1,875                         1,183
                         Canning....................                             0                            36
                         HC dosing..................                             0                           216
                        ----------------------------------------------------------------------------------------
HHD8...................  HHD8 Package...............                         6,457                         2,210
                         Engine hardware............                         2,038                             0

[[Page 17567]]

 
                         Closed crankcase...........                            18                            37
                         Cylinder deactivation......                             0                           206
                         CDPF.......................                         1,067                             0
                         DOC........................                           585                             0
                         SCR........................                         2,750                         1,681
                         Canning....................                             0                            71
                         HC dosing..................                             0                           216
                        ----------------------------------------------------------------------------------------
Urban bus..............  Urban bus Package..........                         4,082                         1,653
                         Engine hardware............                         1,254                             0
                         Closed crankcase...........                            18                            37
                         Cylinder deactivation......                             0                           147
                         CDPF.......................                           567                             0
                         DOC........................                           314                             0
                         SCR........................                         1,929                         1,469
                         Canning....................                             0                             0
                         HC dosing..................                             0                             0
----------------------------------------------------------------------------------------------------------------


    Table V-2--Gasoline Technology and Package Direct Manufacturing Costs per Vehicle by Regulatory Class for
                               Proposed Options 1 and 2, MY2027, 2017 Dollars \a\
----------------------------------------------------------------------------------------------------------------
                                                                                      Proposed Options 1 and 2
 MOVES regulatory class           Technology                    Baseline                (MY2027 increment to
                                                                                              baseline)
----------------------------------------------------------------------------------------------------------------
LHD45..................  LHD45 Package..............                          $832                          $417
                         Engine hardware............                           523                             0
                         Aftertreatment.............                           309                           393
                         ORVR.......................                             0                            24
                        ----------------------------------------------------------------------------------------
MHD67..................  MHD67 Package..............                           832                           417
                         Engine hardware............                           523                             0
                         Aftertreatment.............                           309                           393
                         ORVR.......................                             0                            24
                        ----------------------------------------------------------------------------------------
HHD8...................  HHD8 Package...............                           832                           417
                         Engine hardware............                           523                             0
                         Aftertreatment.............                           309                           393
                         ORVR.......................                             0                            24
----------------------------------------------------------------------------------------------------------------
\a\ Note that the analysis uses the baseline plus the proposal cost--i.e., Baseline+Proposal--when estimating
  total costs; the incremental costs are shown here for ease of understanding the increased costs associated
  with the proposed Option 1 or 2. Note also that all LHD2b3 gasoline vehicles are chassis certified so are not
  expected to incur any costs associated with this proposal.


 Table V-3--CNG Technology and Package Direct Manufacturing Costs per Vehicle by Regulatory Class, for Proposed
                                    Options 1 and 2, MY2027, 2017 Dollars \a\
----------------------------------------------------------------------------------------------------------------
                                                                                      Proposed Options 1 and 2
 MOVES regulatory class           Technology                    Baseline                (MY2027 increment to
                                                                                              baseline)
----------------------------------------------------------------------------------------------------------------
HHD8...................  HHD8 Package...............                        $4,108                           $27
                         Engine hardware............                           896                             0
                         Aftertreatment.............                         3,212                            27
                        ----------------------------------------------------------------------------------------
Urban bus..............  Urban bus Package..........                         3,081                            19
                         Engine hardware............                           672                             0
                         Aftertreatment.............                         2,409                            19
----------------------------------------------------------------------------------------------------------------
\a\ Note that the analysis uses the baseline plus the proposal cost--i.e., Baseline+Proposal--when estimating
  total costs; the incremental costs are shown here for ease of understanding the increased costs associated
  with the proposed Option 1 or 2. MOVES does not have any MHD67 CNG vehicles. Note also that the urban bus
  regulatory class consists of MHD engines but is shown here as urban bus for consistency with MOVES vehicle
  populations and inventories.

    The direct costs are then adjusted to account for learning effects 
going forward from the first year of each phase of implementation for 
proposed Option 1, or simply the first year of implementation for 
proposed Option 2. We describe in detail in Chapter 7 of the draft RIA 
the approach used to apply learning effects in this analysis.

[[Page 17568]]

Learning effects were applied on a technology package cost basis, and 
MOVES-projected sales volumes were used to determine first-year sales 
and cumulative sales. The resultant direct manufacturing costs and how 
those costs decrease over time are presented in Section V.A.3.
2. Indirect Costs
    Indirect costs are all the costs associated with producing the unit 
of output that are not direct costs--for example, they may be related 
to production (such as research and development (R&D)), corporate 
operations (such as salaries, pensions, and health care costs for 
corporate staff), or selling (such as transportation, dealer support, 
and marketing). Indirect costs are generally recovered by allocating a 
share of the indirect costs to each unit of good sold. Although direct 
costs can be allocated to each unit of good sold, it is more 
challenging to account for indirect costs allocated to a unit of goods 
sold. To ensure that regulatory analyses capture the changes in 
indirect costs, markup factors (which relate total indirect costs to 
total direct costs) have been developed and used by EPA and other 
stakeholders. These factors are often referred to as retail price 
equivalent (RPE) multipliers. RPE multipliers provide, at an aggregate 
level, the relative shares of revenues, where:

Revenue = Direct Costs + Indirect Costs
Revenue/Direct Costs = 1 + Indirect Costs/Direct Costs = Retail 
Price Equivalent (RPE)
Resulting in:
Indirect Costs = Direct Costs x (RPE--1)

    If the relationship between revenues and direct costs (i.e., RPE) 
can be shown to equal an average value over time, then an estimate of 
direct costs can be multiplied by that average value to estimate 
revenues, or total costs. Further, that difference between estimated 
revenues, or total costs, and estimated direct costs can be taken as 
the indirect costs. Cost analysts and regulatory agencies have 
frequently used these multipliers to predict the resultant impact on 
costs associated with manufacturers' responses to regulatory 
requirements and we are using that approach in this analysis.
    The proposed cost analysis estimates indirect costs by applying the 
RPE markup factor used in past rulemakings (such as those setting 
greenhouse gas standards for heavy-duty trucks).\730\ The markup 
factors are based on financial filings with the Securities and Exchange 
Commission for several engine and engine/truck manufacturers in the 
heavy-duty industry.\731\ The RPE factors for HD engine manufacturers, 
HD truck manufacturers and for the HD truck industry as a whole are 
shown in Table V-4. Also shown in Table V-4 are the RPE factors for 
light-duty vehicle manufacturers.\732\
---------------------------------------------------------------------------

    \730\ 76 FR 57106; 81 FR 73478.
    \731\ Heavy Duty Truck Retail Price Equivalent and Indirect Cost 
Multipliers, Draft Report, July 2010.
    \732\ Rogozhin, A., et al., Using indirect cost multipliers to 
estimate the total cost of adding new technology in the automobile 
industry. International Journal of Production Economics (2009), 
doi:10.1016/j.ijpe.2009.11.031.

 Table V-4--Retail Price Equivalent Factors in the Heavy-Duty and Light-
                             Duty Industries
------------------------------------------------------------------------
                                                                   LD
                 Cost contributor                    HD truck   vehicle
                                                     industry   industry
------------------------------------------------------------------------
Direct manufacturing cost.........................       1.00       1.00
Warranty..........................................       0.03       0.03
R&D...............................................       0.05       0.05
Other (admin, retirement, health, etc.)...........       0.29       0.36
Profit (cost of capital)..........................       0.05       0.06
RPE...............................................       1.42       1.50
------------------------------------------------------------------------

    For this analysis, EPA based indirect cost estimates for diesel and 
CNG regulatory classes on the HD Truck Industry RPE values shown in 
Table V-4. Because most of the proposed changes apply to engines, we 
first considered using the HD Engine Manufacturer values. However, the 
industry is becoming more vertically integrated and the costs we are 
analyzing are those that occur at the end purchaser, or retail, level. 
For that reason, we believe that the truck industry values represent 
the most appropriate factors for this analysis. For gasoline regulatory 
classes, we used the LD Vehicle Industry values shown in Table V-4 
since they more closely represent the cost structure of manufacturers 
in that industry--Ford, General Motors, and Chrysler.
    Of the cost contributors listed in Table V-4, Warranty and R&D are 
the elements of indirect costs that the proposed requirements are 
expected to impact. As discussed in Section III of the preamble, EPA is 
proposing to lengthen the warranty period, which we expect to increase 
the contribution of warranty costs to the RPE. EPA is also proposing to 
extend the regulatory useful life, which we expect to result in 
increased R&D expenses as compliant systems are developed. Profit is 
listed to highlight that profit is being considered and included in the 
analysis. All other indirect cost elements--those encapsulated by the 
``Other'' category, including General and Administrative Costs, 
Retirement Costs, Healthcare Costs, and other overhead costs--as well 
as Profits, are expected to scale according to their historical levels 
of contribution.
    As mentioned, Warranty and R&D are the elements of indirect costs 
that the proposed requirements are expected to impact. Warranty 
expenses are the costs that a business expects to or has already 
incurred for the repair or replacement of goods that it has sold. The 
total amount of warranty expense is limited by the warranty period that 
a business typically allows. After the warranty period for a product 
has expired, a business no longer incurs a warranty liability; thus, a 
longer warranty period results in a longer period of liability for a 
product. At the time of sale, companies are expected to set aside money 
in a warranty liability account to cover any potential future warranty 
claims. If and when warranty claims are made by customers, the warranty 
liability account is debited and a warranty claims account is credited 
to cover warranty claim expenses.\733\
---------------------------------------------------------------------------

    \733\ Warranty expense is recognized in the same period as the 
sales for the products that were sold, if it is probable that an 
expense will be incurred and the company can estimate the amount of 
the expense (AccountingTools.com, December 24, 2020, accessed 
January 28, 2021).
---------------------------------------------------------------------------

    To address the expected increased indirect cost contributions 
associated with warranty (increased funding of the warranty liability 
account) due to the proposed longer warranty requirements,

[[Page 17569]]

we have applied scaling factors commensurate with the changes in 
proposed Option 1 or Option 2 to the number of miles included in the 
warranty period (i.e., VMT-based scaling factors). For example, the 
current required emission warranty period for Class 8 diesel trucks are 
5 years or 100,000 miles. Proposed Option 1 would extend the required 
warranty period for a Class 8 diesel to 7 years or 450,000 miles for 
MYs 2027 through 2030, and then extend further to 10 years or 600,000 
miles for MYs 2031 and beyond. As such, in our analysis of proposed 
Option 1 for Class 8 diesel trucks we applied a scaling factor of 4.5 
(450/100) to the 0.03 warranty contribution factor for MYs 2027 through 
2030, and applied a scaling factor of 6.0 (600/100) for MYs 2031 and 
later. This same approach is followed for the other regulatory classes, 
and for our analysis of proposed Option 2.
    Similarly, for R&D on that same Class 8 truck, the proposed Option 
1 would extend regulatory useful life from 10 years or 435,000 miles to 
11 years or 600,000 miles beginning in MY 2027, and then extend further 
to 12 years or 800,000 miles for MYs 2031 and later, we have applied a 
scaling factor of 1.38 (600/435) to the 0.05 R&D contribution factor 
for MYs 2027 through 2029, and then 1.33 (800/600) for MYs 2031 through 
2033. Notice the different treatment of the scaling factors for R&D 
versus those for warranty. We would expect that once the development 
efforts into longer useful life are complete, increased expenditures 
would return to their normal levels of contribution. As such, we have 
implemented the R&D scalars in three-year increments (2027 through 2029 
and then 2031 through 2033). In MY 2034 and later (under the proposal), 
the R&D scaling factor would no longer be applied.
    The VMT-based scaling factors applied to warranty and R&D cost 
contributors used in our cost analysis of proposed Options 1 and 2 are 
shown in Table V-5 for diesel and CNG regulatory classes and in Table 
V-6 for gasoline regulatory classes.

        Table V-5--Scaling Factors Applied to RPE Contribution Factors To Reflect Changes in Their Contributions, Diesel & CNG Regulatory Classes
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         Warranty scalars                     R&D scalars
                    Scenario                           MOVES regulatory class      ---------------------------------------------------------------------
                                                                                      MY2027-2030    MY2031+     MY2027-2029     MY2031-2033    MY2034+
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline.......................................  LHD..............................            1.00       1.00            1.00            1.00       1.00
                                                 LHD45............................            1.00       1.00            1.00            1.00       1.00
                                                 MHD67............................            1.00       1.00            1.00            1.00       1.00
                                                 HHD8.............................            1.00       1.00            1.00            1.00       1.00
                                                 Urban Bus........................            1.00       1.00            1.00            1.00       1.00
Option 1.......................................  LHD..............................            1.50       2.10            1.73            1.42       1.00
                                                 LHD45............................            1.50       2.10            1.73            1.42       1.00
                                                 MHD67............................            2.20       2.80            1.46            1.30       1.00
                                                 HHD8.............................            4.50       6.00            1.38            1.33       1.00
                                                 Urban Bus........................            4.50       6.00            1.38            1.33       1.00
Option 2.......................................  LHD..............................            1.10       1.10            2.27            1.00       1.00
                                                 LHD45............................            1.10       1.10            2.27            1.00       1.00
                                                 MHD67............................            1.50       1.50            1.76            1.00       1.00
                                                 HHD8.............................            3.50       3.50            1.49            1.00       1.00
                                                 Urban Bus........................            3.50       3.50            1.49            1.00       1.00
--------------------------------------------------------------------------------------------------------------------------------------------------------


          Table V-6--Scaling Factors Applied to RPE Contribution Factors To Reflect Changes in Their Contributions, Gasoline Regulatory Classes
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         Warranty scalars                     R&D scalars
                    Scenario                           MOVES regulatory class      ---------------------------------------------------------------------
                                                                                      MY2027-2030    MY2031+     MY2027-2029     MY2031-2033    MY2034+
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline.......................................  LHD45............................            1.00       1.00            1.00            1.00       1.00
                                                 MHD67............................            1.00       1.00            1.00            1.00       1.00
                                                 HHD8.............................            1.00       1.00            1.00            1.00       1.00
Option 1.......................................  LHD45............................            2.20       3.20            1.41            1.29       1.00
                                                 MHD67............................            2.20       3.20            1.41            1.29       1.00
                                                 HHD8.............................            2.20       3.20            1.41            1.29       1.00
Option 2.......................................  LHD45............................            2.20       2.20            1.82            1.00       1.00
                                                 MHD67............................            2.20       2.20            1.82            1.00       1.00
                                                 HHD8.............................            2.20       2.20            1.82            1.00       1.00
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Lastly, as mentioned in Section V.A.1, the markups for estimating 
indirect costs are applied to our estimates of the absolute direct 
manufacturing costs for emission-control technology shown in Table V-1, 
Table V-2 and Table V-3, not just the incremental costs associated with 
the proposal (i.e., the Baseline+Proposal costs, not just the 
incremental costs of proposed Option 1 or 2). This is an important 
element of the analysis as shown by the hypothetical example in Table 
V-7. In the example, which is only for illustration, we assume that the 
baseline technology cost is $5,000, the proposed incremental cost is 
$1,000, and the indirect cost warranty contribution is 0.03 with a 
simple scalar of 1.5 associated with a longer warranty period. In this 
case, the costs could be calculated according to two approaches, as 
shown. By including the baseline costs, we are estimating new warranty 
costs in the proposal as illustrated by the example where including 
baseline costs results in warranty costs of $270 while excluding 
baseline costs results in warranty costs of $45.

[[Page 17570]]

    We request comment on the approach used here. Specifically, we 
request comment on the application of indirect costs to baseline plus 
incremental costs as just described and as illustrated in Table V-7. We 
also request comment on the scaling approach used to estimate indirect 
cost impacts and the relative scaling of research and development costs 
along with their return to traditional levels following a three year 
period, and the absolute scaling of warranty costs and their 
continuation at those levels in perpetuity rather than returning to 
traditional levels at some future point.

  Table V-7--Simplified Hypothetical Example of Indirect Warranty Costs
    Calculated on an Incremental vs. Absolute Technology Package Cost
    [Values Are Not From the Analysis and Are for Presentation Only]
------------------------------------------------------------------------
                                   Excluding baseline       Including
                                         costs           baseline costs
------------------------------------------------------------------------
Direct Manufacturing Cost (DMC)  $1000................  $5000 + $1000 =
                                                         $6000
Indirect Warranty Costs........  $1000 x 0.03 x 1.5 =   $6000 x 0.03 x
                                  $45.                   1.5 = $270
DMC + Warranty.................  $1000 + $45 = $1045..  $1000 + $270 =
                                                         $1270
------------------------------------------------------------------------

3. Technology Costs per Vehicle
    The following tables present the technology costs estimated for the 
proposed Options 1 and 2 on a per-vehicle basis for MY 2027 and MY 
2031. Reflected in these tables are learning effects on direct 
manufacturing costs and scaling effects--associated with increased 
costs due to proposed program elements--on indirect costs. The sum is 
also shown and reflects the cost per vehicle in the specific model year 
that would be multiplied by sales to estimate the total costs 
associated with each proposed option.\734\
---------------------------------------------------------------------------

    \734\ Note that we have not estimated sales impacts associated 
with the proposal (see Section X), so sales projections are 
equivalent across scenarios.
---------------------------------------------------------------------------

    We show costs per vehicle here, but it is important to note that 
these are costs and not prices. We are not estimating how manufacturers 
would price their products. Manufacturers may pass costs along to 
purchasers via price increases in a manner consistent with what we show 
here. However, manufacturers may also price certain products higher 
than what we show while pricing others lower--the higher-priced 
products thereby subsidizing the lower-priced products. This is true in 
any market, not just the heavy-duty highway industry. This may be 
especially true with respect to the indirect costs we have estimated 
because, for example, R&D done to improve emission durability can 
readily transfer across different engines whereas technology added to 
an engine is uniquely tied to that engine. We request comment on this 
issue--while we believe that the RPE markup and the indirect cost 
contributor scaling approach is a reasonable approach to estimating 
indirect costs, would it be preferable to consider indirect costs in 
aggregate rather than on a per engine or per vehicle basis?

  Table V-8--MY2027 & MY2031 Technology Costs per Vehicle for LHD2b3 Diesel, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $3,788       $114       $189     $1,099       $189     $5,379
                               Baseline+Propos      5,404        243        467      1,567        270      7,952
                                ed Option 1.
                               Baseline+Propos      5,404        178        614      1,567        270      8,034
                                ed Option 2.
                               Option 1             1,616        130        277        469         81      2,572
                                increase from
                                Baseline.
                               Option 2             1,616         65        425        469         81      2,655
                                increase from
                                Baseline.
2031.........................  Baseline.......      3,504        105        175      1,016        175      4,976
                               Baseline+Propos      4,863        306        346      1,410        243      7,168
                                ed Option 1.
                               Baseline+Propos      4,863        160        243      1,410        243      6,920
                                ed Option 2.
                               Option 1             1,358        201        170        394         68      2,192
                                increase from
                                Baseline.
                               Option 2             1,358         55         68        394         68      1,944
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


   Table V-9--MY2027 & MY2031 Technology Costs per Vehicle for LHD45 Diesel, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $3,806       $114       $190     $1,104       $190     $5,405
                               Baseline+Propos      5,459        246        471      1,583        273      8,032
                                ed Option 1.
                               Baseline+Propos      5,459        180        620      1,583        273      8,115
                                ed Option 2.
                               Option 1             1,653        131        281        479         83      2,627
                                increase from
                                Baseline.
                               Option 2             1,653         66        430        479         83      2,710
                                increase from
                                Baseline.
2031.........................  Baseline.......      3,515        105        176      1,019        176      4,991
                               Baseline+Propos      4,900        309        348      1,421        245      7,223
                                ed Option 1.
                               Baseline+Propos      4,900        162        245      1,421        245      6,973
                                ed Option 2.
                               Option 1             1,385        203        172        402         69      2,232
                                increase from
                                Baseline.

[[Page 17571]]

 
                               Option 2             1,385         56         69        402         69      1,982
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


 Table V-10--MY2027 & MY2031 Technology Costs per Vehicle for MHD67 Diesel, Average per Vehicle, 2017 Dollars *
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $4,032       $121       $202     $1,169       $202     $5,725
                               Baseline+Propos      5,651        373        412      1,639        283      8,358
                                ed Option 1.
                               Baseline+Propos      5,080        229        254      1,473        254      7,290
                                ed Option 2.
                               Option 1             1,619        252        211        470         81      2,632
                                increase from
                                Baseline.
                               Option 2             1,357        117         68        394         68      2,003
                                increase from
                                Baseline.
2031.........................  Baseline.......      3,723        112        186      1,080        186      5,287
                               Baseline+Propos      5,080        427        329      1,473        254      7,563
                                ed Option 1.
                               Baseline+Propos      5,080        229        254      1,473        254      7,290
                                ed Option 2.
                               Option 1             1,357        315        143        394         68      2,276
                                increase from
                                Baseline.
                               Option 2             1,357        117         68        394         68      2,003
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


   Table V-11--MY2027 & MY2031 Technology Costs per Vehicle for HHD8 Diesel, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $6,457       $194       $323     $1,873       $323     $9,169
                               Baseline+Propos      8,668      1,170        598      2,514        433     13,382
                                ed Option 1.
                               Baseline+Propos      8,668        910        648      2,514        433     13,172
                                ed Option 2.
                               Option 1             2,210        976        275        641        111      4,213
                                increase from
                                Baseline.
                               Option 2             2,210        716        325        641        111      4,003
                                increase from
                                Baseline.
2031.........................  Baseline.......      5,961        179        298      1,729        298      8,465
                               Baseline+Propos      7,813      1,406        521      2,266        391     12,396
                                ed Option 1.
                               Baseline+Propos      7,813        820        391      2,266        391     11,680
                                ed Option 2.
                               Option 1             1,851      1,227        223        537         93      3,931
                                increase from
                                Baseline.
                               Option 2             1,851        641         93        537         93      3,215
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


Table V-12--MY2027 & MY2031 Technology Costs per Vehicle for Urban Bus Diesel, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $4,082       $122       $204     $1,184       $204     $5,796
                               Baseline+Propos      5,734        774        395      1,663        287      8,854
                                ed Option 1.
                               Baseline+Propos      5,734        602        428      1,663        287      8,715
                                ed Option 2.
                               Option 1             1,653        652        191        479         83      3,058
                                increase from
                                Baseline.
                               Option 2             1,653        480        224        479         83      2,918
                                increase from
                                Baseline.
2031.........................  Baseline.......      3,769        113        188      1,093        188      5,352
                               Baseline+Propos      5,153        928        344      1,494        258      8,177
                                ed Option 1.
                               Baseline+Propos      5,153        541        258      1,494        258      7,704
                                ed Option 2.
                               Option 1             1,385        815        155        402         69      2,825
                                increase from
                                Baseline.
                               Option 2             1,385        428         69        402         69      2,353
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


 Table V-13--MY2027 & MY2031 Technology Costs per Vehicle for LHD45, MHD67 & HHD8 Gasoline, Average per Vehicle,
                                                  2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......       $832        $25        $42       $299        $50     $1,248
                               Baseline+Propos      1,249         82         88        450         75      1,944
                                ed Option 1.
                               Baseline+Propos      1,249         82        114        450         75      1,969
                                ed Option 2.
                               Option 1               417         57         46        150         25        696
                                increase from
                                Baseline.
                               Option 2               417         57         72        150         25        722
                                increase from
                                Baseline.
2031.........................  Baseline.......        768         23         38        277         46      1,152
                               Baseline+Propos      1,118        107         72        402         67      1,767
                                ed Option 1.

[[Page 17572]]

 
                               Baseline+Propos      1,118         74         56        402         67      1,717
                                ed Option 2.
                               Option 1               350         84         34        126         21        614
                                increase from
                                Baseline.
                               Option 2               350         51         17        126         21        565
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


    Table V-14--MY2027 & MY2031 Technology Costs per Vehicle for HHD8 CNG, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $4,108       $123       $205     $1,191       $205     $5,833
                               Baseline+Propos      4,135        558        285      1,199        207      6,384
                                ed Option 1.
                               Baseline+Propos      4,135        434        309      1,199        207      6,284
                                ed Option 2.
                               Option 1                27        435         80          8          1        551
                                increase from
                                Baseline.
                               Option 2                27        311        104          8          1        450
                                increase from
                                Baseline.
2031.........................  Baseline.......      3,793        114        190      1,100        190      5,386
                               Baseline+Propos      3,816        687        254      1,107        191      6,054
                                ed Option 1.
                               Baseline+Propos      3,816        401        191      1,107        191      5,705
                                ed Option 2.
                               Option 1                23        573         65          7          1        668
                                increase from
                                Baseline.
                               Option 2                23        287          1          7          1        318
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------


  Table V-15--MY2027 & MY2031 Technology Costs per Vehicle for Urban Bus CNG, Average per Vehicle, 2017 Dollars
----------------------------------------------------------------------------------------------------------------
                                                                                                       Tech cost
          Model year               Scenario        DMC      Warranty     R&D       Other      Profit      sum
----------------------------------------------------------------------------------------------------------------
2027.........................  Baseline.......     $3,081        $92       $154       $893       $154     $4,375
                               Baseline+Propos      3,100        419        214        899        155      4,787
                                ed Option 1.
                               Baseline+Propos      3,100        326        232        899        155      4,711
                                ed Option 2.
                               Option 1                19        326         60          6          1        412
                                increase from
                                Baseline.
                               Option 2                19        233         78          6          1        336
                                increase from
                                Baseline.
2031.........................  Baseline.......      2,845         85        142        825        142      4,039
                               Baseline+Propos      2,861        515        191        830        143      4,539
                                ed Option 1.
                               Baseline+Propos      2,861        300        143        830        143      4,277
                                ed Option 2.
                               Option 1                16        430         48          5          1        500
                                increase from
                                Baseline.
                               Option 2                16        215          1          5          1        237
                                increase from
                                Baseline.
----------------------------------------------------------------------------------------------------------------

B. Operating Costs

    We have estimated three impacts on operating costs associated with 
the proposed criteria pollutant standards: Increased diesel exhaust 
fluid (DEF) consumption by diesel vehicles due to increased DEF dose 
rates to enable compliance with more stringent NOX 
standards; decreased fuel costs by gasoline vehicles due to new onboard 
refueling vapor recovery systems that allow burning (in engine) of 
otherwise evaporated hydrocarbon emissions; and emission repair 
impacts. For the repair impacts we expect that the longer duration 
warranty would result in lower owner/operator-incurred repair costs 
since those costs would be borne by the manufacturer, and that the 
longer duration useful life periods would result in increased emission 
control system durability and fewer failing parts needing repair. 
However, the possibility exists that higher-cost emission control 
systems may result in higher repair costs if and when repairs are 
needed. We have estimated the net effect on repair costs and describe 
our approach, along with increased DEF consumption and reduced gasoline 
consumption, below. Additional details on our methodology and estimates 
of operating costs per mile impacts are included in draft RIA Chapter 
7.2.
1. Costs Associated With Increased Diesel Exhaust Fluid (DEF) 
Consumption in Diesel Engines
    Consistent with the approach used to estimate technology costs, we 
have estimated both baseline case DEF consumption and DEF consumption 
under the proposed Options 1 and 2. For the baseline case, we estimated 
DEF consumption using the relationship between DEF dose rate and the 
reduction in NOX over the SCR catalyst. The relationship 
between DEF dose rate and NOX reduction across the SCR 
catalyst is based on methodology presented in the Technical Support 
Document to the 2012 Nonconformance Penalty rule (the NCP Technical 
Support Document, or NCP TSD).\735\ The DEF dose rate to NOX 
reduction relationship based on that methodology considered FTP 
emissions and, as such, the DEF dose rate increased as FTP tailpipe 
emissions decreased. The DEF dose rate used is 5.18 percent of fuel 
consumed.
---------------------------------------------------------------------------

    \735\ Nonconformance Penalties for On-highway Heavy-duty Diesel 
Engines: Technical Support Document; EPA-420-R-12-014, August 2012.
---------------------------------------------------------------------------

    To estimate DEF consumption impacts under the proposed Options 1 
and 2, which involve changes to not only the FTP emission standards but 
also the RMC and LLC standards along with new idle standards, we 
developed a new approach to estimating DEF consumption. For this 
analysis, we scaled DEF consumption with the NOX

[[Page 17573]]

reductions achieved under proposed Options 1 and 2. This was done by 
considering the molar mass of NOX, the molar mass of urea, 
the mass concentration of urea in DEF along with the density of DEF to 
estimate the theoretical gallons of DEF consumed per ton of 
NOX reduced. We estimated theoretical DEF consumption per 
ton of NOX reduced at 442 gallons/ton which we then adjusted 
based on testing to 527 gallons/ton, the value used in this analysis. 
We describe this in more detail in Section 7.2.1 of the draft RIA.
    These two DEF consumption metrics--dose rate per gallon and DEF 
consumption per ton of NOX reduced--were used to estimate 
total DEF consumption in the baseline, as well as the proposed Options 
1 and 2. These DEF consumption rates were then multiplied by DEF price 
per gallon, adjusted from the DEF prices presented in the NCP TSD, to 
arrive at the impacts on DEF costs for diesel engines. These are shown 
in Table V-16.
2. Costs Associated With ORVR and the Estimated Reduction in Fuel Costs 
for Gasoline Engines
    We have estimated a decrease in fuel costs, i.e., fuel savings, 
associated with the proposed ORVR requirements on gasoline engines. Due 
to the ORVR systems, evaporative emissions that would otherwise be 
emitted into the atmosphere would be trapped and subsequently burned in 
the engine. We describe the approach taken to estimate these impacts in 
Chapter 7.2.2 of the draft RIA. These newly captured evaporative 
emissions are converted to gallons and then multiplied by AEO 2018 
reference case gasoline prices to arrive at the monetized impacts. 
These impacts are shown in Table V-16.\736\
---------------------------------------------------------------------------

    \736\ We estimate that the ORVR requirements in both the 
proposal and Alternative 1 would result in a reduction of 
approximately 0.3 million (calendar year 2027) to 4.8 million 
(calendar year 2045) gallons of gasoline, representing roughly 0.1 
percent of gasoline consumption from impacted vehicles.
---------------------------------------------------------------------------

3. Repair Cost Impacts Associated With Longer Warranty and Useful Life 
Periods
    The extended warranty and useful life requirements being proposed 
would have an impact on emission-related repair costs incurred by truck 
owners. Researchers have noted the relationships among quality, 
reliability, and warranty for a variety of goods.\737\ Wu,\738\ for 
instance, examines how analyzing warranty data can provide ``early 
warnings'' on product problems that can then be used for design 
modifications. Guajardo et al. describe one of the motives for 
warranties to be ``incentives for the seller to improve product 
quality;'' specifically for light-duty vehicles, they find that buyers 
consider warranties to substitute for product quality, and to 
complement service quality.\739\ Murthy and Jack, for new products, and 
Saidi-Mehrabad et al. for second-hand products, consider the role of 
warranties in improving a buyer's confidence in quality of the 
good.740 741
---------------------------------------------------------------------------

    \737\ Thomas, M., and S. Rao (1999). ``Warranty Economic 
Decision Models: A Summary and Some Suggested Directions for Future 
Research.'' Operations Research 47(6):807-820.
    \738\ Wu, S (2012). Warranty Data Analysis: A Review. Quality 
and Reliability Engineering International 28: 795-805.
    \739\ Guajardo, J., M Cohen, and S. Netessine (2016). ``Service 
Competition and Product Quality in the U.S. Automobile Industry.'' 
Management Science 62(7):1860-1877. The other rationales are 
protection for consumers against failures, provision of product 
quality information to consumers, and a means to distinguish 
consumers according to their risk preferences.
    \740\ Murthy, D., and N. Jack (2009). ``Warranty and 
Maintenance,'' Chapter 18 in Handbook of Maintenance Management and 
Engineering, Mohamed Ben-Daya et al., editors. London: Springer.
    \741\ Saidi-Mehrabad, M., R. Noorossana, and M. Shafiee (2010). 
``Modeling and analysis of effective ways for improving the 
reliability of second-hand products sold with warranty.'' 
International Journal of Advanced Manufacturing Technology 46: 253-
265.
---------------------------------------------------------------------------

    On the one hand, we would expect owner-incurred emission repair 
costs to decrease due to the proposed program because the longer 
emission warranty requirements would result in more repair costs 
covered by the OEMs. Further, we would expect improved serviceability 
in an effort by OEMs to decrease repair costs they would incur. We 
would also expect that the longer useful life periods in proposed 
Options 1 or 2 would result in more durable parts to ensure regulatory 
compliance over the longer timeframe. On the other hand, we would also 
expect that the more costly emission control systems required by the 
proposed Options 1 or 2 would result in higher repair costs which could 
increase OEM costs during the warranty period and owner costs outside 
the warranty period. As further explained below, while the longer 
warranty period could potentially increase repair costs incurred by 
OEMs, such costs would fall under our estimated warranty cost increases 
as part of our indirect cost estimates described in Section V.A.2.
    As discussed in Section V.A.2, we have estimated increased OEM 
indirect costs associated with increased warranty liability (i.e., 
longer warranty periods), and for more durable parts resulting from the 
longer useful life periods. These costs are accounted for via increased 
warranty costs scaled by the longer warranty period, and increased 
research and development (R&D) costs scaled by the longer useful life 
period. We also included additional aftertreatment costs in the direct 
manufacturing costs to address the increased useful life requirements 
(e.g., larger catalyst volume; see Chapters 2 and 4 of the draft RIA 
for detailed discussions). We estimate that these efforts would help to 
reduce emission repair costs during the emission warranty and 
regulatory useful life periods, and possibly beyond.
    To estimate impacts on emission repair costs, we began with an 
emission repair cost curve.\742\ We describe in detail how we generated 
the emission repair cost curve and the data from which it was derived 
in Chapter 7 of the draft RIA. Figure V-1 shows, conceptually, the 
nature of the emission repair cost curve (the solid line) and the 
maintenance and repair cost curve--all maintenance and repair, not just 
emission repair--from which it was derived (the dotted line). The 
emission repair cost curve is lower than the curve for all maintenance 
and repairs since not all repair is emission-related.\743\ We have not 
estimated any impact on maintenance costs associated with the longer 
warranty and useful life periods in proposed Options 1 and 2, and we 
have estimated that just over 10 percent of repair costs are emission-
related repairs impacted by the proposed action (see Chapter 7 of the 
draft RIA for this derivation, which is based on the industry 
whitepaper).\744\ From the generic emission repair cost curve in Figure 
V-1, we generated a unique emission repair cost curve for each type of 
vehicle (combination long-haul, single unit short-haul, etc.), 
regulatory class (medium heavy-duty, heavy heavy-duty, etc.) and fuel 
type (diesel, gasoline, etc.).
---------------------------------------------------------------------------

    \742\ See ``Mitigating Rising Maintenance & Repair Costs for 
Class-8 Truck Fleets, Effective Data & Strategies to Leverage Newer 
Trucks to Reduce M&R Costs,'' Fleet Advantage Whitepaper Series, 
2018.
    \743\ Maintenance includes oil changes, tire replacements, brake 
replacements, etc., i.e., items that are expected to wear out and 
require replacement. Repair is the fixing of broken parts that are 
not necessarily expected to break. Repairs might include replacing a 
cracked particulate filter or a broken mirror or door handle.
    \744\ See ``Mitigating Rising Maintenance & Repair Costs for 
Class-8 Truck Fleets, Effective Data & Strategies to Leverage Newer 
Trucks to Reduce M&R Costs,'' Fleet Advantage Whitepaper Series, 
2018.
---------------------------------------------------------------------------

    As noted, Figure V-1 shows conceptually the relationship between 
repair costs and the estimated age at

[[Page 17574]]

which the warranty period is reached for any given vehicle, where 
repair costs are relatively low during the warranty period and repair 
cost rates begin to increase every year beyond the warranty period. 
Similarly, at the estimated age at which the useful life period ends, 
maintenance and repair cost rates increase yet again until, in the 
figure, costs flatten out. The ``estimated ages'' mentioned are meant 
to reflect not the required warranty and/or useful life ages, but 
rather the age at which the warranty (or useful life) is reached based 
on the average miles traveled per year by a given vehicle type relative 
to the required warranty/useful life ages and mileages. For example, a 
current long-haul Class-8 truck has a required warranty of 5 years or 
100,000 miles, whichever occurs first. Since the mileage accumulation 
of such a vehicle is over 100,000 miles in the first year, the 
``estimated age'' at which the warranty is reached would be 1 
year.\745\
---------------------------------------------------------------------------

    \745\ See ``Estimated Warranty and Useful Life Ages Used in 
Estimating Emission Repair Costs'' memorandum from Todd Sherwood to 
docket EPA-HQ-OAR-2019-0055.
---------------------------------------------------------------------------

    The flattening of costs per mile shown in Figure V-1 is due to a 
lack of data beyond seven years of operation and, as such, we have 
chosen to maintain a flat repair cost rate for subsequent years.\746\ 
We considered estimating increases in maintenance and repair cost per 
mile beyond the useful life, but decided that increases in the cost per 
mile rate applied to both the baseline case and the proposal would have 
no net impact.
---------------------------------------------------------------------------

    \746\ The only data source we are aware of is this industry 
whitepaper, which includes costs through seven years of operation; 
``Mitigating Rising Maintenance & Repair Costs for Class-8 Truck 
Fleets, Effective Data & Strategies to Leverage Newer Trucks to 
Reduce M&R Costs,'' Fleet Advantage Whitepaper Series, 2018.
[GRAPHIC] [TIFF OMITTED] TP28MR22.003

    Figure V-2 illustrates how the generic cost curve was adjusted to 
estimate the emission repair cost per mile for specific vehicles. To do 
this, we first estimated the vehicle age (in years) at which the 
warranty and useful life periods would end based on the typical miles 
driven per year over the first seven years of operation.\747\ The 
vehicle ages at which the warranty and useful life periods are 
estimated to end are then applied to the generic emission repair cost 
curve to generate a unique emission repair cost curve for each vehicle 
depending on the unique warranty/useful life provisions and mileage 
accumulation rates for that vehicle. Figure V-2 shows, conceptually, 
the baseline emission repair cost curve (the solid line in Figure V-1 
but now the dotted line, note the new y-axis scale) and the emission 
repair cost curve under the proposal (the solid line, not shown in 
Figure V-1). In this conceptual example, the warranty would expire in 
year 5 instead of year 1. Further, the age at which the useful life has 
been reached would be year 9 instead of year 6. Lastly, the emission 
repair cost curve would reach a higher cost/mile level during the 
warranty period, at the end of useful life, and then beyond the useful 
life. This is due to the more costly emission controls that we estimate 
would be fitted to engines as a result of the proposed requirements (as 
discussed in Section V.A).
---------------------------------------------------------------------------

    \747\ We have chosen 7 years for this estimate as a fair 
snapshot on costs; including fewer years would result in a higher 
average number of miles/year given that mileage accumulation rates 
tend to decrease year-over-year and, therefore, including more years 
would tend to result in a lower average mileage accumulation rate. 
We chose seven years as the fair, middle ground.

---------------------------------------------------------------------------

[[Page 17575]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.004

    The emission repair cost/mile curves shown in Figure V-2 would 
result in an incremental cost/mile that is negative for the operating 
years 2 through 7. During the first year, the incremental cost/mile 
would be slightly higher due to the marginal technology costs 
associated with the hypothetical proposed standard. From years 1 
through 7, the cost/mile would be lower on increment due to the longer 
warranty and useful life periods and the efforts we are estimating 
manufacturers would undertake to improve durability to avoid warranty 
costs after sale (efforts paid for in upfront indirect costs as 
described in Section V.A.2). In the years of operation beyond the 
useful life, emission repair costs/mile would then be expected to be 
marginally higher, again due to the marginal technology costs 
associated with the hypothetical proposed standard. Importantly, in 
those later years of operation, miles driven per year tend to decrease 
year-over-year, which serves to offset somewhat the effect of the 
higher estimated cost/mile value on a cost/year basis. In the end, for 
most vehicle types (i.e., MOVES sourcetypes) our analysis shows that, 
in general, the net emission repair costs over the first 10 years of 
operation would decrease (see Section 7.2.3 of the draft RIA).
    We believe that it is reasonable to estimate that the emission 
repair costs would remain flat, as shown in Figure V-2, during the 
longer warranty periods being proposed under either option because of 
the increased warranty and research and development costs we are 
estimating in our technology costs. Note that we are also estimating 
that the emission repair costs beyond the useful life would increase at 
a slightly higher rate based on the source data which suggested such a 
trend. Again, cost/mile rates are estimated to flatten beyond the 
useful life since the source data included operating costs through only 
seven years. It is possible that cost/mile rates continue to increase 
with age and that those would increase at similar rates in both the 
baseline case and under the proposed options. If true, the net effect 
would be the same as estimated here and the net effect is of primary 
concern in our analysis.
    As noted, our methodology and estimated impacts are presented in 
more detail in Chapter 7 of the draft RIA. We request comment on all 
aspects of our approach. In particular, we request comment on how we 
have used the data from which our repair cost curve was derived and how 
we have adjusted that curve to represent costs for all of the vehicle 
types under consideration. Further, we request data that would allow us 
to build upon our approach or change our approach if a better one 
exists.

C. Program Costs

    Using the cost elements outlined in Sections V.A and V.B, we have 
estimated the costs associated with the proposed criteria pollutant 
standards; costs associated with proposed Options 1 and 2 are shown in 
Table V-16 and Table V-17, respectively. Costs are presented in more 
detail in Chapter 7 of the draft RIA. As noted earlier, costs are 
presented in 2017 dollars in undiscounted annual values along with net 
present values at both 3 and 7 percent discount rates with values 
discounted to the 2027 calendar year.
    We are not including an analysis of the costs of the Alternative 
(described in Sections III and IV) because we currently do not have 
sufficient information to conclude that the Alternative standards would 
be feasible in the MY 2027 timeframe.
    As shown in these tables, and more clearly in Figure V-3, our 
analysis shows that the proposed Options 1 and 2 would result in 
similar costs in the early years, but proposed Option 1 would result in 
lower costs the longer term, despite higher costs in the mid-term 
years, compared to proposed Option 2.

[[Page 17576]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.005


[[Page 17577]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.006


[[Page 17578]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.007

VI. Estimated Emission Reductions From the Proposed Program

    The proposed criteria pollutant emission control program described 
in Sections III and IV is expected to reduce emissions from highway 
heavy-duty engines in several ways.\748\ We project reduced tailpipe 
emissions of NOX as a result of the proposed emission 
standards for heavy-duty diesel engines. The combination of the 
proposed low-load duty-cycle standard and off-cycle standards for 
diesel engines would help to ensure that the reduction in tailpipe 
emissions is achieved in-use, not only under high-speed, on-highway 
conditions, but under low-load and idle conditions as well. We also 
project reduced tailpipe emissions of NOX, CO, PM, and VOCs 
from heavy-duty gasoline engines, particularly under cold-start and 
high-load operating conditions. The proposed longer emission warranty 
and regulatory useful life requirements for heavy-duty diesel and 
gasoline engines would help to maintain the expected emission 
reductions for all pollutants for a longer portion of the operational 
life of the engine.\749\ The proposed onboard refueling vapor recovery 
requirements for heavy-duty gasoline engines would reduce VOCs and 
associated air toxics. See draft RIA Chapter 5, Appendix 5.3 for 
details on projected emission reductions of each pollutant.
---------------------------------------------------------------------------

    \748\ This section describes estimated emission reductions from 
the proposed criteria pollutant program described in Sections III 
and IV. Discussion on estimated emission impacts from the proposed 
revisions to the HD GHG Phase 2 rule are addressed in Section XI.
    \749\ See Section IV.A for more discussion on the operational 
life of the engine relative to useful life.
---------------------------------------------------------------------------

    Section VI.A provides an overview of the methods used to estimate 
emission reductions from our proposed program. All of the projected 
emission reductions from the proposed Option 1 or 2 are outlined in 
Section VI.B, with more details provided in the draft RIA Chapter 5. 
Section VI.C presents projected emission reductions from Option 1 or 2 
by engine operations and processes (e.g., medium-to-high load or low-
load engine operations). Section VI.D presents results of the 
Alternative that we analyzed. Section VI.E discusses how heavy-duty 
electric vehicles could affect the baseline emission inventory in the 
final rule and requests comment on this topic.
    As discussed in Section I and detailed in Sections III and IV, 
proposed Option 2 is generally less stringent than MY 2031 standards in 
proposed Option 1 due to the combination of higher numeric levels of 
the NOX emission standards and shorter useful life periods 
in proposed Option 2. The Alternative is more stringent than the Option 
1 MY 2031 standards due to the combination of shorter lead time, lower 
numeric levels of the NOX and HC emission standards, and 
longer useful life periods in the Alternative. The proposed Options 1 
and 2 standards generally contain values that represent a lower and 
upper bound of the combined range of options that we are considering 
for lead time, duty-cycle test standards, off-cycle standards, emission 
warranty, and useful life requirements. We would need additional 
information to be able to project that the Alternative is feasible in 
the MY 2027 timeframe and thereby consider adopting it in the final 
rule (see Section III for details).
    The proposed Options 1 and 2 thus generally bracket the overall 
range of options that EPA is currently considering and the range of 
estimated emission inventory impacts that we currently project (see 
Section I.G for discussion on potentially finalizing a program 
different from our proposal based on additional data that we collect 
and stakeholder input on this proposal).

A. Emission Inventory Methodology

    To estimate the emission reductions from the proposed program as a 
whole, we updated EPA's Motor Vehicle Emission Simulator (MOVES) model 
to include several changes related

[[Page 17579]]

specifically to heavy-duty vehicle emissions and activity (e.g., heavy-
duty engine start and running exhaust emission rates, heavy-duty 
vehicle start and idle activity). These model updates are summarized in 
Chapter 5.2 of the draft RIA and described in detail in several peer-
reviewed technical reports that are available in the docket for this 
proposed rulemaking.\750\
---------------------------------------------------------------------------

    \750\ Sonntag, Darrell. Memorandum to docket EPA-HQ-OAR-2019-
0055: ``Updates to MOVES for Emissions Analysis of the HD 2027 
NPRM``. May 2021
---------------------------------------------------------------------------

    The draft RIA also provides a detailed description of our 
methodology to develop model inputs for the proposed and alternative 
control scenarios (see draft RIA Chapter 5.3.2 and 5.3.3). The model 
inputs for the proposed and alternative control scenarios capture 
emission reductions outlined in the introduction to this section.\751\
---------------------------------------------------------------------------

    \751\ Note that our modeling does not include emission 
reductions from the proposed useful life and warranty requirements 
for gasoline and natural gas vehicles. These proposed control 
requirements are expected to further decrease heavy-duty engine 
emissions. See draft RIA Chapter 5 for details on anticipated 
emission impacts and our expectations for modeling emission impacts 
in the final rule where feasible based on data and modeling 
capabilities.
---------------------------------------------------------------------------

    We invite stakeholders to comment and provide additional 
information on our approaches to use MOVES for modeling the proposed 
duty-cycle and off-cycle standards, as well as longer warranty and 
useful life periods; commenters may also provide input on other data or 
modeling approaches that EPA should consider when estimating emission 
inventory impacts in the final rulemaking.

B. Estimated Emission Reductions From the Proposed Criteria Pollutant 
Program

    As discussed in Sections I.G and III, EPA is co-proposing two 
regulatory options with different numeric levels of emission standards, 
as well as different regulatory useful life and emissions warranty 
periods.\752\ Our estimates of the emission impacts that would result 
from the proposed Options 1 and 2 in calendar years 2030, 2040, and 
2045 are presented below in Table VI-1 Table VI-2, respectively. As 
shown in Table VI-1, we estimate that the criteria pollutant program in 
proposed Option 1 would reduce NOX emissions from highway 
heavy-duty vehicles by 61 percent nationwide in 2045. We also estimate 
a 26 percent reduction in primary exhaust PM2.5 from highway 
heavy-duty vehicles. VOC emissions from heavy-duty vehicles would be 21 
percent lower. Emissions of CO from heavy-duty vehicles are estimated 
to decrease by 17 percent. Emission impacts of the proposed Option 1 on 
other pollutants, including air toxics, range from an estimated 
reduction of about 27 percent for benzene to no change in 1,3-
butadiene.\753\ As shown in Table VI-2, proposed Option 2 is estimated 
to reduce heavy-duty vehicle NOX emissions by 47 percent in 
2045; the estimated reductions in other pollutants are similar to 
reductions from proposed Option 1. Draft RIA Chapter 5.5.3 includes 
additional details on the emission reductions by vehicle fuel type; 
Chapter 5.5.5 provides our estimates of criteria pollutant emissions 
reductions for calendar years 2027 through 2045.
---------------------------------------------------------------------------

    \752\ As summarized in Section I and detailed in Sections III 
and IV, the proposed Option 1 would be implemented in two steps, 
while the proposed Option 2 would be implemented in a single step 
starting in MY 2027. The numeric values of the proposed Option 2 
standards are less stringent than the proposed Option 1 MY 2031 
standards, with useful life and warranty mileages similar to those 
in proposed Option 1 MY 2027 standards.
    \753\ No change is observed in 1,3-butadiene emissions in the 
control scenarios because 1,3-butadiene emissions do not contribute 
to VOC emissions from MY 2027 and later diesel running and start 
emissions, heavy-duty gasoline running emissions, and gasoline 
refueling emissions in the version of MOVES updated for use in this 
rulemaking, referred to as MOVES CTI NPRM.
---------------------------------------------------------------------------

    As the proposed standards are implemented, emission reductions are 
expected to increase over time as the fleet turns over to new, 
compliant engines.\754\ Under either proposed Option 1 or 2, we 
estimate no change in CO2 emissions, based on data in our feasibility 
and cost analyses of the proposed criteria pollutant program (see 
Section III for more discussion).\755\ As shown in Tables VI-1 and 
Table VI-2, we estimate a less than 1% reduction in CH4 emissions from 
heavy-duty vehicles.\756\ On the whole, we expect either proposed 
Option 1 or 2 to have only minor impacts on GHG emissions; however, we 
request comment on the potential for GHG emission impacts from proposed 
Option 1 or 2.
---------------------------------------------------------------------------

    \754\ We do not currently expect the proposed rule to 
incentivize additional market shifts to electrification; however, if 
such shifts were to occur then additional emission reductions beyond 
those projected in Section VI.B could occur.
    \755\ This estimate includes the assumption that vehicle sales 
will not change in response to the proposed rule. See Section X for 
further discussion on vehicle sales impacts of this proposed rule. 
See Section XI for discussion on estimated CO2 emission 
impacts of the proposed revisions to the Heavy Duty GHG Phase 2 
rulemaking.
    \756\ The CH4 emissions reductions would be due to lower total 
hydrocarbon emission rates from the tailpipe of heavy-duty gasoline 
vehicles (see draft RIA Chapter 5.2.2 for more detail).

Table VI-1--Annual Emission Reductions From Heavy-Duty Vehicles in Calendar Years (CY) 2030, 2040, and 2045--Proposed Option 1 Emissions Relative to the
                                                          Heavy-Duty Vehicle Emissions Baseline
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      CY2030                          CY2040                          CY2045
                        Pollutant                        -----------------------------------------------------------------------------------------------
                                                          US short  tons   %  Reduction   US short  tons   %  Reduction   US short  tons   %  Reduction
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX.....................................................         153,608            16.4         491,318            55.9         558,780            60.5
VOC.....................................................           4,681             5.0          15,199            18.7          17,975            21.0
Primary Exhaust PM2.5...................................             408             3.4           1,741            23.7           2,005            26.4
CO......................................................          51,154             3.2         241,974            15.2         289,835            17.2
1,3-Butadiene...........................................               0             0.0               0             0.0               0             0.0
Acetaldehyde............................................               8             0.4              46             2.5              52             2.7
Benzene.................................................              42             4.1             181            23.1             221            26.8
Formaldehyde............................................              12             0.5              63             4.1              75             4.6
Methane (CH4)...........................................             166             0.2             881             0.7           1,025             0.7
Naphthalene.............................................             1.3             0.9             6.5            14.3               8            16.7
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 17580]]


Table VI-2--Annual Emission Reductions From Heavy-Duty Vehicles in Calendar Years (CY) 2030, 2040, and 2045--Proposed Option 2 Emissions Relative to the
                                                          Heavy-Duty Vehicle Emissions Baseline
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      CY 2030                         CY 2040                         CY 2045
                        Pollutant                        -----------------------------------------------------------------------------------------------
                                                          US short  tons   %  Reduction   US short  tons   %  Reduction   US short  tons   %  Reduction
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX.....................................................         140,691            15.0         383,350            43.6         437,869            47.4
VOC.....................................................           4,645             5.0          14,623            18.0          17,283            20.2
Primary Exhaust PM2.5...................................             408             3.4           1,600            21.8           1,856            24.4
CO......................................................          51,154             3.2         216,413            13.6         262,574            15.6
1,3-Butadiene...........................................               0             0.0               0             0.0               0             0.0
Acetaldehyde............................................               8             0.4              32             1.8              37             1.9
Benzene.................................................              41             4.0             167            21.3             202            24.5
Formaldehyde............................................              12             0.5              51             3.3              61             3.7
Methane (CH4)...........................................             160             0.1             654             0.5             770             0.6
Naphthalene.............................................             1.2             0.8             5.7            12.6               7            14.6
--------------------------------------------------------------------------------------------------------------------------------------------------------

C. Estimated Emission Reductions by Engine Operations and Processes

    Looking more closely at the NOX emission inventory from 
highway heavy-duty vehicles, our analysis shows that the proposed 
standards would reduce emissions across several engine operations and 
processes, with the greatest reductions attributable to medium-to-high 
load engine operations, low-load engine operations, and age effects 
(i.e., deterioration and mal-maintenance of emission controls, as well 
as tampering). As noted in Section I, without the proposed program, 
these processes are projected to contribute the most to the heavy-duty 
NOX emission inventory in 2045. Table VI-3 compares 
NOX emissions in 2045 from different engine operations and 
processes with and without the proposed Options 1 and 2 standards. 
Additional details on our analysis of NOX emissions by 
process are included in the draft RIA Chapter 5.5.4.

                                           Table VI-3--Heavy-Duty NO Emission Reductions by Process in CY2045
                                                                        [US tons]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                             Emission              Tons reduced               Percent reduction from            Emission inventory
                                             inventory   --------------------------------          baseline  (%)            contribution with  proposed
                                           contribution                                  --------------------------------          options  (%)
       Engine operation or process            without        Proposed        Proposed                                    -------------------------------
                                             proposed        Option 1        Option 2        Proposed        Proposed        Proposed        Proposed
                                           options  (%)                                      Option 1        Option 2        Option 1        Option 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Medium- to High-Load....................              36         286,661         243,887              81              73              17              18
Low-Load................................              28         183,971         149,913              70              57              21              23
Aging...................................              24          82,340          23,389              38              11              38              40
Extended Idle & APU.....................               2          11,717          10,340              66              58               2               2
Starts..................................               4          12,091          10,341              31              26               8               6
Historical Fleet (MY 2010 to 2026)......               6               0               0               0               0              14              11
--------------------------------------------------------------------------------------------------------------------------------------------------------

D. Estimated Emission Reductions From the Alternative

    As discussed in Section III, in addition to the proposed program, 
EPA analyzed an alternative set of emission standards, with different 
regulatory useful life and emissions warranty periods.\757\ Our 
estimates of the emission impacts that would result from the 
Alternative are presented below in Table VI-4. The Alternative is 
estimated to reduce heavy-duty vehicle NOX emissions by 61 
percent in 2045; estimated reductions in other pollutants are generally 
higher in the Alternative compared to the proposed Options 1 or 2.
---------------------------------------------------------------------------

    \757\ Under the Alternative, the numeric values of the 
NOX and HC standards are lower than the proposed Option 1 
MY 2031 standards; the useful life and warranty mileages are also 
longer than those in proposed Option 1 for MY 2031.

  Table VI-4--Annual Emission Reductions From Heavy-Duty Vehicles in Calendar Years 2030, 2040, and 2045--``the Alternative'' Emissions Relative to the
                                                          Heavy-Duty Vehicle Emissions Baseline
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      CY 2030                         CY 2040                         CY 2045
                        Pollutant                        -----------------------------------------------------------------------------------------------
                                                          US short  tons   %  Reduction   US short  tons   %  Reduction   US short  tons   %  Reduction
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX.....................................................         155,954            16.7         500,367            56.9         566,100            61.3
VOC.....................................................           4,716             5.0          15,312            18.9          18,069            21.1
Primary Exhaust PM2.5...................................             408             3.4           1,822            24.8           2,090            27.5
CO......................................................          51,154             3.2         247,475            15.5         295,561            17.5
1,3-Butadiene...........................................               0             0.0               0             0.0               0             0.0

[[Page 17581]]

 
Acetaldehyde............................................               9             0.4              49             2.7              56             2.9
Benzene.................................................              44             4.3             183            23.3             222            26.9
Formaldehyde............................................              13             0.6              66             4.3              78             4.7
Methane (CH4)...........................................             172             0.2             934             0.7           1,076             0.8
Naphthalene.............................................             1.4             0.9             6.6            14.6             8.0            16.9
--------------------------------------------------------------------------------------------------------------------------------------------------------

E. Evaluating Emission Impacts of Electric Vehicles in the Proposed 
Emission Inventory Baseline

    As described in Section III, we relied on next-generation emission 
control technologies for CI and SI engines in our technology 
feasibility assessment for the proposed standards. Since BEV and FCEV 
technologies were not included in our feasibility assessment, and 
because these technologies currently make up less than 1 percent of the 
current heavy-duty market based on current EPA certification data, we 
did not include BEV and FCEV technologies in our emission inventory 
analysis described in Sections VI.B through VI.D, and detailed in draft 
RIA Chapter 5.\758\ However, we have conducted a sensitivity analysis 
of BEV and FCEV tailpipe emission impacts based on potential market 
adoption (see draft RIA Chapter 1.4 and Chapter 5.5.5). Results of our 
analysis show that we would not expect a significant change in the 
percent emission reductions from the proposed criteria pollutant 
program if BEVs were to make up a larger percentage of heavy-duty 
vehicles in the 2045 baseline emission inventory (i.e., 28 percent of 
medium heavy-duty and 10 percent of heavy heavy-duty vehicle sales in 
MY 2045).759 760
---------------------------------------------------------------------------

    \758\ In MY 2019 manufacturers certified approximately 350 
heavy-duty BEVs, based on production volume reports submitted to the 
agency. This is out of nearly 615,000 heavy-duty diesel vehicles 
certified in MY 2019, which represents approximately 0.06 percent of 
the market. See Sections IV and XI, and RIA Chapter 1.4 for more 
details on current and potential future production volumes of BEVs 
and FCEVs.
    \759\ See Preamble Section XI for discussion on our current 
expectations for how additional electrification of the heavy-duty 
market could impact the emission reductions expected from the HD GHG 
Phase 2 program.
    \760\ We used proposed Option 1 to conduct this sensitivity 
analysis but expect similar results with proposed Option 2.
---------------------------------------------------------------------------

    We recognize that it is important to properly define the baseline 
emission inventory for the final rule (i.e., heavy-duty emissions 
without emission controls from this proposed EPA rule as finalized), 
which could include projected market penetration rates of BEVs and 
FCEVs. Specifically, in the final rule we may account for the recent 
Advanced Clean Truck (ACT) rulemaking in California,\761\ and the 
Memorandum of Understanding (MOU) signed by 15 states.\762\
---------------------------------------------------------------------------

    \761\ As noted in Section I.D, EPA is reviewing a waiver request 
under CAA section 209(b) from California for the ACT rule; we may 
consider including some analyses that account for BEVs and FCEVs 
produced to meet the CARB ACT requirements in the final EPA rule.
    \762\ ``Multi-state Medium- and Heavy-Duty Zero Emission Vehicle 
Memorandum of Understanding'' July 13, 2020. Available online at: 
https://www.nescaum.org/topics/zero-emission-vehicles.
---------------------------------------------------------------------------

    As discussed in the draft RIA Chapter 1.4.2.3, the CA ACT requires 
manufacturers to sell a certain percentage of zero emission heavy-duty 
vehicles (BEVs or FCEVs) for each model year, starting in MY 
2024.763 764 765 The sales requirements vary by vehicle 
class, but start at 5 to 9 percent of total MY 2024 heavy-duty vehicle 
sales in California and increase up to 40 to 75 percent of sales for MY 
2035 and beyond.\766\ The 15-state MOU affirms a commitment to strive 
towards at least 30 percent of new heavy-duty vehicle sales being zero 
emission vehicles by 2030 and to reach 100 percent of new sales by 
2050. While the MOU does not impose any binding requirements, it may 
result in higher sales of BEVs and FCEVs in participating states.
---------------------------------------------------------------------------

    \763\ California Air Resources Board. ``Notice of Decision: 
Advanced Clean Truck Regulation.'' June 2020. Available online at: 
https://ww3.arb.ca.gov/regact/2019/act2019/nod.pdf.
    Additional discussion on the CARB ACT is also included in 
Preamble XI.
    \764\ Buysse and Sharpe. (July 20, 2020) ``California's Advanced 
Clean Trucks regulation: Sales requirements for zero-emission heavy-
duty trucks``, available online at: https://theicct.org/publications/california-hdv-ev-update-jul2020 (last accessed August 
11, 2021).
    \765\ California is also developing an Advanced Clean Fleets 
regulation that would require fleets that are well suited for 
electrification to transition to BEVs or FCEVs where feasible. For 
more information, see: California Air Resources Board. ``Advanced 
Clean Fleets Fact Sheet.'' August 2021. Available at: https://ww2.arb.ca.gov/resources/fact-sheets/advanced-clean-fleets-fact-sheet.
    \766\ CARB. ``Appendix A Proposed Regulation Order'' Advanced 
Clean Truck Regulation.'' May 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/30dayatta.pdf (accessed July 24, 
2020).
---------------------------------------------------------------------------

    EPA solicits comment on whether and how to reflect the expectations 
for higher sales volumes of BEVs and FCEVs in California and other 
states in the baseline emission inventory for the final rule (i.e., 
without this EPA rule as finalized). EPA will consider public comments 
and other relevant information in deciding to how to reflect future 
sales volumes of BEVs and FCEVs in the emission inventory analysis of 
the final rule.

VII. Air Quality Impacts of the Proposed Program

    As discussed in Section VI, we expect the standards in the proposed 
Options 1 and 2 to result in meaningful reductions in emissions of 
NOX, VOC, CO and PM2.5. In this section, we 
summarize the results of our air quality modeling based on the 
projected emission reductions from the proposed Option 1 
standards.\767\ The ``base'' case represents 2016 air quality. The 
``reference'' scenario represents projected 2045 air quality without 
the proposed rule and the ``control'' scenario represents projected 
2045 emissions with proposed Option 1. Air quality modeling was done 
for the future year 2045 when the program would be fully implemented 
and when most of the regulated fleet would have turned over.
---------------------------------------------------------------------------

    \767\ Due to resource constraints, we only conducted air quality 
modeling for the proposed Option 1. As noted in Chapter 5.4 of the 
draft RIA, while we refer to this modeling as for the proposed 
Option 1, there are differences between the proposed Option 1 
standards, emission warranty, and useful life provisions presented 
in Sections III and IV of this preamble and those included in the 
control scenario modeled for the air quality analysis.
---------------------------------------------------------------------------

    The air quality modeling predicts decreases in ambient 
concentrations of air pollutants in 2045 due to the proposed Option 1, 
including significant improvements in ozone concentrations. Ambient 
PM2.5, NO2 and CO concentrations are also

[[Page 17582]]

predicted to improve in 2045 as a result of the proposed Option 1. The 
proposed Option 1 is expected to result in improvements in nitrogen 
deposition and visibility but is predicted to have relatively little 
impact on ambient concentrations of air toxics. Additional information 
and maps showing expected changes in ambient concentrations of air 
pollutants in 2045 due to proposed Option 1 are included in Chapter 6 
of the draft RIA and in the Air Quality Modeling Technical Support 
Document.\768\
---------------------------------------------------------------------------

    \768\ USEPA (2021) Technical Support Document: Air Quality 
Modeling for the HD 2027 Proposal. EPA-HQ-OAR-2019-0055. October 
2021.
---------------------------------------------------------------------------

A. Ozone

    The proposed rule would reduce 8-hour ozone design values 
significantly in 2045. The proposed Option 1 would decrease ozone 
design values by more than 2 ppb in over 150 counties, and over 200 
additional modeled counties are projected to have decreases in ozone 
design values of between 1 and 2 ppb in 2045. Our modeling projections 
indicate that some counties would have design values above the level of 
the 2015 NAAQS in 2045, and the proposed Option 1 would help those 
counties, as well as other counties, in reducing ozone concentrations. 
Table VII-1 shows the average projected change in 2045 8-hour ozone 
design values due to the proposed Option 1 standards. Counties within 
10 percent of the level of the NAAQS are intended to reflect counties 
that, although not violating the standard, would also be affected by 
changes in ambient levels of ozone as they work to ensure long-term 
attainment or maintenance of the ozone NAAQS. The projected changes in 
design values, summarized in Table VII-1, indicate in different ways 
the overall improvement in ozone air quality due to emission reductions 
from the proposed Option 1 standards, if implemented as modeled.

      Table VII-1--Average Change in Projected 8-Hour Ozone Design Values in 2045 Due to Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                                                                                    Population-
                                                                                                     weighted
                                                     Number of         2045       Average change      average
         Projected design value category             counties      Population\a\  in 2045 design     change in
                                                                                   value  (ppb)    design value
                                                                                                       (ppb)
----------------------------------------------------------------------------------------------------------------
All modeled counties............................             457     246,949,949           -1.87           -2.23
Counties with 2016 base year design values above             118     125,319,158           -2.12           -2.43
 the level of the 2015 8-hour ozone standard....
Counties with 2016 base year design values                   245      93,417,097           -1.83           -2.10
 within 10% of the 2015 8-hour ozone standard...
Counties with 2045 reference design values above              15      37,758,488           -2.26           -3.03
 the level of the 2015 8-hour ozone standard....
Counties with 2045 reference design values                    56      39,302,665           -1.78           -2.02
 within 10% of the 2015 8-hour ozone standard...
Counties with 2045 control design values above                10      27,930,138           -2.36           -3.34
 the level of the 2015 8-hour ozone standard....
Counties with 2045 control design values within               42      31,395,617           -1.69           -1.77
 10% of the 2015 8-hour ozone standard..........
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
  Database. Washington, DC. https://www.woodsandpoole.com/index.php.

B. Particulate Matter

    The proposed rule would reduce 24-hour and annual PM2.5 
design values in 2045. The proposed Option 1 standards would decrease 
projected annual PM2.5 design values in the majority of 
modeled counties by between 0.01 and 0.05 ug/m3 and by greater than 
0.05 ug/m3 in over 75 additional counties. The proposed Option 1 
standards would decrease projected 24-hour PM2.5 design 
values by between 0.15 and 0.5 ug/m3 in over 150 counties and by 
greater than 0.5 ug/m3 in 5 additional counties. Our air quality 
modeling projections indicate that some counties would have design 
values above the level of the 2012 PM2.5 NAAQS in 2045 and 
the proposed Option 1 would help those counties, as well as other 
counties, in reducing PM2.5 concentrations. Table VII-2 and 
Table VII-3 present the average projected changes in 2045 annual and 
24-hour PM2.5 design values. Counties within 10 percent of 
the level of the NAAQS are intended to reflect counties that, although 
not violating the standards, would also be affected by changes in 
ambient levels of PM2.5 as they work to ensure long-term 
attainment or maintenance of the annual and/or 24-hour PM2.5 
NAAQS. The projected changes in PM2.5 design values, 
summarized in Table VII-2 and Table VII-3, indicate in different ways 
the overall improvement in PM2.5 air quality due to the 
emission reductions resulting from the proposed Option 1 standards, if 
implemented as modeled.

      Table VII-2--Average Change in Projected Annual PM2.5 Design Values in 2045 Due to Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                                                                                    Population-
                                                                                  Average change     weighted
                                                     Number of         2045       in 2045 design  average change
         Projected design value category             counties     Population \a\    value  (ug/      in design
                                                                                       m\3\)        value (ug/
                                                                                                       m\3\)
----------------------------------------------------------------------------------------------------------------
All modeled counties............................             568     273,604,437           -0.04           -0.04

[[Page 17583]]

 
Counties with 2016 base year design values above              17      26,726,354           -0.09           -0.05
 the level of the 2012 annual PM2.5 standard....
Counties with 2016 base year design values                     5       4,009,527           -0.06           -0.06
 within 10% of the 2012 annual PM2.5 standard...
Counties with 2045 reference design values above              12      25,015,974           -0.10           -0.05
 the level of the 2012 annual PM2.5 standard....
Counties with 2045 reference design values                     6       1,721,445           -0.06           -0.06
 within 10% of the 2012 annual PM2.5 standard...
Counties with 2045 control design values above                10      23,320,070           -0.10           -0.05
 the level of the 2012 annual PM2.5 standard....
Counties with 2045 control design values within                8       3,417,349           -0.08           -0.09
 10% of the 2012 annual PM2.5 standard..........
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
  Database. Washington, DC. https://www.woodsandpoole.com/index.php.


      Table VII-3--Average Change in Projected 24-Hour PM2.5 Design Values in 2045 Due to Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                                                                                    Population-
                                                                                  Average change     weighted
                                                     Number of         2045       in 2045 design  average change
         Projected design value category             counties     Population \a\    value  (ug/      in design
                                                                                       m\3\)        value (ug/
                                                                                                       m\3\)
----------------------------------------------------------------------------------------------------------------
All modeled counties............................             568     272,852,777           -0.12           -0.17
Counties with 2016 base year design values above              33      28,394,253           -0.40           -0.67
 the level of the 2006 daily PM2.5 standard.....
Counties with 2016 base year design values                    15      13,937,416           -0.18           -0.27
 within 10% of the 2006 daily PM2.5 standard....
Counties with 2045 reference design values above              29      14,447,443           -0.38           -0.55
 the level of the 2006 daily PM2.5 standard.....
Counties with 2045 reference design values                    12      22,900,297           -0.30           -0.59
 within 10% of the 2006 daily PM2.5 standard....
Counties with 2045 control design values above                29      14,447,443           -0.38           -0.55
 the level of the 2006 daily PM2.5 standard.....
Counties with 2045 control design values within               10      19,766,216           -0.26           -0.60
 10% of the 2006 daily PM2.5 standard...........
----------------------------------------------------------------------------------------------------------------
\a\ Population numbers based on Woods & Poole data. Woods & Poole Economics, Inc. (2015). Complete Demographic
  Database. Washington, DC. https://www.woodsandpoole.com/index.php.

C. Nitrogen Dioxide

    Our modeling indicates that in 2045 the proposed Option 1 would 
decrease annual NO2 concentrations in most urban areas and 
along major roadways by more than 0.3 ppb and would decrease annual 
NO2 concentrations by between 0.01 and 0.1 ppb across much 
of the rest of the country. The proposed Option 1 emissions reductions 
would also likely decrease 1-hour NO2 concentrations and 
help any potential nonattainment areas attain and maintenance areas 
maintain the NO2 standard.\769\ Section 6.3.4 of the draft 
RIA contains more detail on the impacts of the proposed Option 1 on 
NO2 concentrations.
---------------------------------------------------------------------------

    \769\ As noted in Section II, there are currently no 
nonattainment areas for the NO2 NAAQS.
---------------------------------------------------------------------------

D. Carbon Monoxide

    Our modeling indicates that in 2045 the proposed Option 1 would 
decrease annual CO concentrations by more than 0.5 ppb in many urban 
areas and would decrease annual CO concentrations by between 0.02 and 
0.5 ppb across much of the rest of the country. The emissions 
reductions from proposed Option 1 would also likely decrease 1-hour and 
8-hour CO concentrations and help any potential nonattainment areas 
attain and maintenance areas maintain the CO standard.\770\ Section 
6.3.5 of the draft RIA contains more detail on the impacts of the 
proposed Option 1 on CO concentrations.
---------------------------------------------------------------------------

    \770\ As noted in Section II, there are currently no 
nonattainment areas for the CO NAAQS.
---------------------------------------------------------------------------

E. Air Toxics

    In general, our modeling indicates that the proposed Option 1 would 
have relatively little impact on national average ambient 
concentrations of the modeled air toxics in 2045. The proposed Option 1 
standards would have smaller impacts on air toxic pollutants dominated 
by primary emissions (or a decay product of a directly emitted 
pollutant), and relatively larger impacts on air toxics that primarily 
result from photochemical transformation, in this case due to the 
projected large reductions in NOX emissions. Specifically, 
in 2045, our modeling projects that the proposed Option 1 would 
decrease ambient benzene and naphthalene concentrations by less than 
0.001 ug/m3 across the country.

[[Page 17584]]

Acetaldehyde concentrations would increase slightly across most of the 
country, while formaldehyde would generally have small decreases in 
most areas and some small increases in urban areas. Section 6.3.6 of 
the draft RIA contains more detail on the impacts of the proposed 
Option 1 on air toxics concentrations.

F. Visibility

    Air quality modeling of Option 1 was used to project visibility 
conditions in 145 Mandatory Class I Federal areas across the U.S. The 
results show that the proposed Option 1 standards would improve 
visibility in these areas.\771\ The average visibility at all modeled 
Mandatory Class I Federal areas on the 20 percent most impaired days is 
projected to improve by 0.04 deciviews, or 0.37 percent, in 2045 due to 
the proposed Option 1. Section 6.3.7 of the draft RIA contains more 
detail on the visibility portion of the air quality modeling.
---------------------------------------------------------------------------

    \771\ The level of visibility impairment in an area is based on 
the light-extinction coefficient and a unitless visibility index, 
called a ``deciview'', which is used in the valuation of visibility. 
The deciview metric provides a scale for perceived visual changes 
over the entire range of conditions, from clear to hazy. Under many 
scenic conditions, the average person can generally perceive a 
change of one deciview. The higher the deciview value, the worse the 
visibility. Thus, an improvement in visibility is a decrease in 
deciview value.
---------------------------------------------------------------------------

G. Nitrogen Deposition

    Our air quality modeling conducted for the proposed rule projects 
substantial decreases in nitrogen deposition in 2045 as a result of the 
proposed Option1. The proposed Option 1 standards would result in 
annual decreases of greater than 4 percent in some areas and greater 
than 1 percent over much of the rest of the country. For maps of 
deposition impacts, and additional information on these impacts, see 
Section 6.3.8 of the draft RIA.

H. Demographic Analysis of Air Quality

    When feasible, EPA's Office of Transportation and Air Quality 
conducts full-scale photochemical air quality modeling to demonstrate 
how its national mobile source regulatory actions affect ambient 
concentrations of regional pollutants throughout the United States. As 
described in draft RIA Chapter 6.2, the air quality modeling we 
conducted supports our analysis of future projections of 
PM2.5 and ozone concentrations in a ``baseline'' scenario 
absent the proposed rule and in a ``control'' scenario that assumes the 
proposed Option 1 is in place. The incremental reductions in estimated 
air quality concentrations between the two scenarios are therefore 
attributed to the proposed rule. These baseline and control scenarios 
are also used as inputs to the health benefits analysis. As 
demonstrated in draft RIA Chapter 6.3 and Chapter 8.6, the ozone and 
PM2.5 improvements that are projected to result from the 
proposed rule, and the health benefits associated with those pollutant 
reductions would be substantial.
    This air quality modeling data can also be used to conduct a 
demographic analysis of human exposure to future air quality in 
scenarios with and without the proposed rule in place. To compare 
demographic trends, we sorted projected 2045 baseline air quality 
concentrations from highest to lowest concentration and created two 
groups: areas within the contiguous U.S. with the worst air quality 
(highest 5 percent of concentrations) and the rest of the country. This 
approach can then answer two principal questions to determine disparity 
among people of color:
    1. What is the demographic composition of areas with the worst 
baseline air quality in 2045?
    2. Are those with the worst air quality benefiting more from the 
proposed rule?
    We found that in the 2045 baseline, the number of people of color 
projected to live within the grid cells with the highest baseline 
concentrations of ozone (26 million) is nearly double that of NH-Whites 
(14 million). Thirteen percent of people of color are projected to live 
in areas with the worst baseline ozone, compared to seven percent of 
NH-Whites. The number of people of color projected to live within the 
grid cells with the highest baseline concentrations of PM2.5 
(93 million) is nearly double that of NH-Whites (51 million). Forty-six 
percent of people of color are projected to live in areas with the 
worst baseline PM2.5, compared to 25 percent of NH-Whites.
    We also found that the largest predicted improvements in both ozone 
and PM2.5 are estimated to occur in areas with the worst 
baseline air quality, where larger numbers of people of color are 
projected to reside. Chapter 6.3.9 of the draft RIA describes the data 
and methods used to conduct the demographic analysis and presents our 
results in detail. We seek comment on how to improve this analysis for 
the final rule.

VIII. Benefits of the Proposed Program

    The highway heavy-duty engines and vehicles subject to the proposed 
criteria pollutant program are significant sources of mobile source air 
pollution, including emissions of directly-emitted PM2.5 as 
well as NOX and VOCs (both precursors to ozone formation and 
secondarily-formed PM2.5). The proposed program would reduce 
exhaust emissions of these pollutants from the regulated engines and 
vehicles, which would reduce ambient concentrations of ozone and 
PM2.5 (see Section VII). Exposures to these pollutants are 
linked to adverse environmental and human health impacts, such as 
premature deaths and non-fatal illnesses (see Section II).
    In this section, we present the quantified and monetized human 
health benefits from reducing concentrations of ozone and 
PM2.5 using the air quality modeling results described in 
Section VII. For the proposed rulemaking, we have quantified and 
monetized health impacts in 2045, representing projected benefits in a 
year when the program would be fully implemented and when most of the 
regulated fleet would have turned over. Overall, we estimate that the 
proposed program would lead to a substantial decrease in adverse 
PM2.5- and ozone-related health impacts.
    We adopt an updated analysis approach that was recently used to 
quantify the benefits of changes in PM2.5 and ozone in the 
final Revised Cross-State Air Pollution Rule (CSAPR) Update 
RIA.772 773 While the steps to performing a criteria 
pollutant benefits analysis remain unchanged from past mobile source 
rulemakings (e.g., Tier 3 Motor Vehicle Emission and Fuel Standards 
Final Rule),\774\ the final CSAPR RIA updated the suite of quantified 
health endpoints included in the benefits analysis, as well as the data 
used to quantify each health endpoint, to reflect more recent 
scientific evidence. These updates were based on information drawn from 
the recent PM2.5 and ozone Integrated Science Assessments 
(ISAs), which were reviewed by the Clean Air Science Advisory Committee 
(CASAC) and the public,775 776 and are summarized in a

[[Page 17585]]

technical support document (TSD) originally published for the final 
Revised CSAPR Update titled Estimating PM2.5- and Ozone-
Attributable Health Benefits.\777\
---------------------------------------------------------------------------

    \772\ U.S. Environmental Protection Agency (U.S. EPA). 2021. 
Regulatory Impact Analysis for the Final Revised Cross-State Air 
Pollution Rule (CSAPR) Update for the 2008 Ozone NAAQS. EPA-452/R-
21-002. March.
    \773\ On March 15, 2021, EPA finalized the Revised Cross-State 
Air Pollution Rule Update for the 2008 ozone National Ambient Air 
Quality Standards (NAAQS). Starting in the 2021 ozone season, the 
rule will require additional emissions reductions of nitrogen oxides 
(NOX) from power plants in 12 states. https://www.epa.gov/csapr/revised-cross-state-air-pollution-rule-update.
    \774\ U.S. Environmental Protection Agency (U.S. EPA). 2014. 
Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle 
Emission and Fuel Standards Rule Regulatory Impact Analysis. EPA-
420-R-14-005. March.
    \775\ U.S. Environmental Protection Agency (U.S. EPA). 2019. 
Integrated Science Assessment (ISA) for Particulate Matter (Final 
Report, 2019). U.S. Environmental Protection Agency, Washington, DC, 
EPA/600/R-19/188, 2019.
    \776\ U.S. Environmental Protection Agency (U.S. EPA). 2020. 
Integrated Science Assessment (ISA) for Ozone and Related 
Photochemical Oxidants (Final Report). U.S. Environmental Protection 
Agency, Washington, DC, EPA/600/R-20/012, 2020.
    \777\ U.S. Environmental Protection Agency (U.S. EPA). 2021. 
Estimating PM2.5- and Ozone-Attributable Health Benefits. 
Technical Support Document (TSD) for the Final Revised Cross-State 
Air Pollution Rule Update for the 2008 Ozone Season NAAQS. EPA-HQ-
OAR-2020-0272. March.
---------------------------------------------------------------------------

    Table VIII-1 and Table VIII-2 present quantified health benefits 
from reductions in human exposure to ambient PM2.5 and 
ozone, respectively, from proposed Option 1 in 2045.\778\ Table VIII-3 
presents the total monetized benefits attributable to the proposed 
Option 1 in 2045.
---------------------------------------------------------------------------

    \778\ As noted in Section VII, due to resource constraints we 
only conducted air quality modeling for the proposed Option 1. Since 
the air quality modeling results are necessary to quantify estimates 
of avoided mortality and illness attributable to changes in ambient 
PM2.5 or ozone due to the proposed rule, we only have 
these estimates for proposed Option 1.
---------------------------------------------------------------------------

    We estimate that in 2045, the proposed Option 1 criteria pollutant 
program would result in total annual monetized benefits of $12 and $33 
billion at a 3 percent discount rate and $10 and $30 billion at a 7 
percent discount rate (2017 dollars).
    There are additional human health and environmental benefits 
associated with reductions in exposure to ambient concentrations of 
PM2.5, ozone, and NO2 that EPA has not quantified due to 
data, resource, or methodological limitations. There would also be 
benefits associated with reductions in air toxic pollutant emissions 
that result from the proposed program, but EPA is not currently able to 
monetize those impacts due to methodological limitations. The proposed 
criteria pollutant standards would also reduce methane (CH4) 
emissions due to lower total hydrocarbon emission rates from the 
tailpipe of heavy-duty gasoline vehicles (see draft RIA Chapter 5.2.2 
for more detail). The estimated benefits of the proposal would be 
larger if we were able to monetize all unquantified benefits at this 
time. We request comment on how to address the climate benefits and 
other categories of non-monetized benefits of the proposed rule. For 
more detailed information about the benefits analysis conducted for the 
proposal, please refer to draft RIA Chapter 8 that accompanies this 
preamble.

Table VIII-1--Estimated Avoided PM2.5 Mortality and Illnesses for the Proposed Option 1 Policy Scenario for 2045
                                    [95 percent confidence interval] \a\ \b\
----------------------------------------------------------------------------------------------------------------
                                                                                          Proposed option 1
----------------------------------------------------------------------------------------------------------------
                                           Avoided premature mortality
----------------------------------------------------------------------------------------------------------------
                                              Turner et al. (2016)--Ages 30+......                           740
                                                                                                    (500 to 980)
                                              Di et al. (2017)--Ages 65+..........                           800
                                                                                                    (780 to 830)
                                              Woodruff et al. (2008)--Ages < 1....                           4.1
                                                                                                    (-2.6 to 11)
----------------------------------------------------------------------------------------------------------------
                                      Non-fatal heart attacks among adults
----------------------------------------------------------------------------------------------------------------
Short-term exposure.........................  Peters et al. (2001)................                           790
                                                                                                  (180 to 1,400)
                                              Pooled estimate.....................                            85
                                                                                                     (31 to 230)
----------------------------------------------------------------------------------------------------------------
                                                Morbidity effects
----------------------------------------------------------------------------------------------------------------
Long-term exposure..........................  Asthma onset........................                         1,600
                                                                                                (1,500 to 1,600)
                                              Allergic rhinitis symptoms..........                        10,000
                                                                                               (2,500 to 18,000)
                                              Stroke..............................                            41
                                                                                                      (11 to 70)
                                              Lung cancer.........................                            52
                                                                                                      (16 to 86)
                                              Hospital Admissions--Alzheimer's                               400
                                               disease.                                             (300 to 500)
                                              Hospital Admissions--Parkinson's                                43
                                               disease.                                               (22 to 63)
----------------------------------------------------------------------------------------------------------------
Short-term exposure.........................  Hospital admissions--cardiovascular.                           110
                                                                                                     (76 to 130)
                                              ED visits--cardiovascular...........                           210
                                                                                                    (-82 to 500)
                                              Hospital admissions--respiratory....                            68
                                                                                                     (23 to 110)
                                              ED visits--respiratory..............                           400
                                                                                                     (78 to 830)
                                              Asthma symptoms.....................                       210,000
                                                                                           (-100,000 to 520,000)

[[Page 17586]]

 
                                              Minor restricted-activity days......                       460,000
                                                                                            (370,000 to 550,000)
                                              Cardiac arrest......................                            10
                                                                                                    (-4.2 to 24)
                                              Lost work days......................                        78,000
                                                                                              (66,000 to 90,000)
----------------------------------------------------------------------------------------------------------------
\a\ Values rounded to two significant figures.
\b\ PM2.5 exposure metrics are not presented here because all PM health endpoints are based on studies that used
  daily 24-hour average concentrations. Annual exposures are estimated using daily 24-hour average
  concentrations.


Table VIII-2--Estimated Avoided Ozone Mortality and Illnesses for the Proposed Option 1 Policy Scenario for 2045
                                      [95 percent confidence interval] \a\
----------------------------------------------------------------------------------------------------------------
                                                                Metric and season
                                                                       \b\                Proposed Option 1
----------------------------------------------------------------------------------------------------------------
                                           Avoided premature mortality
----------------------------------------------------------------------------------------------------------------
Long-term exposure...............  Turner et al. (2016).....  MDA8................                         2,100
                                                              April-September.....              (1,400 to 2,700)
Short-term exposure..............  Katsouyanni et al (2009).  MDA1................                           120
                                                              April-September.....                  (-69 to 300)
----------------------------------------------------------------------------------------------------------------
                                                Morbidity effects
----------------------------------------------------------------------------------------------------------------
Long-term exposure...............  Asthma onset \c\.........  MDA8................                        16,000
                                                              June-August.........            (14,000 to 18,000)
Short-term exposure..............  Allergic rhinitis          MDA8................                        88,000
                                    symptoms.                 May-September.......           (47,000 to 130,000)
                                   Hospital admissions--      MDA1................                           350
                                    respiratory.              April-September.....                  (-91 to 770)
                                   ED visits--respiratory...  MDA8................                         5,100
                                                              May-September.......             (1,400 to 11,000)
                                   Asthma symptoms--Cough     MDA8................                       920,000
                                    \d\.                      May-September.......        (-50,000 to 1,800,000)
                                   Asthma symptoms--Chest     MDA8................                       770,000
                                    Tightness \d\.            May-September.......         (85,000 to 1,400,000)
                                   Asthma symptoms--          MDA8................                       390,000
                                    Shortness of Breath \d\.  May-September.......       (-330,000 to 1,100,000)
                                   Asthma symptoms--Wheeze    MDA8................                       730,000
                                    \d\.                      May-September.......        (-57,000 to 1,500,000)
                                   Minor restricted-activity  MDA1................                     1,600,000
                                    days \d\.                 May-September.......        (650,000 to 2,600,000)
                                   School absence days......  MDA8................                     1,100,000
                                                              May-September.......       (-150,000 to 2,200,000)
----------------------------------------------------------------------------------------------------------------
\a\ Values rounded to two significant figures.
\b\ MDA8--maximum daily 8-hour average; MDA1--maximum daily 1-hour average. Studies of ozone vary with regards
  to season, limiting analyses to various definitions of summer (e.g., April-September, May-September or June-
  August). These differences can reflect state-specific ozone seasons, EPA-defined seasons or another seasonal
  definition chosen by the study author. The paucity of ozone monitoring data in winter months complicates the
  development of full year projected ozone surfaces and limits our analysis to only warm seasons.
\c\ The underlying metric associated with this risk estimate is daily 8-hour average from 10 a.m.-6 p.m. (AVG8);
  however, we ran the study with a risk estimate converted to MDA8.
\d\ Applied risk estimate derived from full year exposures to estimates of ozone across a May-September ozone
  season. When risk estimates based on full-year, long-term ozone exposures are applied to warm season air
  quality projections, the resulting benefits assessment may underestimate impacts, due to a shorter timespan
  for impacts to accrue.


[[Page 17587]]


    Table VIII-3--Total Ozone and PM2.5-Attributable Benefits for the
               Proposed Options 1 Policy Scenarios in 2045
         [95 percent confidence interval; billions of 2017$] a b
------------------------------------------------------------------------
                                              Total annual benefits in
                                                        2045
------------------------------------------------------------------------
3% Discount Rate..........................  $12 ($0.72 to $31) \c\ and
                                             $33 ($3.5 to $87) \d\
7% Discount Rate..........................  $10 ($0.37 to $28) \c\ and
                                             $30 ($3.0 to $78) \d\
------------------------------------------------------------------------
\a\ The benefits associated with the standards presented here do not
  include the full complement of health, environmental, and climate-
  related benefits that, if quantified and monetized, would increase the
  total monetized benefits.
\b\ Values rounded to two significant figures. The two benefits
  estimates separated by the word ``and'' signify that they are two
  separate estimates. The estimates do not represent lower- and upper-
  bound estimates though they do reflect a grouping of estimates that
  yield more and less conservative benefit totals. They should not be
  summed.
\c\ Sum of benefits using the Katsouyanni et al. (2009) short-term
  exposure ozone respiratory mortality risk estimate and the Turner et
  al. (2016) long-term exposure PM2.5 all-cause risk estimate.
\d\ Sum of benefits using the Turner et al. (2016) long-term exposure
  ozone respiratory mortality risk estimate and the Di et al. (2017)
  long-term exposure PM2.5 all-cause risk estimate.

    The full-scale criteria pollutant benefits analysis for Option 1 
presented in this section reflects spatially and temporally allocated 
emissions inventories (see draft RIA Chapter 5), photochemical air 
quality modeling (see draft RIA Chapter 6), and PM2.5 and 
ozone benefits generated using BenMAP-CE (see draft RIA Chapter 8), all 
for conditions projected to occur in calendar year 2045. As we 
presented in Sections V and VI, national estimates of emissions and 
program costs were generated for each analysis year from Option 1's 
proposed implementation to a year when Option 1 would be fully phased-
in and the vehicle fleet would be approaching full turnover (2027-
2045). The computational requirements needed to conduct photochemical 
air quality modeling to support a full-scale benefits analysis for 
Option 2 in 2045 and for all Option 1 and Option 2 analysis years from 
2027 to 2044 precluded the Agency from conducting benefits analyses 
comparable to the calendar year 2045 Option 1 benefits analysis. 
Instead, we have used a reduced-form approach to scale total Option 1 
benefits in 2045 back to 2027 using projected reductions in year-over-
year NOX emissions so that we can estimate the present and 
annualized values of the stream of estimated benefits for Option 1. We 
have also used year-over-year Option 2 NOX emissions 
reductions to scale the total benefits associated with Option 1 to 
derive a best estimate of criteria pollutant benefits associated with 
Option 2.\779\ For more information on the benefits scaling approach we 
applied to estimate criteria pollutant benefits over time for the 
proposed Options 1 and 2, please refer to draft RIA Chapter 8.7 that 
accompanies this preamble.
---------------------------------------------------------------------------

    \779\ Because NOX is the dominating pollutant 
controlled by the proposed Options, we make a simplifying assumption 
that total PM and ozone benefits can be scaled by NOX 
emissions, even though emissions of other pollutants are controlled 
in smaller amounts by the proposed program.
---------------------------------------------------------------------------

    Table VIII-4 and Table VIII-5 present the annual, estimated 
undiscounted total health benefits (PM2.5 plus ozone) for 
the stream of years beginning with the first year of rule 
implementation, 2027, through 2045 for the proposed Options 1 and 
2.\780\ The tables also present the present and annualized values of 
benefits over this time series, discounted using both 3 percent and 7 
percent discount rates and reported in 2017 dollars. Table VIII-4 
presents total benefits as the sum of short-term ozone respiratory 
mortality benefits for all ages, long-term PM2.5 all-cause 
mortality benefits for ages 30 and above, and all monetized avoided 
illnesses. Table VIII-5 presents total benefits as the sum of long-term 
ozone respiratory mortality benefits for ages 30 and above, long-term 
PM2.5 all-cause mortality benefits for ages 65 and above, 
and all monetized avoided illnesses.
---------------------------------------------------------------------------

    \780\ We are not including an analysis of benefits of the 
Alternative (described in Sections III and IV) because we currently 
do not have sufficient information to conclude that the Alternative 
standards would be feasible in the MY 2027 timeframe (see Section 
III for details).

 Table VIII-4--Undiscounted Stream and Present Value of Human Health Benefits From 2027 Through 2045: Monetized
  Benefits Quantified as Sum of Short-Term Ozone Respiratory Mortality Ages 0-99, and Long-Term PM2.5 All-Cause
                                               Mortality Ages 30+
                         [Discounted at 3 percent and 7 percent; billions of 2017$] a b
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1               Proposed Option 2
                                                 ---------------------------------------------------------------
                                                        3%              7%              3%              7%
----------------------------------------------------------------------------------------------------------------
2027............................................           $0.57           $0.51           $0.52           $0.47
2028............................................             1.2             1.1             1.1            0.98
2029............................................             1.8             1.7             1.7             1.5
2030............................................             2.5             2.3             2.3             2.1
2031............................................             3.4             3.1             3.1             2.7
2032............................................             4.3             3.9             3.8             3.4
2033............................................             5.0             4.5             4.3             3.9
2034............................................             5.6             5.0             4.9             4.4
2035............................................             6.3             5.7             5.4             4.8
2036............................................             6.9             6.2             5.8             5.3
2037............................................             7.8             7.0             6.3             5.7
2038............................................             8.6             7.7             6.7             6.0
2039............................................             9.1             8.2             7.1             6.4
2040............................................             9.6             8.6             7.5             6.7
2041............................................              10             9.0             7.8             7.1
2042............................................              10             9.4             8.2             7.4
2043............................................              11             9.8             8.5             7.6
2044............................................              11              10             8.8             7.9
2045 \c\........................................              12              10             9.1             8.2
Present Value...................................              87              50              71              41

[[Page 17588]]

 
Annualized Value................................             6.1             4.9             5.0             4.0
----------------------------------------------------------------------------------------------------------------
\a\ The benefits associated with the standards presented here do not include the full complement of health,
  environmental, and climate-related benefits that, if quantified and monetized, would increase the total
  monetized benefits.
\b\ Benefits calculated as value of avoided: PM2.5--attributable deaths (quantified using a concentration-
  response relationship from the Turner et al. 2016 study); Ozone-attributable deaths (quantified using a
  concentration-response relationship from the Katsouyanni et al. 2009 study); and PM2.5 and ozone-related
  morbidity effects.
\c\ Year in which PM2.5 and ozone air quality associated with Option 1 was simulated (2045).


 Table VIII-5--Undiscounted Stream and Present Value of Human Health Benefits From 2027 Through 2045: Monetized
   Benefits Quantified as Sum of Long-Term Ozone Respiratory Mortality Ages 30+, and Long-Term PM2.5 All-Cause
                                               Mortality Ages 65+
                         [Discounted at 3 percent and 7 percent; billions of 2017$] a b
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1               Proposed Option 2
                                                 ---------------------------------------------------------------
                                                        3%              7%              3%              7%
----------------------------------------------------------------------------------------------------------------
2027............................................            $1.6            $1.4            $1.4            $1.3
2028............................................             3.3             2.9             3.0             2.7
2029............................................             5.1             4.6             4.7             4.2
2030............................................             7.0             6.3             6.4             5.8
2031............................................             9.6             8.6             8.5             7.6
2032............................................              12              11              11             9.5
2033............................................              14              13              12              11
2034............................................              16              14              14              12
2035............................................              18              16              15              14
2036............................................              20              18              17              15
2037............................................              22              20              18              16
2038............................................              24              22              19              17
2039............................................              26              23              20              18
2040............................................              28              25              21              19
2041............................................              29              26              23              20
2042............................................              30              27              24              21
2043............................................              31              28              24              22
2044............................................              32              29              25              23
2045 \c\........................................              33              30              26              23
Present Value...................................             250             140             200             120
Annualized Value................................              17              14              14              11
----------------------------------------------------------------------------------------------------------------
\a\ The benefits associated with the standards presented here do not include the full complement of health,
  environmental, and climate-related benefits that, if quantified and monetized, would increase the total
  monetized benefits.
\b\ Benefits calculated as value of avoided: PM2.5--attributable deaths (quantified using a concentration-
  response relationship from the Di et al. 2017 study); Ozone-attributable deaths (quantified using a
  concentration-response relationship from the Turner et al. 2016 study); and PM2.5 and ozone-related morbidity
  effects.
\c\ Year in which PM2.5 and ozone air quality for Option 1 was simulated (2045).

    This analysis includes many data sources as inputs that are each 
subject to uncertainty. Input parameters include projected emission 
inventories, air quality data from models (with their associated 
parameters and inputs), population data, population estimates, health 
effect estimates from epidemiology studies, economic data, and 
assumptions regarding the future state of the world (i.e., regulations, 
technology, and human behavior). When compounded, even small 
uncertainties can greatly influence the size of the total quantified 
benefits. Please refer to draft RIA Chapter 8 for more information on 
the uncertainty associated with the benefits presented here.

IX. Comparison of Benefits and Costs

    This section compares the estimated range of total monetized health 
benefits to total costs associated with proposed Options 1 and 2 of the 
criteria pollutant program. This section also presents the range of 
monetized net benefits (benefits minus costs) associated with the same 
options. Criteria pollutant program costs are detailed and presented in 
Section V of this preamble. Those costs include costs for both the new 
technology and the operating costs associated with that new technology, 
as well as costs associated with the proposed warranty and useful life 
provisions for Options 1 and 2. Criteria pollutant program benefits are 
presented in Section VIII. Those benefits are the monetized economic 
value of the reduction in PM2.5- and ozone-related premature 
deaths and illnesses that result from reductions in NOX 
emissions and directly emitted PM2.5 attributable to 
implementation of the proposed options.
    As noted in Sections IV through VIII, these estimated benefits, 
costs, and net benefits do not reflect all of the anticipated impacts 
of the proposed

[[Page 17589]]

revisions to the criteria pollutant program.\781\
---------------------------------------------------------------------------

    \781\ As noted in draft RIA Chapter 5.4, there are differences 
between the standards, emission warranty, and useful life provisions 
of proposed Option 1 presented in Sections III and IV and those 
included in our control case scenario modeled for the air quality 
analysis (as noted in Section VII, due to resource constraints we 
only conducted air quality modeling for the proposed Option 1). As 
detailed in draft RIA Chapter 8, estimates of health benefits are 
based on our air quality analysis, and thus differences between 
proposed Option 1 and modeling are not reflected in the benefits 
analysis.
---------------------------------------------------------------------------

A. Methods

    EPA presents three different benefit-cost comparisons for proposed 
Options 1 and 2: \782\
---------------------------------------------------------------------------

    \782\ We are not including an analysis of costs or benefits of 
the Alternative (described in Sections III and IV) because we 
currently do not have sufficient information to conclude that the 
Alternative standards would be feasible in the MY 2027 timeframe 
(see Section III for details).
---------------------------------------------------------------------------

    1. A future-year snapshot comparison of annual benefits and costs 
in the year 2045, chosen to approximate the annual health benefits that 
would occur in a year when the program would be fully implemented and 
when most of the regulated fleet would have turned over. Benefits, 
costs and net benefits are presented in year 2017 dollars and are not 
discounted. However, 3 percent and 7 percent discount rates were 
applied in the valuation of avoided premature deaths from long-term 
pollution exposure to account for a twenty-year segmented cessation 
lag.
    2. The present value (PV) of the stream of benefits, costs and net 
benefits calculated for the years 2027-2045, discounted back to the 
first year of implementation of the proposed rule (2027) using both a 3 
percent and 7 percent discount rate, and presented in year 2017 
dollars. Note that year-over-year costs are presented in Section V and 
year-over-year benefits can be found in Section VIII.
    3. The equivalent annualized value (EAV) of benefits, costs and net 
benefits representing a flow of constant annual values that, had they 
occurred in each year from 2027 to 2045, would yield an equivalent 
present value to those estimated in method 2 (using either a 3 percent 
or 7 percent discount rate). Each EAV represents a typical benefit, 
cost or net benefit for each year of the analysis and is presented in 
year 2017 dollars.
    The two estimates of monetized benefits (and net benefits) in each 
of these benefit-cost comparisons reflect alternative combinations of 
the economic value of PM2.5- and ozone-related premature 
deaths summed with the economic value of illnesses for each discount 
rate (see draft RIA Chapter 8 for more detail).

B. Results

    Table IX-1 presents the benefits, costs and net benefits of 
proposed Options 1 and 2 in annual terms for year 2045, in PV terms, 
and in EAV terms.

 Table IX-1--Annual Value, Present Value and Equivalent Annualized Value of Costs, Benefits and Net Benefits of
                                       the Proposed Option 1 and Option 2
                                              [Billions, 2017$] a b
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1               Proposed Option 2
                                                 ---------------------------------------------------------------
                                                    3% Discount     7% Discount     3% Discount     7% Discount
----------------------------------------------------------------------------------------------------------------
2045:
    Benefits....................................         $12-$33         $10-$30        $9.1-$26        $8.2-$23
    Costs.......................................            $2.3            $2.3            $2.9            $2.9
    Net Benefits................................        $9.2-$31        $8.1-$28        $6.2-$23        $5.3-$21
Present Value:
    Benefits....................................        $88-$250        $52-$150        $71-$200        $41-$120
    Costs.......................................             $27             $19             $30             $21
    Net Benefits................................        $61-$220        $33-$130        $41-$170         $21-$96
Equivalent Annualized Value:
    Benefits....................................        $6.0-$17        $4.7-$13        $5.0-$14        $4.0-$11
    Costs.......................................            $1.9            $1.9            $2.1            $2.0
    Net Benefits................................        $4.1-$15        $2.9-$12        $2.9-$12       $2.0-$9.3
----------------------------------------------------------------------------------------------------------------
\a\ All benefits estimates are rounded to two significant figures; numbers may not sum due to independent
  rounding. The range of benefits (and net benefits) in this table are two separate estimates and do not
  represent lower- and upper-bound estimates, though they do reflect a grouping of estimates that yield more and
  less conservative benefits totals. The costs and benefits in 2045 are presented in annual terms and are not
  discounted. However, all benefits in the table reflect a 3 percent and 7 percent discount rate used to account
  for cessation lag in the valuation of avoided premature deaths associated with long-term exposure.
\b\ The benefits associated with the standards presented here do not include the full complement of health,
  environmental, and climate-related benefits that, if quantified and monetized, would increase the total
  monetized benefits.

    Annual benefits of proposed Option 1 are larger than the annual 
costs in 2045, with annual net benefits of $8.1 and $28 billion using a 
7 percent discount rate, and $9.2 and $31 billion using a 3 percent 
discount rate.\783\ Benefits also outweigh the costs when expressed in 
PV terms (net benefits of $33 and $130 billion using a 7 percent 
discount rate, and $61 and $220 billion using a 3 percent discount 
rate) and EAV terms (net benefits of $2.9 and $12 billion using a 7 
percent discount rate, and $4.1 and $15 billion using a 3 percent 
discount rate).\784\
---------------------------------------------------------------------------

    \783\ The range of benefits and net benefits presented in this 
section reflect a combination of assumed PM2.5 and ozone 
mortality risk estimates and selected discount rate.
    \784\ As noted in Chapter 5.4 of the draft RIA, there are 
differences between the proposed Option 1 standards, emission 
warranty, and useful life provisions presented in Sections III and 
IV of this preamble and those included in the control scenario 
modeled for the air quality analysis. In contrast, our cost analysis 
includes the proposed Option 1 standards, emission warranty, and 
useful life provisions presented in Sections III and IV. As such, 
our comparisons of benefits and costs of the proposed options may 
underestimate the true benefits of each option.
---------------------------------------------------------------------------

    The benefits also outweigh the costs in annual 2045 terms when 
looking at proposed Option 2, with annual net benefits of $5.3 and $21 
billion using a 7 percent discount rate and $6.2 billion and $23 
billion using a 3 percent discount rate. The benefits of proposed 
Option 2 also outweigh the costs in PV and EAV terms.
    Comparing proposed Options 1 and 2, our analysis shows that Option 
2 has lower net benefits than Option 1 due to both higher costs and 
lower emission reductions relative to Option 1. As outlined in Section 
I.G and detailed in

[[Page 17590]]

Sections III and IV, we have considered several other factors, 
including lead time and technological feasibility, in developing these 
options and considering possible regulatory options.
    Given these results, EPA expects that implementation of either 
proposed option would provide society with a substantial net gain in 
welfare, notwithstanding the health and other benefits we were unable 
to quantify (see draft RIA Chapter 8.8 for more information about 
unquantified benefits). EPA does not expect the omission of 
unquantified benefits to impact the Agency's evaluation of regulatory 
options since unquantified benefits generally scale with the emissions 
impacts of the proposed options.

X. Economic Impact Analysis

    This section describes our Economic Impact Analysis for the 
proposed rule. Our analysis focuses on the potential impacts of the 
proposed standards on heavy-duty (HD) vehicles (sales, mode shift, 
fleet turnover) and employment in the HD industry. The sub-sections 
below describe our evaluation.

A. Impact on Vehicle Sales, Mode Shift, and Fleet Turnover

    This proposed rulemaking, if finalized, would require HD engine 
manufacturers to develop and implement emission control technologies 
capable of controlling NOX at lower levels over longer 
emission warranty and regulatory useful life periods. These changes in 
requirements would increase the cost of producing and selling compliant 
HD vehicles. These increased costs are likely to lead to increases in 
prices for HD vehicles, which might lead to reductions in truck sales. 
In addition, there may be a period of ``pre-buying'' in anticipation of 
potentially higher prices, during which there is an increase in new 
vehicle purchases before the implementation of new requirements, 
followed by a period of ``low-buying'' directly after implementation, 
during which new vehicle purchases decrease. EPA acknowledges that the 
proposed standards may lead to some pre-buy before the implementation 
date of the standards, and some low-buy after the standards are 
implemented. EPA is unable to estimate sales impacts based on existing 
literature, and as such contracted with ERG to complete a literature 
review, as well as conduct original research to estimate sales impacts 
for previous EPA HD vehicle standards on pre- and low-buy for HD 
vehicles. The resulting analysis examines the effect of four HD truck 
regulations, those that became effective in 2004, 2007, 2010 and 2014, 
on the sales of Class 6, 7 and 8 vehicles over the twelve months before 
and after each standard. The 2004, 2007 and 2010 rules focused on 
reducing criteria pollutant emissions. The 2014 regulation focused on 
reducing GHG emissions. The report finds little evidence of sales 
impacts for Class 6 and 7 vehicles. For Class 8 vehicles, evidence of 
pre-buy was found before the 2010 and 2014 standards, and evidence of 
low-buy was found after the 2002, 2007 and 2010 standards. Based on the 
results of this study, EPA is outlining an approach that could be used 
to estimate pre- and low-buy effects in the final RIA. In the draft 
RIA, we explain the methods used to estimate sales effects, as well as 
how the results could be applied to a regulatory analysis (see the 
draft RIA, Chapter 10.1, for further discussion). Our example results 
for proposed Option 1 suggest pre- and low-buy for Class 8 trucks may 
range from zero to an approximately two percent increase in sales over 
a period of up to 8 months before the 2031 standards begin (pre-buy), 
and a decrease in sales from zero to approximately two percent over a 
period of up to 12 months after the 2031 standards begin (low-buy). We 
request comment on the approach that is discussed in the draft RIA, as 
well as the specific inputs and methods. In addition, we request 
comment on how additional external factors, including the current 
global COVID-19 pandemic, might impact any pre- or low-buy that may 
result from this proposed rulemaking. Commenters are encouraged to 
provide data on how factors such as the pandemic may affect HD vehicle 
sales, including on any possible pre- and low-buy resulting from this 
proposed rule, as well as on the length of the possible sales effects.
    In addition to potential sales impacts from changes in purchase 
price, the proposed requirement for longer useful life and emission 
warranty periods may also affect vehicle sales. While longer emission 
warranty periods are likely to increase the purchase price of new HD 
vehicles, these increases may be offset by reduced operating costs. 
This is because longer useful life periods are expected to make 
emission control technology components more durable, and more durable 
components, combined with manufacturers paying for repairs during the 
proposed longer warranty periods, would in turn reduce repair costs for 
vehicle owners. These combined effects may increase (or reduce the 
decrease in) sales of new HD vehicles if fleets and independent owner-
operators prefer to purchase more durable vehicles with overall lower 
repair costs.\785\ EPA is unable to quantify these effects because 
existing literature does not provide clear guidance on the relationship 
between warranty changes, increases in prices due to increased warranty 
periods, and sales impacts. EPA continues to investigate methods for 
estimating sales impacts of extended warranty provisions, and requests 
comment on data and methods to use in such analysis. See the draft RIA, 
Chapter 10.1.1, for more information.
---------------------------------------------------------------------------

    \785\ The reduced repair costs may counteract some of the sales 
effect of increased vehicle purchase cost. As a result, they may 
reduce incentives for pre- and low-buy and mitigate adverse sales 
impacts.
---------------------------------------------------------------------------

    In addition to potential sales impacts, another potential effect of 
the proposed standards is transportation mode shift, which is a change 
from truck to another mode of transportation (typically rail or 
marine). Whether shippers switch to a different transportation mode for 
freight depends not only on the cost per mile of the shipment (freight 
rate), but also the value of the shipment, the time needed for 
shipment, and the availability of supporting infrastructure. This 
proposed rule is not expected to have a large impact on truck freight 
rates given that the price of the truck is only a small part of the 
cost per mile of a ton of goods. For that reason, we expect little mode 
shift due to the proposed standards. The draft RIA, Chapter 10.1.3, 
discusses this issue.
    Another potential area of impact of the proposed standards is on 
fleet turnover and the associated reduction in emissions from new 
vehicles. After the implementation of the proposed standards, each 
individual new vehicle sold would produce lower emissions per mile 
relative to legacy vehicles. However, the proposed standards would 
reduce total HD highway fleet emissions gradually. This is because, 
initially, the vehicles meeting the proposed standards would be only a 
small portion of the total fleet; over time, as more vehicles subject 
to the standards enter the market and older vehicles leave the market, 
greater emission reductions would occur. If pre-buy and low-buy 
behaviors occur, then the initial emission reductions are likely to be 
smaller than expected. This is because, under pre-buy conditions, the 
pre-bought vehicles would be certified to less stringent standards and 
their emission reductions would be smaller than would be realized if 
those vehicles were subject to the proposed standards. However, the new 
vehicles are likely less polluting than the older vehicles

[[Page 17591]]

that they are most likely to displace, and there may be an earlier 
reduction in emissions than would have occurred without the standards 
since the vehicles are being purchased ahead of the implementation of 
new standards, rather than at a natural point in the purchase cycle. 
Under low-buy, emission reductions would be slower because there is 
slower adoption of new vehicles than without the standards. See the 
draft RIA, Chapter 10.1.2, for more information on this, as well as the 
vehicle miles traveled (VMT) discussion below.
    An additional possible effect of the standards is a net reduction 
in new vehicle sales if there is either a smaller pre-buy than the 
post-standards low-buy, or some potential buyers decide not to purchase 
at all. In this case, the VMT of older vehicles may increase to 
compensate for the ``missing'' vehicles. To the extent that the older 
vehicles emit more than the vehicles for which they are substituting, 
emissions may increase. However, the VMT is more likely to be shifted 
to the newer HD vehicles among the existing fleet. Because most of 
those vehicles are expected to be in compliance with the previous tiers 
of HD vehicle standards, the emission effect of increased VMT for older 
vehicles is expected to be small.
    EPA requests comment on all aspects of the estimated impact on 
vehicle sales, mode shift, and fleet turnover, including the approach 
outlined in the draft RIA to quantify sales impacts, and requests 
stakeholder to recommend any additional methods and data that could be 
used to inform our understanding of potential impacts on HD VMT, fleet 
turnover, mode shift and vehicles sales.

B. Employment Impacts

    This section discusses potential employment impacts due to this 
proposed regulation, as well as our partial estimates of those impacts. 
We focus our analysis on the motor vehicle manufacturing and the motor 
vehicle parts manufacturing sectors because these sectors are most 
directly affected.\786\ While the proposed rule primarily affects heavy 
duty vehicle engines, the employment effects are expected to be felt 
more broadly in the motor vehicle and parts sectors due to the effects 
of the standards on sales.
---------------------------------------------------------------------------

    \786\ The employment analysis in the draft RIA is part of the 
EPA's ongoing effort to ``conduct continuing evaluations of 
potential loss or shifts of employment which may result from the 
administration or enforcement of [the Act]'' pursuant to CAA section 
321(a). Though the rule primarily affects heavy-duty engines, the 
employment effects will be felt more broadly in the motor vehicle 
and parts sectors due to the potential effects of the standards on 
sales.
---------------------------------------------------------------------------

    In general, the employment effects of environmental regulation are 
difficult to disentangle from other economic changes (especially the 
state of the macroeconomy) and business decisions that affect 
employment, both over time and across regions and industries. In light 
of these difficulties, we look to economic theory to provide a 
constructive framework for approaching these assessments and for better 
understanding the inherent complexities in such assessments.
    Economic theory of labor demand indicates that employers affected 
by environmental regulation may change their demand for different types 
of labor in different ways. They may increase their demand for some 
types, decrease demand for other types, or maintain demand for still 
other types. To present a complete picture, an employment impact 
analysis describes both positive and negative changes in employment. A 
variety of conditions can affect employment impacts of environmental 
regulation, including baseline labor market conditions, employer and 
worker characteristics, industry, and region.
    In the draft RIA, we describe three ways employment at the firm 
level might be affected by changes in a firm's production costs due to 
environmental regulation: A demand effect, caused by higher production 
costs increasing market prices and decreasing demand; a cost effect, 
caused by additional environmental protection costs leading regulated 
firms to increase their use of inputs; and a factor-shift effect, in 
which post-regulation production technologies may have different labor 
intensities than their pre-regulation counterparts.787 788
---------------------------------------------------------------------------

    \787\ Morgenstern, Richard D., William A. Pizer, and Jhih-Shyang 
Shih (2002). ``Jobs Versus the Environment: An Industry-Level 
Perspective.'' Journal of Environmental Economics and Management 43: 
412-436.
    \788\ Berman and Bui have a similar framework in which they 
consider output and substitution effects that are similar to 
Morgenstern et al.'s three effect (Berman, E. and L.T.M. Bui (2001). 
``Environmental Regulation and Labor Demand: Evidence from the South 
Coast Air Basin.'' Journal of Public Economics 79(2): 265-295).
---------------------------------------------------------------------------

    Due to data limitations, EPA is not quantifying the impacts of the 
proposed regulation on firm-level employment for affected companies, 
although we acknowledge these potential impacts. Instead, we discuss 
demand, cost and factor-shift employment effects for the regulated 
sector at the industry level in the draft RIA. In general, if the 
proposed regulation causes HD sales to decrease, fewer people would be 
needed to assemble trucks and to manufacture their components. If pre-
buy occurs, HD vehicle sales may increase temporarily in advance of the 
standards, leading to temporary increases in employment, but if low-buy 
occurs following the standards, there could be temporary decreases in 
employment. Though we have outlined a method to quantify sales impacts, 
we are not using them to estimate effects on fleet turnover in this 
proposed rulemaking. As such, we cannot determine which of these 
effects would dominate and therefore we do not estimate the demand-
effect impact on employment due to the proposed standards. In addition, 
we do not have information on changes in labor intensity of production 
due to the standards, and therefore we cannot estimate the factor-shift 
effect on employment.
    We do estimate partial employment impacts, namely labor effects 
associated with increased costs of production. This cost effect 
includes the impact on employment due to the increase in production 
costs needed for vehicles to meet the standards. (Note that this 
analysis is separate from any employment effect due to changes in 
vehicle sales; in other words, the analysis holds output constant.) In 
the draft RIA, we capture these effects using the historic share of 
labor as a part of the cost of production to extrapolate future 
estimates of the share of labor as a cost of production. This provides 
a sense of the order of magnitude of expected impacts on employment.
    These estimates are averages, covering all the activities in these 
sectors. The estimates may not be representative of the labor effects 
when expenditures are required on specific activities, or when 
manufacturing processes change sufficiently that labor intensity 
changes. In addition, these estimates do not include changes in 
industries that supply these sectors, such as steel or electronics 
producers, or in other potentially indirectly affected sectors (such as 
shipping). Other sectors that sell, purchase, or service HD vehicles 
may also face employment impacts due to the proposed standards. The 
effects on these sectors would depend on the degree to which compliance 
costs are passed through to prices for HD vehicles and the effects of 
warranty requirements on demand for vehicle repair and maintenance. EPA 
does not have data to estimate the full range of possible employment 
impacts. For more information on how we estimate the employment impacts 
due to increased costs, see Chapter 10 of the draft RIA.
    Table X-1 shows the estimated employment effects due to increases 
in

[[Page 17592]]

vehicle costs based on the ratio of labor to production costs derived 
from historic data for proposed Option 1 and proposed Option 2. We only 
quantitatively estimate employment impacts due to cost effects. In this 
proposed rule, we provide estimates of sales impacts as part of an 
example approach for commenters to consider, therefore we do not 
estimate potential changes in employment due to changes in vehicle 
sales. Results are shown in job-years, where a job-year is, for 
example, one year of full-time work for one person, or one year of 
half-time work for two people. Increased costs of vehicles and parts 
would, by itself and holding labor intensity constant, be expected to 
increase employment by 400 to 2,200 job years, and 300 to 1,800 job 
years in 2027 and 2032 respectively under proposed Option 1. Employment 
would be expected to increase by 400 to 2,200 job years, and 300 to 
1,500 job years in 2027 and 2032 respectively under proposed Option 2.

   Table X-1--Employment Effects Due to Increased Costs of Vehicles and Parts (Cost Effect), in Job-Years \a\
----------------------------------------------------------------------------------------------------------------
                                                         Proposed Option 1               Proposed Option 2
                                                 ---------------------------------------------------------------
                                                      Minimum         Maximum         Minimum         Maximum
                      Year                          employment      employment      employment      employment
                                                    due to cost     due to cost     due to cost     due to cost
                                                    effect \b\      effect \c\      effect \b\      effect \c\
----------------------------------------------------------------------------------------------------------------
2027............................................             400           2,200             400           2,200
2028............................................             400           2,100             400           2,000
2029............................................             400           2,000             400           1,900
2030............................................             300           1,800             300           1,700
2031............................................             400           1,900             300           1,600
2032............................................             300           1,800             300           1,500
----------------------------------------------------------------------------------------------------------------
\a\ Due to the data limitations, results do not reflect employment effects that result from changes in heavy-
  duty vehicle sales.
\b\ Minimum employment impacts under both proposed Options are estimated in ASM for NAICS code 336112, Light
  Truck and Utility Vehicle Manufacturing.
\c\ Maximum employment impacts under both proposed Options are estimated in EC for NAICS code 3363, Motor
  Vehicle Parts Manufacturing.

    While we estimate employment impacts, measured in job-years, 
beginning with program implementation, some of these employment gains 
may occur earlier as vehicle manufacturers and parts suppliers hire 
staff in anticipation of compliance with the standards. Additionally, 
holding all other factors constant, demand-effect employment may 
increase prior to MY 2027 due to pre-buy, and may decrease, potentially 
temporarily, afterwards.\789\ We present a range of possible results 
because our analysis consists of data from multiple industrial sectors 
that we expect would be directly affected by the proposed regulation, 
as well as data from multiple sources. For more information on the data 
we use to estimate the cost effect, see Chapter 10.2 of the draft RIA.
---------------------------------------------------------------------------

    \789\ Note that the standards are not expected to provide 
incentives for manufacturers to shift employment between domestic 
and foreign production. This is because the proposed standards would 
apply to vehicles sold in the U.S. regardless of where they are 
produced.
---------------------------------------------------------------------------

XI. Targeted Updates to the Phase 2 Heavy-Duty Greenhouse Gas Emissions 
Program

    The transportation sector is the largest U.S. source of GHG 
emissions, representing 29 percent of total GHG emissions.\790\ Within 
the transportation sector, heavy-duty vehicles are the second largest 
contributor, at 23 percent.\791\ GHG emissions have significant impacts 
on public health and welfare as evidenced by the well-documented 
scientific record and as set forth in EPA's Endangerment and Cause or 
Contribute Findings under CAA section 202(a).\792\ Therefore, continued 
emission reductions in the heavy-duty vehicle sector are appropriate.
---------------------------------------------------------------------------

    \790\ Inventory of U.S. Greenhouse Gas Emissions and Sinks: 
1990-2019 (EPA-430-R-21-005, published April 2021). Can be accessed 
at https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks.
    \791\ Ibid.
    \792\ 74 FR 66496, December 15, 2009; 81 FR 54422, August 15, 
2016.
---------------------------------------------------------------------------

    We are at the early stages of a significant transition in the 
history of the heavy-duty on-highway sector--a shift to zero-emission 
vehicle technologies. This change is underway and presents an 
opportunity for significant reductions in heavy-duty vehicle emissions. 
Major trucking fleets, manufacturers and U.S. states have announced 
plans to shift the heavy-duty fleet toward zero-emissions technology, 
and over just the past few years we have seen the early introduction of 
zero-emission technology into a number of heavy-duty vehicle market 
segments. These developments have demonstrated that further 
CO2 reductions in the MY 2027 timeframe are appropriate 
considering cost, lead time, and other factors. This proposed action 
would adjust the existing HD GHG Phase 2 program to account for the 
growth in the market.
    Proposed adjustments to the existing HD GHG Phase 2 program are 
responsive to Executive Order 14037 on Strengthening American 
Leadership in Clean Cars and Trucks, which identifies three potential 
regulatory actions for the heavy-duty vehicle sector for EPA to 
consider undertaking: (1) This proposed rule for heavy-duty vehicles 
for new criteria pollutant standards and strengthening of the MY 2027 
GHG standards; (2) a separate rulemaking to establish more stringent 
criteria and GHG emission standards for medium-duty vehicles for MY 
2027 and later (in combination with light-duty vehicles); and (3) a 
third rulemaking to establish new GHG standards for heavy-duty vehicles 
for MY 2030 and later.\793\ The first step includes considering 
targeted revisions to the already stringent HD GHG Phase 2 emission 
standards for heavy-duty vehicles beginning with MY 2027 in 
consideration of the role that heavy-duty zero-emission vehicles (HD 
ZEVs) might have in further reducing emissions from certain market 
segments. As part of this proposal, we are proposing to increase the 
stringency of the existing CO2 emission standards for MY 
2027 and later vehicles for many of the vocational vehicle and tractor 
subcategories, specifically those where we project early introductions 
of zero-emission vehicles. The proposed

[[Page 17593]]

increase in stringency is appropriate considering lead time, costs, and 
other factors, including the market shifts to zero-emission 
technologies in certain segments of the heavy-duty vehicle sector that 
are occurring since the HD GHG Phase 2 rule was promulgated in 2016. In 
addition, we are requesting comment on potential changes to the 
advanced technology incentive program for electric vehicles beginning 
in MY 2024. The proposed increased stringency is intended to balance 
further incentivizing zero and near-zero emission vehicle development 
with ensuring that the standards achieve an appropriate fleet-wide 
level of CO2 emissions reductions. The proposed changes to 
the CO2 standards are targeted and apply only to certain MY 
2027 standards; the HD GHG Phase 2 program overall remains largely 
unchanged.
---------------------------------------------------------------------------

    \793\ 86 FR 43583, August 5, 2021. Executive Order 14037. 
Strengthening American Leadership in Clean Cars and Trucks.
---------------------------------------------------------------------------

    As discussed in the Executive Summary, a number of stakeholders 
have urged EPA to put in place policies that rapidly advance ZEVs in 
this current rulemaking in order to prioritize environmental justice in 
communities that are impacted by freight transportation and already 
overburdened by pollution.\794\ One policy stakeholders have asked EPA 
to consider is the establishment of a ZEV sales mandate (i.e., a 
nationwide requirement for manufacturers to produce a portion of their 
new vehicle fleet as ZEVs), which would culminate in standards 
requiring 100 percent of all new heavy-duty vehicles be zero-emission 
no later than 2035. In this current rulemaking EPA is not proposing to 
establish a heavy-duty ZEV sales mandate; rather, in this rulemaking we 
are considering how the development and deployment of ZEVs can further 
the goals of environmental protection and best be reflected in the 
establishment of EPA's standards and regulatory program for MY 2027 and 
later heavy-duty vehicles. As discussed earlier in this section EPA 
will also be considering the important role of ZEV technologies in the 
upcoming light-duty and medium-duty vehicle proposal for MY 2027 and 
later and in the heavy-duty vehicle proposal for MY 2030 and later. EPA 
requests comment under this proposal on how we can best consider the 
potential for ZEV technology to significantly reduce air pollution from 
the heavy-duty vehicle sector (including but not limited to whether and 
how to consider including specific sales requirements for HD ZEVs).
---------------------------------------------------------------------------

    \794\ Letter to EPA Administrator Michael Regan from the Moving 
Forward Network. October 26, 2021.
---------------------------------------------------------------------------

    In Sections XI.A through XI.F, we provide background on the 
existing EPA heavy-duty GHG standards and the details of our proposed 
updates to the Model Year 2027 GHG standards. EPA requests comment on 
all aspects of these proposed updates.

A. Background on Heavy-Duty Greenhouse Gas Emission Standards

    EPA sets HD GHG emission standards under its authority in CAA 
section 202(a). Section 202(a)(1) states that ``the Administrator shall 
by regulation prescribe (and from time to time revise) . . . standards 
applicable to the emission of any air pollutant from any class or 
classes of new motor vehicles or new motor vehicle engines . . ., which 
in his judgment cause, or contribute to, air pollution which may 
reasonably be anticipated to endanger public health or welfare.'' 
Section 202(a)(2) provides that standards under section 202(a) apply to 
such vehicles and engines ``after such period as the Administrator 
finds necessary to permit the development and application of the 
requisite technology, giving appropriate consideration to the cost of 
compliance within such period'' and ``for their useful life.'' EPA also 
may consider other factors and in previous heavy-duty vehicle GHG 
standards rulemakings has considered the impacts of potential GHG 
standards on the industry, fuel savings, oil conservation, energy 
security and other energy impacts, as well as other relevant 
considerations such as safety.
    EPA finalized the Heavy-Duty Greenhouse Gas Emissions Phase 2 
program in 2016.\795\ This comprehensive program included GHG emission 
standards tailored to highway heavy-duty engines and each of four 
regulatory vehicle categories, including tractors and vocational 
vehicles. In Phase 2, EPA set CO2 emission standards, in 
addition to other GHG emission standards, for HD engines and vehicles 
that phase in starting in MY 2021 through MY 2027. The HD GHG Phase 2 
standards built upon the Phase 1 program promulgated in 2011, which 
established the first set of GHG emission standards for heavy-duty 
engines and trucks.\796\
---------------------------------------------------------------------------

    \795\ Id. The U.S. Department of Transportation through the 
National Highway Traffic Safety Administration (NHTSA) also 
established coordinated Phase 2 fuel efficiency standards in this 
same action as part of a joint EPA--NHTSA final rulemaking.
    \796\ 76 FR 57106 (September 15, 2011).
---------------------------------------------------------------------------

1. Background on the CO2 Emission Standards in the HD GHG 
Phase 2 Program
    In the Phase 1 and Phase 2 Heavy-Duty GHG rules, we finalized GHG 
emission standards tailored for each of the three regulatory 
categories--heavy-duty pickups and vans; vocational vehicles, and 
combination tractors. In addition, we set separate standards for the 
engines that power combination tractors and vocational vehicles. The 
heavy-duty vehicle CO2 emission standards are measured in 
grams per ton-mile, which represents the grams of CO2 
emitted to move one ton of payload one mile. In this section we provide 
background information on the two Phase 2 program categories for which 
we are proposing to make targeted changes: vocational vehicles and 
tractors.
i. Vocational Vehicles
    Class 2b-8 vocational vehicles include a wide variety of vehicle 
types and serve a wide range of functions. We define Class 2b-8 
vocational vehicles as all heavy-duty vehicles that are not included in 
the Heavy-duty Pickup Truck and Van or the Class 7 and 8 Tractor 
categories. Some examples include service for urban delivery, refuse 
hauling, utility service, dump, concrete mixing, transit service, 
shuttle service, school bus, emergency, motor homes, and tow trucks. 
The HD GHG Phase 2 program also includes a special regulatory category 
called vocational tractors, which covers vehicles that are technically 
tractors but generally operate more like vocational vehicles than line-
haul tractors. These vocational tractors include those designed to 
operate off-road and in certain intra-city delivery routes.\797\
---------------------------------------------------------------------------

    \797\ 40 CFR 1037.630.
---------------------------------------------------------------------------

    The HD GHG Phase 2 vocational vehicle CO2 standards are 
based on the performance of a wide array of control technologies. In 
particular, the Phase 2 vocational vehicle standards recognize detailed 
characteristics of vehicle powertrains and drivelines. Driveline 
improvements present a significant opportunity for reducing fuel 
consumption and CO2 emissions from vocational vehicles. 
However, there is no single package of driveline technologies that will 
be equally suitable for all vocational vehicles, because there is an 
extremely broad range of driveline configurations available in the 
market. This is due in part to the variety of final vehicle build 
configurations, ranging from a purpose-built custom chassis to a 
commercial

[[Page 17594]]

chassis that may be intended as a multi-purpose stock vehicle. 
Furthermore, the wide range of applications and driving patterns of 
these vehicles leads manufacturers to offer a variety of drivelines, as 
each performs differently in use.
    The final HD GHG Phase 2 rule has a structure for vocational 
standards that allows the technologies that perform best at highway 
speeds and those that perform best in urban driving to each be properly 
recognized over appropriate drive cycles, while avoiding potential 
unintended results of forcing vocational vehicles that are designed to 
serve in different applications to be measured against a single drive 
cycle. The final HD GHG Phase 2 rule includes three drive cycles with 
the intent of balancing the competing pressures to recognize the 
varying performance of technologies, serve the wide range of customer 
needs, and maintain reasonable regulatory simplicity. The HD GHG Phase 
2 primary vocational standards therefore have subcategories for 
Regional, Multi-purpose, and Urban drive cycles in each of the three 
weight classes (Light Heavy-Duty, Medium Heavy-Duty and Heavy-Heavy 
Duty), which results in nine unique subcategories. These nine 
subcategories apply for diesel (CI) vehicles. We separately, but 
similarly, established six subcategories of gasoline (SI) vehicles. In 
other words, there are 15 separate numerical performance-based emission 
standards for each model year. In addition, we established optional 
custom chassis CO2 emission standards for Motorhomes, Refuse 
Haulers, Coach Buses, School Buses, Transit Buses, Concrete Mixers, 
Mixed Use Vehicles, and Emergency Vehicles. In total, EPA set 
CO2 emission standards for 15 subcategories of vocational 
vehicles and eight subcategories of specialty vehicle types for a total 
of 23 vocational vehicle subcategories.
    The HD GHG Phase 2 standards phase in over a period of seven years, 
beginning in the 2021 model year. The HD GHG Phase 2 program progresses 
in three-year stages with an intermediate set of standards in MY 2024 
and final standards in MY 2027 and beyond. In the 2016 final rule we 
identified a potential technology path for complying with each of the 
three increasingly stringent stages of the HD GHG Phase 2 program 
standards. These standards were based on the performance of more 
efficient engines, workday idle reduction technologies, improved 
transmissions including mild hybrid powertrains, axle technologies, 
weight reduction, electrified accessories, tire pressure systems, and 
tire rolling resistance improvements. The Phase 2 vocational vehicle 
CO2 standards were not premised on electric vehicles or fuel 
cell vehicles. Details regarding the standards can be found in the 
Phase 2 final rulemaking preamble and in 40 CFR part 1037.\798\
---------------------------------------------------------------------------

    \798\ 81 FR 73682-73729 (October 25, 2016).
---------------------------------------------------------------------------

ii. Tractors
    EPA promulgated HD GHG Phase 2 CO2 emission standards 
for combination tractors that reflect reductions that can be achieved 
through improvements in the tractor's powertrain, aerodynamics, tires, 
idle reduction, and other vehicle systems. EPA did not premise the HD 
Phase 2 tractor standards on hybrid powertrains, fuel cells, or 
electric vehicles, though we foresaw some limited use of these 
technologies in 2021 and beyond.\799\ In the HD GHG Phase 2 final rule, 
EPA analyzed the feasibility of achieving the CO2 standards 
and identified means of achieving these standards.\800\ The tractor 
regulatory structure is attribute-based in terms of dividing the 
tractor category into ten subcategories based on the tractor's gross 
vehicle weight rating (GVWR), cab configuration, and roof height. The 
tractor cab configuration is either day cab or sleeper cab. Day cab 
tractors are typically used for shorter haul operations, whereas 
sleeper cabs are often used in long haul operations. EPA set 
CO2 emission standards for 10 tractor subcategories. Similar 
to the vocational program, the HD GHG Phase 2 tractor standards begin 
implementation in MY 2021 and fully phase-in in MY 2027. More details 
can be found in the HD GHG Phase 2 final rulemaking preamble and in 40 
CFR part 1037.\801\
---------------------------------------------------------------------------

    \799\ 81 FR 73639 (October 25, 2016).
    \800\ 81 FR 73573-73639 (October 25, 2016).
    \801\ Id.
---------------------------------------------------------------------------

2. Background on the Advanced Technology Credit Multipliers in the HD 
GHG Phase 1 and 2 Program
    EPA provided advanced technology credits in HD GHG Phase 1 for 
hybrid powertrains, Rankine cycle waste heat recovery systems on 
engines, all-electric vehicles, and fuel cell vehicles to promote the 
implementation of advanced technologies that were not included in our 
technical basis of the feasibility of the Phase 1 standards (see 40 CFR 
86.1819-14(k)(7), 1036.150(h), and 1037.150(p)). The HD GHG Phase 2 
CO2 emission standards that followed Phase 1 were premised 
on the use of mild hybrid powertrains in vocational vehicles and waste 
heat recovery systems in a subset of the engines and tractors, making 
them equivalent to other fuel-saving technologies in this context. At 
the time of the HD GHG Phase 2 final rule, we believed the HD GHG Phase 
2 standards themselves provided sufficient incentive to develop those 
specific technologies. However, none of the HD GHG Phase 2 standards 
were based on projected utilization of the other even more-advanced 
Phase 1 advanced credit technologies (e.g., plug-in hybrid vehicles, 
all-electric vehicles, and fuel cell vehicles). Overall, the comments 
on the HD GHG Phase 2 proposal in 2016 indicated that there was support 
for such advanced technology credit incentives among operators, 
suppliers, and states. For HD GHG Phase 2, EPA promulgated the 
following advanced credit multipliers through MY 2027, as shown in 
Table XI-1 (see also 40 CFR 1037.150(p)).

 Table XI-1--Advanced Technology Multipliers in Existing HD GHG Phase 2
------------------------------------------------------------------------
                         Technology                           Multiplier
------------------------------------------------------------------------
Plug-in hybrid electric vehicles............................         3.5
All-electric vehicles.......................................         4.5
Fuel cell vehicles..........................................         5.5
------------------------------------------------------------------------

    As stated in the HD GHG Phase 2 rulemaking, our intention with 
these multipliers was to create a meaningful incentive to those 
considering adopting these qualifying advanced technologies into their 
vehicles. The multipliers are consistent with values recommended by 
California Air Resources Board (CARB) in their supplemental HD GHG 
Phase 2 comments.\802\ CARB's values were based on a cost analysis that 
compared the costs of these technologies to costs of other conventional 
GHG-reducing technologies. Their cost analysis showed that multipliers 
in the range we ultimately promulgated would make these technologies 
more competitive with the conventional technologies and could allow 
manufacturers to more easily generate a viable business case to develop 
these technologies for heavy-duty vehicles and bring them to market at 
a competitive price.
---------------------------------------------------------------------------

    \802\ Letter from Michael Carter, CARB, to Gina McCarthy, 
Administrator, EPA and Mark Rosekind, Administrator, NHTSA, June 16, 
2016. EPA Docket ID EPA-HQ-OAR-2014-0827_attachment 2.
---------------------------------------------------------------------------

    In establishing the multipliers in the final HD GHG Phase 2 rule, 
we also considered the tendency of the heavy-duty sector to lag the 
light-duty sector in the adoption of a number of advanced technologies. 
There are many possible reasons for this, such as:
     Heavy-duty vehicles are more expensive than light-duty 
vehicles,

[[Page 17595]]

which makes it a greater monetary risk for purchasers to invest in 
unproven technologies.
     These vehicles are primarily work vehicles, which makes 
predictable reliability and versatility important.
     Sales volumes are much lower for heavy-duty vehicles, 
especially for specialized vehicles.
    At the time of the HD GHG Phase 2 rulemaking, we concluded that as 
a result of factors such as these, and the fact that adoption rates for 
these advanced technologies in heavy-duty vehicles were essentially 
non-existent in 2016, it seemed unlikely that market adoption would 
grow significantly within the next decade without additional 
incentives.
    As we stated in the 2016 HD GHG Phase 2 final rule preamble, we 
determined that it was appropriate to provide such large multipliers 
for these advanced technologies at least in the short term, because 
they have the potential to provide very large reductions in GHG 
emissions and fuel consumption and advance technology development 
substantially in the long term. However, because the credit multipliers 
are so large, we also stated that we should not necessarily allow them 
to continue indefinitely. Therefore, they were included in the HD GHG 
Phase 2 final rule as an interim program continuing only through MY 
2027.

B. What has changed since we finalized the HD GHG Phase 2 rule?

    When the HD GHG Phase 2 rule was promulgated in 2016, we 
established CO2 standards and advanced technology incentives 
on the premise that electrification of the heavy-duty market was 
unlikely to occur in the timeframe of the program. Several factors have 
changed our outlook for heavy-duty electric vehicles since 2016. First, 
the heavy-duty market has evolved such that in 2021, there are a number 
of manufacturers producing fully electric heavy-duty vehicles in 
several applications. Second, the State of California has adopted an 
Advanced Clean Trucks (ACT) program that includes a manufacturer sales 
requirement for zero-emission truck sales, specifically that 
``manufacturers who certify Class 2b-8 chassis or complete vehicles 
with combustion engines would be required to sell zero-emission trucks 
as an increasing percentage of their annual California sales from 2024 
to 2035.'' 803 804 Finally, other states have signed a 
Memorandum of Understanding establishing goals to increase the heavy-
duty electric vehicle market.\805\ These developments have demonstrated 
that further CO2 emission reductions in the MY 2027 
timeframe are feasible considering cost, lead time, and other factors. 
We discuss the impacts of these factors on the heavy-duty market in 
more detail in the following subsections.
---------------------------------------------------------------------------

    \803\ CARB (2021) Advanced Clean Truck Regulation, available 
online at: https://ww2.arb.ca.gov/rulemaking/2019/advancedcleantrucks.
    \804\ EPA is reviewing a waiver request under CAA section 209(b) 
from California for the ACT rule; we may consider including the ACT 
in some of our analyses for the final rule.
    \805\ Multi-State Zero Emission Medium and Heavy-Duty Vehicle 
Initiative--Memorandum of Understanding (2020), available online at: 
https://www.nescaum.org/documents/multistate-truck-zev-governors-mou-20200714.pdf.
---------------------------------------------------------------------------

1. The HD Battery Electric Vehicle Market
    Since 2012, manufacturers have developed a number of prototype and 
demonstration heavy-duty BEV projects, particularly in the state of 
California, establishing feasibility and durability of the technology 
for specific applications used for specific services, as well as 
building out necessary infrastructure.\806\ In 2019, approximately 60 
makes and models of BEVs were available for purchase, with additional 
product lines in prototype or other early development 
stages.807 808 809 Current production volumes of BEVs are 
small, with the North American Council for Freight Efficiency (NACFE) 
estimating fewer than 100 BEV Class 7/8 trucks in production in the 
U.S. in 2019.\810\ In 2020, approximately 900 heavy-duty BEVs were sold 
in the U.S. and Canada combined, consisting primarily of transit buses 
(54 percent), school buses (33 percent), and straight trucks (13 
percent).\811\ M.J. Bradley's analysis of the heavy-duty BEV market in 
2021 found 30 manufacturers that have at least one BEV model for sale 
and an additional nine companies that have made announcements to begin 
BEV production by 2025.\812\ BEV technology is increasingly used in the 
transit bus market, with electric bus sales growing from 300 to 650 in 
the U.S. between 2018 to 2019.813 814 Draft RIA Chapter 
1.4.2 provides a snapshot of BEVs in the heavy-duty truck and bus 
markets as of 2019, according to one source; however, given the dynamic 
nature of the BEV market, the number and types of vehicles available 
are changing fairly rapidly.\815\
---------------------------------------------------------------------------

    \806\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \807\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers''. American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \808\ The composition of all-electric truck models was: 36 
buses, 10 vocational trucks, 9 step vans, 3 tractors, 2 street 
sweepers, and 1 refuse truck (Nadel and Jung (2020) citing AFDC 
(Alternative Fuels Data Center). 2018. ``Average Annual Vehicle 
Miles Traveled by Major Vehicle Categories.'' www.afdc.energy.gov/data/widgets/10309.
    \809\ Note that there are varying estimates of BEV and FCEV 
models in the market; NACFE (2019) ``Guidance Report: Viable Class 
7/8 Electric, Hybrid and Alternative Fuel Tractors``, available 
online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/ (NACFE 2019) provided slightly lower estimates than those 
included here from Nadel and Jung 2020. A recent NREL study suggests 
that there may be more models available, but it is unclear how many 
are no longer on the market since the inventory includes vehicles 
introduced and used in commerce starting in 2012 (Smith et al. 
2019).
    \810\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \811\ International Council on Clean Transportation. ``Fact 
Sheet: Zero-Emission Bus and Truck Market in the United States and 
Canada: A 2020 Update.'' Pages 3-4. May 2021.
    \812\ M.J. Bradley and Associates (2021) ``Medium- and Heavy-
Duty Vehicles: Market Structure, Environmental Impact, and EV 
Readiness.'' Page 21. July 2021.
    \813\ Tigue, K. (2019) ``U.S. Electric Bus Demand Outpaces 
Production as Cities Add to Their Fleets'' Inside Climate News, 
November 14. https://insideclimatenews.org/news/14112019/electric-bus-cost-savings-health-fuel-charging.
    \814\ Note that ICCT (2020) estimates 440 electric buses were 
sold in the U.S. and Canada in 2019, with 10 of those products being 
FCEV pilots. The difference in estimates of number of electric buses 
available in the U.S. may lie in different sources looking at 
production vs. sales of units.
    \815\ Union of Concerned Scientists (2019) ``Ready for Work: Now 
Is the Time for Heavy-Duty Electric Vehicles''; www.ucsusa.org/resources/ready-work.
---------------------------------------------------------------------------

    EPA conducted an analysis for this proposal of manufacturer-
supplied end-of-year production reports provided to us as a requirement 
of the certification process for heavy-duty vehicles to our GHG 
emission standards.\816\ Based on the end-of-year production reports 
for MY 2019, manufacturers produced approximately 350 certified heavy-
duty BEVs. This is out of nearly 615,000 heavy-duty diesel vehicles 
produced in MY 2019, which represents approximately 0.06 percent of the 
market. In MY 2020, 380 BEVs were certified. The BEVs were certified in 
a variety of the Phase 1 vehicle subcategories, including light, 
medium, and heavy heavy-duty vocational vehicles and vocational 
tractors. Out of the 380 vehicles certified in MY 2020, a total of 177 
unique makes and models were available for purchase by 52 producers in 
regulatory weight classes 3-8.
---------------------------------------------------------------------------

    \816\ Memo to Docket. HD 2027 Proposed Changes to Heavy-Duty 
Greenhouse Gas Emissions. November 2021.

---------------------------------------------------------------------------

[[Page 17596]]

    Based on current trends, manufacturer announcements, and state-
level actions, electrification of the heavy-duty market is expected to 
substantially increase from current levels. However, the rate of growth 
varies widely across models. For instance, the 2021 Annual Energy 
Outlook projects heavy-duty BEVs making up 0.12 percent of new truck 
sales in 2027.\817\ A National Renewable Energy Laboratory (NREL) study 
evaluated three electrification scenarios to assess the power sector 
requirements where HD electric vehicle sales in 2050 ranged between 
less than one percent in the Reference scenario and up to 41 percent in 
the High scenario.\818\ Though these projections should not be viewed 
as a market driven projection, they do illustrate a wide range of 
future possibilities. A variety of factors will influence the extent to 
which BEVs are available for purchase and enter the market. NACFE 
looked at 22 factors by which to compare BEVs with heavy-duty diesel 
vehicles; they found that for the Class 7/8 market, a current lack of 
availability of production-level vehicles resulted in BEVs being ranked 
lower than diesels in 2019, but being ranked equal to or better than 
diesel on most factors by 2030.\819\ Manufacturers also are announcing 
their projections for zero emission heavy-duty vehicles, but they vary 
across the industry. For example, Volvo recently issued a press release 
that stated, ``Volvo Trucks believes the time is right for a rapid 
upswing in electrification of heavy road transport.'' \820\ Similarly, 
Daimler Trucks stated that it ``has the ambition to offer only new 
vehicles that are CO2-neutral in driving operation ('from 
tank to wheel') in Europe, North America and Japan by 2039.'' \821\ 
Cummins targets net-zero carbon emissions by 2050.\822\ We request 
comment on these and other estimates and projections for the heavy-duty 
EV market.
---------------------------------------------------------------------------

    \817\ U.S. Energy Information Administration. ``Annual Energy 
Outlook 2021.'' Table 49. Can be accessed at https://www.eia.gov/outlooks/aeo/tables_ref.php.
    \818\ Mai, et al. ``Electrification Futures Study: Scenarios of 
Electric Technology Adoption and Power Consumption for the United 
States.'' National Renewable Energy Laboratory. Pages 25-30. https://www.nrel.gov/docs/fy18osti/71500.pdf.
    \819\ Factors that NACFE considered fell into the following 
categories: Weight, cost, maintenance effort, vehicle life, range, 
``fuel'' availability, and general; for additional information on 
the factors and how they compare in 2019 and 2030, see NACFE (2019) 
``Guidance Report: Viable Class 7/8 Electric, Hybrid and Alternative 
Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \820\ AB Volvo. ``Volvo Trucks ready to electrify a large part 
of goods transports (volvogroup.com).'' April 20, 2021. Last 
accessed on September 10, 2021 at https://www.volvogroup.com/en/news-and-media/news/2021/apr/news-3948719.html.
    \821\ Daimler Trucks. ``CO2-Neutral Commercial 
Vehicle Fleet by 2039.'' October 25, 2019. Last accessed on 
September 10, 2021 at https://www.daimler.com/sustainability/co2-neutral-commercial-vehicle-fleet-until-2039.html.
    \822\ Cummins, Inc. ``Cummins Unveils New Environmental 
Sustainability Strategy to Address Climate Change, Conserve Natural 
Resources.'' November 14, 2019. Last accessed on September 10, 2021 
at https://www.cummins.com/news/releases/2019/11/14/cummins-unveils-new-environmental-sustainability-strategy-address-climate.
---------------------------------------------------------------------------

    The lifetime total cost of ownership (TCO), which includes 
maintenance and fuel costs, is likely a primary factor for heavy-duty 
fleets considering BEV purchases. In fact, a 2018 survey of fleet 
owners showed ``lower cost of ownership'' as the second most important 
motivator for electrifying their fleet.\823\ An International Council 
for Clean Transportation (ICCT) analysis suggests that TCO for light- 
and medium heavy-duty battery-electric vehicles could reach cost parity 
with diesel in the early 2020s, while heavy heavy-duty battery-electric 
or hydrogen vehicles are likely to reach cost parity with diesel closer 
to the 2030 timeframe.\824\ Recent findings from Phadke et al. suggest 
that BEV TCO could be 13 percent less than that of a diesel truck if 
electricity pricing is optimized.\825\
---------------------------------------------------------------------------

    \823\ The primary motivator for fleet managers was 
``Sustainability and environmental goals''; the survey was conducted 
by UPS and GreenBiz.
    \824\ ICCT (2019) ``Estimating the infrastructure needs and 
costs for the launch of zero-emissions trucks''; available online 
at: https://theicct.org/publications/zero-emission-truck-infrastructure.
    \825\ Phadke, A., et al. (2021) ``Why Regional and Long-Haul 
Trucks are Primed for Electrification Now''; available online at: 
https://eta-publications.lbl.gov/sites/default/files/updated_5_final_ehdv_report_033121.pdf.
---------------------------------------------------------------------------

    As both the ICCT and Phadke et al. studies suggest, fuel costs are 
an important part of TCO. While assumptions about vehicle weight and 
size can make direct comparisons between heavy-duty BEVs and ICEs 
challenging, data show greater energy efficiency of battery-electric 
technology relative to an ICE.826 827 Better energy 
efficiency leads lower electricity costs for BEVs relative to ICE fuel 
costs.828 829 Maintenance and service costs are also an 
important component within TCO; although there is limited data 
available on actual maintenance costs for heavy-duty BEVs, early 
experience with BEV medium heavy-duty vehicles and transit buses 
suggests the potential for lower maintenance costs after an initial 
period of learning to refine both component durability and maintenance 
procedures.\830\ To facilitate heavy-duty fleets transitioning to BEVs, 
some manufacturers are currently including maintenance in leasing 
agreements with fleets; it is unclear the extent to which a full 
service leasing model will persist or will be transitioned to a more 
traditional purchase after an initial period of 
learning.831 832
---------------------------------------------------------------------------

    \826\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors,'' available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \827\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers.'' American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \828\ NACFE (2019) ``Guidance Report: Viable Class 7/8 Electric, 
Hybrid and Alternative Fuel Tractors'', available online at: https://nacfe.org/downloads/viable-class-7-8-alternative-vehicles/.
    \829\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers''. American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \830\ U.S. Department of Energy Alternative Fuels Data Center 
(AFDC), ``Developing Infrastructure to Charge Plug-In Electric 
Vehicles'', https://afdc.energy.gov/fuels/electricity_infrastructure.html (accessed 2-27-20).
    \831\ Fisher, J. (2019) ``Volvo's First Electric VNR Ready for 
the Road.'' Fleet Owner, September 17. www.fleetowner.com/blue-fleets/volvo-s-first-electric-vnr-ready-road.
    \832\ Gnaticov, C. (2018). ``Nikola One Hydrogen Electric Semi 
Hits the Road in Official Film.'' Carscoops, Jan. 26. 
www.carscoops.com/2018/01/nikola-one-hydrogen-electric-semi-hits-road-official-film/.
---------------------------------------------------------------------------

    The potential for lower fuel and maintenance costs to outweigh a 
higher upfront cost for heavy-duty BEVs is reflected in ICCT and 
others' projections of BEVs reaching cost parity with diesels within 
the next several years; however, the current upfront cost can exceed 
that of a diesel vehicle by 60 percent or more.\833\ Upfront purchase 
price was listed as the primary barrier to heavy-duty fleet 
electrification in a 2017 survey of fleet managers, which suggests that 
state or local incentive programs to offset BEV purchase costs will 
play an important role in the near term, with improvements in battery 
costs playing a role in reducing costs in the longer-
term.834 835
---------------------------------------------------------------------------

    \833\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers.'' American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
    \834\ Other barriers that fleet managers prioritized for fleet 
electrification included: Inadequate charging infrastructure--our 
facilities, inadequate product availability, inadequate charging 
infrastructure--public; for the full list of top barriers see Nadel 
and Junga (2020), citing UPS and GreenBiz 2018.
    \835\ Nadel, S. and Junga, E. (2020) ``Electrifying Trucks: From 
Delivery Vans to Buses to 18-Wheelers.'' American Council for an 
Energy-Efficient Economy White Paper, available online at: https://aceee.org/white-paper/electrifying-trucks-delivery-vans-buses-18.
---------------------------------------------------------------------------

    The BEV market for transit and school buses continues to grow. Los 
Angeles Department of Transportation (LADOT) is one of the first 
transit organizations

[[Page 17597]]

in the country to develop a program committed to transition to zero-
emission vehicles (ZEV). Started in 2017, this program stipulates that 
all LADOT transit fleets will transition to entirely electric by 2030 
or sooner--a target that is 10 years sooner than CARB's Innovative 
Clean Transportation (ICT) regulation for all public transit to be 
electric by 2040.\836\ Since these announcements, LADOT has purchased 
27 EV transit and school buses from BYD and Proterra; by 2030, the 
number of EV buses in the LADOT fleet is expected to grow to 492 buses. 
Outside of California, major metropolitan areas including Chicago, 
Seattle, New York City, and Washington DC have zero-emissions transit 
programs with 100 percent ZEV target dates ranging from 2040-2045.\837\
---------------------------------------------------------------------------

    \836\ LADOT, (2020). ``LADOT Transit Zero-Emission Bus Rollout 
Plan'' https://ww2.arb.ca.gov/sites/default/files/2020-12/LADOT_ROP_Reso_ADA12172020.pdf.
    \837\ https://www.sustainable-bus.com/electric-bus/cta-chicago-electric-buses/, https://dcist.com/story/21/06/10/metro-goal-entirely-electric-bus-fleet-2045/, https://kingcounty.gov/depts/transportation/metro/programs-projects/innovation-technology/zero-emission-fleet.aspx, and https://www.amny.com/transit/mta-says-45-to-60-more-buses-in-recent-procurement-will-be-zero-emissions/.
---------------------------------------------------------------------------

    EV school bus programs, frequently in partnership with local 
utilities, are also being piloted across the country. These programs 
include school districts in, but not limited to, California, Virginia, 
Massachusetts, Michigan, Maryland, Illinois, New York, and 
Pennsylvania.\838\ While these school districts may not have an EV 
school bus target, the EV school bus program is a part of a broader 
initiative for regional carbon neutrality.
---------------------------------------------------------------------------

    \838\ https://www.mass.gov/info-details/ev-programs-incentives, 
https://chargedevs.com/newswire/nycs-new-school-bus-contract-includes-electric-bus-pilot/, https://olivineinc.com/wp-content/uploads/2020/10/Pittsburg-USD-Electric-School-Bus-Final-Project-Report-Final.pdf, https://cleantechnica.com/2020/01/12/largest-electric-school-bus-program-in-united-states-launching-in-virginia/, 
https://www.greentechmedia.com/articles/read/on-heels-of-253m-raise-highland-electric-lands-biggest-electric-school-bus-contract-in-the-u.s, and https://richmond.com/news/state-and-regional/govt-and-politics/va-house-slows-down-bill-that-would-allow-dominion-to-profit-off-electric-school-bus/article_edc69a16-5c2c-51c9-9733-8618d768106b.html.
---------------------------------------------------------------------------

    In a parallel path, large private heavy-duty fleet owners are also 
committed to increasing their electric fleet.\839\ A report by 
international agency International Energy Agency (IEA) provides a 
comprehensive accounting of recent announcements made by UPS, Fedex, 
DHL, Walmart, Anheuser-Busch, Amazon and PepsiCo for fleet 
electrification.\840\ Amazon and UPS, for example, placed orders in 
2020 for 10,000 BEV delivery vans from EV start-up Rivian, and Amazon 
has plans to scale up to 100,000 BEV vans by 2030. Likewise, by the end 
of 2021, PepsiCo will add 15 Tesla Semis, out of the 100 planned, to 
its fleet. These announcements include not only orders for electric 
delivery vans and semi-trucks, but more specific targets and dates to 
full electrification or net-zero emissions. Amazon, Fedex, DHL, and 
Walmart have set a commitment to fleet electrification, net-zero 
emissions or carbon neutrality by 2040. We recognize that certain 
delivery trucks and vans will likely fall into the Class 2b and 3 
regulatory category, which are not covered in this rule's proposed 
updates, but rather intend to address in a future light and medium-duty 
vehicle rulemaking.
---------------------------------------------------------------------------

    \839\ Environmental Defense Fund (2021) Zero-Emission Truck 
Deployments and Pledges in the U.S., available online at: https://blogs.edf.org/energyexchange/2021/07/28/edf-analysis-finds-american-fleets-are-embracing-electric-trucks/and https://docs.google.com/spreadsheets/d/1l0m2Do1mjSemrb_DT40YNGou4o2m2Ee-KLSvHC-5vAc/edit#gid=2049738669.
    \840\ Global EV Outlook 2021. https://iea.blob.core.windows.net/assets/ed5f4484-f556-4110-8c5c-4ede8bcba637/GlobalEVOutlook2021.pdf.
---------------------------------------------------------------------------

    In summary, the heavy-duty BEV market seems to be growing fastest 
in the areas of school buses, transit buses, delivery trucks, and short 
haul tractors. As the industry is dynamic and rapidly changing, the 
policy and vehicle examples presented here represent only a sampling of 
the BEV HDV policies and markets; outside of the US, Europe and Asia 
will also contribute to the greater zero-emissions vehicle market. We 
request comment on our assessment of the HD ZEV market and any 
additional data sources we should consider.
2. California's Advanced Clean Trucks Rule
    Heavy-duty vehicle sales and populations are significant in the 
state of California. Approximately ten percent of U.S. heavy-duty 
conventional vehicles (those powered by internal combustion engines) in 
2016 were registered in California.\841\ California adopted an Advanced 
Clean Trucks (ACT) rule in 2020, which could also influence the market 
trajectory for battery-electric and fuel cell technologies.\842\ The 
ACT requires manufacturers to sell a certain percentage of zero 
emission heavy-duty vehicles (BEVs or fuel cell vehicles) for each 
model year, starting in MY 2024. The sales requirements vary by vehicle 
class, as shown in Table XI-2, starting at 5 to 9 percent of total MY 
2024 heavy-duty vehicle sales in California and increasing to 40 to 75 
percent of MY 2035 and later sales.\843\
---------------------------------------------------------------------------

    \841\ FHWA. U.S. Highway Statistics. Available online at: 
https://www.fhwa.dot.gov/policyinformation/statistics.cfm.
    \842\ CARB. ``Notice of Decision: Advanced Clean Truck 
Regulation.'' June 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/nod.pdf. For more information on 
this proposed rulemaking in California see: https://ww2.arb.ca.gov/rulemaking/2019/advancedcleantrucks.
    \843\ CARB. ``Appendix A Proposed Regulation Order'' Advanced 
Clean Truck Regulation. May 2020. Available online at: https://ww3.arb.ca.gov/regact/2019/act2019/30dayatta.pdf (accessed July 24, 
2020).

                           Table XI-2--CARB's ACT ZEV Sales Requirements by Model Year
----------------------------------------------------------------------------------------------------------------
                                                                                                     Class 7-8
                         Model year (MY)                            Class 2b-3       Class 4-8       tractors
                                                                     (percent)       (percent)       (percent)
----------------------------------------------------------------------------------------------------------------
2024............................................................               5               9               5
2025............................................................               7              11               7
2026............................................................              10              13              10
2027............................................................              15              20              15
2028............................................................              20              30              20
2029............................................................              25              40              25
2030............................................................              30              50              30
2031............................................................              35              55              35
2032............................................................              40              60              40
2033............................................................              45              65              40
2034............................................................              50              70              40

[[Page 17598]]

 
2035+...........................................................              55              75              40
----------------------------------------------------------------------------------------------------------------

3. States' Interest in Shifting to Zero Emissions HD Vehicles
    Outside of California, several states have signaled interest in 
shifting to heavy-duty ZEV technologies and/or establishing specific 
goals to increase the heavy-duty electric vehicle market. As one 
example, a 2020 memorandum of understanding (MOU) entitled ``Multi-
State Medium- and Heavy-Duty Zero Emission Vehicle,'' organized by 
Northeast States for Coordinated Air Use Management (NESCAUM), sets 
targets ``to make all sales of new medium and heavy-duty vehicles [in 
the jurisdictions of the signatory states] zero emission vehicles by no 
later than 2050'' with an interim goal of 30 percent of all sales of 
new MD and HD vehicles being zero emission vehicles no later than 
2030.\844\ The NESCAUM MOU was signed by governors and mayor of 15 
states and districts including California, Colorado, Connecticut, 
Hawaii, Maine, Maryland, Massachusetts, New Jersey, New York, North 
Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, and 
the District of Columbia. The MOU outlines more specific commitments of 
the states to move toward zero-emissions vehicles through the Multi-
State ZEV Task Force and provides an action plan for zero-emissions 
MHDVs with measurable sales targets and a focus on overburdened and 
underserved communities. Several states that signed the MOU have since 
issued proposals to adopt California's ACT under CAA section 177, and 
we anticipate more states to follow with similar 
proposals.845 846 847 848
---------------------------------------------------------------------------

    \844\ 15 states and one district sign Multi-State MOU. https://www.nescaum.org/documents/multistate-truck-zev-governors-mou-20200714.pdf.
    \845\ EPA has not yet received a waiver request under CAA 
section 209(b) from California for the ACT rule; if we were to 
receive and grant a waiver request(s) for the ACT rule, then we may 
consider including this rule in our analyses for the final rule.
    \846\ Medium- and Heavy-Duty (MHD) Zero Emission Truck Annual 
Sales Requirements and Large Entity Reporting. New York State 
Register. September 8, 2021. Volume XLIII, Issue 36. Available 
online at: https://dos.ny.gov/system/files/documents/2021/09/090821.pdf.
    \847\ Advanced Clean Trucks Program and Fleet Reporting 
Requirements. New Jersey State Register. April 19, 2021. Available 
online at: https://www.nj.gov/dep/rules/proposals/20210419a.pdf.
    \848\ Amending Chapter 173-423 WAC Low Emission Vehicles. State 
of Washington Department of Ecology. June 22, 2021. Available online 
at: https://ecology.wa.gov/DOE/files/29/291ec96d-5aca-4c40-a249-4ef82bca6026.pdf.
---------------------------------------------------------------------------

C. Proposed Changes to HD GHG Phase 2 CO2 Standards for Targeted 
Subcategories

    EPA is proposing under its authority in CAA section 202(a) to 
revise CO2 emissions standards for a subset of MY 2027 
heavy-duty vehicles. As discussed in Section XI.B, major trucking 
fleets, manufacturers and U.S. states have announced plans to shift the 
heavy-duty fleet toward zero-emissions technology beyond levels we 
accounted for in setting the existing HD GHG Phase 2 standards in 2016. 
We developed a proposed approach to make targeted updates that reflect 
this growing HD electric vehicle market without fundamentally changing 
the HD GHG Phase 2 program. Specifically, we propose to adjust HD GHG 
Phase 2 vehicle CO2 emission standards by sales-weighting 
the projected EV production levels of school buses, transit buses, 
delivery trucks, and short-haul tractors and by lowering the applicable 
CO2 emission standards for these vehicle types in MY 2027 
accordingly. We are proposing to target these four vehicle types 
because they will likely have the highest EV sales of all heavy-duty 
vehicle types between now and 2030. These four EV vehicle types do not 
correspond directly with specific HD GHG Phase 2 standards 
subcategories (subcategories differentiated by vehicle weight, use, 
fuel type, etc.), so we have used EPA certification data to determine 
which subcategories of standards would be affected by EV production in 
MY 2027. By sales-weighing the projected production levels of the four 
EV vehicle types in 2027, our proposed approach would adjust 17 of the 
33 MY 2027 HD GHG Phase 2 vocational vehicle and tractor standards. EPA 
is not proposing to change any MY 2021 or MY 2024 vocational vehicle or 
tractor CO2 emission standards, any Class 2b/3 
CO2 emission standards, or any heavy-duty engine 
CO2 emission standards.
    To update the MY 2027 vehicle CO2 standards from the HD 
GHG Phase 2 rulemaking to reflect the recent and projected trends in 
the electrification of the HD market, we considered the impact these 
trends would have on the emissions reductions from conventional 
vehicles we had intended to achieve in setting the existing HD GHG 
Phase 2 standards. As described in this section's technology cost 
discussion, we derived the existing HD GHG Phase 2 standards by 
evaluating combinations of emission-reducing technologies and adoption 
rates in ``technology packages'' developed for each vehicle 
subcategory, e.g., advanced aerodynamics, more efficient engines, etc. 
We set the existing HD GHG Phase 2 standards at levels that would 
require all conventional vehicles to install varying combinations of 
emission-reducing technologies (the degree and types of technology can 
differ, with some vehicles that have less being offset by others with 
more), leading to CO2 emissions reductions.\849\ As 
discussed in this section and quantified in more detail in a memo to 
the docket, recent and projected developments in the electrification of 
the heavy-duty vehicle market over the next several years have 
demonstrated that further CO2 emission reductions in the MY 
2027 timeframe are feasible considering lead time, cost, and other 
factors.\850\ While we did anticipate some growth in electrification, 
we did not expect the level of innovation observed that California 
would adopt a requirement for such a large number of heavy-duty 
electric vehicles to be sold in the timeframe of the 
program.851 852 We are proposing adjustments to the MY 2027 
HD GHG Phase 2 standards to reflect this innovation and facilitate the 
transition to more stringent longer-term standards such that all 
conventional vehicles would need some level and

[[Page 17599]]

combination of GHG emissions-reducing technology, as intended in the 
original HD GHG Phase 2 rulemaking. Based on our evaluation of the 
heavy-duty EV market in the MY 2027 timeframe, we expect school buses, 
transit buses, delivery trucks, and short haul tractors to have the 
highest EV sales of all heavy-duty vehicle types between now and 2030. 
Therefore, we propose to make targeted changes to the MY 2027 standards 
that are projected to be affected by these four types of electric 
vehicles. As we describe in the next section, EPA has considered the 
technological feasibility and cost of the proposed standards and the 
available lead time for manufacturers to comply with the proposed 
standards in MY 2027. We request comment on all aspects of these 
proposed targeted updates to the MY 2027 HD GHG Phase 2 program, 
including our projections that these four vehicle categories are the 
appropriate heavy-duty vehicles EPA should focus on for our proposed 
revisions, and if there are additional vehicle categories we should be 
considering. We are also considering whether it would be appropriate in 
the final rule to increase the stringency of the standards more than 
what we have proposed. Therefore, we request information on heavy-duty 
electric vehicle sales projections, including projections based on 
future product plans, to help inform our HD electric vehicle sales 
projections in the MY 2024 through MY 2029 timeframe. Furthermore, we 
also request comment on potential impacts on small business vehicle 
manufacturers if we finalize standards that are more stringent than the 
proposal. We also request comment on whether to finalize the proposed 
standards for small business vehicle manufacturers even if we finalize 
more stringent standards for other manufacturers and whether to allow 
small business vehicle manufacturers to voluntarily comply with more 
stringent standards, if finalized, than those required for small 
manufacturers (either under the existing Phase 2 standards or as 
updated, if finalized).
---------------------------------------------------------------------------

    \849\ Considering technological feasibility, compliance cost, 
lead time, and other factors.
    \850\ Memo to Docket. HD 2027 Proposed Changes to Heavy-Duty 
Greenhouse Gas Emissions. November 2021.
    \851\ EPA has not yet received a waiver request under CAA 
section 209(b) from California for the ACT rule.
    \852\ ACT requires manufacturers to sell a certain percentage of 
zero emission heavy-duty vehicles (BEVs or fuel cell vehicles) for 
each model year, starting in MY 2024. The sales requirements vary by 
vehicle class, starting at 5 to 9 percent of total MY 2024 heavy-
duty vehicle sales in California and increasing to 15 to 20 percent 
of MY 2027 sales. Several states have followed suit and issued 
proposals to adopt California's ACT under CAA section 177, and we 
anticipate more states to follow with similar proposals.
---------------------------------------------------------------------------

    We also are considering whether to establish more stringent 
standards beyond MY 2027, specifically in MY 2028 and MY 2029, using 
the methodology discussed in Section XI.C.1 but adjusted by MY based on 
projected penetration rates of ZEV technology for those years both 
inside and outside of California. We request comment on the appropriate 
stringency and supporting data for each of those model years, and 
whether to finalize such an increase in stringency for those model 
years' standards in a one-step (single MY) or multi-step (multiple MY) 
approach. EPA requests comment and supporting data that could support 
higher penetrations of HD ZEVs in the MY 2027 to 2029 timeframe which 
could serve as the basis for the increase in the stringency 
CO2 standards for specific Phase 2 vehicle subcategories. 
For example, what information and data are available that would support 
HD ZEV penetration rates of 5 percent or 10 percent (or higher) in this 
timeframe, and in what HD vehicle applications and categories. We also 
request comment on whether EPA should adjust our proposed approach to 
allow HD ZEV manufacturers to generate NOX emission credits 
if we were to increase the stringency of the CO2 standards 
for specific Phase 2 vehicle subcategories based on higher projected 
penetrations of HD ZEVs in the MY 2027 to 2029 timeframe (see Section 
IV.I for our proposal to allow HD ZEV manufacturers to generate 
NOX emission credits).
1. Determining the Proposed Standards
    In Section XI.A we described how the HD GHG Phase 2 vehicle 
CO2 standards are differentiated by vehicle weight, use, 
fuel type, etc. to recognize the diverse nature of the industry, 
resulting in 15 subcategories for vocational vehicle standards, with an 
additional eight subcategories for specialty vehicle types, and 10 
subcategories for tractor standards. These HD GHG Phase 2 standard 
subcategories for vocational vehicles and tractors do not correspond 
directly with our projections for the four high-sales EV vehicle 
types--school buses, transit buses, delivery trucks, and short-haul 
tractors. For example, there is no subcategory with a specific standard 
for a ``delivery truck''; rather, a vocational vehicle used for 
deliveries may fall into any one of several different subcategories 
depending on its weight and use pattern. In fact, based on our review 
of the applications for certification of MY 2020 and MY 2021 vehicles, 
HD electric vehicle manufacturers of these four vehicle types are 
certifying them into several of the EPA regulatory vocational vehicle 
CI subcategories, the school bus and transit bus custom chassis 
subcategories, and into all three of the Class 8 day cab tractor 
subcategories.\853\
---------------------------------------------------------------------------

    \853\ Note that the Class 7 Tractor CO2 emission 
standards in 40 CFR 1037.106 apply to ``All Cab Styles'', but nearly 
all tractors that are subject to these standards are day cabs. 
Therefore, we refer to these as day cab tractor standards throughout 
this section.
---------------------------------------------------------------------------

    The changes we are proposing apply only to a subset of the MY 2027 
heavy-duty CO2 vehicle emission standards. We are not 
proposing any changes to the heavy-duty engine CO2 emission 
standards. The current HD GHG Phase 2 engine standards only apply to 
engines that are ``internal combustion engines.'' \854\ Electric 
vehicles are not powered by internal combustion engines. Furthermore, 
the CO2 emission credits generated from electric vehicles 
are not allowed to be brought into the engine averaging sets.\855\ 
Therefore, electric vehicles have no effect on manufacturers' 
strategies for meeting the HD engine GHG standards, and EPA is not 
proposing to modify the HD engines GHG standards.
---------------------------------------------------------------------------

    \854\ 40 CFR 1036.5(d).
    \855\ 40 CFR 1036.740.
---------------------------------------------------------------------------

    After careful consideration of an approach that would achieve 
appropriate emission reductions and account for the emerging HD EV 
market without changing the HD GHG Phase 2 program as a whole, we are 
proposing to adjust the HD GHG Phase 2 vehicle CO2 emission 
standards based on sales-weighting the projected EV production levels 
of the four types of EVs and using that information to lower the 
emission standards only for the vocational vehicle and six tractor 
subcategories that are applicable to these four types of EVs (depending 
on weight and use pattern) in MY 2027.
    Our proposed approach involves three steps. First, we projected the 
number of sales of electric school buses, transit buses, delivery 
trucks, and short-haul tractors in MY 2027 based on sales data and 
projections outlined in the next paragraph. Second, we determined the 
percentage EVs relative to the total number of vehicles produced in the 
nine CI vocational vehicle and day cab tractor subcategories, plus the 
optional school bus and transit bus subcategories.\856\ Third, we 
reduced the numeric level of the standards for the vocational vehicle 
subcategories and the applicable tractor subcategories by the projected 
percentage of electric vehicles. Under the resulting revised standards 
that we are proposing and our projections of EVs, manufacturers would 
need to either incorporate additional emissions reductions or not 
generate as many emissions credits,

[[Page 17600]]

compared to our estimates at the time of the HD GHG Phase 2 rule. This 
approach would adjust 17 of the 33 MY 2027 HD GHG Phase 2 standards. We 
believe that it is not appropriate to propose updates to the sleeper 
cab tractor standards in this action because the typical usage and 
daily miles travelled by these vehicles is beyond the range available 
in current electric tractors under development. We request comment on 
this approach and the proposed revisions to MY 2027 CO2 
emission standards.
---------------------------------------------------------------------------

    \856\ We propose that vocational EVs could certify to any of the 
CI subcategory standards, but would not be allowed to certify to any 
SI subcategory standard. This is consistent with the approach 
finalized for heavy-duty vehicles under 14,000 pounds (see 40 CFR 
86.1819(a)(2)(ii)). The GHG credit averaging sets for vehicles are 
based on GVWR and are not differentiated by SI or CI. Therefore, 
credits generated from EVs would be used within an averaging set 
that includes both SI and CI vehicles. We are not proposing any 
changes to the SI vehicle standards.
---------------------------------------------------------------------------

    Projecting the production levels of conventional and electric HD 
vehicles in MY 2027 and beyond is challenging. For this proposal, we 
used information such as the projected number of zero emission vehicles 
in the MY 2027 and beyond timeframe from CARB's ACT rulemaking 
documents, the current level of national EV sales data from the 
International Council on Clean Transportation, the number of 
conventional vehicles and electric vehicles sold based on EPA's heavy-
duty vehicle GHG certification programs, product announcements, and 
engineering judgment to inform our projection of EV production in the 
national market for MY 2027, described in the next paragraph. We 
request comment on this information, and on identification and 
description of other available information sources including, more 
specifically, data and product plans, to help inform these projections. 
If additional data is submitted by commenters related to the approach 
described in this section, we would consider it for the final rule, 
including the potential for a more stringent adjustment to the MY 2027 
standards.
    As a starting point for our national projections, CARB's ACT 
rulemaking includes (1) projections for the total number of heavy-duty 
vehicles sold in California in MY 2024 through MY 2030 and (2) a 
mandate requiring manufacturers to sell a specific percentage of zero-
emission vehicles each model year.\857\ As shown in Table XI-2, 20 
percent of vocational vehicles and 15 percent of tractor vehicles sold 
in California in MY 2027 are required by the mandate to be zero-
emission vehicles. Combining these two sets of information, we 
estimated the number of electric vehicles that would be sold in 
California in MY 2027, shown in Table XI-3.
---------------------------------------------------------------------------

    \857\ CARB. Advanced Clean Trucks Regulation. Standardized 
Regulatory Impact Analysis. Page 25. August 8, 2019.

 Table XI-3--Projected Number of HD Electric Vehicles Sold in California
                in MY 2027 Based on the CARB ACT Program
------------------------------------------------------------------------
                                             Projected
                                             number of       Projected
                                           conventional      number of
                                           and electric      electric
                                          vehicles in CA  vehicles in CA
------------------------------------------------------------------------
Class 4-8 Vocational Vehicles...........          15,945           3,189
Tractors................................           4,993             749
------------------------------------------------------------------------

    We analyzed the information provided in a recent report by the 
International Council on Clean Transportation to extrapolate the number 
of new heavy-duty electric vehicles that we would expect to be sold in 
the entire U.S. in MY 2027.\858\ The report includes the number of 
heavy-duty electric vehicles registered by state and province in the 
U.S. and Canada as of 2020. Based on these values, we estimate that 
approximately 42 percent of the heavy-duty electric vehicle sales in 
the U.S. are in California. Using this figure, we estimated the total 
number of electric vehicles in the other 49 states in MY 2027, shown in 
Table XI-4.
---------------------------------------------------------------------------

    \858\ ICCT. ``Zero-emission bus and truck market in the United 
States and Canada: A 2020 Update.'' May 2021. Pages 5-6. Can be 
accessed online at https://theicct.org/publications/canada-race-to-zero-FS-may2021.

                 Table XI-4--Projected Number of HD Electric Vehicles Sold Nationally in MY 2027
----------------------------------------------------------------------------------------------------------------
                                                                                     Projected
                                                                     Projected       number of       Projected
                                                                     number of       electric     total electric
                                                                     electric      vehicles sold   vehicles sold
                                                                   vehicles sold    in other 49     nationally
                                                                   in California      states
----------------------------------------------------------------------------------------------------------------
Class 4-8 Vocational Vehicles...................................           3,189           4,404           7,593
Tractors........................................................             749           1,034           1,783
                                                                 -----------------------------------------------
    Total.......................................................           3,938           5,538           9,376
----------------------------------------------------------------------------------------------------------------

    Next, we project the total number of U.S. heavy-duty vocational 
vehicle and tractor sales in MY 2027. Our projections come from the 
sales split by vehicle category used in the HD GHG Phase 2 
rulemaking.\859\ Furthermore, we assumed the fraction of short-haul 
tractors relative to the overall tractor sales at 37 percent based on 
the split used in MOVES3 for heavy-duty vehicles in 2027.\860\ The 
total number of projected HD vocational vehicle and day cab tractor 
sales in MY 2027 are shown in Table XI-5.
---------------------------------------------------------------------------

    \859\ U.S. EPA. ``Regulatory Impact Analysis: Greenhouse Gas 
Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty 
Engines and Vehicles--Phase 2.'' Table 7-55. Page 7-49. April 2016.
    \860\ U.S. EPA. ``Population and Activity of Onroad Vehicles in 
MOVES3.'' Table 4-44. Page 30. April 2021. Can be accessed at 
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1011TF8.pdf.

[[Page 17601]]



                     Table XI-5--Projected Number of HD Vehicles Sold Nationally in MY 2027
----------------------------------------------------------------------------------------------------------------
                                                                                                  Total day cab
             Total Class 4-8 vocational vehicles                Total tractors   Total day cab    and vocational
                                                                                    tractors         vehicles
----------------------------------------------------------------------------------------------------------------
523,805......................................................         155,682           57,602          581,407
----------------------------------------------------------------------------------------------------------------

    We are proposing an approach of aggregating the total number of 
heavy-duty electric vehicles and total number of day cab tractors and 
vocational vehicles to calculate the proposed value to account for the 
fact that many of the EV tractors will likely be certified as 
``vocational'' tractors and certified to a vocational subcategory. We 
estimate the overall percentage of heavy-duty electric vehicles in MY 
2027 based on the values shown in Table XI-4 and Table XI-5 at 
approximately 1.5 percent. EPA requests comment on this percent 
projection, including if this value should be lower or higher, and the 
data and rational for alternative projections which EPA should 
consider.
    At this projected level of EVs in MY 2027, we estimate that 
approximately five percent of conventional heavy-duty vehicles would be 
able to meet the current HD GHG Phase 2 standards without installing 
emission-reducing technologies because the standards apply as a fleet-
average.\861\ As an example for the Class 8 high roof day cab tractor 
subcategory, a manufacturer could produce 1.5 percent electric tractors 
that emit 0 gram/ton-mile; 93.5 percent of conventional vehicles with 
technology packages that emit on average at the MY 2027 standard of 
75.7 g/ton-mile; and 5 percent vehicles that emit at the baseline level 
of 98.2 g/ton-mile (i.e., no additional CO2 emission-
reducing technologies beyond Phase 1).\862\ On average, this example 
fleet would meet the current HD GHG Phase 2 MY 2027 standard of 75.7 g/
ton-mile.
---------------------------------------------------------------------------

    \861\ Memo to Docket. HD 2027 Proposed Changes to Heavy-Duty 
Greenhouse Gas Emissions. November 2021.
    \862\ For the baseline value, see 81 FR 73588.
---------------------------------------------------------------------------

    EPA's heavy-duty vehicle GHG certification data shows that EV 
products are being certified in most of the compression-ignition 
vocational vehicle subcategories, including the school buses and 
transit buses optional custom chassis subcategories, and the day cab 
tractor subcategories (about half of the total tractor subcategories). 
Therefore, we propose to revise the existing CO2 emission 
standards in these 17 subcategories. The existing vocational vehicle 
and tractor standards that would be affected are shown in Table XI-6 
and Table XI-8.
    With this proposed stringency increase, we intend for the five 
percent fraction of conventional vehicles that theoretically would not 
need additional technology to meet current HD GHG Phase 2 standards to 
need to install some combination of emissions-reducing technologies 
that on average would meet the current HD GHG Phase 2 standards. 
Applying the proposed revisions to the MY 2027 standards to the Class 8 
high roof day cab tractor subcategory example, in this hypothetical 
fleet a manufacturer would produce 1.5 percent electric tractors and 
all of the remaining conventional vehicles would themselves on average 
have CO2 emission-reducing technologies that meet the 
current HD GHG Phase 2 MY 2027 standard of 75.7 g/ton-mile standard. We 
propose the revised MY 2027 standards for the vocational vehicle and 
tractors standards, as shown in Table XI-7 and Table XI-9.\863\ In 
addition, we propose that electric vocational vehicles beginning in MY 
2027 be required to certify in one of the nine standards for 
compression-ignition vehicles or the optional custom chassis 
standards.\864\ This is consistent with the approach finalized for 
heavy-duty vehicles under 14,000 pounds GVWR (see 40 CFR 
86.1819(a)(2)(ii)). The GHG credit averaging sets for vehicles are 
based on GVWR and are not differentiated by SI or CI. Therefore, 
credits generated from EVs would be used within an averaging set that 
includes both SI and CI vehicles. We are not proposing any changes to 
the SI vehicle standards. We request comment on this approach.
---------------------------------------------------------------------------

    \863\ See proposed 40 CFR 1037.105 and 1037.106.
    \864\ See proposed 40 CFR 1037.101(c)(3).

                     Table XI-6--Existing MY 2027 Vocational Vehicle CO2 Emission Standards
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
                                                                                     CI medium
                                                                  CI light heavy       heavy      CI heavy heavy
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             367             258             269
Multi-Purpose...................................................             330             235             230
Regional........................................................             291             218             189
Optional Custom Chassis: School Bus.............................             271
Optional Custom Chassis: Transit Bus............................             286
----------------------------------------------------------------------------------------------------------------


                     Table XI-7--Proposed MY 2027 Vocational Vehicle CO2 Emission Standards
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
                                                                                     CI medium
                                                                  CI light heavy       heavy      CI heavy heavy
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             361             254             265
Multi-Purpose...................................................             325             231             226
Regional........................................................             286             215             186
Optional Custom Chassis: School Bus.............................             267
Optional Custom Chassis: Transit Bus............................             282
----------------------------------------------------------------------------------------------------------------


[[Page 17602]]


       Table XI-8--Existing MY 2027 Tractor CO2 Emission Standards
                              [g/ton-mile]
------------------------------------------------------------------------
                                                     Class 7
                                                     (all cab   Class 8
                                                     styles)   (day cab)
------------------------------------------------------------------------
Low Roof Day Cab..................................       96.2       73.4
Mid Roof Day Cab..................................      103.4       78.0
High Roof Day Cab.................................      100.0       75.7
------------------------------------------------------------------------


       Table XI-9--Proposed MY 2027 Tractor CO2 Emission Standards
                              [g/ton-mile]
------------------------------------------------------------------------
                                                     Class 7
                                                     (all cab   Class 8
                                                     styles)   (day cab)
------------------------------------------------------------------------
Low Roof..........................................       94.8       72.3
Mid Roof..........................................      101.8       76.8
High Roof.........................................       98.5       74.6
------------------------------------------------------------------------

2. Technology Costs for the Proposed Changes
    In HD GHG Phase 2, EPA projected that the CO2 emissions 
reductions can be feasibly, and cost effectively, met through 
technological improvements in several areas of the heavy-duty engine 
and vehicle.\865\ The combination of improvements in the HD GHG Phase 2 
analysis included advanced aerodynamics, more efficient engines, idle 
reduction technologies, transmission and driveline improvements, and 
lower rolling resistance tires and automatic inflation systems. In 
establishing the HD GHG Phase 2 standards and determining the 
associated technology costs, we evaluated each technology and its 
effectiveness and estimated the most appropriate adoption rate of the 
technology in each vehicle subcategory. A technology package that 
combined the technologies and adoption rate was developed for each 
vehicle subcategory and used to derive the current HD GHG Phase 2 
standards. In proposing revised standards, we apply the same technology 
packages and cost estimates developed for the existing HD GHG Phase 2 
program in 2016 to the conventional vehicles that would not otherwise 
need to apply technology due to the increase in electric vehicles 
projected for MY 2027 and beyond, absent the changes we are proposing 
in this document.
---------------------------------------------------------------------------

    \865\ 81 FR 73585 through 73613 (October 25, 2016); 81 FR 73693 
through 73719 (October 25, 2016).
---------------------------------------------------------------------------

    The fleet-average incremental per-vehicle technology package costs 
for each subcategory are summarized in the 2016 HD GHG Phase 2 preamble 
with additional details provided in the HD GHG Phase 2 RIA Chapter 
2.12. The technology cost analyses reflected both the direct costs and 
indirect costs, which included items such as warranty. Table XI-10 and 
Table XI-11 provide the per-vehicle costs of the technology packages to 
meet the HD GHG Phase 2 MY 2027 CO2 emission standards for 
tractors and vocational vehicles, respectively.866 867 As 
discussed in the HD GHG Phase 2 preamble, the per vehicle costs 
represent approximately a 12 percent increase in typical vehicle price 
for tractors and 3 percent for vocational vehicles.\868\ However, the 
benefits of the technology greatly exceed the costs and the payback 
periods are short meaning that the purchaser will see substantial new 
savings over the vehicle lifetime primarily due to reduced fuel 
costs.\869\ These same per-vehicle technology costs would apply to the 
subset of conventional vehicles that would require the technology 
package to meet the proposed revised standards, as was originally 
intended under the HD GHG Phase 2 program. We believe the technology 
costs developed during HD GHG Phase 2 are still appropriate, but we 
welcome comments on revising the technology costs.
---------------------------------------------------------------------------

    \866\ 81 FR 73621, Table III-27 (October 25, 2016).
    \867\ 81 FR 73718, Table V-30 (October 25, 2016).
    \868\ 81 FR 73482 (October 25, 2016).
    \869\ 81 FR 73481 (October 25, 2016).

                      Table XI-10--Tractor Technology Incremental Average Costs for MY 2027
                                                     [2013$]
----------------------------------------------------------------------------------------------------------------
                                                                 Class 7 high   Class 8 low/mid    Class 8 high
                 Class 7 low/mid roof day cab                    roof day cab     roof day cab     roof day cab
----------------------------------------------------------------------------------------------------------------
$10,235......................................................         $10,298          $10,439          $10,483
----------------------------------------------------------------------------------------------------------------


                                    Table XI-11--Vocational Vehicle Technology Incremental Average Costs for MY 2027
                                                                         [2013$]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                              Light HD                                                Medium HD                                 Heavy HD
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                             Multi-                                    Multi-                                    Multi-
                  Urban                      purpose      Regional        Urban        purpose      Regional        Urban        purpose      Regional
--------------------------------------------------------------------------------------------------------------------------------------------------------
$2,533..................................       $2,571        $1,486        $2,727        $2,771        $1,500        $4,151        $5,025        $5,670
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In HD GHG Phase 2, we calculated the payback period, or time it 
would take for the increase in technology package and associated costs 
to be offset by the savings in operating costs, most notably fuel 
costs. This analysis included the hardware costs of the new 
technologies and their associated fixed costs, insurance, taxes, and 
maintenance. In HD GHG Phase 2, we found that the fuel savings 
significantly exceed the costs associated with the technologies over 
the lifetime of the vehicles, with payback occurring in the fourth year 
of operation for vocational vehicle and in the second year for tractor-
trailers.\870\ This same payback analysis would apply to the proposed 
revised standards, again as we are applying the same technology 
packages with the same costs and fuel saving to conventional vehicles 
that were originally intended to have these packages under the existing 
HD GHG Phase 2 program but would not with the current rise in 
electrification, absent these changes we are proposing in this action.
---------------------------------------------------------------------------

    \870\ 81 FR 73904 (October 25, 2016).
---------------------------------------------------------------------------

3. Consistency of the Revised Standards With the Agency's Legal 
Authority
    The intent of the existing HD GHG Phase 2 program was to set the 
stringency of the standards at a level

[[Page 17603]]

that all conventional vehicles would need to install some level and 
combination of emission-reducing technologies or offset another 
conventional vehicle not installing such technology, since at that time 
we predicted very little market penetration of EVs. The proposed 
revised standards are based on the same technology packages used to 
derive the current HD GHG Phase 2 standards. To calculate the proposed 
standards, we applied these same technology packages to the subset of 
the vehicles that would otherwise not require CO2 emission-
reducing technologies due to the higher projection of HD electric 
vehicles in MY 2027 and beyond. The HD GHG Phase 2 standards were based 
on adoption rates for technologies in technology packages that EPA 
regards as appropriate under CAA section 202(a) for the reasons given 
in the HD GHG Phase 2 rulemaking in Section III.D.1 for tractors and 
Section V.C.1 for vocational vehicles.\871\ We continue to believe 
these technologies can be adopted at the estimated technology adoption 
rates for these proposed revised standards within the lead time 
provided. The fleet-wide average cost per tractor projected to meet the 
proposed revised MY 2027 standards is approximately $10,200 to $10,500. 
The fleet-wide average cost per vocational vehicle to meet the proposed 
revised MY 2027 standards ranges between $1,500 and $5,700. These 
increased costs would be recovered in the form of fuel savings during 
the first two years of ownership for tractors and first four years for 
vocational vehicles, which we still consider to be reasonable.\872\ In 
addition, manufacturers retain leeway to develop alternative compliance 
paths, increasing the likelihood of the standards' successful 
implementation. In this proposal we have considered feasibility, cost, 
lead time, emissions impact, and other relevant factors, and therefore 
these revised proposed MY 2027 standards are appropriate under CAA 
section 202(a).\873\
---------------------------------------------------------------------------

    \871\ 81 FR 73585 through 73613 (October 25, 2016); 81 FR 73693 
through 73719 (October 25, 2016).
    \872\ 81 FR 73904 (October 25, 2016).
    \873\ See Phase 2 Safety Impacts at 81 FR 73905 through 73909 
(October 25, 2016).
---------------------------------------------------------------------------

D. HD GHG Phase 2 Advanced Technology Credits for CO2 Emissions

    EPA continues to believe there is a need to incentivize the 
development of EVs in the heavy-duty sector in the near term as a path 
towards zero-emissions in the long term. Early state action and 
industry innovation related to EVs will achieve more GHG reductions in 
the near term and help set the stage for longer-term actions. However, 
the advanced technology credit multipliers for CO2 emissions 
in HD GHG Phase 2 may no longer be appropriate based on our current 
understanding of the heavy-duty market. The existing large advanced 
technology credit multipliers could result in potential reductions in 
the effective stringency of the existing MY 2024 through 2027 
standards, particularly in combination with the rise in EVs including, 
but not limited to, those built to satisfy the California ACT 
requirement. In addition, an increase in production volumes of EVs 
would likely reduce the cost differential between EVs and conventional 
vehicles, correspondingly reducing the need for large, advanced 
technology multipliers. Given these factors, we are requesting comment 
on three approaches that would reduce the number of incentive credits 
produced by electric vehicles in the MY 2024 through MY 2027 timeframe 
(i.e., credit multiplier approach for EVs certified to meet 
California's ACT Rule, advance technology credit cap approach, and 
transitional credit cap approach). We are not proposing any one of 
these approaches and request comment on all aspects of all three 
approaches.
    The HD GHG Phase 2 program currently includes advanced technology 
credit multipliers for CO2 emissions for all-electric 
vehicles, plug-in hybrid electric vehicles, and fuel cell 
vehicles.\874\ The HD GHG Phase 2 credit multipliers begin in MY 2021 
and end after MY 2027.
---------------------------------------------------------------------------

    \874\ 40 CFR 1037.150(p).
---------------------------------------------------------------------------

    The CO2 emission credits for heavy-duty vehicles are 
calculated using Equation XI-1. The CO2 emission credits for 
heavy-duty electric vehicles built between MY 2021 and MY 2027 are then 
multiplied by 4.5 and, for discussion purposes, can be visualized as 
split into two shares.\875\ The first share of credits comes from the 
reduction in CO2 emissions realized by the environment from 
an electric vehicle that is not emitting from the tailpipe, represented 
by the first 1.0 portion of the multiplier. For all-electric vehicles, 
the family emission level (FEL) value is deemed to be 0 grams/ton-
mile.\876\ Therefore, each electric vehicle produced receives emission 
credits equivalent to the level of the standard, even before taking 
into account the effect of a multiplier. The second share of credits 
does not represent CO2 emission reductions realized in the 
real world, but was established by EPA to help incentivize a nascent 
market: The emission credits for electric vehicles built between MY 
2021 and 2027 receive an advanced technology credit multiplier of 4.5, 
i.e., an additional 3.5 multiple of the standard.
---------------------------------------------------------------------------

    \875\ 40 CFR 1037.705.
    \876\ 40 CFR 1037.150(f).
---------------------------------------------------------------------------

Equation XI-1: CO2 Emission Credit Calculation for Heavy-Duty Vehicles

Emission credits (Mg) = (Std-FEL) [middot] (PL) [middot] (Volume) 
[middot] (UL) [middot] (10-6)

Where:

Std = the emission standard associated with the specific regulatory 
subcategory (g/ton-mile)
FEL = the family emission limit for the vehicle subfamily (g/ton-
mile)
PL = standard payload, in tons
Volume = U.S.-directed production volume of the vehicle subfamily
UL = useful life of the vehicle, in miles, as described in 40 CFR 
1037.105 and 1037.106

    The HD GHG Phase 2 advanced technology credit multipliers represent 
a tradeoff between encouraging a new technology that could have 
significant benefits well beyond what is required under the standards 
and providing credits that do not reflect real world reductions in 
emissions which in effect allow for emissions increases by other 
engines and vehicles. At the time we finalized the HD GHG Phase 2 
program in 2016, we balanced these factors based on our estimate that 
there would be very little market penetration of EVs in the heavy-duty 
market in the MY 2021 to MY 2027 timeframe, during which the advanced 
technology credit multipliers would be in effect. In fact, the primary 
technology packages used to determine the HD GHG Phase 2 standards did 
not include any EVs. For MY 2019, EPA's heavy-duty vehicle GHG 
certification data show that approximately 0.06 percent of heavy-duty 
vehicles certified were electric vehicles. At low adoption levels, we 
believe the balance between the benefits of encouraging additional 
electrification as compared to any negative emissions impacts of 
multipliers would be appropriate and would justify maintaining the 
current advanced technology multipliers. This is consistent with our 
assessment conducted during the development of HD GHG Phase 2 where we 
found only one all-electric HD vehicle manufacturer had certified 
through 2016, and we projected ``limited adoption of all-electric 
vehicles into the market.'' \877\ However, as discussed in Section 
XI.B, we are now in a transitional period where manufacturers are 
actively increasing their zero-emission HD vehicle offerings, and we 
expect this

[[Page 17604]]

growth to continue through the timeframe of the HD GHG Phase 2 program.
---------------------------------------------------------------------------

    \877\ 81 FR 75300 (October 25, 2016).
---------------------------------------------------------------------------

    While we did anticipate some growth in electrification would occur 
due to the credit incentives in the HD GHG Phase 2 rule, we did not 
expect the level of innovation observed or that California would adopt 
a requirement for such a large number of heavy-duty electric vehicles 
to be sold at the same time these advanced technology multipliers were 
in effect. 878 879 Based on this new information, we believe 
that the existing advanced technology multiplier credit levels may no 
longer be appropriate for maintaining the balance between encouraging 
manufactures to continue to invest in new technologies over the long 
term and potential emissions increases in the short term. We believe 
that if left as is, the multiplier credits could allow for backsliding 
of emission reductions expected from internal combustion engine 
vehicles for some manufacturers in the near term, as sales of advanced 
technology vehicles continue to increase. We show an example of this in 
Figure XI-1 using the heavy heavy-duty vehicle averaging set. At 
approximately 8.5 percent EV adoption rate into this averaging set, 
approximately 100 percent of the projected reductions from HD GHG Phase 
2 would be lost.
---------------------------------------------------------------------------

    \878\ EPA has not yet received a waiver request under CAA 
section 209(b) from California for the ACT rule.
    \879\ ACT requires manufacturers to sell a certain percentage of 
zero emission heavy-duty vehicles (BEVs or fuel cell vehicles) for 
each model year, starting in MY 2024. The sales requirements vary by 
vehicle class, starting at 5 to 9 percent of total MY 2024 heavy-
duty vehicle sales in California and increasing to 15 to 20 percent 
of MY 2027 sales. Several states have followed suit and issued 
proposals to adopt California's ACT under CAA section 177, and we 
anticipate more states to follow with similar proposals.
[GRAPHIC] [TIFF OMITTED] TP28MR22.008

    Therefore, EPA is seeking comment on the potential need to update 
the HD GHG Phase 2 advanced technology incentive program. In this 
proposal, we seek comment on three potential approaches that would be 
in addition to the proposed revised MY 2027 CO2 emission 
standards. Each of these approaches is distinct and we would only 
consider finalizing a single approach.
    California's ACT rule was adopted in 2020 and is expected to cause 
a shift in heavy-duty electric vehicle production in the U.S. The ACT 
requires manufacturers to sell a certain percentage of zero emission 
heavy-duty vehicles (BEVs or fuel cell vehicles) for each model year, 
starting in MY 2024. The sales requirements vary by vehicle class, 
starting at 5 to 9 percent of total MY 2024 heavy-duty vehicle sales in 
California and increasing to 15 to 20 percent of MY 2027 sales. EPA has 
received a waiver request under CAA section 209(b) from California for 
the ACT rule and is reviewing that request. The first approach outlined 
in this section is predicated on one potential outcome from the review 
process, which is granting a waiver request for the ACT rule. Given the 
timing of this proposed rulemaking, we have considered the

[[Page 17605]]

potential impacts of the California ACT rule on the HD GHG Phase 2 
program and we solicit comment on how we could address such potential 
impacts.
    In all three approaches, the changes would begin in MY 2024 to 
align with California's ACT program. If we finalize changes to the 
advanced technology credit program in a final rule in 2022, then we 
would be providing one year of lead time for the manufacturers' product 
planning and two years to adjust the calculations in the ABT reports 
for the MY 2024 changes.\880\ We request comment on the lead time 
needed for each of these approaches. We are also seeking comment on 
whether there are better, alternative methods that EPA should consider 
and whether we should consider changes to the advanced technology 
incentive program for fuel cell vehicles and/or plug-in hybrid 
vehicles.
---------------------------------------------------------------------------

    \880\ 40 CFR 1037.730.
---------------------------------------------------------------------------

1. Credit Multiplier Approach for EVs Certified to Meet California's 
ACT Rule
    When EPA finalized the HD GHG Phase 2 program, including the 
advanced technology credit program, we did not envision a large number 
of EVs such as required in the California ACT rule. All multipliers 
reduce the overall stringency of the standards as a trade-off for 
encouraging early innovation and adoption of new technologies, and a 
large number of vehicles that qualify for the credits can allow for 
emissions increases by other engines and vehicles at the national 
level. However, our view is that EVs built to satisfy California's ACT 
requirement would not need an additional advanced technology credit 
incentive from the HD GHG Phase 2 program. The technology feasibility 
of the proposed revised standards, as we explain in Section XI.C, and 
the flexibilities that would still be included in meeting those 
standards with the 1.0 multiplier for the EVs, show that manufacturers 
would still be able to meet the existing HD GHG Phase 2 standards in 
the MY 2024 through MY 2026 timeframe and the proposed revised MY 2027 
standards without the credits from the multipliers. Therefore, we are 
requesting comment on an approach that would treat all EVs certified in 
California in the MY 2024 through MY 2027 timeframe differently than 
the vehicles certified outside of California. Under this approach, the 
MY 2024 through MY 2027 EVs certified in California would not receive 
the advanced technology credit multiplier that currently exists. We 
note that these EVs would still continue to be deemed to have zero 
grams CO2 per ton-mile emissions and receive significant 
credits reflective of the difference between the applicable 
CO2 emission standard and zero grams. The approach to EVs 
certified to the EPA program for new vehicles sold outside of 
California and not subject to California standards in other states 
under Section 177 would remain unchanged and receive the advanced 
credit multiplier. We request comment on this approach in general, and 
we request specific comment on whether maintaining this multiplier for 
EVs sold outside of California could impact manufacturer production 
plans.
2. Advanced Technology Credit Cap Approach
    In Phase 1, EPA included a provision that capped the amount of 
advanced technology credits that could be brought into any averaging 
set in any model year at 60,000 Mg of CO2 emissions to 
prevent market distortions.\881\ The second approach we are requesting 
comment on is similar to the Phase 1 advanced technology credit cap 
approach. We did not finalize such a cap in HD GHG Phase 2 because, as 
described at the beginning of this section, we believe we appropriately 
balanced encouraging new technologies and potential emissions increases 
under the assumption that there would be very limited adoption of EVs 
during the HD GHG Phase 2 timeframe. However, the option for unlimited 
advanced technology credit multipliers for CO2 emissions in 
HD GHG Phase 2 may no longer be appropriate considering the observed 
and projected rise in electrification.
---------------------------------------------------------------------------

    \881\ 76 FR 57246 (September 15, 2011). Regulations can be found 
in 40 CFR 1036.740(c)(1).
---------------------------------------------------------------------------

    Under this credit cap approach, advanced technology credits 
generated due to the production of EVs on an annual basis that are 
under the cap would remain unchanged. Above the cap, the multiplier 
would effectively be a value of 1.0; in other words, after a 
manufacturer reaches their cap in any model year, the multiplier would 
no longer be available and would have no additional effect on credit 
calculations. Each electric vehicle produced would still receive 
emission credits equivalent to the level of the standard (the real-
world emission reduction), but this effect would not be multiplied to 
generate additional credits for that manufacturer.
    The first step in developing this approach would be to determine 
the appropriate level of EV adoption rate above which to apply the cap. 
The cap could be set at a lower level to be more protective of the 
environment or at a higher level to continue to provide strong 
incentives to the development of heavy-duty EVs. In setting the value 
EPA would consider how the selected cap level limits losses of the HD 
GHG Phase 2 program's emission reduction efficacy.
    We seek comment on an approach that would set a cap at a level that 
would restrict the credit multipliers for EVs produced above a 
threshold of one percent of the total projected vehicle production 
volumes. We first projected the number of total vehicles certified in 
each averaging set.\882\ In MY 2019, the most recent year for which we 
have data, approximately 167,000 HD vehicles were certified into light 
heavy-duty; approximately 177,000 into medium heavy-duty; and 
approximately 267,000 into heavy heavy-duty averaging sets. Next, we 
determined the number of EV manufacturers. In MY 2019, there were a 
total of 26 manufacturers that had either certified electric vehicles 
or notified EPA that they were a small manufacturer that produced 
vehicles that were excluded from the regulations due to the small 
business provision in 40 CFR 1037.150(c)(3). The potential cap values 
represent approximately 65 vehicles per manufacturer per year in each 
of the light and medium heavy-duty averaging sets and approximately 100 
vehicles per manufacturer per year for the heavy heavy-duty averaging 
sets. This advanced technology credit cap approach would limit the 
credits generated by a manufacturer's use of the advanced technology 
credit multipliers for battery electric vehicles to the following 
levels of CO2 per manufacturer per model year beginning in 
MY 2024 and extending through MY 2027:
---------------------------------------------------------------------------

    \882\ Memo to Docket. HD 2027 Approaches to Change the Heavy-
Duty GHG Phase 2 Advanced Technology Credit Incentive Program. 
September 2021.

 Light Heavy-Duty Vehicle Averaging Set: 42,000 Mg 
CO2
 Medium Heavy-Duty Vehicle Averaging Set: 75,000 Mg 
CO2
 Heavy Heavy-Duty Vehicle Averaging Set: 325,000 Mg 
CO2

    We request comment on applying this general approach to a different 
EV threshold based on a sales percentage or absolute emissions cap, the 
structure of the credit cap, the assumptions that would be used in 
developing the numerical value of the caps, and whether these credit 
caps also should apply to plug-in hybrids and fuel cell vehicles.

[[Page 17606]]

3. Transitional Credit Multipliers Approach
    A third option to limit the credit multiplier impact would be to 
reduce and phase-out the magnitude of the credit multipliers over a 
period of model years. EPA has always intended the credit multipliers 
to serve as a temporary incentive for manufacturers to develop and use 
zero-emission technologies. The HD GHG Phase 2 advanced technology 
credit multipliers currently end after MY 2027. The credit multipliers 
were not considered in determining the feasibility of the HD GHG Phase 
2 CO2 emission standards. The feasibility was determined 
through the evaluation of conventional technologies, as described in 
Section XI.C.
    As noted in Section XI.A.2, the HD GHG Phase 2 advanced technology 
credit multipliers were derived based on CARB's cost analysis that 
compared the costs of BEVs in the 2015/2016 timeframe to costs of other 
conventional CO2-reducing technologies. CARB's cost analysis 
showed that multipliers in the range we finalized for HD GHG Phase 2 
would make these technologies closer to cost-competitive with the 
conventional technologies. Since 2016, the electric vehicle market has 
grown and is now projected to continue growing in ways we did not 
anticipate in HD GHG Phase 2: Namely that we did anticipate small 
growth in electrification due to the credit incentives, but we did not 
predict the large numbers of heavy-duty EVs associated with 
California's ACT requirement, as described in Section XI.B.2. 
Therefore, the projected costs of electric vehicles in the future 
continue to decrease to reflect the increase in learning and production 
levels. For this proposal, EPA recreated the BEV technology cost 
analysis to determine new values under consideration for the advanced 
technology credits. The analysis was updated using new information on 
the cost of EVs in the form of CARB's incremental BEV costs developed 
in 2019.\883\ We maintained the conventional vehicle technology costs 
and associated final HD GHG Phase 2 CO2 emission standards 
in this analysis as we believe the cost of the conventional technology 
packages developed under HD GHG Phase 2 is still appropriate. The 
analysis for MY 2024 is shown in Table XI-12 and for MY 2027 in Table 
XI-13.
---------------------------------------------------------------------------

    \883\ California Air Resources Board. Advanced Clean Trucks 
Regulation. Standardized Regulatory Impact Analysis. Table G8, Page 
31. August 8, 2019.
[GRAPHIC] [TIFF OMITTED] TP28MR22.009


[[Page 17607]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.010

    Under this approach, based on the values calculated in Table XI-12 
and Table XI-13, EPA is taking comment on revising the advanced 
technology multipliers for BEVs to transition by model year as shown in 
Table XI-14. We request comment on this approach, the values used in 
the credit multiplier calculations, and the impact of decrementing the 
credit multipliers on the timeframe shown in Table XI-14. We request 
comment on all aspects of this approach.

                                                   Table XI-14--Advanced Technology Credit Multipliers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               2023            2024            2025            2026            2027            2028
--------------------------------------------------------------------------------------------------------------------------------------------------------
Existing Advanced Credit Multipliers for Electric                    4.5             4.5             4.5             4.5             4.5             1.0
 Vehicles...............................................
Advanced Credit Multipliers for Electric Vehicles under              4.5             3.5             3.0             2.0             1.5             1.0
 Consideration..........................................
--------------------------------------------------------------------------------------------------------------------------------------------------------

E. Emissions and Cost Impacts of Proposed Revised MY 2027 CO2 Emission 
Standards

    As discussed throughout this section, we established the HD GHG 
Phase 2 program in 2016 based in part on projections that 
electrification of the heavy-duty market was unlikely to occur in the 
timeframe of the program. The recent rise in EV product offerings, 
which are projected to grow through MY 2027 and beyond, could affect 
the amount of technology required to be installed on conventional 
vehicles to meet the standards. As noted in Section XI.C, we derived 
the HD GHG Phase 2 standards based on a ``technology package'' that 
combined emission-reducing technologies with adoption rates developed 
for each vehicle subcategory. We set the current HD GHG Phase 2 
standards at levels that would require conventional vehicles to install 
some combination of these technologies, leading to CO2 
emissions reductions.\884\ We estimate that the increase in electric 
vehicles in the timeframe of the HD GHG Phase 2 program would now allow 
approximately five percent of conventional vehicles to meet the 
standards without installing emission-reducing technologies.\885\ The 
increase in the stringency we propose adjusts the standard levels such 
that this five percent fraction of conventional vehicles would on 
average need to install some combination of emissions-reducing 
technology. As shown in Section XI.C, we estimate the overall 
percentage of electric vehicles in the vocational and day cab tractor 
subcategories in MY 2027 to be 1.5 percent, deriving the increase in 
stringency from this value. The existing HD GHG Phase 2 program was 
estimated to reduce CO2 emissions by approximately 1 billion 
metric tons over the life of vehicles and engines sold during the 
program and provide over $200 billion in net societal benefits at an 
aggregate technology cost to HD vehicle buyers and operators of roughly 
$25 billion (using a 3 percent discount rate).\886\ The small 
adjustment to the select standards we are proposing would generally 
maintain the anticipated costs and benefits of the HD GHG Phase 2 
program, with a less than one percent decrease in CO2 
emissions and less than two percent increase in technology costs 
projected for the 2027 MY vehicles in the HD GHG Phase 2 rulemaking.
---------------------------------------------------------------------------

    \884\ Considering technological feasibility, compliance cost, 
lead time and other factors noted in Section I.C.
    \885\ Memo to Docket. HD 2027 Proposed Changes to Heavy-Duty 
Greenhouse Gas Emissions. November 2021.
    \886\ 81 FR 73482, and 73894-73905 (October 25, 2016).
---------------------------------------------------------------------------

    The proposed revised MY 2027 CO2 emission standards 
would result in

[[Page 17608]]

modest additional changes in CO2 emission reductions. With 
the existing HD GHG Phase 2 emission standards and our projected 
increase in electric vehicles in the MY 2027, the MY 2027 vocational 
vehicles and tractors are projected to emit 29 million metric tons of 
CO2 emissions in calendar year 2027, as shown in the 
Reference Case column of Table XI-15.\887\ Also as shown in Table XI-
15, the proposed increase in stringency of the MY 2027 vocational 
vehicle and day cab tractor standards would lead to a 1.5 percent 
reduction in the CO2 emissions only from the subcategories 
of vehicles with the proposed revised standards. Overall, the proposed 
standards would lead to a reduction of approximately 222,000 metric 
tons in 2027 beyond the current HD GHG Phase 2 program. This represents 
a 0.7 percent reduction in CO2 emissions from the overall 
heavy-duty vocational vehicle and tractor sector (that includes sleeper 
cab tractors that remain unchanged) in 2027 compared to the emissions 
from these sectors with the existing HD GHG Phase 2 standards if they 
were to remain unchanged. Similar levels of annual reductions in 
CO2 emissions would be expected in the years beyond 2027 for 
these MY 2027 vehicles, though those future-year impacts have not been 
quantified.
---------------------------------------------------------------------------

    \887\ Memo to Docket. HD 2027 Proposed Changes to Heavy-Duty 
Greenhouse Gas Emissions. November 2021.
---------------------------------------------------------------------------

    There would be climate-related benefits associated with the 
CO2 emission reductions achieved by the targeted revisions, 
but we are not monetizing them in this proposal.\888\ We request 
comment on how to address the climate benefits and other categories of 
non-monetized benefits of the proposed rule. We intend to conduct 
additional analysis for the final rule after reviewing public comments 
related to the proposed revised standards and considering any changes 
to the proposed advanced technology credit program.
---------------------------------------------------------------------------

    \888\ The U.S. District Court for the Western District of 
Louisiana has issued an injunction concerning the monetization of 
the benefits of greenhouse gas emission reductions by EPA and other 
defendants. See Louisiana v. Biden, No. 21-cv-01074-JDC-KK (W.D. La. 
Feb. 11, 2022).

    Table XI-15--CO2 Emissions Impact of Proposed Standards for 2027
                              Calendar Year
------------------------------------------------------------------------
                                          Reference case
                                           CO2 emissions   CO2 emission
                                           from MY 2027     reductions
                                             vehicles      (metric tons)
                                           (metric tons)
 
------------------------------------------------------------------------
Light Heavy Vocational..................       2,419,884          36,298
Medium Heavy Vocational.................       3,433,171          51,498
Heavy Heavy Vocational..................         955,382          14,331
Medium Heavy Day Cab Tractors...........       4,068,458          61,027
Heavy Heavy Day Cab Tractors............       3,921,448          58,822
Heavy Heavy Sleeper Cab Tractors........      14,290,255  ..............
                                         -------------------------------
    Total...............................      29,088,598         221,975
------------------------------------------------------------------------

    The aggregate technology costs resulting from the proposed changes 
in the MY 2027 standards are shown in Table XI-16. The average costs 
per vehicle represent the technology package costs developed for 
conventional vehicles to meet the HD GHG Phase 2 standards. The 
projected sales in MY 2027 were generated from MOVES3. The percentage 
of conventional vehicles needed to improve to meet the proposed revised 
standards are approximately five percent, as discussed in Section XI.C. 
The aggregated technology cost in MY 2027 of the proposed revised 
standards is approximately $98 million. This compares to the MY 2027 
technology costs of the HD GHG Phase 2 rule of $5.2 billion 
(2013$).\889\ We request comment on this cost analysis.
---------------------------------------------------------------------------

    \889\ U.S. EPA and NHTSA. ``Regulatory Impact Analysis: 
Greenhouse Gas Emission and Fuel Efficiency Standards for Medium- 
and Heavy-Duty Vehicles--Phase 2.'' EPA-420-R-16-900. August 2016. 
Page 7-21.

              Table XI-16--Technology Cost Due to Proposed Increase in Emission Standard Stringency
----------------------------------------------------------------------------------------------------------------
                                                                                      Phase 2
                                     Projected     Percentage of     Number of      technology      Total cost
                                    sales in MY    conventional    conventional      cost  per        (2013$
                                       2027          vehicles        vehicles         vehicle        millions)
                                                   affected (%)      affected       (2013$) \a\
----------------------------------------------------------------------------------------------------------------
Light Heavy Vocational..........         141,716               5           7,086          $2,533           $17.9
Medium Heavy Vocational.........         180,432               5           9,021           2,727            24.6
Heavy Heavy Vocational..........         138,453               5           6,923           4,151            28.7
Medium Heavy Day Cab Tractors...          10,558               5             528          10,235             5.4
Heavy Heavy Day Cab Tractors....          41,334               5           2,067          10,439            21.6
                                 -------------------------------------------------------------------------------
    Total.......................  ..............  ..............  ..............  ..............              98
----------------------------------------------------------------------------------------------------------------
\a\ 81 FR 73620 and 73716 (October 25, 2016) noting the Urban subcategory costs.


[[Page 17609]]

F. Summary of Proposed Changes to HD GHG Phase 2

    In summary, we are proposing some updates to the existing HD GHG 
Phase 2 and seeking comment on other potential changes. First, we 
propose to reduce the MY 2027 CO2 emission standards for the 
compression-ignition vocational vehicles subcategories, the optional 
school bus and other bus subcategories, and the day cab tractor 
subcategories. We are also considering whether it would be appropriate 
in the final rule to increase the stringency of the standards even more 
than what we propose, specifically for MYs 2027, 2028, and/or 2029. 
Second, we seek comment on three different approaches to potentially 
revise the credits generated by a manufacturer's use of the advanced 
technology credit multipliers for battery electric vehicles in MY 2024 
through MY 2027. We request comments about all aspects of these 
proposed updates to the CO2 emission standards and revisions 
under consideration for the advanced technology incentive program.

XII. Other Amendments

    This section describes several amendments to correct, clarify, and 
streamline a wide range of regulatory provisions for many different 
types of engines, vehicles, and equipment.\890\ Section XII.A includes 
technical amendments to compliance provisions that apply broadly across 
EPA's emission control programs to multiple industry sectors, including 
light-duty vehicles, light-duty trucks, marine diesel engines, 
locomotives, and various types of nonroad engines, vehicles, and 
equipment. Some of those amendments are for broadly applicable testing 
and compliance provisions in 40 CFR parts 1065, 1066, and 1068. Other 
cross-sector issues involve making the same or similar changes in 
multiple standard-setting parts for individual industry sectors.
---------------------------------------------------------------------------

    \890\ A docket memo includes redline text to highlight all the 
changes to the regulations in the proposed rule. See ``Redline 
Document Showing Proposed Changes to Regulatory Text in the Heavy-
Duty 2027 Rule'', EPA memorandum from Alan Stout to Docket EPA-HQ-
OAR-2019-0055.
---------------------------------------------------------------------------

    We are proposing amendments in two areas of note for the general 
compliance provisions in 40 CFR part 1068. First, we are proposing to 
take a comprehensive approach for making confidentiality determinations 
related to compliance information that companies submit to EPA. We are 
proposing to apply these provisions for all highway, nonroad, and 
stationary engine, vehicle, and equipment programs, as well as aircraft 
and portable fuel containers. Second, we are proposing provisions that 
include clarifying text to establish what qualifies as an adjustable 
parameter and to identify the practically adjustable range for those 
adjustable parameters. The adjustable parameters proposal also includes 
specific provisions related to electronic controls that aim to deter 
tampering.
    The rest of Section XII describes proposed amendments that apply 
uniquely for individual industry sectors. These proposed amendments 
would apply to heavy-duty highway engines and vehicles, light-duty 
motor vehicles, large nonroad SI engines, small nonroad SI engines, 
recreational vehicles and nonroad equipment, marine diesel engines, 
locomotives, and stationary emergency CI engines.

A. General Compliance Provisions (40 CFR Part 1068) and Other Cross-
Sector Issues

    The regulations in 40 CFR part 1068 include compliance provisions 
that apply broadly across EPA's emission control programs for engines, 
vehicles, and equipment. This section describes several proposed 
amendments to these regulations. This section also includes amendments 
that make the same or similar changes in multiple standard-setting 
parts for individual industry sectors. The following sections describe 
these cross-sector issues.
1. Proposed Confidentiality Determinations
    EPA adopts emission standards and corresponding certification 
requirements and compliance provisions that apply to on-highway CI and 
SI engines (such as those proposed in this action for on-highway heavy-
duty engines) and vehicles, and to stationary and nonroad CI and SI 
engines, vehicles, and equipment. Nonroad applications include marine 
engines, locomotives, and a wide range of other land-based vehicles and 
equipment. Standards and certification requirements also apply for 
portable fuel containers and for fuel tanks and fuel lines used with 
some types of nonroad equipment. Standards and certification 
requirements also apply for stationary engines and equipment, such as 
generators and pumps. EPA also has emission standards for aircraft and 
aircraft engines. Hereinafter, these are all ``sources.'' Under this 
proposal, certain information the manufacturers must submit under the 
standard-setting parts \891\ for certification, compliance oversight, 
and in response to certain enforcement activities \892\ would be 
subject to disclosure to the public without further notice.
---------------------------------------------------------------------------

    \891\ 40 CFR parts 2, 59, 60, 85, 86, 87, 1068, 1030, 1033, 
1036, 1037, 1039, 1042, 1043, 1045, 1048, 1051, 1054, and 1060. 
These parts are hereinafter collectively referred to as ``the 
standard-setting parts.''
    \892\ We also receive numerous FOIAs for information once 
enforcement actions have concluded. In responding to those requests, 
to the extent the information corresponds to a category of 
certification or compliance information that we are proposing a 
determination for in this rulemaking, if finalized we would 
similarly consider such information emissions data or otherwise not 
entitled to confidential treatment, or CBI.
---------------------------------------------------------------------------

    The CAA states that ``[a]ny records, reports or information 
obtained under [section 114 and parts B and C of Subchapter II] shall 
be available to the public. . . .'' \893\ Thus, the CAA begins with a 
presumption that the information submitted to EPA will be available to 
be disclosed to the public.\894\ It then provides a narrow exception to 
that presumption for information that ``would divulge methods or 
processes entitled to protection as trade secrets. . . .'' \895\ The 
CAA then narrows this exception further by excluding ``emission data'' 
from the category of information eligible for confidential treatment. 
While the CAA does not define ``emission data,'' EPA has done so by 
regulation at 40 CFR 2.301(a)(2)(i). EPA releases, on occasion, some of 
the information submitted under CAA sections 114 and 208 to parties 
outside of the Agency of its own volition, through responses to 
requests submitted under the Freedom of Information Act 
(``FOIA''),\896\ or through civil litigation. Typically, manufacturers 
may claim some of the information is entitled to confidential treatment 
as confidential business information (``CBI''), which is exempt from 
disclosure under Exemption 4 of the FOIA.\897\ Generally, when we have 
information that we intend to disclose publicly that is covered by a 
claim of confidentiality under FOIA Exemption 4, EPA has a process to 
make case-by-case or class determinations under 40 CFR part 2 to 
evaluate whether such information qualifies for confidential treatment 
under the exemption.\898\
---------------------------------------------------------------------------

    \893\ CAA section 114(c) and 208(c); 42 U.S.C. 7414(c) and 
7542(c).
    \894\ CAA section 114(c) and 208(c); 42 U.S.C. 7414(c) and 
7542(c).
    \895\ CAA section 114(c) and 208(c); 42 U.S.C. 7414(c) and 
7542(c).
    \896\ 5 U.S.C. 552.
    \897\ 5 U.S.C. 552(b)(4).
    \898\ 40 CFR 2.205.
---------------------------------------------------------------------------

    This rulemaking proposes provisions regarding the confidentiality 
of information that is submitted for a wide range of engines, vehicles, 
and equipment that are subject to emission

[[Page 17610]]

standards and other requirements under the CAA. This includes motor 
vehicles and motor vehicle engines, nonroad engines and nonroad 
equipment, aircraft and aircraft engines, and stationary engines. It 
also includes portable fuel containers regulated under 40 CFR part 59, 
subpart F, and fuel tanks, fuel lines, and related fuel system 
components regulated under 40 CFR part 1060. The proposed regulatory 
provisions regarding confidentiality determinations for these products 
would be codified broadly in 40 CFR part 1068, with additional detailed 
provisions for specific sectors in the regulatory parts referenced in 
40 CFR 1068.1. With this rulemaking, EPA is proposing to make 
categorical emission data and CBI determinations in advance through 
this notice and comment rulemaking for some information collected by 
EPA for engine, vehicle, and equipment certification and compliance, 
including information collected during certain enforcement 
actions.\899\ At this time, we are not proposing to determine that any 
information is CBI or entitled to confidential treatment. We are 
proposing to maintain the 40 CFR part 2 process for the information we 
are not determining to be emission data or otherwise not entitled to 
confidential treatment in this rulemaking. As explained further below, 
the emission data and CBI determinations proposed in this action are 
intended to increase the efficiency with which the Agency responds to 
FOIA requests and to provide consistency in the treatment of the same 
or similar information collected under the standard-setting parts. We 
believe doing these determinations through this rulemaking will provide 
predictability for both information requesters and submitters. We also 
believe that the proposed emission data and CBI determinations will 
lead to greater transparency in the certification programs.
---------------------------------------------------------------------------

    \899\ Throughout this preamble, we refer to certification and 
compliance information. Hereinafter, the enforcement information 
covered by this proposed confidentiality determination is included 
when we refer to certification and compliance information.
---------------------------------------------------------------------------

    In 2013 EPA published CBI class determinations for information 
related to certification of engines and vehicles under the standard-
setting parts.\900\ These determinations established whether those 
particular classes of information were releasable or entitled to 
treatment as CBI and could be instructive when making case-by-case 
determinations for other similar information within the framework of 
the CAA and the regulations. However, the determinations did not 
resolve all confidentiality questions regarding information submitted 
to the Agency for the standard-setting parts, and EPA receives numerous 
requests each year to disclose information that is not within the scope 
of these 2013 CBI class determinations.
---------------------------------------------------------------------------

    \900\ EPA, Class Determination 1-13, Confidentiality of Business 
Information Submitted in Certification Applications for 2013 and 
subsequent model year Vehicles, Engines and Equipment, March 28, 
2013, available at https://www.epa.gov/sites/default/files/2020-02/documents/1-2013_class_determination.pdf.
---------------------------------------------------------------------------

    Prior to this rulemaking, the Agency has followed the existing 
process in 40 CFR part 2 when making case-by-case or class 
confidentiality determinations. The part 2 CBI determination process is 
time consuming for information requesters, information submitters, and 
EPA. The determinations proposed in this rulemaking would allow EPA to 
process requests for information more quickly, as the Agency would not 
need to go through the part 2 process to make case-by-case 
determinations. Additionally, the proposed determinations would also 
provide predictability and consistency to information submitters on how 
EPA will treat their information. Finally, the part 2 CBI determination 
process is very resource-intensive for EPA, as it requires personnel in 
the program office to draft letters to the manufacturers (of which 
there may be many) requesting that they substantiate their claims of 
confidentiality, review each manufacturer's substantiation response, 
and provide a recommendation, and for the Office of General Counsel to 
review all of the materials and make a final determination on the 
entitlement of the information to confidential treatment. For these 
reasons, we are proposing to amend our regulations in 40 CFR parts 2 
and 1068 to establish a broadly applicable set of CBI determinations by 
categories of information, through rulemaking. With this action, we 
propose to supersede the class determinations made in 2013, though we 
intend this rulemaking to be consistent with the 2013 class 
determinations for Tables 1 and 2. Specifically, the CBI class 
determinations reflected in Table 1 and Table 2 of the 2013 
determination are consistent with the proposed determinations described 
in Section XII.A.1.i. and Section XII.A.1.iii, respectively. However, 
for the reasons described in Section XII.A.1.iv, we propose that the 
information in Table 3 of the 2013 determination will be subject to the 
existing part 2 process, such that EPA would continue to make case-by-
case CBI determinations as described below in Section XII.A.1.iv.
    In this action, EPA is proposing regulations to establish 
categories for the information submitted under the standard-setting 
parts and to determine whether such categories of information are 
entitled to confidential treatment, including proposed revisions to 40 
CFR parts 2, 59, 60, 85, 86, 87, 1030, 1033, 1036, 1037, 1043, 1045, 
1048, 1051, 1054, 1060, and 1068. The proposed confidentiality 
determinations for these categories, and the basis for such proposed 
determinations, are described below. Additionally, a detailed 
description of the specific information submitted under the standard-
setting parts that currently falls within these categories is also 
available in the docket for this rulemaking.\901\ The proposed 
determinations made in this rulemaking, if finalized, will serve as 
notification of the Agency's decisions on (1) the categories of 
information the Agency will not treat as confidential, and (2) the 
categories of information that may be claimed as confidential but will 
remain subject to the existing part 2 process. We are not proposing in 
this rulemaking to make a determination in favor of confidential 
treatment for any information collected for certification and 
compliance of engines, vehicles, equipment, and products subject to 
evaporative emission standards. In responding to requests for 
information not determined in this proposal to be emission data or 
otherwise not entitled to confidential treatment, we propose to apply 
the existing part 2 case-by-case process.
---------------------------------------------------------------------------

    \901\ See Zaremski, Sara. Memorandum to docket EPA-HQ-OAR-2019-
0055. ``Supplemental Information for CBI Categories for All 
Industries and All Programs''. October 1, 2021, and attachment ``CBI 
Categories for All Industries All Programs'' (hereinafter ``CBI 
Chart''), available in the docket for this action.
---------------------------------------------------------------------------

    For future use, we are proposing provisions in the Agency's Clean 
Air Act-specific FOIA regulations at 40 CFR 2.301(j)(2) and 2.301(j)(4) 
concerning information determined to be entitled to confidential 
treatment through rulemaking in 40 CFR part 1068. These provisions are 
very similar to the regulations established by the Greenhouse Gas 
Reporting Program from 40 CFR part 98 that is addressed at 40 CFR 
2.301(d). The proposed regulation at 40 CFR 2.301(j)(4)(ii) is intended 
for the Agency to reconsider a determination that information is 
entitled to confidential treatment under 40 CFR 2.204(d)(2) if there is 
a change in circumstance in the future. This provision is intended to 
maintain flexibility the Agency currently has

[[Page 17611]]

under its part 2 regulations. These proposed regulations at 40 CFR 
2.301(j)(2) and (4) do not have any effect at this time since the 
Agency is not proposing to find any information to be entitled to 
confidential treatment in this rulemaking, but are being proposed for 
future use.
    The information categories we are proposing in this action are:
    (1) Certification and compliance information,
    (2) fleet value information,
    (3) source family information,
    (4) test information and results,
    (5) averaging, banking, and trading (``ABT'') credit information,
    (6) production volume information,
    (7) defect and recall information, and
    (8) selective enforcement audit (``SEA'') compliance information.
    The information submitted to EPA under the standard-setting parts 
can be grouped in these categories based on their shared 
characteristics. That said, much of the information submitted under the 
standard-setting parts could be logically grouped into more than one 
category. For the sake of organization, we have chosen to label 
information as being in just one category where we think it fits best. 
We believe this approach will promote greater accessibility to the CBI 
determinations proposed here, reduce redundancy within the categories 
that could lead to confusion, and ensure consistency in the treatment 
of similar information in the future. We are requesting comment on the 
following: (1) Our proposed categories of information; (2) the proposed 
confidentiality determination on each category; and (3) our placement 
of each data point under the category proposed.
i. Information That Is Emission Data and Therefore Not Entitled to 
Confidential Treatment.
    In this proposal, we are applying the regulatory definition of 
``emission data'' in 40 CFR 2.301(a)(2)(i) to propose that certain 
categories of source certification and compliance information are not 
entitled to confidential treatment. As relevant here, a source is 
generally the engine, vehicle, or equipment covered by a certificate of 
conformity. Alternatively, a source is each individual engine, vehicle, 
or equipment produced under a certificate of conformity. The CAA 
provides in sections 114 and 208 that certain information may be 
entitled to confidential treatment; however, it expressly excludes 
emission data from that category of information. The CAA does not 
define ``emission data,'' but EPA has done so by regulation in 40 CFR 
2.301(a)(2)(i).
    Agency regulations broadly define emission data as information that 
falls into one or more of three types of information. Specifically, 
emission data is defined in 40 CFR 2.301(a)(2)(i), for any source of 
emission of any substance into the air as:
     Information necessary to determine the identity, amount, 
frequency, concentration, or other characteristics (to the extent 
related to air quality) of any emission which has been emitted by the 
source (or of any pollutant resulting from any emission by the source), 
or any combination of the foregoing;
     Information necessary to determine the identity, amount, 
frequency, concentration, or other characteristics (to the extent 
related to air quality) of the emissions which, under an applicable 
standard or limitation, the source was authorized to emit (including, 
to the extent necessary for such purposes, a description of the manner 
or rate of operation of the source); and
     A general description of the location and/or nature of the 
source to the extent necessary to identify the source and to 
distinguish it from other sources (including, to the extent necessary 
for such purposes, a description of the device, installation, or 
operation constituting the source).
    However, 40 CFR 2.301(a)(2)(ii) additionally provides a limitation 
on the timing of any release to the public of emission data concerning 
``any product, method, device, or installation (or any component 
thereof) designed and intended to be marketed or used commercially but 
not yet so marketed or used.'' Consistent with this limitation, and as 
described in Sections XII.A.1.i and iii, we are proposing to maintain 
confidential treatment prior to the introduction-into-commerce date for 
the information included in an application for certification. Though we 
are proposing that the information in these categories is emission 
data, we are proposing that the information would not become subject to 
release until the product for which the information was submitted has 
been introduced into commerce, consistent with 40 CFR 2.301(a)(2)(ii). 
The introduction to commerce date is specified in an application for 
certification, unless a certificate of conformity is issued after the 
introduction-into-commerce date, at which point we propose to use the 
date of certificate issuance as the introduction-into-commerce date, as 
stated in the proposed 40 CFR 1068.10(d)(1).
    We are proposing to establish in 40 CFR 1068.11(a) that certain 
categories of information the Agency collects in connection with the 
Title II programs are information that meets the regulatory definition 
of emission data under 40 CFR 2.301(a)(2)(i). The following sections 
describe the categories of information we are proposing to determine to 
be emission data, based on application of the definition at 40 CFR 
2.301(a)(2)(i) to the shared characteristics of the information in each 
category and our rationale for each proposed determination. The CBI 
Chart in the docket provides a comprehensive list of the current 
regulatory citations under which we collect the information that we 
propose to group into each proposed category and can be found in the 
docket for this proposal. For ease of reference, we have also indicated 
in the CBI Chart the reason(s) explained in Sections XII.A.1 and 3 of 
this proposal for why the information submitted to EPA would not be 
considered confidential. The CBI Chart provides the information EPA 
currently collects that is covered by this proposed determination, the 
regulatory citation the information is collected under, the information 
category we propose for the information, the confidentiality 
determination for the information, and the rationale used to determine 
whether the information is not entitled to confidential treatment 
(i.e., the information qualifies as emission data under one or more 
subparagraph of the regulatory definition of emission data, is both 
emission data and publicly available after the introduction-into-
commerce-date, etc.). We explain in this proposal that much of the 
information covered by these proposed determinations are emission data 
under more than one basis under the regulatory definition of emission 
data, as described at the end of each of the sections that follow, 
where each basis alone would support EPA finalizing a given proposed 
determination. Therefore, we request that commenters provide responses 
to every rationale presented in the CBI Chart, available in the docket, 
for information we are proposing to determine is emission data.

[[Page 17612]]

a. Information Necessary To Determine the Identity, Amount, Frequency, 
Concentration, or Other Characteristics (to the Extent Related to Air 
Quality) of Any Emission Which Has Been Emitted by the Source (or of 
Any Pollutant Resulting From Any Emission by the Source), or Any 
Combination of the Foregoing
    We are proposing the categories of information identified and 
proposing to determine that the information in them meets the 
regulatory definition of emission data under 40 CFR 2.301(a)(2)(i)(A), 
which defines emission data to include ``[i]nformation necessary to 
determine the identity, amount, frequency, concentration, or other 
characteristics (to the extent related to air quality) of any emission 
which has been emitted by the source (or of any pollutant resulting 
from any emission by the source), or any combination of the 
foregoing[.]'' \902\ For shorthand convenience, we refer to information 
that qualifies as emission data under subparagraph (A) in the 
definition of emission data as merely ``paragraph A information.''
---------------------------------------------------------------------------

    \902\ 40 CFR 2.301(a)(2)(i)(A).
---------------------------------------------------------------------------

    EPA collects emission information during certification, compliance 
reporting, SEAs, defect and recall reporting, in ABT programs, and in 
various testing programs like production line testing (``PLT'') and in-
use testing. We are proposing that the following categories of 
information are emission data under 40 CFR 2.301(a)(2)(i)(A):
    (1) Fleet value information,
    (2) test information and results (including certification testing, 
PLT, in-use testing, fuel economy testing, and SEA testing),
    (3) ABT credit information,
    (4) production volume,
    (5) defect and recall information, and
    (6) SEA compliance information.
    All these categories include information that fits under the other 
emission data regulatory definition subparagraphs, therefore, the lists 
in this section are not exhaustive of the information in each category. 
We are proposing that the paragraph A information we identify in this 
section under each of the categories is also emission data under 
subparagraph (B) of the definition of emission data and may also be 
emission data under subparagraph (C) of the definition of emission 
data. In the CBI Chart in the docket, we have identified for every 
piece of information in every category all the applicable emission data 
definition subparagraphs. Nevertheless, under this proposal, we have 
chosen to explain each piece of information in detail only under the 
most readily understandable subparagraph of emission data, while 
highlighting that the information could also qualify as emission data 
under another subparagraph of the regulatory definition of emission 
data. Consistent with 40 CFR 2.301(a)(2)(ii), under this proposed 
determination, we would not release information included in an 
application for certification prior to the introduction-into-commerce-
date, except under the limited circumstances already provided for in 
that regulatory provision. The introduction-into-commerce-date is 
specified in an application for certification or in the certificate 
itself, if the certificate is issued after the introduction-into-
commerce-date.
    Fleet Value Information: We are proposing that the fleet value 
information category includes the following information that underlies 
the ABT compliance demonstrations and fleet average compliance 
information for on-highway and nonroad: Offsets, displacement, useful 
life, power payload tons, load factor, integrated cycle work, cycle 
conversion factor, and test cycle. The information in this proposed 
category underlies the fleet average calculations, which are necessary 
to understand the type and amount of emissions released in-use from 
sources regulated under the standard-setting parts that require a fleet 
average compliance value. These values represent compounds emitted, 
though the raw emissions from an individual source may be different 
from these values due to other variables in the fleet value 
calculation. For these reasons, we propose to determine the fleet value 
information category is emission data because it is necessary to 
identify and determine the amount of emissions emitted by sources.\903\ 
Note, we are also proposing that a portion of the fleet value 
information category meets another basis in the emission data 
definition, as discussed in more detail in Section XII.A.1.i.b, as it 
additionally provides ``[i]nformation necessary to determine the 
identity, amount, frequency, concentration, or other characteristics 
(to the extent related to air quality) of the emissions which, under an 
applicable standard or limitation, the source was authorized to emit 
(including, to the extent necessary for such purposes, a description of 
the manner or rate of operation of the source)[.]'' \904\
---------------------------------------------------------------------------

    \903\ Id.
    \904\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    Test Information and Results: The proposed test information and 
results category includes information collected during the 
certification process, PLT testing, in-use testing programs, testing to 
determine fuel economy, and testing performed during an SEA. This 
category encompasses the actual test results themselves and information 
necessary to understand how the test was conducted, and other 
information to fully understand the results. We are proposing to 
include in the test information and results category the certification 
test results information, including emission test results which are 
required under the standard-setting parts. Before introducing a source 
into commerce, manufacturers must certify that the source meets the 
applicable emission standards and emissions related requirements. To do 
this, manufacturers conduct specified testing during the useful life of 
a source and submit information related to those tests. Emission test 
results are a straightforward example of emission data, as they 
identify and measure the compounds emitted from the source during the 
test. Furthermore, the tests were designed and are performed for the 
explicit purpose of determining the identity, amount, frequency, 
concentration, or other air quality characteristics of emissions from a 
source. For these reasons, we propose to determine that test 
information and results category is emission data because it is 
necessary to determine the emissions emitted by a source.\905\ We are 
also proposing that all the information in the test information and 
results category, except fuel label information, meets another basis in 
the emission data definition, as it is also ``[i]nformation necessary 
to determine the identity, amount, frequency, concentration, or other 
characteristics (to the extent related to air quality) of the emissions 
which, under an applicable standard or limitation, the source was 
authorized to emit (including, to the extent necessary for such 
purposes, a description of the manner or rate of operation of the 
source)[.]'' \906\ See Section XII.A.1.i.b for a more detailed 
discussion for issues related to test information and results. See 
Section XII.A.1.iv for additional discussion of fuel label information.
---------------------------------------------------------------------------

    \905\ 40 CFR 2.301(a)(2)(i)(A).
    \906\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    The following test information and results are collected from the 
PLT program: (1) For CI engines and vehicles: CO results, particulate 
matter (PM) results, NOX results, NOX + HC 
results, and HC results, and (2) for SI

[[Page 17613]]

engines and vehicles and for products subject to the evaporative 
emission standards: Fuel type used, number of test periods, actual 
production per test period, adjustments, modifications, maintenance, 
test number, test duration, test date, end test period date, service 
hours accumulated, test cycle, number of failed engines, initial test 
results, final test results, and cumulative summation. Production line 
testing is conducted under the standard-setting parts to ensure that 
the sources produced conform to the certificate issued. PLT results are 
emission test results and, for that reason, are among the most 
straightforward examples of emission data, as they identify and measure 
the compounds emitted from the source during the test. For example, the 
measured amounts of specified compounds (like HC results, CO results, 
and PM results) are measured emissions, the literal results of testing. 
Similarly, the number of failed engines is emission data as it reflects 
the results of emissions testing. Additionally, adjustments, 
modifications, maintenance, and service hours accumulated are 
information necessary for understanding the test results. We propose 
that the information listed in this paragraph is necessary to 
understand the context and conditions in which the test was performed, 
like test number, test duration, test date, number of test periods, 
actual production per test period, end test period, and is, therefore, 
emission data because it is information necessary for understanding the 
characteristics of the test as performed, the test results, and the 
information that goes into the emissions calculations. Furthermore, PLT 
is performed for the explicit purpose of determining the identity, 
amount, frequency, concentration, or other air quality characteristics 
of emissions from a source. For these reasons, we propose to determine 
that test information and results category is emission data because it 
is necessary to determine the emissions emitted by a source.\907\ Note, 
we are also proposing that the PLT information in the test information 
and results category meets another basis in the emission data 
definition, as discussed in more detail in Section XII.A.1.i.b, as it 
additionally provides ``[i]nformation necessary to determine the 
identity, amount, frequency, concentration, or other characteristics 
(to the extent related to air quality) of the emissions which, under an 
applicable standard or limitation, the source was authorized to emit 
(including, to the extent necessary for such purposes, a description of 
the manner or rate of operation of the source)[.]'' \908\
---------------------------------------------------------------------------

    \907\ 40 CFR 2.301(a)(2)(i)(A).
    \908\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    The proposed test information and results category also includes 
the following information from the in-use testing program: A 
description of how the manufacturer recruited vehicles, the criteria 
use to recruit vehicles, the rejected vehicles and the reason they were 
rejected, test number, test date and time, test duration and shift-days 
of testing, weather conditions during testing (ambient temperature and 
humidity, atmospheric pressure, and dewpoint), differential back 
pressure, results from all emissions testing, total hydrocarbons (HC), 
NMHC, carbon monoxide, carbon dioxide, oxygen, NOX, PM, and 
methane, applicable test phase (Phase 1 or Phase 2), adjustments, 
modifications, repairs, maintenance history, vehicle mileage at start 
of test, fuel test results, total lifetime operating hours, total non-
idle operation hours, a description of vehicle operation during 
testing, number of valid Not to Exceed (NTE) events, exhaust flow 
measurements, recorded one-hertz test data, number of engines passed, 
vehicle pass ratio, number of engines failed, outcome of Phase 1 
testing, testing to determine why a source failed, the number of 
incomplete or invalid tests, usage hours and use history, vehicle on 
board diagnostic (``OBD'') system history, engine diagnostic system, 
number of disqualified engines, and number of invalid tests. The in-use 
testing information includes actual test results and the information 
that goes into the emissions calculations. For example, the measured 
amounts of specified compounds (like total HC) are measured emissions, 
and adjustments, modifications, and repairs are information necessary 
for understanding the test results. It is necessary to know if and how 
a source has changed from its certified condition during its use, as 
these changes may impact the source's emissions. Total lifetime 
operating hours and usage hours information is also used to calculate 
emissions during in-use testing. The diagnostic system information is 
necessary for understanding emissions, as well, because it provides 
context to and explains the test results; if an issue or question 
arises from the in-use testing, the diagnostic system information 
allows for greater understanding of the emissions performance. 
Additionally, the number of disqualified engines is necessary to 
determine the sources tested, if an end user has modified the source 
such that it cannot be used for in-use testing, this directly relates 
to the sources eligible for in-use testing and the emission 
measurements resulting from those tests. For these reasons, we propose 
to determine that the in-use testing information is emission data 
because it is necessary to determine the emissions emitted by 
sources.\909\ Note, we are also proposing that the in-use testing 
information meets another basis in the emission data definition, as 
discussed in more detail in Section XII.A.1.i.b, as it additionally 
provides ``[i]nformation necessary to determine the identity, amount, 
frequency, concentration, or other characteristics (to the extent 
related to air quality) of the emissions which, under an applicable 
standard or limitation, the source was authorized to emit (including, 
to the extent necessary for such purposes, a description of the manner 
or rate of operation of the source)[.]'' \910\
---------------------------------------------------------------------------

    \909\ 40 CFR 2.301(a)(2)(i)(A).
    \910\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    We are also proposing that the test information and results 
category include the underlying information necessary to determine the 
adjusted and rounded fuel economy label values and the resulting label 
values. The underlying information includes test result values that are 
plugged into a calculation included in the standard-setting parts that 
establish the fuel economy rating. These results represent emissions, 
the rate at which they are released, and are necessary to understanding 
the fuel economy rating. For these reasons, we propose that the fuel 
economy label information is appropriately included in the test 
information and results category. Accordingly, we propose to determine 
that fuel economy label information is emission data because it is 
necessary to determine the emissions emitted by sources.\911\ Note, we 
are also proposing that a portion of the fuel economy label information 
is not entitled to confidential treatment because it is required to be 
publicly available and is discussed in more detail in Section 
XII.A.1.iii. We are proposing in this rulemaking to supersede the 2013 
class determination Table 3 for all fuel economy label information, but 
our proposed CBI determination here applies only to a portion of the 
fuel economy label information, as explained in Section XII.A.1.iv.
---------------------------------------------------------------------------

    \911\ 40 CFR 2.301(a)(2)(i)(A).
---------------------------------------------------------------------------

    We are proposing that the test information and results category 
include the following information from SEA testing: The test procedure, 
initial test results, rounded test results, final test results, final 
deteriorated test results,

[[Page 17614]]

the number of valid tests conducted, the number of invalid tests 
conducted, adjustments, modifications, repairs, test article 
preparation, test article maintenance, and the number of failed engines 
and vehicles. SEAs can be required of manufacturers that obtain 
certificates of conformity for their engines, vehicles, and equipment. 
SEA test information includes emission test results from tests 
performed on production engines and equipment covered by a certificate 
of conformity. These tests measure the emissions emitted from the test 
articles; therefore, we propose that they are emission data and not 
entitled to confidentiality. The information supporting the test 
results, such as the number of valid tests conducted, the adjustments, 
modifications, repairs, and maintenance regarding the test article, is 
necessary to understand the test results and is, therefore, also 
emission data. For these reasons, we also propose to determine that SEA 
test information is appropriately grouped in test information and 
results category and is emission data because it is necessary to 
identify and determine the amount of emissions from a source.\912\ The 
SEA test information, like all the information in the test information 
and results category, is also emission data under another basis in the 
emission data definition, as discussed in more detail in Section 
XII.A.1.i.b, as it provides ``[i]nformation necessary to determine the 
identity, amount, frequency, concentration, or other characteristics 
(to the extent related to air quality) of the emissions which, under an 
applicable standard or limitation, the source was authorized to emit 
(including, to the extent necessary for such purposes, a description of 
the manner or rate of operation of the source)[.]'' \913\
---------------------------------------------------------------------------

    \912\ Id.
    \913\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    Production Volume: We are proposing to determine that the 
production volume category is emission data and is not entitled to 
confidential treatment because the information is necessary to 
determine the total emissions emitted by the source, where the source 
is the type of engine, vehicle, or equipment covered by a certificate 
of conformity. The certificate of conformity for a source does not, on 
its face, provide aggregate emissions information for all of the 
sources covered by that certificate. Rather, it provides information 
relative to each single unit of the source covered by a certificate. 
The production volume is necessary to understand the amount, frequency, 
and concentration of emissions emitted from the aggregate of units 
covered by a single certificate that comprise the source. In other 
words, unless there will only ever be one single engine, vehicle, or 
equipment covered by the certificate of conformity, the emissions from 
that source will not be expressed by the certificate and compliance 
information alone. The total number of engines, vehicles, or equipment 
produced, in combination with the certificate information, is necessary 
to know the real-world impact on emissions from that source. 
Additionally, the production volume is also collected for the purpose 
of emission modeling. For example, engine population (the number of 
engines in use) is used in the non-road emissions model to establish 
emission standards. Production volume, when used in combination with 
the other emission data we collect (certification test results, in-use 
test results, defects and recalls, etc.), also allows EPA and 
independent third parties to calculate total mobile source air 
emissions. For these reasons, production volume is ``necessary to 
determine the identity, amount, frequency, concentration, or other 
characteristics (to the extent related to air quality) of any emission 
which has been emitted by the source (or of any pollutant resulting 
from any emission by the source), or any combination of the 
foregoing[.]'' \914\ Note, we are also proposing to determine that the 
production volume category meets another basis in the emission data 
definition, as discussed in more detail in Section XII.A.1.i.c, as it 
additionally provides ``[a] general description of the location and/or 
nature of the source to the extent necessary to identify the source and 
to distinguish it from other sources (including, to the extent 
necessary for such purposes, a description of the device, installation, 
or operation constituting the source).'' \915\
---------------------------------------------------------------------------

    \914\ 40 CFR 2.301(a)(2)(i)(A).
    \915\ 40 CFR 2.301(a)(2)(i)(C).
---------------------------------------------------------------------------

    Defect and Recall Information: We propose to determine that the 
defect and recall information category is emission data and not 
entitled to confidential treatment because it is information necessary 
to determine the emissions from a source that has been issued a 
certificate of conformity.\916\ The only defects and recalls that 
manufacturers or certificate holders are required to report to EPA are 
ones that impact emissions or could impact emissions. Therefore, if a 
defect or recall is reported to us, it is because it causes or may 
cause increased emissions and information relating to that defect or 
recall is necessarily emission data, as it directly relates to the 
source's emissions. The proposed defect and recall information category 
includes any reported emission data available. This information is the 
available test results that a manufacturer has after conducting 
emission testing, and an estimate of the defect's impact on emissions, 
with an explanation of how the manufacturer calculated this estimate 
and a summary of any available emission data demonstrating the impact 
of the defect. Note, we are only proposing to determine that a portion 
of the defect and recall information category is paragraph A 
information. As discussed in Section XII.A.1.iv, we are not proposing 
to make a confidentiality determination on the defect investigation 
report at this time. We are also proposing to determine that the 
information in this category, excluding the defect investigation 
report, meets another basis in the emission data definition, as 
discussed in more detail in Section XII.A.1.i.b, as it additionally 
provides ``[i]nformation necessary to determine the identity, amount, 
frequency, concentration, or other characteristics (to the extent 
related to air quality) of the emissions which, under an applicable 
standard or limitation, the source was authorized to emit (including, 
to the extent necessary for such purposes, a description of the manner 
or rate of operation of the source)[.]'' \917\
---------------------------------------------------------------------------

    \916\ 40 CFR 2.301(a)(2)(i)(A).
    \917\ 40 CFR 2.301(a)(2)(i)(B) and (C).
---------------------------------------------------------------------------

    As noted throughout this section, the information included in the 
proposed categories identified as paragraph A information could also 
meet another prong of the definition of emission data.\918\ See Section 
XII.A.1.i.b for our discussion of why we are proposing that this 
information could also be emission data as defined at 40 CFR 
2.301(a)(2)(i)(B). See Section XII.A.1.i.c for our discussion of why we 
are proposing that this information could also be emission data as 
defined at 40 CFR 2.301(a)(2)(i)(C).
---------------------------------------------------------------------------

    \918\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

b. Information Necessary To Determine the Identity, Amount, Frequency, 
Concentration, or Other Characteristics (to the Extent Related to Air 
Quality) of the Emissions Which, Under an Applicable Standard or 
Limitation, the Source Was Authorized To Emit (Including, to the Extent 
Necessary for Such Purposes, a Description of the Manner or Rate of 
Operation of the Source)
    We are proposing that information within the proposed categories

[[Page 17615]]

explained in this subsection meets the regulatory definition of 
emission data under 40 CFR 2.301(a)(2)(i)(B) because it is 
``[i]nformation necessary to determine the identity, amount, frequency, 
concentration, or other characteristics (to the extent related to air 
quality) of the emissions which, under an applicable standard or 
limitation, the source was authorized to emit (including, to the extent 
necessary for such purposes, a description of the manner or rate of 
operation of the source)[.]'' We will refer to subparagraph (B) in the 
definition of emission data as ``paragraph B information'' throughout 
this section.
    The vast majority of the information we collect for certification 
and compliance fits within this subparagraph of the definition of 
emission data. We are proposing that the following categories are 
paragraph B information and not entitled to confidential treatment: (1) 
Certification and compliance information, (2) ABT credit information, 
(3) fleet value information, (4) production volumes, (5) test 
information and results, (6) defect and recall information, and (7) SEA 
compliance information. These categories are summarized here and 
described in more detail below. Certification and compliance 
information category includes information that is submitted in 
manufacturers' certificate of conformity applications and information 
reported after the certificate is issued to ensure compliance with both 
the certificate and the applicable standards, which is required under 
EPA's regulation. ABT credit information shows whether a manufacturer 
participating in an ABT program has complied with the applicable 
regulatory standards. Additionally, fleet value information is 
collected in order to calculate average and total emissions for a fleet 
of sources, thereby demonstrating compliance with the applicable 
regulatory standards when a manufacturer participates in an ABT program 
or for fleet averaging programs. A portion of the test and test result 
category of information is distinguishable under the paragraph A 
information basis. This portion of the test information and results 
category includes information that explains how the tests and test 
results demonstrate compliance with the applicable standards and is 
identified and discussed in this section. The test information and 
results described in Section XII.A.1.i.a is also necessary to 
understand whether a source is in compliance with the applicable 
standard-setting parts; however, we are only describing information 
once in this preamble, though it may qualify under more than one 
subparagraph of the emission data definition. The SEA compliance 
information category includes information related to understanding how 
the results of the SEA reflect whether a source was in compliance with 
the applicable standard-setting parts. Consistent with 40 CFR 
2.301(a)(2)(ii), under this proposed determination, we would not 
release information included in an application for certification prior 
to the introduction-into-commerce-date, except under the limited 
circumstances already provided for in that regulatory provision. The 
introduction-into-commerce-date is specified in an application for 
certification, or in the certificate itself if the certificate is 
issued after the introduction-into-commerce-date.
    These categories apply to information submitted for certification 
and compliance reporting across the standard-setting parts. These 
categories make up the largest amount of information addressed by the 
proposed confidentiality determinations.
    Certification and Compliance Information: Once a source is 
certified as conforming to applicable emission standards (i.e., the 
source has a certificate of conformity), all sources the manufacturer 
produces under that certificate must conform to the requirements of the 
certificate for the useful life of the source. In short, a source's 
compliance is demonstrated against the applicable certificate of 
conformity through inspection and testing conducted by EPA and the 
manufacturers. Therefore, certification and compliance information 
falls under subparagraph B of emission data because it is ``necessary 
to determine the identity, amount, frequency, concentration, or other 
characteristic (to the extent related to air quality) of the emissions 
which, under an applicable standard or limitation, the source was 
authorized to emit (including, to the extent necessary for such 
purposes, a description of the manner or rate of operation of the 
source)[.]'' \919\ The certification and compliance information 
category includes models and parts information, family determinants, 
general emission control system information, and certificate request 
information (date, requester, etc.), contact names, importers, agents 
of service, and ports of entry used. The models and parts information 
is necessary to determine that the sources actually manufactured 
conform to the specifications of the certificate. Lastly, certificate 
request information is general information necessary to identify the 
applicable certificate of conformity for a source, as well as 
understanding the timing and processing of the request. For these 
reasons, we propose to determine certificate information is emission 
data because it is necessary to determine whether a source has achieved 
compliance with the applicable standards.\920\ Note, we are also 
proposing that a portion of the category of certification and 
compliance information meets another basis in the emission data 
definition, as discussed in more detail in Section XII.A.1.i.c, as it 
additionally provides ``[a] general description of the location and/or 
nature of the source to the extent necessary to identify the source and 
to distinguish it from other sources (including, to the extent 
necessary for such purposes, a description of the device, installation, 
or operation constituting the source).'' \921\
---------------------------------------------------------------------------

    \919\ Id.
    \920\ Id.
    \921\ 40 CFR 2.301(a)(2)(i)(C).
---------------------------------------------------------------------------

    ABT Credit Information: ABT programs are an option for compliance 
with certain emissions standards. In ABT programs, manufacturers may 
generate credits when they certify that their vehicles, engines, and 
equipment achieve greater emission reductions than the applicable 
standards require. ``Averaging'' within ABT programs means exchanging 
emission credits between vehicle or engine families within a given 
manufacturer's regulatory subcategories and averaging sets. This can 
allow a manufacturer to certify one or more vehicle or engine families 
within the same averaging set at levels worse than the applicable 
emission standard under certain regulatory conditions. The increased 
emissions over the standard would need to be offset by one or more 
vehicle or engine families within that manufacturer's averaging set 
that are certified better than the same emission standard, such that 
the average emissions from all the manufacturer's vehicle or engine 
families, weighted by engine power, regulatory useful life, and 
production volume, are at or below the level required by the applicable 
standards. ``Banking'' means the retention of emission credits by the 
manufacturer for use in future model year averaging or trading. 
``Trading'' means the exchange of emission credits between 
manufacturers, which can then be used for averaging purposes, banked 
for future use, or traded again to another manufacturer. The proposed 
ABT credit information category includes a manufacturer's banked 
credits,

[[Page 17616]]

transferred credits, traded credits, total credits, credit balance, and 
annual credit balance. Because manufacturers participating in ABT 
programs use credits to demonstrate compliance with the applicable 
standards, ABT information is ``necessary to determine the identity, 
amount, frequency, concentration, or other characteristic (to the 
extent related to air quality) of the emissions which, under an 
applicable standard or limitation, the source was authorized to emit 
(including, to the extent necessary for such purposes, a description of 
the manner or rate of operation of the source)[.]'' \922\ For these 
reasons, we propose to determine ABT credit information is emission 
data because it is necessary to determine whether a source has achieved 
compliance with the applicable standards.\923\
---------------------------------------------------------------------------

    \922\ 40 CFR 2.301(a)(2)(i)(B).
    \923\ Id.
---------------------------------------------------------------------------

    Fleet Value Information: ABT credit information must be reviewed in 
conjunction with the fleet value information, which underlies a 
manufacturer's credit balance. The two categories are distinct from 
each other, though the information under the two categories is closely 
related. In addition to reasons described in Section XII.A.1.i.a, fleet 
value information is also used for compliance reporting under ABT 
programs, though some fleet value information is collected during 
certification for the on-highway sectors. The proposed fleet value 
information category includes: Source classification, averaging set, 
engine type or category, conversion factor, engine power, payload tons, 
intended application, advanced technology (``AT'') indicator, AT 
CO2 emission, AT improvement factor, AT CO2 
benefit, innovative technology (``IT'') indicator, IT approval code, 
and IT CO2 improvement factor. Additionally, the proposed 
fleet value information category includes the following for light-duty 
vehicles and engines, non-road SI engines, and products subject to 
evaporative emission standards: Total area of the internal surface of a 
fuel tank, adjustment factor, and deterioration factor. Fleet value 
information is used in ABT programs to explain and support a 
manufacturer's ABT credit balance. For the standard-setting parts that 
require a fleet average compliance value, the fleet value information 
is used to demonstrate compliance with the applicable standard setting 
parts. For these reasons, we propose to determine that the fleet value 
information category is emission data because it is information 
necessary to understand the ABT compliance demonstration and compliance 
with the fleet average value, as applicable.\924\ Additionally, a 
portion of the fleet value information is emission data, as described 
in Section XII.A.1.i.a, because it is ``necessary to determine the 
identity, amount, frequency, concentration, or other characteristics 
(to the extent related to air quality) of any emission which has been 
emitted by the source (or of any pollutant resulting from any emission 
by the source), or any combination of the foregoing[.]'' \925\
---------------------------------------------------------------------------

    \924\ Id.
    \925\ 40 CFR 2.301(a)(2)(i)(A).
---------------------------------------------------------------------------

    Production Volumes: The production volume category is emission data 
because it is necessary to determine compliance with the standards when 
a manufacturer meets requirements in an ABT credit, PLT, or in-use 
testing program, and also for GHG fleet compliance assessment. When a 
manufacturer is subject to these programs, the production volume is 
necessary to determine whether that manufacturer has complied with the 
applicable standards and limitations. In ABT programs, the averages 
used to calculate credit balances are generated based on the production 
volumes of the various families certified. For GHG standards 
compliance, manufacturers comply based on their overall fleet average, 
therefore, the production volume is necessary to calculate the fleet 
average and whether the manufacturers' fleet complies with the 
applicable standards. For these reasons, we propose that production 
volume information is necessary to understanding the calculations 
behind a manufacturer's credit generation and use, as well as a 
manufacturer's fleet average, which are then used to demonstrate 
compliance with the applicable standards.\926\ Additionally, for PLT 
and in-use testing, production volumes are used to determine whether 
and how many sources are required to be tested or, in some cases, 
whether the testing program needs to be undertaken at all. In this way, 
production volume is tied to compliance with the PLT and in-use testing 
requirements and is paragraph B information necessary for demonstrating 
compliance with an applicable standard. Note, we are proposing to 
determine that the production volume category is emission data for 
multiple reasons, as discussed in Sections X.A.1.i.a and X.A.1.i.c.
---------------------------------------------------------------------------

    \926\ 40 CFR 2.301(a)(2)(i)(B).
---------------------------------------------------------------------------

    Test Information and Results: The proposed test information and 
results category includes the testing conducted by manufacturers and is 
necessary to demonstrate that the test parameters meet the requirements 
of the regulations. This ensures that the test results are reliable and 
consistent. If a test does not meet the requirements in the applicable 
regulations, then the results cannot be used for certification or 
compliance purposes. The parameters and underlying information of an 
emissions test is information necessary to understanding the test 
results themselves. Adjustable parameter information is necessary to 
understand the tests used to certify a source and, therefore, also 
necessary to understand the test results and whether the source 
achieved compliance with the applicable standard. For these reasons, we 
propose that the test information and results category is ``necessary 
to determine the identity, amount, frequency, concentration, or other 
characteristic (to the extent related to air quality) of the emissions 
which, under an applicable standard or limitation, the source was 
authorized to emit (including, to the extent necessary for such 
purposes, a description of the manner or rate of operation of the 
source[.]'' \927\ Test information and results collected under the 
standard-setting parts includes the following: Test temperature, 
adjustable test parameters, exhaust emission standards and family 
emission limits (FELs), emission deterioration factors, fuel type used, 
intended application, CO standard, particulate matter (``PM'') 
standard, NOX + HC standard, NOX standard, HC 
standard, CO2 alternate standard, alternate standard 
approval code, CO2 family emission limit (``FEL''), 
CO2 family certification level (``FCL''), NOX and 
NMHC + NOX standard, NOX and NMHC + 
NOX alternate standard, N2O standard, 
N2O FEL, CH4 standard, CH4 FEL, 
NOX or NMHC + NOX FEL, PM FEL, test number, test 
time, engine configuration, green engine factor, the test article's 
service hours, the deterioration factor type, test location, test 
facility, the manufacturer's test contact, fuel test results, vehicle 
mileage at the start of the test, exhaust aftertreatment temperatures, 
engine speed, engine brake torque, engine coolant temperature, intake 
manifold temperature and pressure, throttle position, parameter sensed, 
emission-control system controlled, fuel-injection timing, NTE 
threshold, limited testing region, meets vehicle pass criteria (i.e., 
whether the test passes the applicable emission standard), number of 
engines tested, number of engines still needing to be tested, number of 
engines passed,

[[Page 17617]]

purpose of diagnostics, instances for OBD illuminated or set trouble 
codes, instance of misfuelling, incomplete or invalid test information, 
the minimum tests required, diagnostic system, and the number of 
disqualified engines. For the reasons given, we propose to determine 
that test information and results is emission data because it is both 
necessary to understand how the source meets the applicable standards, 
including, but not limited to, ABT compliance demonstrations, and to 
ensure a source is complying with its certificate of conformity.\928\ 
Additionally, we are proposing that a portion of the information 
included in the test information and results category meets another 
basis in the emission data definition, as discussed in more detail in 
Section XII.A.1.i.a, as it is also ``[i]nformation necessary to 
determine the identity, amount, frequency, concentration, or other 
characteristics (to the extent related to air quality) of any emission 
which has been emitted by the source (or of any pollutant resulting 
from any emission by the source), or any combination of the 
foregoing[.]'' \929\
---------------------------------------------------------------------------

    \927\ Id.
    \928\ Id.
    \929\ 40 CFR 2.301(a)(2)(i)(A).
---------------------------------------------------------------------------

    Defect and Recall Information: We propose to determine that the 
defect and recall information category is emission data and not 
entitled to confidential treatment because it is information necessary 
to determine compliance with an applicable standard or limitation.\930\ 
The only defects and recalls that manufacturers are required to report 
to EPA are ones that impact emissions or could impact emissions. 
Therefore, if a defect is reported to us, it is because it causes or 
may cause increased emissions and information relating to that defect 
is necessarily emission data, as it directly relates to the source's 
compliance with an applicable standard. The proposed defect and recall 
information category, including information collected under the 
standard-setting parts, includes: System compliance reporting type, EPA 
compliance report name, manufacturer compliance report, manufacturer 
compliance report identifier, contact identifier, process code, 
submission status, EPA submission status and last modified date, 
submission creator, submission creation date, last modified date, last 
modified by, EPA compliance report identifier, compliance report type, 
defect category, defect description, defect emissions impact estimate, 
defect remediation plan explanation, drivability problems description, 
emission data available indicator, OBD MIL illumination indicator, 
defect identification source/method, plant address where defects were 
manufactured, certified sales area, carline manufacturer code, 
production start date, defect production end date, total production 
volume of affected engines or vehicles, estimated or potential number 
of engines or vehicles affected, actual number identified, estimated 
affected percentage, make, model, additional model identifier, specific 
displacement(s) impacted description, specific transmission(s) impacted 
description, related defect report indicator, related EPA defect report 
identifier, related defect description, remediation description, 
proposed remedy supporting information, description of the impact on 
fuel economy of defect remediation, description of the impact on 
drivability from remediation, description of the impact on safety from 
remediation, recalled source description, part availability method 
description, repair performance/maintenance description, repair 
instructions, nonconformity correction procedure description, 
nonconformity estimated correction date, defect remedy time, defect 
remedy facility, owner demonstration of repair eligibility description, 
owner determination method description, owner notification method 
description, owner notification start date, owner notification final 
date, number of units involved in recall, calendar quarter, calendar 
year, quarterly report number, related EPA recall report/remedial plan 
identifier, number of sources inspected, number of sources needing 
repair, number of sources receiving repair, number of sources 
ineligible due to improper maintenance, number of sources ineligible 
for repair due to exportation, number of sources ineligible for repair 
due to theft, number of sources ineligible for repair due to scrapping, 
number of sources ineligible for repair due to other reasons, 
additional owner notification indicator, and the number of owner 
notifications sent. We are not proposing to include defect 
investigation reports in this proposed category, and instead we propose 
to continue with the part 2 process as described in Section XII.A.1.iv 
for defect investigation reports. Additionally, we are proposing that a 
portion of the information included in this category meets another 
basis in the emission data definition, as discussed in more detail in 
Section XII.A.1.i.a, as it is also ``[i]nformation necessary to 
determine the identity, amount, frequency, concentration, or other 
characteristics (to the extent related to air quality) of any emission 
which has been emitted by the source (or of any pollutant resulting 
from any emission by the source), or any combination of the 
foregoing[.]'' \931\
---------------------------------------------------------------------------

    \930\ 40 CFR 2.301(a)(2)(i)(B).
    \931\ 40 CFR 2.301(a)(2)(i)(A).
---------------------------------------------------------------------------

    SEA Compliance Information: We are proposing that the SEA 
compliance information category is emission data because it is 
necessary to determine whether a source is in compliance with its 
certificate and the standards. This proposed category includes the 
facility name and location where the SEA was conducted, number of tests 
conducted, model year, build date, hours of operation, location of 
accumulated hours, the date the engines shipped, how the engines were 
stored, and, for imported engines, the port facility and date of 
arrival. This information collected through SEAs is necessary for 
determining whether a source that was investigated through an SEA is in 
compliance with the applicable standards. For that reason, EPA is 
proposing to make a determination that this category is emission data 
as defined at 40 CFR 2.301(a)(2)(i)(B). Additionally, certain 
information collected during an SEA is included in the test information 
and results category. We propose that SEA compliance information is 
emission data because it is both paragraph B information and 
``[i]nformation necessary to determine the identity, amount, frequency, 
concentration, or other characteristics (to the extent related to air 
quality) of any emission which has been emitted by the source (or of 
any pollutant resulting from any emission by the source), or any 
combination of the foregoing[.]'' \932\
---------------------------------------------------------------------------

    \932\ Id.
---------------------------------------------------------------------------

c. Information That Is Emission Data Because It Provides a General 
Description of the Location and/or Nature of the Source to the Extent 
Necessary To Identify the Source and To Distinguish It From Other 
Sources (Including, to the Extent Necessary for Such Purposes, a 
Description of the Device, Installation, or Operation Constituting the 
Source)
    We are proposing that certain categories of information meet the 
regulatory definition of emission data under 40 CFR 2.301(a)(2)(i)(C) 
because they convey a ``[g]eneral description of the location and/or 
nature of the source to the extent necessary to identify the source and 
to distinguish it from other sources (including, to the extent 
necessary for such purposes, a description of the device, installation, 
or

[[Page 17618]]

operation constituting the source).'' \933\ We will refer to 
subparagraph (C) in the definition of emission data as ``paragraph C 
information'' throughout this section. We are proposing that two 
categories of information fall primarily under this regulatory 
definition of emissions data: (1) Source family information, and (2) 
production volume information. We propose these categories are 
paragraph C information and are, therefore, emission data and would not 
be entitled to confidential treatment. However, under this proposed 
determination, consistent with 40 CFR 2.301(a)(2)(ii), we would not 
release information included in an application for certification prior 
to the introduction-into-commerce-date, except under the limited 
circumstances already provided for in that regulatory provision. The 
introduction-into-commerce-date is specified in an application for 
certification or in the certificate itself, if the certificate is 
issued after the introduction-into-commerce-date.
---------------------------------------------------------------------------

    \933\ 40 CFR 2.301(a)(2)(i)(C).
---------------------------------------------------------------------------

    Source Family Information: The information included in the source 
family information category includes engine family information, vehicle 
family information, evaporative family information, equipment family 
information, subfamily name, engine family designation, emission family 
name, and test group information. The engine, vehicle, and evaporative 
family information includes information necessary to identify the 
emission source for which the certificate was issued; this determines 
the emission standards that apply to the source and distinguishes the 
source's emissions from other sources. Manufacturers request 
certification using the family name of the engines, vehicles, or 
equipment they intend to produce for sale in the United States. Test 
group information identifies the sources tested and covered by a 
certificate. The source family is the basic unit used to identify a 
group of sources for certification and compliance purposes. The source 
family is a code with 12 digits that identifies all parts of that 
particular source. More specifically, information conveyed in the 
source family code include the model year, manufacturer, industry 
sector, engine displacement, and the manufacturer's self-designated 
code for the source family. We are proposing that the source family 
information category of information is emission data because it is 
information that provides a ``[g]eneral description of the location 
and/or nature of the source to the extent necessary to identify the 
source and to distinguish it from other sources (including, to the 
extent necessary for such purposes, a description of the device, 
installation, or operation constituting the source).'' \934\
---------------------------------------------------------------------------

    \934\ 40 CFR 2.301(a)(2)(i)(C).
---------------------------------------------------------------------------

    Production Volume: Additionally, we are proposing that production 
volume is emission data necessary to identify the source. Where the 
source is each individual engine, vehicle, or equipment produced, the 
production volume provides information necessary for EPA or the public 
to identify that source (the certificate only identifies one source, 
where the production volume identifies all the sources) and distinguish 
that source's emissions from the emissions of other sources. In other 
words, actual production volume provides necessary information to 
identify the number of sources operating under a certificate of 
conformity and distinguish their total emissions from other sources. In 
this way, the total number of sources operating under a certificate of 
conformity provides a ``[g]eneral description . . . of nature of the 
source'' or, alternatively, provides information necessary such that 
the source can be identified in total, since it is generally unlikely 
that only a single unit of any engine, vehicle, or equipment would be 
produced under a certificate. For this additional reason, we are 
proposing to determine that the production volume category is emission 
data, not only for the reasons provided in Sections X.A.1.i.a and b, 
but also because it also provides a ``[g]eneral description of the 
location and/or nature of the source to the extent necessary to 
identify the source and to distinguish it from other sources 
(including, to the extent necessary for such purposes, a description of 
the device, installation, or operation constituting the source).'' 
\935\
---------------------------------------------------------------------------

    \935\ Id.
---------------------------------------------------------------------------

ii. EPA Will Treat Preliminary and Superseded Information With the Same 
Confidentiality Treatment It Provides to the Final Reported Information
    In the course of certifying and demonstrating compliance, 
manufacturers may submit information before the applicable deadline, 
and that information may be updated or corrected before the deadline 
for certification or compliance reporting. Similarly, manufacturers 
routinely update their applications for certification to include more 
or different information. EPA views this information as Agency records 
as soon as it is received through the Engine and Vehicle Certification 
Information System (EVCIS). We are proposing to apply the same 
confidentiality determinations to this ``early'' information by 
category as is applied to information included in the final 
certification request or compliance report in the categories generally. 
However, EPA does not intend to proactively publish or release such 
preliminary or superseded information, because we believe that the 
inclusion of preliminary information in Agency publications could lead 
to an inaccurate or misleading understanding of emissions or of a 
manufacturer's compliance status. Note, since such early information 
are Agency records upon receipt, we may be obligated to release 
information from those preliminary or superseded documents that does 
not qualify as CBI if a FOIA requester specifically identifies such 
pre-final information in the FOIA request. EPA also does not intend to 
disclose information in submitted reports until we have reviewed them 
to verify the reports' accuracy, though the Agency may be required to 
release such information if it is specifically requested under the 
FOIA. We request comment on how the Agency can treat this kind of 
preliminary or superseded information to protect the public from 
incomplete or inaccurate information.
iii. Information That Is Never Entitled to Confidential Treatment 
Because It Is Publicly Available or Discernible Information or Becomes 
Public After a Certain Date.
    We are also proposing to determine that information that is or 
becomes publicly available under the applicable standard-setting parts 
is not entitled to confidential treatment by EPA. Information submitted 
under the standard-setting parts generally becomes publicly available 
in one of two ways: (1) Information is required to be publicly 
disclosed under the standard-settings parts, or (2) information becomes 
readily measurable or observable after the introduction to commerce 
date. Information that is required to be publicly available under the 
standard-setting parts includes: Information contained in the fuel 
economy label, the vehicle emission control information (``VECI'') 
label, the engine emission control information label, owner's manuals, 
and information submitted by the manufacturer expressly for public 
release. The information in the labels is designed to make the public 
aware of certain emissions related information and thus is in no way 
confidential. Similarly, manufacturers submit documents specifically 
prepared for public disclosure to EPA with the

[[Page 17619]]

understanding that they are intended for public disclosure. We propose 
that these public facing documents are not entitled to confidential 
treatment, as they are prepared expressly for public availability. 
Additionally, we propose to determine that the information provided in 
the list below that is measurable or observable by the public after the 
source is introduced into commerce is not entitled to confidential 
treatment by EPA after the introduction to commerce date. This 
information may be emission data and included in the one of the 
categories proposed in this action, accordingly, we propose that it is 
emission data as described in Section XII.A.1.i. The fact that this 
information is or becomes publicly available is an additional reason 
for it to be not entitled to confidential treatment after the 
introduction into commerce date. This information includes: Model and 
parts information, source footprint information, manufacturer, model 
year, category, service class, whether the engine is remanufactured, 
engine type/category, engine displacement, useful life, power, payload 
tons, intended application, model year, fuel type, tier, and vehicle 
make and model. Footprint information is readily observable by the 
public after the introduction to commerce date, as one can measure and 
calculate that value once the source is introduced into commerce. 
Additionally, models and parts information is also readily available to 
the public after the source is introduced into commerce. Because this 
information is publicly available, it is not entitled to confidential 
treatment. Though EPA is also proposing that these proposed categories 
containing this information are not entitled to confidential treatment 
because they are emission data, as described in Section XI.A.1.i, the 
fact that the information becomes public after introduction to commerce 
is an additional basis for determining that the information is not 
entitled to confidential treatment. Therefore, we would not provide any 
additional notice or process prior to releasing this information in the 
future.
iv. Information Not Included in This Rule's Proposed Determinations 
Would Be Treated as Confidential, if the Submitter Claimed it as Such, 
Until a Confidentiality Substantiation Is Submitted and a Determination 
Made Under the 40 CFR Part 2 Process.
    We are not proposing to make a confidentiality determination under 
40 CFR 1068.11 for certain information submitted to us for 
certification and compliance. This information, if claimed as 
confidential by the submitters, would be treated by EPA as confidential 
until such time as it is requested under the FOIA or EPA otherwise goes 
through a case-by-case or class determination process. At that time, we 
would pursue a confidentiality determination in accordance with 40 CFR 
part 2, and as proposed in this rulemaking under 40 CFR 2.301(j)(4). We 
are proposing to supersede the Table 3 CBI class determination made in 
2013, such that the same categories of information in Table 3 would not 
have an applicable class determination and would be subject to the part 
2 process. The information we are not proposing to include in this 
determination, and that would remain subject to the part 2 process, 
includes:

    (1) Projected production and sales,
    (2) production start and end dates outside of the defect and 
recall context,
    (3) specific and detailed descriptions of the emissions control 
operation and function,
    (4) design specifications related to aftertreatment devices,
    (5) specific and detailed descriptions of auxiliary emission 
control devices (AECDs),
    (6) plans for meeting regulatory requirements (e.g., ABT pre-
production plans),
    (7) procedures to determine deterioration factors and other 
emission adjustment factors and any information used to justify 
those procedures,
    (8) financial information related to ABT credit transactions 
(including dollar amount, parties to the transaction and contract 
information involved) and manufacturer bond provisions (including 
aggregate U.S. asset holdings, financial details regarding specific 
assets, whether the manufacturer or importer obtains a bond, and 
copies of bond policies),
    (9) serial numbers or other information to identify specific 
engines or equipment selected for testing,
    (10) procedures that apply based on the manufacturers request to 
test engines or equipment differently than we specify in the 
applicable standard-setting parts,
    (11) information related to testing vanadium catalysts in 40 CFR 
part 1065, subpart L (proposed in this rule),
    (12) GPS data identifying the location and route for in-use 
emission testing, and
    (13) defect investigation reports. The information contained in 
defect investigation reports may encompass both emission data and 
information that may be CBI, so we are not proposing a determination 
for this report as whole. Instead, procedurally we will treat these 
reports in accordance with the existing part 2 process.

    Additionally, we are proposing a category of information to include 
information received through ``comments submitted in the comment 
field,'' where EPA's compliance reporting software has comment fields 
to allow manufacturers to submit clarifying information. We are not 
proposing to make a determination on this broad category of potential 
information at this time, as the comments may or may not contain 
emission data. Therefore, EPA is proposing to undertake a case-by-case 
determination pursuant to part 2 for any information provided in a 
comment field. After further consideration, EPA is also not proposing 
to make a determination at this time regarding whether the information 
in Table 3 of the 2013 determination may meet the definition of 
emission data or otherwise may not be entitled to confidential 
treatment in certain circumstances under individual standard-setting 
parts, and instead thinks that a case-by-case determination process is 
better suited to these categories of information.
2. Adjustable Parameters
    One of the goals of the certification process is to ensure that the 
emission controls needed to meet emission standards cannot be bypassed 
or rendered inoperative. Consistent with this goal, the standard-
setting parts generally require that engines, vehicles, and equipment 
with adjustable parameters meet all the requirements of part 1068 for 
any adjustment in the physically adjustable range. This applies for 
testing pre-production engines, production engines, and in-use engines.
    The underlying principles of the current regulations and policy can 
be traced to the early emission standards for mechanically controlled 
engines. The regulations at 40 CFR 86.094-22(e) illustrate how the 
relevant provisions currently apply for heavy-duty highway engines. The 
earliest generation of engines with emission control technology subject 
to emission standards included components such as simple screws to 
adjust a variety of engine operating parameters, including fuel-air 
ratio and idle speed. Owners were then able to adjust the engines based 
on their priority for power, efficiency, or durability. At the same 
time, manufacturers sought to reduce emissions by limiting the physical 
range of adjustment of these parameters, so EPA developed regulations 
to ensure that the engines' limitations were sufficiently robust to 
minimize operation outside the specified range (48 FR 1418, January 12, 
1983).
    Since then, heavy-duty highway engine manufacturers have developed 
new technologies that did not exist when we adopted the existing 
regulations related to adjustable parameters. The regulations at 40 CFR 
86.094-22(e) therefore provide a limited framework under which to 
administer

[[Page 17620]]

the current certification for heavy-duty highway engines. Current 
certification practice consists of applying these broad principles to 
mechanically controlled operating parameters in a way that is similar 
for both highway and nonroad applications. EPA developed guidance with 
detailed provisions for addressing adjustable parameters at 
certification for land-based nonroad spark-ignition engines below 19 
kW.\936\ Electronically controlled operating parameters have generally 
not been treated as adjustable parameters, except that manufacturers 
need to identify all available operating modes (such as eco-performance 
or rabbit/turtle operation).
---------------------------------------------------------------------------

    \936\ ``Clean Air Act Requirements for Small Nonroad Spark-
Ignition Engines: Reporting Adjustable Parameters and Enforcement 
Guidance,'' EPA Guidance CD-12-11, August 24, 2012.
---------------------------------------------------------------------------

    Manufacturers are required by existing regulations to describe in 
their application for certification how they address potentially 
adjustable operating parameters. As with all elements of certification, 
the regulations require manufacturers to use good engineering judgment 
for decisions related to adjustable parameters. The regulations also 
describe a process for manufacturers to ask for preliminary approval 
for decisions related to new technologies, substantially changed engine 
designs, or new methods for limiting adjustability. See, for example, 
40 CFR 1039.115 and 1039.210.
    We are proposing a new 40 CFR 1068.50 to update the current 
regulatory provisions to better describe how the established principles 
and requirements related to adjustable parameters also apply for 
current technologies. Thus, the new provisions would describe how our 
established principles regarding adjustable parameters apply for the 
full range of emission control technologies.
    The proposed provisions are largely based on the regulations that 
already apply for highway engines and vehicles under 40 CFR 86.094-
22(e) and 86.1833-01. Most of what we are proposing in 40 CFR 1068.50 
is an attempt to codify in one place a set of provisions that are 
consistent with current practice. Some proposed provisions may 
represent new or more detailed approaches, as described further below, 
especially in the context of electronic controls. The proposed 
provisions in 40 CFR 1068.50 are intended to apply broadly across EPA's 
engine, vehicle, and equipment programs. The proposed language attempts 
to capture the full range of engine technologies represented by spark-
ignition and compression-ignition engines used in highway, nonroad, and 
stationary applications. We are accordingly proposing to apply the new 
provisions for all the types of engines, vehicles and equipment that 
are broadly subject to 40 CFR part 1068, as described in 40 CFR 1068.1. 
For example, the proposed provisions would apply for nonroad sectors 
and for heavy-duty highway engines, but not for highway motorcycles or 
motor vehicles subject to standards under 40 CFR part 86, subpart S. As 
with other provisions in 40 CFR part 1068, if the standard-setting part 
specifies some provisions that are different than 40 CFR 1068.50, the 
provisions in the standard-setting part would apply instead of the 
provisions in 40 CFR 1068.50. For example, we propose to continue to 
rely on the provisions related to adjusting air-fuel ratios in 40 CFR 
part 1051 for recreational vehicles in addition to the new provisions 
from 40 CFR 1068.50. We are also proposing some minor adjustments to 
the regulatory provisions in the standard-setting parts to align with 
the proposed language in 40 CFR 1068.50.
i. Operating Parameters, Adjustable Parameters, and Statement of 
Adjustable Range
    The proposed regulations would codify the different meanings of the 
terms ``operating parameter'' and ``adjustable parameter''. As 
proposed, ``operating parameter'' would generally mean any feature that 
can, by the nature of its design, be adjusted to affect emission 
performance--whether that feature is a single component, a system of 
components, or an electronic signal. This may include engine components 
that are designed to be replaced. It may also include elements of 
design involving consumption and replenishment, such as diesel exhaust 
fluid (DEF) or hybrid batteries (see Section XII.A.2.i.c for a 
discussion of these parameters). See proposed 40 CFR 1068.50(c).
    Under the proposed regulations, an ``adjustable parameter'' would 
generally be any operating parameter that is practically adjustable and 
that can be adjusted using available tools in a way that affects 
emissions without significantly degrading engine performance. For 
example, while spark plug gap and valve lash are practically adjustable 
operating parameters, we do not treat them as adjustable parameters 
because adjusting them does not affect emissions without significantly 
degrading engine performance. The following sections describe how we 
propose to consider whether parameters are practically adjustable.
a. Mechanically Controlled Parameters
    We propose in 40 CFR 1068.50(d)(1) that a mechanically controlled 
parameter is considered ``not practically adjustable'' if adjustments 
with ordinary tools take more than 15 minutes or involve service parts 
that cost more than $30 for engines at or below 30 kW, or take more 
than 60 minutes or involve service parts that cost more than $60 for 
engines between 30 kW and 560 kW.\937\ This reference to ``ordinary 
tools'' would include hand tools, solvents, or other supplies that are 
available to the operator. Hand tools include screwdrivers, pliers, 
hammers, awls, wrenches, electric screwdrivers, electric drills, and 
any tools supplied by the manufacturer with the product. Any such items 
that are sold at hardware stores, automotive parts supply stores, or on 
the Internet are considered available. The proposed thresholds are 
intended to be generally consistent with the provisions that apply 
under current regulations but tailored to represent an appropriate 
level of deterrence relative to typical maintenance experiences for the 
different sizes of engines.
---------------------------------------------------------------------------

    \937\ These costs are in 2020 dollars. Manufacturers would 
adjust these values for certification by comparing to the most 
recently available Consumer Price Index for All Urban Consumers 
value published by the Bureau of Labor Statistics at https://www.usinflationcalculator.com/. The cost thresholds do not include 
the cost of labor or the cost of any necessary tools or 
nonconsumable supplies; the time thresholds refer to the time 
required to access and adjust the parameter, excluding any time 
necessary to purchase parts, tools, or supplies or to perform 
testing.
---------------------------------------------------------------------------

    For engines at or above 560 kW, we propose to consider a 
mechanically controlled parameter ``practically adjustable'' if the 
parameter can be adjusted using any available tools. We would expect 
this arrangement to cause manufacturers to take greater care for 
limiting adjustability with engines at or above 560 kW. This is 
appropriate because we expect owners of these low-volume, high-cost 
engines are more likely to have ready access to experienced mechanics 
to continuously manage the maintenance and performance of their 
engines. For example, owners of marine vessels often have engineers 
traveling with vessels to always be ready to perform extensive repairs 
or maintenance as needed. Owners of engines at or above 560 kW also 
commonly do their own work to substantially overhaul engines.
    Mechanically controlled adjustable parameters usually have physical 
limits or physical stops to limit the range of adjustability. We are 
proposing to identify specific characteristics in 40 CFR 1068.50(e) to 
illustrate how physical limits or stops should function

[[Page 17621]]

to control the adjustable range. For example, a physical stop defines 
the limit of the range of adjustability for a mechanically controlled 
adjustable parameter if operators cannot exceed the travel or rotation 
limits using ordinary tools without causing damage exceeding specified 
thresholds.
b. Electronically Controlled Parameters
    We propose in 40 CFR 1068.50(d)(2) that electronically controlled 
parameters would be considered ``practically adjustable'' if they can 
be adjusted using any available tools (including devices that are used 
to alter computer code). This would apply for engines with any degree 
of electronic control. The proposed 40 CFR 1068.50(d) and (f) would 
also include special provisions for determining whether electronic 
control modules that can be adjusted by changing software or operating 
parameters (``reflashed'') are practically adjustable and to determine 
the practically adjustable range. First, where any of the following 
characteristics apply for a given electronic parameter, it would be 
considered practically adjustable:
     If an engine family includes multiple algorithms that can 
be selected or are easily accessible, the operating parameter would be 
practically adjustable and each of the available settings would be 
within the practically adjustable range.
     If the manufacturer sells software (or other products) 
that could be used to reflash the electronic control module, the 
operating parameter would be practically adjustable and all those 
settings would be within the practically adjustable range.
     If the engines/equipment have other electronic settings 
that can be adjusted using any available service tools (such as fuel 
injection maps), the operating parameter would be practically 
adjustable and all those settings would be within the practically 
adjustable range.
    Injection fuel maps and other similar electronic parameters would 
not be considered practically adjustable if the manufacturer adequately 
prevents access to the electronic control modules with encryption or 
password protection consistent with good engineering judgment, such as 
having adequate protections in place to prevent distribution and use of 
passwords or encryption keys. Manufacturers would be able to exclude 
electronic operating parameters from being considered adjustable 
parameters (or identify them as adjustable parameters but narrow the 
adjustable range) where they appropriately determine that the operating 
parameters will not be subject to in-use adjustment; EPA would retain 
the right to review such statements. The proposed regulations would 
also allow us to specify conditions to ensure that the certified 
configuration includes electronic parameter settings representing 
adjustable ranges that reflect the expected range of in-use adjustment 
or modification.
    To address the safety, financial liability, operational, and 
privacy concerns which can result from tampering, manufacturers, 
industry organizations, and regulators have been working to develop 
standards and design principles to improve the security of ECMs.\938\ 
Since security principles are constantly evolving as new threats are 
identified, requiring them to be applied with specificity in an annual 
emissions certification process could be problematic. In addition, 
manufacturers may choose to utilize different mixes of technical 
standards or principles of those recommended by these organizations, 
and a one-size-fits-all approach with detailed requirements for ECM 
security would be neither practical nor prudent. Manufacturers need the 
flexibility to quickly implement measures to address new or emerging 
threats and vulnerabilities. Accordingly, we are proposing that 
manufacturers inform EPA of their ECM security measures at the time 
they submit an application for certification. Manufacturers would be 
required to identify and describe the measures they are using, whether 
proprietary, industry technical standards, or a combination of both, to 
prevent unauthorized access to the ECM. At a minimum, for determination 
whether the parameter is an operating parameter or an adjustable 
parameter this documentation would need to describe in sufficient 
detail the measures that a manufacturer has used to: prevent 
unauthorized access; ensure that calibration values, software, or 
diagnostic features cannot be modified or disabled; and respond to 
repeated, unauthorized attempts at reprogramming or tampering.
---------------------------------------------------------------------------

    \938\ See SAE J3061, ``Cybersecurity Guidebook for Cyber-
Physical Vehicle Systems,'' January 14, 2016. Efforts are also 
underway to draft a cybersecurity agreement under the auspices of 
the UNECE process for WP.29 (ISO/SAE J21434).
---------------------------------------------------------------------------

    Aftermarket fuel conversions for heavy-duty highway engines and 
vehicles are a special case. We expect aftermarket converters to 
continue their current practice of modifying engines to run on 
alternative fuels under the clean alternative fuel conversion program 
in 40 CFR part 85, subpart F. The anti-tampering provisions proposed in 
40 CFR 1068.50 are not intended to interfere with actions aftermarket 
converters may need to take to modify or replace ECMs as part of the 
conversion process consistent with 40 CFR part 85, subpart F. The 
proposed provisions direct manufacturers to prevent unauthorized access 
to reprogram ECMs. Aftermarket converters would presumably need to 
either use a replacement ECM with a full calibration allowing the 
engine to run on the alternative fuel or perhaps create a piggyback ECM 
that modifies the engine's calibration only as needed to accommodate 
the unique properties of the alternative fuel. Aftermarket converters 
could alternatively work with engine manufacturers to access and change 
the engine's existing ECM programming for operation on the alternative 
fuel. We request comment on any adjustment to the proposed regulatory 
provisions that would be needed to address fuel conversions.
c. Consumption, Replenishment, and the Certified Configuration
    Certain elements of design involving consumption and replenishment 
may be considered adjustable parameters. Two significant examples are 
DEF tank fill level and hybrid battery state of charge. The proposed 
provisions in 40 CFR 1068.50(h) address these issues.
    For these adjustable parameters, the range of adjustability is 
determined based on the likelihood of in-use operation at a given point 
in the physically adjustable range. We may determine that operation in 
certain subranges within the physically adjustable range is 
sufficiently unlikely that the subranges may be excluded from the 
allowable adjustable range for testing. In such cases, the engines/
equipment are not required to meet the emission standards for operation 
in an excluded subrange.
    The proposal in 40 CFR 1068.50(h) describes how we would not 
require new engines to be within the range of adjustability for a 
certified configuration for adjustments related to consumption and 
replenishment. Specifically, manufacturers would not violate the 
prohibition in 40 CFR 1068.101(a)(1) to introduce into commerce a 
vehicle with an empty DEF tank or an uncharged hybrid battery.
    Except for these special cases related to consumption and 
replenishment, engines are not in the certified configuration if 
manufacturers produce them with adjustable parameters set outside the 
range specified in the application for certification. Similarly, 
engines are not in the certified configuration if manufacturers produce 
them with other operating parameters

[[Page 17622]]

that do not conform to the certified configuration. Such engines would 
therefore not be covered by a certificate of conformity and would 
therefore be subject to the violation provisions of 40 CFR 
1068.101(a)(1).
ii. Certification Process
    The existing regulations in each standard-setting part describe how 
manufacturers need to identify their adjustable parameters, along with 
the corresponding physical stops and adjustable ranges. The existing 
certification process includes a review of the manufacturer's specified 
adjustable parameters, including consideration of the limits of 
adjustability. This has generally focused on mechanically controlled 
parameters. We consider the totality of the circumstances as we 
determine whether a manufacturer's effort to prevent inappropriate 
adjustment is adequate. See text further clarifying this principle in 
proposed 40 CFR 1068.50(g). Under the existing certification process we 
may also evaluate the appropriateness of a manufacturer's statement 
regarding an adjustable parameter if we learn from observation of in-
use engines with such parameters or other information that a parameter 
was in fact practically adjustable or that the specified adjustable 
range was in fact not correct.
    We are proposing to require manufacturers in the certification 
application to state, with supporting justification, that they designed 
mechanically controlled adjustable parameters to prevent in-use 
operation outside the intended physically adjustable range, and that 
they have restricted access to the electronic controls as specified in 
the proposed 40 CFR 1068.50 to prevent in-use operation outside the 
practically adjustable range.
    We are proposing in this rule to clarify that manufacturers must 
consider electronically controlled parameters to be operating 
parameters that may also be adjustable. For example, engine 
calibrations may include user-selectable settings for different 
operating modes. Different operating modes may alternatively be 
available for certain users with assistance from dealers or other 
authorized service centers. All operating modes available for selection 
by the operator must be described in the certification application and 
are considered to fall within the engine's practically adjustable 
range. The manufacturer would also describe in the certification 
application how they have restricted access to the electronic controls 
to prevent unauthorized modification of in-use engines. We would expect 
manufacturers to follow accepted industry best practices to include 
password restrictions, encryption, two-step authentication, and other 
methods as appropriate. These practices will change over time and we 
would expect manufacturers to implement those newer methods, especially 
where there are observed cases of unauthorized changes to in-use 
engines.
    Manufacturers would name all available operating modes in the 
application for certification and describe their approach for 
restricting access to electronic controls. This description would 
include naming any applicable encryption protocols, along with any 
additional relevant information to characterize how the system is 
designed to prevent unauthorized access. Manufacturers separately 
identify information regarding their auxiliary emission control 
devices. Manufacturers would not need to report additional detailed 
programming information describing electronically adjustable operating 
parameters that are unavailable to owners.
    While EPA would still retain the right to review the manufacturer's 
specified adjustable parameters in the certification process, the 
manufacturer would be responsible for ensuring all aspects of the 
manufacturer's statements regarding adjustable parameters are 
appropriate for each certification application. EPA may review this 
information each year to evaluate whether the designs are appropriate. 
As industry practices evolve to improve tamper-resistance with respect 
to electronic controls, we may require manufacturers to upgrade tamper-
resistance features to include more effective protocols in order to 
support their statement that the electronic controls are both 
restricted from unauthorized access and limited to the identified 
practically adjustable range.
    We are proposing to apply the new provisions in 40 CFR 1068.50 
starting with model year 2024. This proposed implementation date would 
allow time for updating EPA's certification software and procedures. 
Manufacturers would continue to be required to meet existing 
regulations related to adjustable parameters before model year 2024 
under this proposal. The proposed provisions are intended to include 
only modest changes for mechanically controlled parameters. As 
described in Section XII.2.i.b, engine manufacturers have described 
their significant efforts to limit unauthorized access to 
electronically controlled parameters. We therefore expect that 
manufacturers would not need additional time beyond model year 2024 to 
comply with the new provisions. We request comment on whether this 
proposal provides sufficient time to comply with all the proposed 
provisions in 40 CFR 1068.50.
    The proposed provisions in 40 CFR 1068.50 are not intended to limit 
the tampering prohibition of 40 CFR 1068.101(b)(1) or the defeat device 
prohibition of 40 CFR 1068.101(b)(2). For example, it would be 
prohibited tampering to bypass a manufacturer's stops. Similarly, 
software that reduces the effectiveness of controls specified by the 
manufacturer in the application for certification would be a prohibited 
defeat device. See proposed 40 CFR 1068.50(k).
    If EPA discovers that someone manufactures or installs a modified 
ECM or reflashes an engine's ECM in a way that is not a certified 
configuration represented in the application for certification, those 
persons could be held liable for violating the tampering prohibition of 
40 CFR 1068.101(b)(1) or the defeat-device prohibition in 40 CFR 
1068.101(b)(2). As we gather information about cases where third 
parties have successfully penetrated ECM access restrictions, under our 
proposed regulations the manufacturer would be responsible in each 
certification application for ensuring all aspects of the 
manufacturer's statements regarding such adjustable parameters are 
still appropriate and we may also engage with the manufacturer to see 
if there is need or opportunity to upgrade future designs for better 
protection.
iii. Engine Inspections
    EPA may want to inspect engines to determine if they meet the 
proposed specifications. These inspections could be part of the 
certification process, or we could inspect in-use engines after 
certification. For example, we may request a production line engine be 
sent to an EPA designated lab for inspection to test the limits of the 
adjustable parameters as described in proposed 40 CFR 1068.50(d)(1).
iv. Right To Repair
    Several states are pursuing legislative initiatives to require 
engine manufacturers and other companies to make it easier for owners 
to repair or modify products. As described in Section IV.B.3, this 
proposed rule includes several provisions intended to improve or 
increase access to service information for owners and mechanics. Given 
the complexity of modern engines, access to service information is 
important to sustain the expectation that engines and their emission 
controls will

[[Page 17623]]

continue to work properly over their operating life.
    That objective does not extend to engines to the extent they rely 
on electronic controls to manage engine operation to achieve the 
required level of emission control. In fact, the proposed approach to 
treat electronic controls without adequately restricted access as 
adjustable parameters is intended specifically to prevent owners and 
mechanics from being able to modify those electronic controls to allow 
in-use operation outside of the practically adjustable range. Any state 
regulation requiring manufacturers to provide access to these controls 
would be directly in conflict with the Clean Air Act prohibition 
against tampering with certified engines and the prohibition against 
using defeat devices to circumvent emission standards.
3. Exemptions for Engines, Vehicles, and Equipment Under 40 CFR Part 
1068, Subparts C and D
    40 CFR part 1068, subparts C and D, describe various exemption 
provisions for engines, vehicles and equipment that are subject to 
emission standards and certification requirements. We are proposing to 
amend several of these exemption provisions. The following paragraphs 
use the term engines to refer generically to regulated engines, 
vehicles and equipment.
    The test exemption in 40 CFR 1068.210 applies for certificate 
holders performing test programs ``over a two-year period''. We are 
proposing to remove this time limitation. We may impose reasonable time 
limits on the duration of the exemption for individual engines under 
another existing provision (40 CFR 1068.210(e)). Such limitations may 
take the form of a defined time period for manufacturers to produce 
exempt engines, or a defined time period for individual engines to 
remain in exempt status. This exemption applies for a wide range of 
products and experience has shown that circumstances may call for the 
exemption to apply for longer than (or less than) two years. We may 
therefore continue to apply a two-year limit for producing or using 
exempt engines based on a case-specific assessment of the need for the 
exemption. We could alternatively identify a shorter or longer 
exemption period based on the circumstances for each requested 
exemption. The exemption approval could also allow test engines to 
operate indefinitely, perhaps with additional conditions on modifying 
the engine to include software or hardware changes that result from the 
test program or other design improvements. This approach may be 
appropriate for manufacturing one or more engines as part of a pilot 
project to prove out designs and calibrations for meeting new emission 
standards. Separate provisions apply for importing engines under the 
testing exemption in 40 CFR 1068.325, which we discuss further later in 
this section.
    The display exemption in 40 CFR 1068.220 applies for using 
noncompliant engines/equipment for display purposes that are ``in the 
interest of a business or the general public.'' The regulation 
disallows the display exemption for private use, private collections, 
and any other purposes we determine to be inappropriate. We have been 
aware of several cases involving displays we may have considered to be 
in the interest of the general public but they did not qualify for the 
display exemption because they were mostly for private use. Experience 
has shown that it may be difficult to distinguish private and public 
displays. For example, private collections are sometimes shared with 
the general public. We are accordingly proposing to preserve the 
fundamental limitation of the display exemption to cases involving the 
interest of a business or the general public. We propose to revise 40 
CFR 1068.220 to no longer categorically disallow the display exemption 
for engines and vehicles displayed for private use or for engines in 
private collections. We propose to retain the discretion to disallow 
the display exemption for inappropriate purposes. This would apply, for 
example, if engines or vehicles from a private collection will not be 
displayed for the general public or for any business interest. 
Consistent with longstanding policy, such private displays do not 
warrant an exemption from emission standards.
    The regulation defines provisions that apply for ``delegated 
assembly'' of aftertreatment and other components in 40 CFR 1068.261. 
Under the current regulation, manufacturers must follow a set of 
detailed requirements for shipping partially complete engines to 
equipment manufacturers to ensure that the equipment manufacturer will 
fully assemble the engine into a certified configuration. A much 
simpler requirement applies for engine manufacturers that produce 
engines for installation in equipment that they also produce. 
Manufacturers have raised questions about how these requirements apply 
in the case of joint ventures, subsidiary companies, and similar 
business arrangements. We are proposing to revise 40 CFR 1068.261(b) 
through (d) to clarify that the simpler requirements for intra-company 
shipments apply for engines shipped to affiliated companies. 
Conversely, engine manufacturers shipping partially complete engines to 
any unaffiliated company would need to meet the additional requirements 
that apply for inter-company shipments. We define ``affiliated 
companies'' in 40 CFR 1068.30.
    The identical configuration exemption in 40 CFR 1068.315(h) allows 
for importation of uncertified engines that are identical to engines 
that have been certified. This might apply, for example, for engines 
that meet both European and U.S. emission standards but were originally 
sold in Europe. We are proposing to modify the regulatory language from 
``identical'' to ``identical in all material respects.'' This change 
allows for minor variation in engines/equipment, such as the location 
of mounting brackets, while continuing to require that engines/
equipment remain identical to a certified configuration as described in 
the manufacturer's application for certification.
    The ancient engine/equipment exemption in 40 CFR 1068.315(i) 
includes an exemption for nonconforming engines/equipment that are at 
least 21 years old that are substantially in their original 
configuration. We originally adopted these for nonroad spark-ignition 
engines in 2002 to align with a similar exemption that was in place for 
light-duty motor vehicles (67 FR 68242, November 8, 2002). Now that 
part 1068 applies for a much wider range of applications, many with 
very long operating lives, it has become clear that this exemption is 
no longer appropriate for importing nonconforming engines. Keeping the 
exemption would risk compromising the integrity of current standards to 
the extent importers misuse this provision to import high-emitting 
engines. This was not the original intent of the exemption. We are 
therefore proposing to remove the ancient engine/equipment exemption. 
The identical configuration exemption will continue to be available to 
allow importation of nonconforming engines/equipment that continue to 
be in a configuration corresponding to properly certified engines.
    The regulations at 40 CFR 1068.325 describe provisions that apply 
for temporarily exempting engines/equipment from certification 
requirements. As noted in the introduction to 40 CFR 1068.325, we may 
ask U.S. Customs and Border Protection (CBP) to require a specific bond 
amount to make sure importers comply with applicable requirements.

[[Page 17624]]

We use the imports declaration form (3520-21) to request CBP to require 
a bond equal to the value of these imported engines/equipment for 
companies that are not certificate holders. Several of the individual 
paragraphs describing provisions that apply for specific exemptions 
include a separate statement requiring the importer to post bond for 
these products. We are proposing to remove the reference to the bond 
requirement in the individual paragraphs because the introduction 
addresses the bonding requirement broadly for all of 40 CFR 1068.325.
    We are proposing to revise the diplomatic or military exemption at 
40 CFR 1068.325(e) to clarify that someone qualifying for an exemption 
would show written confirmation of being qualified for the exemption to 
U.S. Customs and Border Protection, not EPA. This may involve 
authorization from the U.S. State Department or a copy of written 
orders for military duty in the United States. Consistent with current 
practice, EPA would not be involved in the transaction of importing 
these exempted products, except to the extent that U.S. Customs and 
Border Protection seeks input or clarification of the requirements that 
apply.
    The regulations at 40 CFR 1068.260(c) currently include an 
exemption allowing manufacturers to ship partially complete engines 
between two of their facilities. This may be necessary for assembling 
engines in stages across short distances. It might also involve 
shipping engines across the country to a different business unit under 
the same corporate umbrella. The regulation at 40 CFR 1068.325(g) 
includes additional provisions for cases involving importation. Multi-
national corporations might also import partially complete engines from 
outside the United States to an assembly plant inside the United 
States. We are proposing to revise 40 CFR 1068.325(g) to require that 
imported engines in this scenario have a label that identifies the name 
of the company and the regulatory cite authorizing the exemption. This 
would provide EPA and U.S. Customs and Border Protection with essential 
information to protect against parties exploiting this provision to 
import noncompliant engines without authorization.
    Most of the exemptions that allow manufacturers to import 
uncertified engines include labeling requirements to identify the 
engine manufacturer and the basis of the exemption. We are proposing to 
add a general requirement in 40 CFR 1068.301 to clarify that labels are 
required on all exempted engines. In cases where there are no labeling 
specifications for a given exemption, we are proposing to create a 
default labeling requirement to add a label for exempted engines to 
identify the engine manufacturer and the basis of the exemption.
4. Other Amendments to 40 CFR Part 1068
    We are proposing the following additional amendments to 40 CFR Part 
1068:
     Section 1068.1: Clarifying how part 1068 applies for older 
engines. This is necessary for nonroad engines certified to standards 
under 40 CFR parts 89, 90, 91, 92, and 94 because those emission 
standards and regulatory provisions have been removed from the CFR. 
These amendments were inadvertently omitted from the rule to remove 
those obsolete parts.
     Section 1068.1: Clarifying how part 1068 applies for motor 
vehicles and motor vehicle engines. Vehicles and engines certified 
under part 86 are subject to certain provisions in part 1068 as 
specified in part 86. Vehicles and engines certified under parts 1036 
and 1037 are subject to all the provisions of part 1068. This 
correction aligns with regulatory text adopted in previous rulemakings.
     Section 1068.101(a): The regulations at 40 CFR 1068.101(a) 
set forth the prohibitions that apply for engines and equipment that 
are subject to EPA emission standards and certification requirements. 
The regulation includes at 40 CFR 1068.101(a)(2) a prohibition related 
to reporting and recordkeeping requirements. Section 1068.101(a)(3) 
similarly includes a prohibition to ensure that EPA inspectors have 
access to test facilities. These prohibitions derive from CAA section 
208(a), which applies the information and access requirements to 
manufacturers ``and other persons subject to the requirements of this 
part or part C.'' The very first provision of 40 CFR part 1068 at 40 
CFR 1068.1(a) clearly makes the provisions of part 1068 applicable ``to 
everyone with respect to the engine and equipment categories as 
described in this paragraph (a)[. . . .] including owners, operators, 
parts manufacturers, and persons performing maintenance''. However, the 
regulation in 40 CFR 1068.101(a) as written inadvertently limits the 
prohibitions to manufacturers. We are accordingly proposing to revise 
the scope of the prohibitions in 40 CFR 1068.101(a) to apply to both 
manufacturers and ``other persons as provided in 40 CFR 1068.1(a)'' in 
accord with those in CAA section 203(a).
     Section 1068.101(b)(5): Removing extraneous words.
     Section 1068.240(a): Removing reference to paragraph (d) 
as an alternative method of qualifying for the replacement engine 
exemption. Paragraph (d) only describes some administrative provisions 
related to labeling partially complete engines so it is not correct to 
describe that as an additional ``approach for exempting'' replacement 
engines.
     Section 1068.240(b) and (c): Adding text to clarify that 
owners may retain possession of old engines after installing an exempt 
replacement engine. This is intended to address a concern raised by 
engine owners that they generally expect to be able to continue to use 
a replaced engine.\939\ Engine owners stated that they expect to use 
the replaced engine for either replacement parts or continued use in a 
different piece of equipment and were surprised to learn that engine 
manufacturers were insisting that the owner turn ownership of the old 
engine to the engine manufacturer. The existing regulation disallows 
simply installing those replaced engines in a different piece of 
equipment, but destroying the engine block and using the engine core as 
a source of replacement parts is acceptable under the existing 
regulation.
---------------------------------------------------------------------------

    \939\ Email exchange regarding replacement engines, August 2020, 
Docket EPA-HQ-OAR-2019-0055.
---------------------------------------------------------------------------

     Sections 1068.601 and 1068.630: Adding provisions to 
establish procedures for hearings related to an EPA decision to approve 
maintenance procedures associated with new technology for heavy-duty 
highway engines. As described in Section IV.B.5.v, we are proposing to 
update regulatory provisions related to engine maintenance for heavy-
duty highway engines. Section XII.A.9 describes how we may eventually 
extend those same provisions for nonroad engines. The provisions 
proposed in this rule include a commitment for EPA to describe approved 
maintenance for new technology in a Federal Register notice, along with 
an allowance for any manufacturer to request a hearing to object to 
EPA's decision. The general provisions related to hearing procedures in 
40 CFR part 1068, subpart G, cover the maintenance-related hearing 
procedures. We are proposing to amend the regulation to provide 
examples of the reasons aa manufacturer may request a hearing, 
including if a manufacturer believes certain EPA decisions may cause 
harm to its competitive position, and to add detailed specifications 
for requesting

[[Page 17625]]

and administering such a hearing for maintenance-related decisions for 
heavy-duty highway engines.
5. Engine and Vehicle Testing Procedures (40 CFR Parts 1036, 1037, 1065 
and 1066)
    The regulations in 40 CFR part 1036, subpart F, 40 CFR part 1037, 
subpart F, and 40 CFR parts 1065 and 1066 describe emission measurement 
procedures that apply broadly across EPA's emission control programs 
for engines, vehicles, and equipment. This rule includes several 
proposed amendments to these regulations.
    We are proposing to delete the hybrid engine test procedure in 40 
CFR 1036.525 as it was applicable only for model year 2014 to 2020 
engines and has been replaced with the hybrid powertrain test procedure 
for model 2021 and later engines in 40 CFR 1037.550.
    We are proposing updates to the engine mapping test procedure in 40 
CFR 1065.510. To generate duty cycles for each engine configuration, 
engine manufacturers identify the maximum brake torque versus engine 
speed using the engine mapping procedures of 40 CFR 1065.510. The 
measured torque values are intended to represent the maximum torque the 
engine can achieve under fully warmed-up operation when using the fuel 
grade recommended by the manufacturer across the range of engine speeds 
expected in real-world conditions. Historically, the mapping procedure 
required the engine to stabilize at discrete engine speed points 
ranging from idle to the electronically limited highest RPM before 
recording the peak engine torque values at any given speed. We adopted 
a provision in 40 CFR 1065.510(b)(5)(ii) that allows manufacturers to 
perform a transient sweep from idle to maximum rated speed, which 
requires less time than stabilizing at each measurement point.
    The proposed updates to the engine mapping test procedure in 40 CFR 
1065.510 are intended to ensure the resulting engine map achieves its 
intended purpose. The current test procedure is intended to generate a 
``torque curve'' that represents the peak torque at any specific engine 
speed point. The transient sweep from idle to maximum rated speed can 
create engine conditions that trigger electronic control features on 
modern heavy-duty spark-ignition engines that result in lower-than-peak 
torque levels. Engine control features that can cause variability in 
the maximum torque levels include spark advance, fuel-air ratio, and 
variable valve timing that temporarily alter torque levels to meet 
supplemental goals (such as torque management for transmissions 
shifts).\940\ If the engine map does not capture the true maximum 
torque, the duty cycles generated using the map may not accurately 
recreate the highest-load conditions that could lead to higher 
emissions in the real-world.
---------------------------------------------------------------------------

    \940\ These AECDS are typically electronic controls that are 
timer-based and initiated for a set duration. In a transient test, 
measurements are taken continuously, and the controls remain 
engaged; the same controls would ``time out'' if each measurement 
was taken at stabilized conditions.
---------------------------------------------------------------------------

    We are proposing to update 40 CFR 1065.510(b)(5)(ii) to require 
that the torque curve established during the mapping procedure 
represent the highest torque level possible when using the 
manufacturer's recommended fuel grade. Specifically, we are proposing 
to require manufacturers to disable electronic controls or other 
auxiliary emission control devices if they are of a transient nature 
and impact peak torque during the engine mapping procedure.\941\ 
Manufacturers would continue to implement their engine control during 
the duty cycle tests, enabling their engines to react to the test 
conditions as they would in real world operation. The proposed changes 
to the mapping procedure would ensure the test duty cycle appropriately 
represents torque output and emissions during high-load and transient 
conditions.
---------------------------------------------------------------------------

    \941\ These electronic controls would be reported as an AECD 
using 40 CFR 1036.205(b).
---------------------------------------------------------------------------

    There may be other ways to update the mapping procedure to ensure 
maximum torque, such as a change to the order or duration of the torque 
measurement points. We seek comment, including relevant data, on the 
proposed procedure update as well as other approaches we should 
consider.
    This rule includes the following additional proposed amendments to 
40 CFR parts 1065 and 1066:
     Sections 1065.301 and 1065.1001: Revising NIST-
traceability requirements to allow the use of international standards 
recognized by the CIPM Mutual Recognition Arrangement without prior EPA 
approval. The current regulation allows us to approve international 
standards that are not NIST-traceable, but this was intended only to 
accommodate laboratories in other countries that meet CIPM requirements 
instead of following NIST-traceable protocols. With this approach there 
would no longer be any need for a separate approval process for using 
international standards that are not NIST-traceable. NIST-traceable 
standards are traceable to the International System of Units (SI) as 
specified in NIST Technical Note 1297, which is referenced in the 
definition of NIST-traceable in 40 CFR part 1065. This same 
traceability to the International System of Units is required of 
standards recognized by the CIPM Mutual Recognition Arrangement, thus 
putting them on par with NIST-traceable standards.
     Section 1065.298: Proposing a new 40 CFR 1065.298 to 
codify the in-use particulate matter (PM) measurement method that 
augments real-time PM measurement with gravimetric PM filter 
measurement for field-testing analysis. This method has been approved 
for use for over 10 years as an alternative method under 40 CFR 1065.10 
and 1065.12.
     Section 1065.410: Clarifying that manufacturers may 
inspect engines using electronic tools to monitor engine performance. 
For example, this may apply for OBD signals, onboard health monitors, 
and other prognostic tools manufacturers incorporate into their engine 
designs. As described in the current regulation, inspection tools are 
limited to those that are available in the marketplace. This prevents 
engine manufacturers from handling a test engine more carefully than 
what would be expected with in-use engines. Extending that principle to 
inspection with electronic tools, we propose to limit the use of those 
inspections to include only information that can be accessed without 
needing specialized equipment.
     Section 1065.650(c)(6): Adding an allowance to determine 
nonmethane nonethane hydrocarbon (NMNEHC) for engines fueled with 
natural gas as 1.0 times the corrected mass of NMHC if the test fuel 
has 0.010 mol/mol of ethane or more. This may result in a higher 
reported NMNEHC emission value. The engine manufacturer may use this 
method if reducing test burden is more important than the potential for 
a slightly higher reported emission value.
     Section 1065.720: Removing the test fuel specification 
related to volatility residue for liquefied petroleum gas. The 
identified reference procedure, ASTM D1837, has been withdrawn, at 
least in part, due to limited availability of mercury thermometers. 
There is no apparent replacement for ASTM D1837. Rather than proposing 
an alternative specification for volatility residue, we would instead 
rely on the existing residual matter specification based on the 
measurement procedure in ASTM D2158. This alternative specification 
should adequately address concerns about nonvolatile impurities in the 
test fuel.
     Section 1065.910(b): Adding a requirement to locate the 
PEMS during field testing in an area that minimizes

[[Page 17626]]

the effects of ambient temperature changes, electromagnetic radiation, 
shock, and vibration. This may involve putting the PEMS in an 
environmental enclosure to reduce the effect of these parameters. We 
are also proposing to remove (1) the recommendation to install the PEMS 
in the passenger compartment because that does not necessarily lead to 
better mitigation of temperature effects as the cab temperature can 
vary during vehicle soaks, (2) ambient pressure as a parameter to 
minimize as there are no known pressure effects on PEMS, and (3) 
ambient hydrocarbon as a parameter because it is more of a PEMS design 
issue that is handled with an activated carbon filter on the burner air 
inlet, which is already covered in 40 CFR 1065.915(c).
     Section 1065.920: Broadening the PEMS calibration and 
verification requirements to make them applicable to the new emission 
measurement bin structure being proposed in 40 CFR part 1036. The 
verification is now generic to verifications for both NTE and binned 
windows where you acquire a shift-day's worth of data over 6 to 9 hours 
and then process the data as you would for an in-use test (either NTE 
or binned windows) and compare the performance of the PEMS to the lab-
based measurement system.
     Section 1065.935(d): Updating the zero and span 
verification requirements to include new provisions for the emission 
measurement bin structure being proposed in 40 CFR part 1036 and 
retaining the current requirements for NTE testing only. The procedure 
now includes the requirement to perform zero-verifications at least 
hourly using purified air. Span verifications must be performed at the 
end of the shift-day or more frequently based on the PEMS 
manufacturer's recommendation or good engineering judgment.
     Section 1065.935(g)(6): Adding a new paragraph to include 
new drift limits instead of those in 40 CFR 1065.550 for the emission 
measurement bin structure being proposed in 40 CFR part 1036. The 
analyzer zero drift limit between the hourly or more frequent zero 
verifications is 2.5 ppm, while the limit over the entire shift-day (or 
more frequently if you perform zero-adjustments) is 10 ppm. The 
analyzer span drift limit between the beginning and end of the shift-
day or more frequent span verification(s) or adjustment(s) must be 
within 4 percent of the measured span value.
     Sections 1065.1123, 1065.1125, and 1065.1127: Adding new 
regulatory sections to migrate the smoke test procedure in 40 CFR part 
86, subpart I, into 40 CFR part 1065. This would provide a common 
location for the test procedure and analyzer requirements for all parts 
that still require smoke measurement with the exception of locomotive 
testing. The locomotive test procedure would continue to reside in 40 
CFR part 1033, subpart F, as it is specific to locomotive testing and 
operation at specific notches. No updates were made to the procedure 
that would affect analyzer requirements and setup or how a laboratory 
would report test results. For all engines required to carry out smoke 
testing, other than locomotive engines, we are proposing to update 
operation at curb idle speed to warm idle speed and rated speed to 
maximum test speed. We believe this proposed change will not adversely 
affect the acceleration and lugging operation modes of the test and 
this update will now make smoke testing consistent with all other 
engine-based testing that now use warm idle speed and maximum test 
speed.
     Part 1066, subpart D: Referencing an updated version of 
SAE J2263 for coastdown measurements. The updated standard incorporates 
EPA guidance for vehicles certified under 40 CFR part 86, subpart 
S.\942\ The updated version of the test method also reduces the wind 
speed allowed for performing measurements, allows for adding ballast to 
vehicles if needed, and adds clarifying procedures for testing on oval 
tracks. These changes align with current practice for light-duty 
vehicles, and the changes would have no substantial effect for 
measurements with heavy-duty vehicles. We are therefore proposing to 
apply the updated version of SAE J2263 for all light-duty and heavy-
duty vehicles.
---------------------------------------------------------------------------

    \942\ ``Determination and Use of Vehicle Road-Load Force and 
Dynamometer Settings'', EPA Guidance Document CD-15-04, February 23, 
2015.
---------------------------------------------------------------------------

     Section 1066.420: Adding the existing 40 CFR 86.140-94 
requirement to zero and span calibrate the hydrocarbon analyzer by 
overflowing the zero and span gas at the hydrocarbon sampling system 
probe inlet during analyzer calibration when testing vehicles that are 
14,000 GVWR or less. This requirement was inadvertently missed during 
the migration of the light-duty test procedures to 40 CFR part 1066.
     Section 1066.831: Removing the reference to 40 CFR part 
1065 regarding how to measure THC emissions, as the method for 
measuring THC emission is already covered in 40 CFR part 1066, subparts 
B and E.
    This rule includes additional proposed amendments that are regarded 
as clarifications in the following sections of 40 CFR parts 1036, 1037, 
1065, and 1066:
    40 CFR 1036.501, 1036.503, 1036.505, 1036.510, 1036.527, 1036.530, 
1036.535, 1036.540, and 1036.543; 40 CFR 1037.320, 1037.510, 1037.515, 
1037.520, 1037.534, 1037.540, 1037.550, 1037.551, 1037.555, 1037.601, 
1037.615, and 1037.725; 40 CFR 1065.1, 1065.5, 1065.10, 1065.12, 
1065.140, 1065.190, 1065.210, 1065.284, 1065.301, 1065.305, 1065.307, 
1065.308, 1065.309, 1065.315, 1065.320, 1065.325, 1065.330, 1065.345, 
1065.350, 1065.410, 1065.501, 1065.510, 1065.512, 1065,514, 1065.545, 
1065.610, 1065.650, 1065.655, 1065.660, 1065.667, 1065.680, 1065.695, 
1065.715, 1065.720, 1065.790, 1065.901, 1065.915, 1065.920, 1065.1001, 
and 1065.1005; and 40 CFR 1066.110, 1066.220, 1066.415, 1066.710, 
1066.815, 1066.835, 1066.845, 1066.1001, and 1066.1005.
6. Vanadium-Based SCR Catalysts
    In certain diesel engine applications vanadium-based SCR catalysts 
may provide a performance and cost advantage over other types of 
catalysts. However, vanadium material can sublime from the catalyst in 
the presence of high exhaust gas temperatures.\943\ Sublimation of 
vanadium catalyst material leads to reduced NOX conversion 
efficiency of the catalyst and possible exposure of the public to 
vanadium emissions. In 2016 EPA provided certification guidance to 
manufacturers of diesel engines equipped with vanadium-based SCR 
catalysts (``2016 guidance'').\944\ The certification guidance 
clarified EPA's expectations for manufacturers using vanadium-based SCR 
catalysts and provided our views and recommendations on reasonable 
steps manufacturers could take to protect against excessive loss of 
vanadium from these SCR systems. We are now proposing to codify these 
provisions as regulatory requirements for using vanadium-based SCR 
catalysts. We propose to adopt these requirements for all types of 
diesel engines. The proposed regulatory provisions are consistent with 
the 2016 guidance and would begin to apply when the final rule becomes 
effective. To make this effective immediately for all current and 
future MY diesel engines, we are proposing to update 40 CFR 86.007-11 
(to cover HD engines through MY 2026) to reference the new 40 CFR 
1036.115(g)(2) which contains this

[[Page 17627]]

requirement. We request comment on any additional time needed by 
manufacturers to comply with the proposed requirements.
---------------------------------------------------------------------------

    \943\ The temperature at which vanadium sublimation occurs 
varies by engine and catalyst and is generally 550[deg] C or higher.
    \944\ ``Certification of Diesel Engines Equipped with Vanadium-
based SCR Catalyst'', EPA guidance document CD-16-09, June 13, 2016.
---------------------------------------------------------------------------

    Specifically, we are proposing that manufacturers of heavy-duty 
diesel engines equipped with vanadium-based SCR catalysts determine 
vanadium sublimation temperatures and thermal management strategies and 
include documentation in their certification applications. EPA would 
use the information submitted by manufacturers in its evaluation of a 
manufacturer's engine and aftertreatment design as part of its 
application for certification.
    In their certification applications, engine manufacturers would be 
required to provide information identifying the vanadium sublimation 
temperature threshold for the specific catalyst product being used. To 
identify the vanadium sublimation temperature, manufacturers would be 
required to use the vanadium sublimation sampling and analytical test 
method identified in the 2016 guidance.\945\ Manufacturers also would 
be required to identify their thermal management strategy for 
preventing the vanadium sublimation temperature from being exceeded. In 
addition, manufacturers would be required to identify how their thermal 
management strategy will protect the catalyst in the event of high 
temperature exotherms resulting from upstream engine component 
failures, as well as exotherms resulting from hydrocarbon buildup 
during normal engine operation. EPA would expect to approve 
applications that include thermal management strategies that prevent 
exhaust gas temperatures from exceeding the sublimation temperature 
threshold (i.e., the temperature below which vanadium emissions are 
less than the method detection limit in the test method proposed to be 
included in 40 CFR part 1065, subpart L).
---------------------------------------------------------------------------

    \945\ EPA is proposing to codify the test method in CD-16-09 in 
40 CFR part 1065, subpart L; 40 CFR 1065.12 describes the process 
for approving alternative test procedures.
---------------------------------------------------------------------------

7. ULSD-Related Exemption for Guam
    EPA's in-use fuel requirements at 40 CFR part 1090 include an 
exemption from the 15-ppm sulfur standard for Guam, American Samoa, and 
the Commonwealth of the Northern Mariana Islands (40 CFR 1090.620). 
Diesel fuel meeting the 15-ppm standard is known as ultra-low sulfur 
diesel or ULSD. EPA's emission standards for highway and nonroad diesel 
engines generally involves SCR as a control technology. The durability 
of SCR systems depends on the use of fuel meeting the 15-ppm ULSD 
standard, so we adopted a corresponding exemption from the most 
stringent emission standards for engines used in these three 
territories (see 40 CFR 86.007-11(f) for heavy-duty highway engines and 
40 CFR 1039.655 for land-based nonroad diesel engines).
    Guam has in the meantime adopted rules requiring the 15-ppm sulfur 
standard for in-use diesel fuel for both highway and nonroad engines 
and vehicles. As a result, there is no longer a reason to keep the 
exemption from emission standards for engines used in Guam. We are 
therefore proposing to remove the exemption for these engines in Guam. 
Since there is no question of feasibility or other issues related to 
availability of certified engines for Guam, we are proposing to remove 
the exemption upon the effective date of the final rule, which we 
anticipate as late in 2022 or early in 2023. We request comment on the 
need for lead time or any other transitional provisions related to 
removing the exemption.
    We are not proposing to remove the exemption from American Samoa 
and the Northern Mariana Islands at this time as we are not aware of 
the adoption of ULSD requirements in those territories. We seek comment 
on the status of the use of ULSD in American Samoa and the Northern 
Mariana Islands.
    We are also proposing to clarify that the exemption for land-based 
nonroad diesel engines at 40 CFR 1039.655 applies only for engines at 
or above 56 kW. Smaller engines are not subject to NOX 
standards that would lead manufacturers to use SCR or other sulfur-
sensitive technologies, so we would not expect anyone to be using this 
exemption for engines below 56 kW in any area where the exemption 
applies. We intend to revisit the exemption from the 15-ppm ULSD 
standard for diesel fuel in Guam under 40 CFR part 1090 in a future 
action. Removal of exemption for diesel fuel in Guam would likely 
involve new or revised regulatory provisions for parties that make, 
distribute, and sell diesel fuel in Guam such as additional reporting, 
recordkeeping, and other compliance-related provisions.
8. Deterioration Factors for Certifying Nonroad Engines
    Section IV describes a proposed approach for manufacturers of 
heavy-duty highway engines to establish deterioration factors (DFs) 
based on bench-aged aftertreatment in combination with a plan for 
testing in-use engines to verify that the original deterioration factor 
properly predicts an engine's emission levels at the end of the useful 
life. As described in Section IV.F, we are proposing the new approach 
for establishing deterioration factors to take advantage of available 
techniques for bench-aging aftertreatment devices to streamline the 
certification and product-development timeline. The leaner up-front 
testing is complemented by measurements from in-use engines to verify 
that the original deterioration factors are still appropriate for 
certifying engines in later model years.
    This same dynamic applies for nonroad applications. We are 
therefore proposing to allow manufacturers of all types of nonroad 
diesel engines and manufacturers of land-based nonroad spark-ignition 
engines above 19 kW to use these same procedures to establish and 
verify DFs. These proposed provisions would apply for 40 CFR parts 
1033, 1039, 1042, and 1048. We are not proposing any changes to the 
existing certification and durability procedures for certifying these 
engines for those who choose not to rely on the proposed provisions 
with bench-aged aftertreatment.
    Most of the DF verification procedures proposed for heavy-duty 
highway engines apply equally for nonroad engines, but unique aspects 
of each certification program call for making the following 
adjustments:
     Marine and land-based nonroad diesel engines are subject 
to not-to-exceed standards and corresponding test procedures that would 
continue to apply instead of the in-use measurement protocols proposed 
in this rule for heavy-duty highway engines.
     Land-based nonroad spark-ignition engines above 19 kW 
(Large SI engines) are subject to field-testing standards and 
corresponding test procedures that would continue to apply instead of 
the in-use measurement protocols proposed in this rule for heavy-duty 
highway engines.
     Locomotives are not subject to off-cycle emission 
standards or emission measurement procedures that apply during normal 
in-use operation. However, manufacturers can perform in situ testing on 
in-use locomotives that meets all the specifications for certification 
testing in a laboratory. This allows for testing in-use engines to 
verify that deterioration factors based on bench-aged aftertreatment 
devices are appropriate for predicting full-life emissions.
     Each type of nonroad diesel engine already has sector-
specific methods for calculating infrequent regeneration adjustment 
factors.
    We are not proposing to allow this approach for certifying 
recreational

[[Page 17628]]

vehicles, land-based nonroad spark-ignition engines at or below 19 kW, 
or marine spark-ignition engines. These engines are generally subject 
to certification of a useful life that is much shorter than the values 
that apply for the types of engines for which we are proposing to allow 
the new DF verification procedures. Many nonroad spark-ignition engines 
are also certified without aftertreatment. As a result, it is not clear 
that there would be any potential for manufacturers of these other 
types of engines to find a benefit of using the proposed DF 
verification procedures.
    We request comment on this proposed alternative for establishing 
and verifying deterioration factors for the identified nonroad engines. 
We also request comment on the adjustments proposed for the identified 
engine types, and on extending the DF verification protocol to the 
other nonroad spark-ignition applications.
9. Serviceability, Allowable Maintenance, and Hearing Procedures
    Section IV describes how we are proposing to update maintenance-
related specifications for heavy-duty highway engines. This includes 
changes to require manufacturers to comply with emission standards 
based on less frequent critical emission-related maintenance and to 
provide greater access to servicing information on the engine's 
emission control information label and in the owners manual. The 
proposal also includes substantial changes to modernize the description 
and organization of the maintenance specifications as part of the 
overall migration of regulatory provisions from 40 CFR part 86 to 40 
CFR part 1036. Many of these structural changes are intended to align 
with analogous provisions already adopted for the various nonroad 
sectors, but the proposal includes several things that depart from 
those other regulations.
    We are not proposing to make changes to maintenance-related 
specifications for nonroad engines or equipment. However, we will 
likely propose amendments in a future rulemaking to align nonroad 
regulations with many of the maintenance-related provisions we adopt in 
this rule. As a result, we encourage commenters to review this proposed 
rule with consideration of the potential for these maintenance-related 
provisions to apply in the future for each of the nonroad sectors as 
appropriate.

B. Heavy-Duty Highway Engine and Vehicle Emission Standards (40 CFR 
Parts 1036 and 1037)

1. Timing of Annual Reports
    We are proposing to simplify annual reporting requirements to 
account for the extensive information submissions related to the 
greenhouse gas emission standards. Vehicle manufacturers are required 
to report on GEM results and production volumes for thousands of 
distinct vehicle configurations at the end of the model year to show 
that emission credits related to calculated average CO2 
emission rates are sufficient to comply with standards. The regulation 
currently requires an interim end-of-year report by March 31 and a 
final report by September 30 (see 40 CFR 1037.730). This same schedule 
is typical for documentation related to emission credits for various 
types of nonroad engines and vehicles. In contrast to those nonroad 
programs, compliance with the heavy-duty highway CO2 
emission standards relies on a detailed assessment of GEM results and 
corresponding production volumes to determine all the necessary credit 
calculations for the model year. We propose to modify the regulation at 
40 CFR 1037.730 to no longer require the interim end-of-year report, 
because we have observed that manufacturers need more time to complete 
their effort to fully document their compliance for the model year and 
we believe the interim end-of-year report is unnecessary for heavy-duty 
vehicles. The regulation allows us to waive this interim report, and we 
have routinely approved such requests. We are not proposing any change 
to the final report due in September and would continue to rely on that 
final report to evaluate compliance with standards.
    Engine manufacturers generate and use emission credits based on 
production volumes that correspond to the vehicle production. As a 
result, it is beneficial for both EPA and engine manufacturers to align 
the emission credit reporting requirements for engines and vehicles. We 
are therefore proposing to revise 40 CFR 1036.730 to also omit the 
interim end-of-year report and instead rely only on the final report 
submitted by September 30 following each model year. In addition, the 
regulations at 40 CFR 1036.250 and 1037.250 currently specify that 
engine and vehicle manufacturers must report their production volumes 
within 90 days after the end of the model year. For the same reasons 
given for modifying the schedule for credit reports, we propose to 
align this production reporting with the final ABT report, requiring 
manufacturers to report their production volumes also by September 30 
following the end of the model year. These proposed changes address a 
comment by the Truck and Engine Manufacturers Association in a recent 
rulemaking.\946\
---------------------------------------------------------------------------

    \946\ ``Comments of the Truck and Engine Manufacturers 
Association'' for Docket EPA-HQ-OAR-2019-0307, June 26, 2020.
---------------------------------------------------------------------------

2. Warranty Period for Medium HDV With Spark-Ignition Engines
    In the HD GHG Phase 2 final rule, we set a vehicle-based warranty 
period for the Medium HDV service class to five years or 100,000 miles 
for 2021 and later model years (81 FR 73478, October 25, 2016), which 
represents an increase in the warranty period for Class 6 through Class 
8 heavy-duty vehicles with spark-ignition engines.\947\ These warranty 
provisions apply for both evaporative and refueling emission standards 
in 40 CFR 1037.103 and for greenhouse gas standards in 40 CFR 1037.105.
---------------------------------------------------------------------------

    \947\ This vehicle service class is defined in 40 CFR 
1037.140(g)(3).
---------------------------------------------------------------------------

    The Medium HDV warranty period differs from the warranty periods 
associated with some engines that may be certified for use in those 
vehicles. Compression-ignition engines from the ``Light HDE'' primary 
intended service class and all spark-ignition engines certified to GHG 
standards under 40 CFR 1036.108 are subject to warranty requirements 
for five years or 50,000 miles (40 CFR 1036.120). We request comment on 
whether to revise the warranty provisions in 40 CFR 1037.120 to include 
a warranty period of five years or 50,000 miles for Medium HDV with 
compression-ignition engines from the ``Light HDE'' primary intended 
service class or with spark-ignition engines to be consistent with the 
GHG warranty periods for those engines.
    In Section IV.B, we propose to increase the warranty periods for 
engines certified to model year 2027 and later criteria pollutant 
standards. Under proposed 40 CFR 1036.150(w), those longer warranty 
periods would not apply for engine technologies that are limited to 
controlling greenhouse gas emissions, but we are not aware of any 
current or projected technologies that would qualify as being dedicated 
to meeting GHG standards. We request comment on whether to instead 
align all warranty periods that apply for engine technologies, 
irrespective of the emissions they are designed to control, with the 
warranty periods that we finalize for criteria pollutant emission 
control.
    For model years 2027 and later, we recognize that our proposed 
engine

[[Page 17629]]

warranty periods would differ from the vehicle warranty periods 
described in this section. All the proposed engine warranties are 
longer than the warranty periods under consideration for heavy-duty 
vehicles. We request comment on whether these misaligned warranties may 
pose a problem for certification or implementation.
3. Scope and Timing for Amending Applications for Certification
    Engines must be produced in a certified configuration to be covered 
by the certificate of conformity. Manufacturers routinely need to amend 
their applications for certification during the model year to reflect 
ongoing product development. These amendments may involve new 
configurations or improvements to existing configurations. The current 
regulations describe how manufacturers can make these amendments in a 
way that allow them to comply with the general requirement to produce 
engines that are in a certified configuration (see 40 CFR 1036.225 and 
1037.225). We generally refer to these amendments as running changes. 
Manufacturers apply these running changes to new engines they continue 
to build during the model year. Applying these running changes to 
engines that have already been produced is referred to as a ``field 
fix''. We have provided ``field-fix'' guidance since the earliest days 
of EPA emission standards.\948\
---------------------------------------------------------------------------

    \948\ ``Field Fixes Related to Emission Control-Related 
Components,'' EPA Advisory Circular, March 17, 1975.
---------------------------------------------------------------------------

    We recently adopted regulatory provisions in 40 CFR parts 1036 and 
1037 to describe how manufacturers may modify engines as reflected in 
the modified application for certification, which included essential 
elements of the 1975 field-fix guidance (80 FR 73478, October 25, 
2016).
    There is also a related field-fix question of how to allow for 
design changes to produced engines (before or after initial shipment) 
that the manufacturer identifies after the end of the model year. The 
preamble for that recent final rule explained that the regulatory 
provisions also included how manufacturers may amend an application for 
certification after the end of the model year to support intended 
modifications to in-use engines.
    After further consideration, we are proposing to revise 40 CFR 
1036.225 and 1037.225 to limit manufacturers to having the ability to 
amend an application for certification only during the production 
period represented by the model year. These proposed revisions would 
become effective upon the effective date of the final rule, if adopted. 
Manufacturers would continue to be able to apply field fixes to engines 
they have already produced if those engine modifications are consistent 
with the amended application for certification.
    The process for amending applications for certification under 
proposed 40 CFR 1036.225 and 1037.225 would not apply to field fixes 
that manufacturers identify after the end of the model year. Like our 
approach in other standard-setting parts for nonroad applications, we 
would refer manufacturers to the 1975 field-fix guidance for 
recommendations on how to approach design changes after the end of the 
model year. EPA's certification software is already set up to 
accommodate manufacturers that submit documentation for field fixes 
related to engine families from earlier model years. We believe this 
approach is effective, and it involves less burden for EPA 
implementation than allowing manufacturers to amend their application 
for certification after the end of the model year.
    We request comment on the proposed regulations for amending 
applications for certification and field-fixes within the model year 
for a given engine family.
    We expect to propose to adopt further regulatory provisions in a 
future rulemaking to update and clarify implementation of the field-fix 
policy for design changes that occur after the end of the model year. 
We expect that rulemaking to include consideration of such provisions 
for all types of highway and nonroad engines and vehicles.
4. Alternate Standards for Specialty Vehicles
    The final rule adopting HD GHG Phase 2 standards for heavy-duty 
highway engines and vehicles included provisions allowing limited 
numbers of specialty motor vehicles to have engines meeting alternate 
standards derived from EPA's nonroad engine programs (80 FR 73478, 
October 25, 2016). The provisions applied for amphibious vehicles, 
vehicles with maximum operating speed of 45 mph or less, and all-
terrain vehicles with portal axles. The provisions also apply for 
hybrid vehicles with engines that provide energy for a Rechargeable 
Energy Storage System, but only through model year 2027.
    We continue to recognize the need for and benefit of alternate 
standards that address limitations associated with specialty vehicles. 
We are therefore proposing to migrate these alternate standards from 40 
CFR 86.007-11 and 86.008-10 into 40 CFR 1036.605 without modification. 
At the same time, we are mindful of two important regulatory and 
technological factors that will cause us to potentially revise the 
alternate standards. First, certifying based on powertrain testing 
addresses the testing limitations associated with nonstandard power 
configurations. Second, emission control technologies may support more 
stringent alternate emission standards than the current nonroad engine 
standards. Furthermore, CARB has not adopted that same approach to 
apply alternate standards for specialty vehicles and we are unaware of 
manufacturers certifying any of these types of specialty vehicles to 
the full engine and vehicle standards. We may therefore consider 
revising the alternate standards, or discontinuing the alternate 
standards entirely. We are also considering whether to sunset the 
provisions for hybrid vehicles at the end of model year 2026 to align 
with the new standards that will start in model year 2027. We have 
prepared a memorandum that further explores these technological and 
regulatory issues, with a discussion of a range of possible options 
that we are considering.\949\ We request comment on all these potential 
changes to the provisions related to alternate standards for specialty 
vehicles. We might make those changes in this rule or in a future rule.
---------------------------------------------------------------------------

    \949\ Stout, Alan. Memorandum to Docket EPA-HQ-OAR-2019-0055. 
``Draft Amendments Related to Alternate Engine Standards for 
Specialty Vehicles''. January 31, 2022.
---------------------------------------------------------------------------

5. Additional Amendments
    We are proposing to revise the regulatory text in 40 CFR parts 1036 
and 1037 to describe units for tire rolling resistance as newtons per 
kilonewton (N/kN) instead of kg/tonne. SAE J2452 treats these as 
interchangeable units, but ISO 28580, which we incorporated by 
reference at 40 CFR 1037.810, establishes N/kN as the appropriate units 
for measuring rolling resistance. Since the units in the numerator and 
denominator cancel each other out either way, this change in units has 
no effect on the numerical values identified in the regulation or on 
data submitted by manufacturers.
    The regulation at 40 CFR 1037.115(e) describes how manufacturers 
demonstrate that they meet requirements related to air conditioning 
leakage. Paragraph (e) allows for alternative demonstration methods 
where the specified method is impossible or impractical, but limits

[[Page 17630]]

that alternative to systems with capacity above 3000 grams of 
refrigerant. We recognize alternative demonstrations may also be 
necessary for systems with smaller capacity and are therefore proposing 
to remove this qualifying criterion. The proposed change is also 
consistent with changes that CARB has made as part of the Omnibus 
rule.\950\
---------------------------------------------------------------------------

    \950\ California Air Resources Board, ``Appendix B-3 Proposed 
30-Day Modifications to the Greenhouse Gas Test Procedures'', May 5, 
2021, Available online: https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2020/hdomnibuslownox/30dayappb3.pdf, page 20.
---------------------------------------------------------------------------

    The SET duty cycle table in 40 CFR 86.1362 contains the engine 
speed and load as well as vehicle speed and road grade to carry out 
either engine or powertrain testing. The table contains two errors in 
the vehicle speed column for modes 1a and 14. The vehicle speed is set 
to ``warm idle speed'' in the table, which is an engine test set point. 
Since this is an idle mode and the vehicle is not moving, the vehicle 
speeds should be set to 0 mi/hr. This correction will have no effect on 
how powertrain testing over this duty cycle is carried out.
    We are proposing to correct a typo in 40 CFR 1036.235(c)(5)(iv)(C) 
regarding EPA's confirmatory testing of a manufacturer's fuel map for 
demonstrating compliance with greenhouse gas emission standards. We 
propose to update the ``greater than or equal to'' to ``at or below'' 
to be consistent with the related interim provision in 40 CFR 
1036.150(q). The intent of the EPA testing is to confirm that the 
manufacturer-declared value is at or below EPA's measured values.
    We are proposing to clarify that ``mixed-use vehicles'' qualify for 
alternate standards under 40 CFR 1037.105(h) if they meet any one of 
the criteria specified in 40 CFR 1037.631(a)(1) or (2). In contrast, 
vehicles meeting the criterion in 40 CFR 1037.631(a)(1) and at least 
one of the criteria in 40 CFR 1037.631(a)(2) automatically qualify as 
being exempt from GHG standards under 40 CFR part 1037.

C. Fuel Dispensing Rates for Heavy-Duty Vehicles (40 CFR Parts 80 and 
1090)

    EPA adopted a regulation limiting the fuel dispensing rate to a 
maximum of 10 gallons per minute for gasoline dispensed into motor 
vehicles (58 FR 16002, March 24, 1993). The dispensing limit 
corresponded with the test procedure for vehicle manufacturers to 
demonstrate compliance with a refueling spitback standard adopted in 
the same final rule. Spitback involves a spray of liquid fuel during a 
refueling event if the vehicle cannot accommodate the flow of fuel into 
the fuel tank. The spitback standard applied only for vehicles at or 
below 14,000 pounds GVWR, so we provided an exemption from the 
dispensing limit for dispensing pumps dedicated exclusively to heavy-
duty vehicles (see 40 CFR 80.22(j) and 1090.1550(b)). Just like for 
spitback testing with vehicles at or below 14,000 pounds GVWR, vehicles 
designed with onboard refueling vapor recovery systems depend on a 
reliable maximum dispensing rate to manage vapor flow into the carbon 
canister.
    Now that we are proposing a requirement for all gasoline-fueled 
heavy-duty highway vehicle manufacturers to comply with refueling 
standards, it is no longer appropriate to preserve the exemption from 
the dispensing rate limit for dispensing pumps dedicated exclusively to 
heavy-duty vehicles. Retail stations and fleets rarely have dispensing 
pumps that are dedicated to heavy-duty vehicles. Since there are no 
concerns of feasibility or other issues related to meeting the 10 
gallon per minute dispensing limit, we are proposing to remove the 
exemption upon the effective date of the final rule. We request comment 
on allowing additional lead time for any legacy installations that 
continue to have higher dispensing rates for gasoline-fueled heavy-duty 
vehicles. We expect few such cases. This may occur, for example, with a 
remaining fleet of gasoline-fueled school buses or with farms that have 
refueling capabilities for delivery trucks along with nonroad 
implements.
    We note that the proposed dispensing rate limits relate only to 
gasoline-fueled motor vehicles. There is no rate restriction on 
dispensing diesel fuel into motor vehicles, or on dispensing any kind 
of fuel into aircraft, marine vessels, other nonroad equipment, or 
portable or permanently installed storage tanks. We are also not 
proposing new dispensing rate limits for these fuels in this action.

D. Refueling Interface for Motor Vehicles (40 CFR Parts 80 and 1090)

    EPA first adopted a requirement for new gasoline-fueled cars and 
trucks to have filler necks fitted with a limiting orifice to prevent 
fueling with leaded fuel (38 FR 26450, Sept. 21, 1973). This purpose 
became obsolete when leaded gasoline was disallowed as a fuel for motor 
vehicles starting January 1, 1996. The requirement has nevertheless 
endured, perhaps to accommodate Stage II refueling controls at retail 
stations or to ensure compatibility with onboard refueling vapor 
recovery systems.
    In 2020, as part of a broader effort to streamline fuel 
regulations, EPA proposed to migrate in-use fuel regulations from 40 
CFR part 80 to 40 CFR part 1090 (85 FR 29034, May 14, 2020). Since the 
requirements related to vehicle-refueling interface were in 40 CFR 
80.24, we proposed to move those vehicle requirements to 40 CFR part 86 
for light-duty vehicles and to 40 CFR part 1037 for heavy-duty 
vehicles. In response to the proposed rule, we received comments 
suggesting that we should modify the requirements for narrow-diameter 
fuel necks to align with published voluntary consensus standards.\951\ 
In finalizing that rule, we deferred action on the proposed migration 
of these provisions to further consider potential modifications (85 FR 
78412, December 4, 2020).
---------------------------------------------------------------------------

    \951\ See SAE J285 ``Dispenser Nozzle Spouts for Liquid Fuels 
Intended for Use with Spark Ignition and Compression Ignition 
Engines'', April 2019 and ISO 9158:1988 ``Road vehicles--Nozzle 
spouts for unleaded gasoline'', March 1998.
---------------------------------------------------------------------------

    In the meantime, we have focused on further understanding the 
handful of heavy-duty vehicle models that have side-mounted fuel tanks. 
These vehicles are generally derived from diesel-fueled truck models 
and therefore are designed with large fuel tanks with no filler neck. 
In evaluating the feasibility of applying refueling standards for these 
vehicles, we again reviewed the narrow-diameter filler-neck 
requirement. The filler-neck restriction is no longer needed to prevent 
misfueling with leaded fuel. There is also no need for new vehicles to 
be designed to accommodate Stage II refueling controls now that they 
are subject to vehicle-based refueling standards. As a result, the only 
remaining need for restricting the filler-neck diameter is for those 
vehicles that depend on such a design to meet spitback and refueling 
standards.
    Since there is no longer an external emission-related design 
constraint for filler necks, vehicle manufacturers will no longer be 
constrained to design their vehicles to meet spitback and refueling 
standards with a limiting orifice. If vehicle manufacturers need to 
have a narrow-diameter filler neck to achieve a mechanical seal for 
onboard refueling vapor recovery or to prevent spitback, then they will 
need to include those design specifications. If they can use a 
different orifice or no orifice at all and still meet spitback and 
refueling standards, that would also represent a compliant 
configuration. We therefore propose to remove the filler-neck 
restrictions from 40 CFR 80.24 without migrating those requirements to 
the CFR parts for light-duty or heavy-duty vehicles.

[[Page 17631]]

    We acknowledge that there are commercial reasons to have 
standardized specifications for filler necks. This is reflected by the 
referenced voluntary consensus standards adopted to accomplish that 
purpose. EPA's existing specifications are compatible with those 
published standards but allow for a much wider range of dimensions. The 
comment from the earlier rulemaking requested that we update our 
specifications to match those in the voluntary consensus standards. We 
request comment on the appropriateness of either keeping the existing 
specifications or adopting the specifications from voluntary consensus 
standards into the EPA regulations. We specifically request comment on 
the benefit of adopting such standards and on the authority for 
adopting such standards under the Clean Air Act considering that we 
intend to remove the now obsolete requirements in 40 CFR 80.24.

E. Light-Duty Motor Vehicles (40 CFR Parts 85, 86, and 600)

    EPA's emission standards, certification requirements, and fuel 
economy provisions for light-duty motor vehicles are in 40 CFR part 85, 
40 CFR part 86, subpart S, and 40 CFR part 600.
1. Testing With Updated Versions of SAE J1634
i. Existing BEV Test Procedures
    EPA's existing regulations for testing Battery Electric Vehicles 
(BEVs) can be found in 40 CFR part 600--Fuel Economy and Greenhouse Gas 
Emissions of Motor Vehicles. The existing EPA regulations (40 CFR 
600.116-12(a) and 600.311-12(j) and (k)) reference the 2012 version of 
the SAE Standard J1634--Battery Electric Vehicle Energy Consumption and 
Range Test Procedure.
    Current regulations (40 CFR 600.116-12(a)) allow manufacturers to 
perform either single cycle tests (SCT) or the multi-cycle test (MCT) 
as described in the EPA regulations and the 2012 version of SAE J1634. 
The SCT and MCT are used to determine the unrounded and unadjusted city 
and highway range values and the city and highway mile per gallon 
equivalent (MPGe) fuel economy values.
    The 2012 version of SAE J1634 specifies 55 miles per hour (mph) as 
the speed to be used during the mid-test and end-of-test constant speed 
cycles of the MCT. The 2017 version of SAE J1634 specifies 65 mph as 
the speed to be used during the constant speed cycles of the MCT. 
Manufacturers have reached out to the Agency and requested to use the 
2017 version of SAE J1634 to reduce the time required to perform the 
MCT and the Agency has generally approved these requests. EPA's fuel 
economy regulations allow manufacturers to use procedures other than 
those specified in the regulations. The special test procedure option 
is described in 40 CFR 600.111-08(h). This option is used when vehicles 
cannot be tested according to the procedures in the EPA regulations or 
when an alternative procedure is determined to be equivalent to the EPA 
regulation.
    EPA regulations found in 40 CFR 600.210-12(d)(3) specify three 
options for manufacturers to adjust the unrounded and unadjusted 2-
cycle (city and highway) results for fuel economy labeling purposes. 
The three methods include: Generating 5-cycle data; multiplying the 2-
cycle values by 0.7; and asking the Administrator to approve adjustment 
factors based on operating data from in-use vehicles. To date the 
Agency has not approved any requests to use operating data from in-use 
vehicles to generate an adjustment factor.
    Many manufacturers use the option to multiply their 2-cycle fuel 
consumption and range result by the 0.7 adjustment factor. The benefit 
of this option for the manufacturer is that the manufacturer does not 
need to perform any of the additional 5-cycle tests to determine the 
label result. This method is equivalent to the derived 5-cycle method 
which allows manufacturers to adjust their 2-cycle fuel economy test 
results for gasoline vehicles based on the EPA determined slope and 
intercept values generated from 5-cycle testing performed on emission 
data vehicles (EDVs).
    A few manufacturers have been using the option to generate 5-cycle 
data which is then used for determining a 5-cycle adjustment factor. 
The specific 5-cycle adjustment factor is then multiplied by the 
unrounded, unadjusted 2-cycle results to determine fuel economy label 
values.
    EPA's current regulations do not specify a method for performing 5-
cycle testing for BEVs. EPA acknowledged this in the 2011 rulemaking 
that created the fuel economy label requirement for BEVs:

    The 5-cycle testing methodology for electric vehicles is still 
under development at the time of this final rule. This final rule 
will address 2-cycle and the derived adjustments to the 2-cycle 
testing, for electric vehicles. As 5-cycle testing methodology 
develops, EPA may address alternate test procedures. EPA regulations 
allow test methods alternate to the 2-cycle and derived 5-cycle to 
be used with Administrator approval. (76 FR 39501, July 6, 2011)

    The first manufacturer to approach EPA and request to perform 5-
cycle testing for BEVs was Tesla, and EPA approved Tesla's request. The 
method Tesla proposed is known as the BEV 5-cycle adjustment factor 
method, and it was added to Appendices B and C of the SAE J1634 
Standard in the 2017 update.
    Since publication of the 2017 version of SAE J1634, BEV 
manufacturers in addition to Tesla have been approaching the Agency and 
seeking to use the 5-cycle adjustment factor methodology outlined in 
Appendices B and C. EPA has generally approved manufacturer requests to 
use this method.
    The 5-cycle method outlined in the 2017 version of SAE J1634 is 
essentially the same method that EPA uses to determine 5-cycle fuel 
economy for vehicles with internal combustion engines. There are, 
however, two differences between the EPA approved BEV 5-cycle 
adjustment factor method compared to the 5-cycle calculation 
methodology outlined in 40 CFR 600.114-12, Vehicle-specific 5-cycle 
fuel economy and carbon-related exhaust emission calculations. The 
first difference is that the numerator of the City and Highway fuel 
economy equations is 0.92 rather than 0.905. This was done to remove 
the ethanol correction from the 5-cycle fuel economy equation for BEVs. 
The second change was to allow BEV manufacturers to use the results of 
a full charge depleting Cold Temperature Test Procedure (CTTP or 
20[deg]F FTP) in the City fuel economy calculation when calculating the 
running fuel consumption. Vehicles with internal combustion engines 
(ICE) use only the bag 2 and bag 3 fuel economy results from the CTTP. 
The CTTP is performed at an ambient temperature of 20[deg]F after the 
vehicle has cold-soaked in the 20[deg]F test chamber for a minimum of 
12 hours and a maximum of 36 hours. In addition, to reduce the testing 
burden the current BEV 5-cycle procedure allows manufacturers to skip 
the 10-minute key-off soak between UDDS cycles after the second UDDS 
cycle. This test procedure allowance was made to reduce the time burden 
for performing full charge depletion testing in the cold test chamber.
ii. Summary of Proposed Changes
    EPA is proposing to update the SAE J1634 standard referenced in 40 
CFR part 600 from the 2012 version to the 2017 version. This update 
will require manufacturers to use 65 mph for the constant speed cycles 
of the MCT. In addition, this update will allow

[[Page 17632]]

manufacturers to use the BEV 5-cycle adjustment factor methodology 
outlined in Appendices B and C of the 2017 version of SAE J1634 with 
the revisions described below.
    For model year 2023, manufacturers may continue to perform full 
charge depletion testing on BEVs when running the CTTP to determine the 
5-cycle adjustment factor. However, EPA is proposing that in model year 
2023 manufacturers would be required to perform a 10-minute key-off 
soak between each UDDS cycle performed as part of the charge depleting 
CTTP. We are not proposing to change the existing requirement to submit 
a written request for EPA approval to perform 5-cycle testing prior to 
beginning 5-cycle adjustment procedure testing. EPA is proposing that 
manufacturers will be required to attest that the vehicle was not 
preconditioned or connected to an external power source during the 
20[deg]F cold soak period.
    Beginning with model year 2024, EPA is proposing that manufacturers 
would be allowed to perform only two UDDS cycles when running the CTTP, 
with a 10-minute key-off soak between the UDDS cycles to generate their 
BEV 5-cycle adjustment factor. The running fuel consumption for the 
City fuel economy equation would be modified from the equation provided 
in Appendix C of the 2017 version of SAE J1634. The charge depletion 
value would be replaced with the results from Bag 2 of the first and 
second UDDS and Bag 1 from the second UDDS. The Agency would allow 
manufacturers to use their existing CTTP test results to make these 
calculations, or they could perform new tests with the option to have 
the vehicle's state-of-charge set to a value specified by the 
manufacturer such that the vehicle can capture regeneration energy 
during the first UDDS cycle.
    The Agency is also proposing additional changes to the procedures 
outlined in the 2017 version of SAE J1634 including: Specifying a 
maximum constant speed phase time of 1 hour with a minimum 5-minute 
soak following each one-hour constant speed phase; specifying the use 
of the methods in Appendix A of the 2017 version of SAE J1634 to 
determine the constant speed cycle's total time for the mid-test 
constant speed cycle; and, specifying that energy depleted from the 
propulsion battery during key-off engine soak periods is not included 
in the useable battery energy (UBE) measurement.
iii. Discussion of Proposed Changes
    The Agency is proposing to adopt portions of Appendix B and C of 
the 2017 version of SAE J1634 as the process for determining the 5-
cycle adjustment factor with modifications. As proposed, manufacturers 
will be required to request Administrator approval to use the process 
outlined in the Appendices with modifications including: Requiring soak 
periods of a minimum of 10 minutes between each UDDS cycle when 
performing the charge depleting CTTP (the Appendices allow skipping the 
key-off soak period between UDDS cycles, after the second UDDS cycle, 
to reduce the charge depleting test burden); adding the specification 
that preconditioning of any vehicle components, including the 
propulsion battery and vehicle cabin, is prohibited; and, beginning in 
the 2024 Model Year allowing only two UDDS cycles to be performed on 
the CTTP instead of allowing manufacturers to choose how many UDDS 
cycles to perform up to and including full charge depletion testing on 
the CTTP.
    The current approved 5-cycle test procedure includes allowing a 
complete charge depleting CTTP to generate data for the city fuel 
economy calculation. As the Agency has gathered data from manufacturers 
performing this test, it has become apparent that the charge depletion 
testing on the CTTP generates fuel consumption data that are not 
representative of the extreme cold start test conditions this test was 
designed to capture. A long-range BEV can complete as many as 50 UDDS 
cycles at -7[deg]C (20[deg]F) before depleting the battery. With the 
allowance to skip the 10-minute key off soak period after the second 
UDDS a long-range BEV will reach a stabilized warmed-up energy 
consumption condition after 6 to 10 UDDS cycles. At this point the 
vehicle is warmed-up and will have approximately the same energy 
consumption for each of the remaining 30 to 40 UDDS cycles. The 
averaged energy consumption value from this full charge depletion 
test--as many as 50 UDDS cycles--is entered into the 5-cycle equation 
for the running fuel consumption for the city fuel economy calculation. 
In contrast, for vehicles using fuels other than electricity the 
running fuel consumption is calculated using the values from Bag 2 of 
the first UDDS cycle and Bag 1 of the second UDDS cycle.
    It has become apparent to the Agency that modifications are needed 
to this method to ensure all vehicles are tested under similar 
conditions and use equivalent data for generating fuel economy label 
values. Allowing BEVs to perform a full charge depletion CTTP creates 
test procedure differences between BEVs and non-BEVs. Non-BEVs are not 
allowed to run more than one UDDS cycle followed by one Bag 1 phase 
from the second UDDS cycle.
    The intent of the CTTP is to capture the performance of vehicles 
under extreme cold start conditions during short trip city driving. The 
CTTP procedure used by vehicles other than BEVs consists of one UDDS 
cycle (consisting of Bag 1 and Bag 2) followed by a 10-minute key-off 
soak followed by the first 505 seconds (Bag 3) of the second UDDS 
cycle. The data from these three bags are utilized by all vehicles, 
other than BEVs, when calculating the vehicle's city fuel economy (40 
CFR 600.114-12). Allowing BEVs to use a fuel consumption value based on 
fully depleting the battery, while not performing any key-off soaks 
between any UDDS cycle after the second UDDS cycle is not 
representative of short trip urban driving or equivalent to the 
procedure performed by vehicles using fuels other than electricity.
    Based on these observations, the Agency has concluded that allowing 
BEVs to perform full charge depletion testing on the CTTP, with only 
one 10-minute key-off soak occuring between the first and second UDDS 
cycle, does not generate data representative of the vehicles' 
performance during extreme cold start short trip city driving 
conditions. Therefore, starting in model year 2024, the Agency proposes 
to allow BEVs to perform only two UDDS cycles with a 10-minute key-off 
soak between them. The Agency proposes the following change to the 
running fuel consumption equation used for calculating the city fuel 
economy outlined in Appendix C of the 2017 Version of SAE J1634:

[[Page 17633]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.012

    The Agency understands that the proposed test procedure and fuel 
economy equation is different from that for non-BEVs. The Agency also 
understands that BEV testing has primarily not consisted of measured 
sample bags and, instead has focused on performing complete UDDS 
cycles. Unlike vehicles using combustion engines, BEVs do not generate 
significant quantities of waste heat from their operation, and 
typically require using stored energy, when not being preconditioned at 
cold ambient temperatures, to produce heat for both the cabin and the 
battery. The Agency expects BEVs will require more than two UDDS cycles 
with a 10-minute key-off soak between them for the vehicle to reach a 
fully warmed up and stabilized operating point. As such, the Agency 
believes it is reasonable to include an additional data point (i.e., 
UDDS2 Bag2) for use in the running fuel consumption equation for BEVs. 
The Agency seeks comment on whether this is a reasonable procedure and 
calculation method for generating BEV fuel economy results that are 
comparable to the procedures and calculations used for non-BEVs, or, if 
the test procedure and fuel economy equation should be the same for 
BEVs and non-BEVs which would entail the BEV CTTP concluding following 
the completion of the first Bag of the second UDDS cycle.
    For model year 2024, the Agency proposes to allow manufacturers to 
recalculate the city fuel economy for models they are carrying-over 
using the first two UDDS cycles from their prior charge depletion CTTP 
test procedures to generate new model year 2024 label values. 
Manufacturers may not want to use these data, as the test may not be 
representative, since the vehicle's regeneration capability may be 
limited by the fully charged battery during the first and possibly 
second UDDS cycles on the CTTP. The Agency proposes to perform the two 
UDDS CTTP with the vehicle initially charged to a level defined by the 
manufacturer and disclosed to the Agency. One possible approach 
consists of charging the vehicle to a level that produces a battery 
state-of-charge (SoC) equivalent to 50 percent following the first UDDS 
cycle. The 2017 version of SAE J1634 refers to this SoC level as the 
mid-point test charge (MC).
    As BEVs have become more efficient and as battery capacities have 
increased over the past decade, the time required to perform CTTP 
charge depletion testing has dramatically increased. This proposal will 
result in significant time savings for manufacturers as the proposed 
BEV CTTP will consist of two UDDS cycles, and no longer allows charge 
depletion testing which, in many instances, would require multiple 
shifts to complete. The Agency also believes the results obtained from 
the proposal will be more representative of the energy consumption 
observed during short urban trips under extreme cold temperature 
conditions. The Agency seeks comment on these proposals for reducing 
test burden and reducing the test procedure variability between BEVs 
and vehicles other than BEVs.
iv. Proposed Changes to Procedures for Testing Electric Vehicles
    EPA is proposing to update from the 2012 to the 2017 version of SAE 
J1634 and proposing to include regulatory provisions that amend or 
clarify the BEV test procedures outlined in the 2017 version. These 
amendments are being proposed to minimize test procedure variations 
allowed in the 2017 version, which the Agency has concluded can impact 
test results. For example, the SAE standard allows for the constant 
speed cycles to be performed as a single phase or broken into multiple 
phases with key-off soak periods. Depending on how the constant-speed 
portion is subdivided, the UBE measurement can vary. These proposed 
changes are intended to reduce the variations between tests and to 
improve test-to-test and laboratory-to-laboratory repeatability.
    The proposed changes include:
     Allowing for Administrator approval for vehicles that 
cannot complete the Multi-Cycle Range and Energy Consumption Test (MCT) 
because of the distance required to complete the test or maximum speed 
for the UDDS or HFEDS cycle.
     In alignment with SAE J1634, Section 8.3.4, a 15 second 
key-on pause time and a 10 minute key-off soak period would be required 
between specific drive cycles where key-off soak periods have to be 
conducted with the key or power switch in the ``off'' position, the 
hood closed, and test cell fan(s) off, and the brake pedal not 
depressed.
     Manufacturers predetermine estimates of the mid-test 
constant speed cycle distance (dM) using the methods in SAE J1634, 
Appendix A.
     Mid-test constant speed cycles that do not exceed one hour 
do not need a key-off soak period. If the mid-test constant speed cycle 
exceeds one hour, the cycle needs to be separated into phases of less 
than one-hour, and a minimum 5-minute key-off soak is needed at the end 
of each phase.
     Using good engineering judgement, end-of-test constant 
speed cycles do not exceed 20 percent of total distance driven during 
the MCT, as described in SAE J1634, Section 8.3.3.
     End-of-test constant speed cycles that do not exceed one 
hour do not a need key-off soak period. If the end-of-test constant 
speed cycle exceeds one hour, the cycle needs to be separated into 
phases of less than one-hour, and a minimum 5-minute key-off soak is 
needed at the end of each phase.
     Discharge energy that occurs during the key-off soak 
periods is not included in the useable battery energy.
     Recharging the vehicle's battery must start within three 
hours after testing.
     The Administrator may approve a manufacturer's request to 
use an earlier version of SAE J1634 for carryover vehicles.
     All label values related to fuel economy, energy 
consumption, and range must be based on 5-cycle testing, or values must 
be adjusted to be equivalent to 5-cycle results. Manufacturers may 
request Administrator approval to use SAE J1634, Appendix B and 
Appendix C for determining 5-cycle adjustment factors.
2. Additional Light-Duty Changes Related to Certification Requirements 
and Measurement Procedures
    We are proposing the following additional amendments related to

[[Page 17634]]

criteria standards and general certification requirements:
     40 CFR part 85, subpart V: Correcting the warranty periods 
identified in the regulation to align with the Clean Air Act, as 
amended, and clarifying that the warranty provisions apply to both 
types of warranty specified in Clean Air Act section 207(a) and (b)--an 
emission defect warranty and an emission performance warranty. EPA 
adopted warranty regulations in 1980 to apply starting with model year 
1981 vehicles (45 FR 34802, May 22, 1980). The Clean Air Act as amended 
in 1990 changed the warranty period for model year 1995 and later 
light-duty vehicles and light-duty trucks to 2 years or 24,000 miles of 
use (whichever occurs first), except that a warranty period of 8 years 
or 80,000 miles applied for specified major emission control 
components.
     Section 86.117-96: Revising paragraph (d)(1), which 
describes how to calculate evaporative emissions from methanol-fueled 
vehicles. The equation in the regulation inadvertently mimics the 
equation used for calculating evaporative emissions from gasoline-
fueled vehicles. We are proposing to revise the equation to properly 
represent the fuel-specific calculations in a way that includes 
temperature correction for the sample volume based on the sample and 
SHED temperatures.
     Section 86.1810: Clarifying the certification 
responsibilities for cases involving small-volume manufacturers that 
modify a vehicle already certified by a different company and recertify 
the modified vehicle to the standards that apply for a new vehicle 
under 40 CFR part 86, subpart S. Since the original certifying 
manufacturer accounts for these vehicles in their fleet-average 
calculations, these secondary vehicle manufacturers should not be 
required to repeat those fleet-average calculations for the affected 
vehicles. This applies to fleet average standards for criteria exhaust 
emissions, evaporative emissions, and greenhouse gas emissions. The 
secondary vehicle manufacturer would need to meet all the same bin 
standards and family emission limits as specified by the original 
certifying manufacturer. We recently proposed a similar amendment (85 
FR 28140, May 12, 2020), but chose to re-propose this to include 
greenhouse gas emissions in response to a comment, rather than 
finalizing a revised provision in that rulemaking.
     Section 86.1819-14: Clarifying that the definition of 
``engine code'' for implementing heavy-duty greenhouse gas standards 
(Class 2b and 3) is the same ``engine code'' definition that applies to 
light-duty vehicles in the part 600 regulations.
     Section 86.1823-08: Revising to specify a simulated test 
weight based on Loaded Vehicle Weight for light light-duty trucks (LDT1 
and LDT2). The regulation inadvertently applies adjusted loaded vehicle 
weight, which is substantially greater and inappropriate for light 
light-duty trucks because they are most often used like lightly loaded 
passenger vehicles rather than cargo-carrying commercial trucks. In 
practice, we have been allowing manufacturers to implement test 
requirements for these vehicles based on Loaded Vehicle Weight. This 
proposed revision is responsive to manufacturers' request to clarify 
test weights for the affected vehicles.
     Section 86.1843-01(f)(2): Delaying the end-of-year 
reporting deadline to May 1 following the end of the model year. 
Manufacturers requested that we routinely allow for later submissions 
instead of setting the challenging deadline of January 1 and allowing 
extensions.
    We are proposing the following additional amendments related to 
greenhouse gas emissions and fuel economy testing:
     Section 86.1823: We are proposing to revise paragraph 
(m)(1) to reflect current business practices with respect to 
CO2 durability requirements. For example, while conventional 
vehicles currently have a multiplicative CO2 deterioration 
factor of one or an additive deterioration factor of zero to determine 
full useful life emissions for FTP and highway fuel economy tests, many 
plug-in hybrid electric vehicles have non-zero additive CO2 
deterioration factors (or manufacturers perform fuel economy tests 
using aged components). Proposed changes have no impact on conventional 
vehicles but strengthen the CO2 durability requirements for 
plug-in hybrid electric vehicles.
     Section 600.002: Revising the definition of ``engine 
code'' to refer to a ``test group'' instead of an ``engine-system 
combination''. This change reflects updated terminology corresponding 
to current certification procedures.
     Part 600, subpart B: Updating test procedures with 
references to 40 CFR part 1066 to reflect the migration of procedures 
from 40 CFR part 86, subpart B. The migrated test procedures allow us 
to delete the following obsolete regulatory sections: 600.106, 600.108, 
600.109, 600.110, and 600.112, along with references to those sections.
     Sections 600.115 and 600.210: EPA issued guidance in 2015 
for the fuel economy program to reflect technology trends.\952\ We are 
proposing to codify these changes in the regulation. First, as outlined 
in the EPA guidance letter and provisions of 40 CFR 600.210-
12(a)(2)(iv), ``[t]he Administrator will periodically update the slopes 
and intercepts through guidance and will determine the model year that 
the new coefficients must take effect.'' Thus, we are proposing to 
update the coefficients used for calculating derived 5-cycle city and 
highway mpg values in Section 600.210 to be consistent with the 
coefficients provided in the 2015 EPA guidance letter and to be more 
representative of the fuel economy characteristics of the current 
fleet. Second, for reasons discussed on page 2 of the EPA guidance 
letter, we are proposing to codify a change to 40 CFR 600.115 to allow 
manufacturers to calculate derived 5-cycle fuel economy and 
CO2 emission values using a factor of 0.7 only for battery 
electric vehicles, fuel cell vehicles, and plug-in hybrid electric 
vehicles (during charge depleting operation only).
---------------------------------------------------------------------------

    \952\ ``Derived 5-cycle Coefficients for 2017 and Later Model 
Years'', EPA Guidance Document CD-15-15, June 22, 2015.
---------------------------------------------------------------------------

     Section 600.210: The regulation already allows 
manufacturers to voluntarily decrease fuel economy values and raise 
CO2 emission values if they determine that the values on the 
fuel economy label do not properly represent in-use performance. The 
expectation is that manufacturers would prefer not to include label 
values that create an unrealistic expectation for consumers. We are 
proposing to add a condition that the manufacturer may adjust these 
values only if the manufacturer changes both values and revises any 
other affected label value accordingly for a model type (including but 
not limited to the fuel economy 1-10 rating, greenhouse gas 1-10 
rating, annual fuel cost, and 5-year fuel cost information). We are 
also proposing to extend these same provisions for electric vehicles 
and plug-in hybrid electric vehicles based on both increasing energy 
consumption values and lowering the electric driving range values.
     Section 600.311: Adding clarifying language to reference 
the adjusted driving ranges to reflect in-use driving conditions. These 
adjusted values are used for fuel economy labeling. For plug-in hybrid 
electric vehicles, we are also correcting terminology from ``battery 
driving range'' to ``adjusted charge-depleting driving range 
(Rcda)'' for clarity and to be consistent with the terms 
used in SAE Recommended Practice J1711.

[[Page 17635]]

     Section 600.510-12: Providing a more detailed cross 
reference to make sure manufacturers use the correct equation for 
calculating average combined fuel economy.
     Section 600.512-12: Delaying the deadline for the model 
year report from the end of March to May 1. The proposal aligns the 
deadline provisions with the proposed amendment for end-of-year 
reporting as described in 40 CFR 86.1843-01(f)(2).

F. Large Nonroad Spark-Ignition Engines (40 CFR Part 1048)

    EPA's emission standards and certification requirements for land-
based nonroad spark-ignition engines above 19 kW are set out in 40 CFR 
part 1048. We are proposing the following amendments to part 1048:
     Section 1048.501: Correct a mistaken reference to duty 
cycles in appendix II.
     Section 1048.620: Remove obsolete references to 40 CFR 
part 89.

G. Small Nonroad Spark-Ignition Engines (40 CFR Part 1054)

    EPA's emission standards and certification requirements for land-
based nonroad spark-ignition engines at or below 19 kW (``Small SI 
engines'') are set out in 40 CFR part 1054. We recently proposed 
several amendments to part 1054 (85 FR 28140, May 12, 2020). Comments 
submitted in response to that proposed rule suggested additional 
amendments related to testing and certifying these Small SI engines. 
The following discussion addresses some of these suggested additional 
amendments that the EPA is proposing in this rule.
1. Engine Test Speed
    The duty cycle established for nonhandheld Small SI engines 
consists of six operating modes with varying load, and with engine 
speed corresponding to typical governed speed for the intended 
application. This generally corresponds to an ``A cycle'' with testing 
at 3060 rpm to represent a typical operating speed for a lawnmower, and 
a ``B cycle'' with testing at 3600 rpm to represent a typical operating 
speed for a generator. While lawnmowers and generators are the most 
common equipment types, there are many other applications with widely 
varying speed setpoints.
    In 2020, we issued guidance to clarify manufacturers' testing 
responsibilities for the range of equipment using engines from a given 
emission family.\953\ We are proposing to adopt the provisions 
described in that guidance document. This includes two main items. 
First, we are proposing to identify all equipment in which the 
installed engine's governed speed at full load is at or above 3400 rpm 
as ``rated-speed equipment'', and all equipment in which the installed 
engine's governed speed at full load is below 3330 rpm as 
``intermediate-speed equipment``. For equipment in which the installed 
engine's governed speed at full load is between 3330 and 3400 rpm, the 
engine manufacturer may consider that to be either ``rated-speed 
equipment'' or ``intermediate-speed equipment''. This allows 
manufacturers to reasonably divide their engine models into separate 
families for testing only on the A cycle or the B cycle, as 
appropriate. For emission families including both rated-speed equipment 
and intermediate-speed equipment, manufacturers would measure emissions 
over both the A cycle and the B cycle and certify based on the worst-
case HC+NOX emission results.
---------------------------------------------------------------------------

    \953\ ``Small Spark-Ignition Nonhandheld Engine Test Cycle 
Selection,'' EPA guidance document CD-2020-06, May 11, 2020.
---------------------------------------------------------------------------

    Second, we are proposing to limit the applicability of the A cycle 
to engines with governed speed at full load that is at or above 2700 
rpm, and limit the applicability of the B cycle to engines with 
governed speed at full load that is at or below 4000 rpm. These values 
represent an approximate 10 percent variation from the nominal test 
speed. For engines with governed speed at full load outside of these 
ranges, we propose to require that manufacturers use the provisions for 
special procedures in 40 CFR 1065.10(c)(2) to identify suitable test 
speeds for those engines. Manufacturers may take reasonable measures to 
name alternate test speeds to represent multiple engine configurations 
and equipment installations.
2. Steady-State Duty Cycles
    As noted in Section XII.G.1, the duty cycle for nonhandheld engines 
consists of a six-mode duty cycle including idle and five loaded test 
points. This cycle is not appropriate for engines designed to be 
incapable of operating with no load at a reduced idle speed. For many 
years, we have approved a modified five-mode duty cycle for these 
engines by removing the idle mode and reweighting the remaining five 
modes. We are proposing to adopt that same alternative duty cycle into 
the regulation and require its use for all engines that are not 
designed to idle. For emission families that include both types of 
engines, manufacturers would measure emissions over both the six-mode 
and five-mode duty cycles and certify based on the worst-case 
HC+NOX emission results.
    The discussion in Section XII.G.1 applies equally for nonhandheld 
engines whether or not they are designed to idle. As a result, if an 
emission family includes engines designed for idle with governed speeds 
corresponding to rated-speed equipment and intermediate-speed 
equipment, and engines in the same emission family that are not 
designed to idle have governed speeds corresponding to rated-speed 
equipment and intermediate-speed equipment, the manufacturer would need 
to perform A cycle and B cycle testing for both the six-mode duty cycle 
and the five-mode duty cycle. Manufacturers would then perform those 
four sets of emission measurements and certify based on the worst-case 
HC+NOX emission results.
    The nonhandheld six-mode duty cycle in appendix II to 40 CFR part 
1054 includes an option to do discrete-mode or ramped-modal testing. 
The ramped-modal test method involves collecting emissions during the 
established modes and defined transition steps between modes to allow 
manufacturers to treat the full cycle as a single measurement. With the 
new five-mode duty cycle, we would need to decide whether to again 
specify a corresponding ramped-modal duty cycle. We are proposing 
rather to remove the ramped-modal test option for the six-mode duty 
cycle. No manufacturer has ever used ramped-modal testing. This appears 
to be based largely on the greater familiarity with discrete-mode 
testing and on the sensitivity of small engines to small variations in 
speed and load. Rather than increasing the complexity of the regulation 
by multiplying the number of duty cycles, we are favoring the leaner 
approach of limiting tests to those tests that manufacturers have 
selected consistently over the years.
3. Engine Family Criteria
    Manufacturers requested that we allow open-loop and closed-loop 
engines to be included together in a certified emission family, with 
the testing demonstration for certification based on the worst-case 
configuration.
    The key regulatory provision for this question is in 40 CFR 
1054.230(b)(8), which says that engine configurations can be in the 
same emission family if they are the same in the ``method of control 
for engine operation, other than governing (mechanical or 
electronic)``.
    Engine families are intended to group different engine models and 
configurations together if they will have similar emission 
characteristics throughout the useful life. The general

[[Page 17636]]

description of an engine's ``method of control for engine operation'' 
requires that EPA apply judgment to establish which fuel-system 
technologies should be eligible for treating together in a single 
engine family. We have implemented this provision by allowing open-loop 
and closed-loop engine configurations to be in the same emission family 
if they have the same design values for spark timing and targeted air-
fuel ratio. This approach allows us to consider open-loop vs. closed-
loop configurations as different ``methods of control'' when the 
engines have fundamentally different approaches for managing 
combustion. We do not intend to change this current practice and we are 
therefore not proposing to amend 40 CFR 1054.230 to address the concern 
about open-loop and closed-loop engine configurations.
    The existing text of 40 CFR 1054.230(b)(8) identifies ``mechanical 
or electronic'' control to be fundamental for differentiating emission 
families. However, as is expected for open-loop and closed-loop 
configurations, we would expect engines with electronic throttle-body 
injection and mechanical carburetion to have very similar emission 
characteristics if they have the same design values for spark timing 
and targeted air-fuel ratio. A more appropriate example to establish a 
fundamental difference in method of control would be the contrast 
between port fuel injection and carburetion (or throttle-body 
injection). We are therefore proposing to revise the regulation with 
this more targeted example. This revision would allow manufacturers to 
group engine configurations with carburetion and throttle-body 
injection into a shared emission family as long as they have the same 
design values for spark timing and targeted air-fuel ratio.
4. Miscellaneous Amendments for Small Nonroad Spark-Ignition Engines
    We are proposing the following additional amendments to 40 CFR part 
1054:
     Section 1054.115: Revising the description of prohibited 
controls to align with similar provisions from the regulations that 
apply for other sectors.
     Appendix I: Clarifying that requirements related to 
deterioration factors, production-line testing, and in-use testing did 
not apply for Phase 1 engines certified under 40 CFR part 90.

H. Recreational Vehicles and Nonroad Evaporative Emissions (40 CFR 
parts 1051 and 1060)

    EPA's emission standards and certification requirements for 
recreational vehicles are set out in 40 CFR part 1051, with additional 
specifications for evaporative emission standards in 40 CFR part 1060. 
We are proposing the following amendments to parts 1051 and 1060:
     Section 1051.115(d): Aligning the time and cost 
specification related to air-fuel adjustments with those that apply for 
mechanically adjustable parameters we are proposing in 40 CFR 
1068.50(d)(1). This would create a uniform set of specifications for 
time and cost thresholds for all adjustable parameters including air-
fuel ratio adjustment.
     Sections 1051.501(c) and 1060.515(c) and (d): Creating an 
exception to the ambient temperature specification for fuel-line 
testing to allow for removing the test article from an environmental 
chamber for daily weight measurements. This proposed change aligns with 
our recent change to allow for this same exception in the measurement 
procedure for fuel tank permeation (86 FR 34308, June 29, 2021).
     Section 1051.501(c): Specifying that fuel-line testing 
involves daily weight measurements for 14 days. This is consistent with 
the specifications in 40 CFR 1060.515. This proposed amendment codifies 
EPA's guidance to address these test parameters that are missing from 
the referenced SAE J30 test procedure.\954\
---------------------------------------------------------------------------

    \954\ ``Evaporative Permeation Requirements for 2008 and Later 
Model Year New Recreational Vehicles and Highway Motorcycles'', EPA 
guidance document CD-07-02, March 26, 2007.
---------------------------------------------------------------------------

     Section 1051.501(d): Updating referenced procedures. The 
referenced procedure in 40 CFR 1060.810 is the 2006 version of ASTM 
D471. We inadvertently left the references in 40 CFR 1051.501 to the 
1998 version of ASTM D471. Citing the standard without naming the 
version allows us to avoid a similar error in the future.
     Section 1051.515: Revising the soak period specification 
to allow an alternative of preconditioning fuel tanks at 435 [deg]C for 10 weeks. The existing regulation allows for a soak 
period that is shorter and higher temperature than the specified soak 
of 285 [deg]C for 20 weeks. This approach to an alternative 
soak period is the same as what is specified in 40 CFR 1060.520(b)(1).
     Section 1060.520: Adding ``'' where that was 
inadvertently omitted in describing the temperature range that applies 
for soaking fuel tanks for 10 weeks.
    We are proposing an additional amendment related to snowmobile 
emission standards. The original exhaust emission standards for 
snowmobiles in 40 CFR 1051.103 included standards for NOX 
emissions. However, EPA removed those NOX emission standards 
in response to an adverse court decision.\955\ We are therefore 
proposing to remove the reference to NOX emissions in the 
description of emission credits for snowmobiles in 40 CFR 1051.740(b).
---------------------------------------------------------------------------

    \955\ ``Bluewater Network vs. EPA, No. 03-1003, September Term, 
2003'' Available here: https://www.govinfo.gov/content/pkg/USCOURTS-caDC-03-01249/pdf/USCOURTS-caDC-03-01249-0.pdf. The Court found that 
the EPA had authority to regulate CO under CAA 213(a)(3) and HC 
under CAA 213(a)(4), but did not have authority to regulate 
NOX under CAA 213(a)(4) as it was explicitly referred to 
in CAA 213(a)(2) and CAA 213(a)(4) only grants authority to regulate 
emissions ``not referred to in paragraph (2).''
---------------------------------------------------------------------------

I. Marine Diesel Engines (40 CFR parts 1042 and 1043)

    EPA's emission standards and certification requirements for marine 
diesel engines under the CAA are in 40 CFR part 1042. Emission 
standards and related fuel requirements that apply internationally are 
in 40 CFR part 1043.
1. Production-Line Testing
    Engine manufacturers have been testing production engines as 
described in 40 CFR part 1042. This generally involves testing up to 1 
percent of production engines for engine families with production 
volumes greater than 100 engines. We adopted these testing provisions 
in 1999 with the expectation that most families would have production 
volumes greater than 100 engines per year (64 FR 73300, December 29, 
1999). That was the initial rulemaking to set emission standards for 
marine diesel engines. As a result, there was no existing certification 
history to draw on for making good estimates of the number of engine 
families or the production volumes in those engine families. Now that 
we have almost 20 years of experience in managing certification for 
these engines, we can observe that manufacturers have certified a few 
engine families with production volumes substantially greater than 100 
engines per year, but many engine families are not subject to 
production-line testing because production volumes are below 100 
engines per year. As a result, manufacturers test several engines in 
large engine families, but many engine families have no production-line 
testing at all.
    We are proposing to revise the production-line testing regimen for 
marine diesel engines to reflect a more tailored approach. The biggest 
benefit of production-line testing for this sector is

[[Page 17637]]

to confirm that engine manufacturers can go beyond the prototype engine 
build for certification and move to building compliant engines in a 
production environment. From this perspective, the first test is of 
most value, with additional tests adding assurance of proper quality 
control procedures for ongoing production. Additional testing might 
also add value to confirm that design changes and updated production 
practices over time do not introduce problems.
    We are proposing to set up a default engine sampling rate of one 
test per family. An engine test from a prior year would count as a 
sufficient demonstration as long as the manufacturer certifies the 
engine family using carryover emission data. At the same time, we are 
proposing to remove the testing exemption for small-volume engine 
manufacturers and low-volume engine families. In summary, this approach 
would:
     Remove the testing exemption for low-volume families and 
small-volume manufacturers, and remove the 1 percent sampling rate. 
Revise the engine sampling instruction to require one test for each 
family. A test from a prior year can meet the test requirement for 
carryover families. This includes tests performed before these changes 
to the regulation become effective. This may also involve shared 
testing for recreational and commercial engine families if they rely on 
the same emission-data engine.
     Require a single test engine randomly selected early in 
the production run. EPA may direct the manufacturer to select a 
specific configuration and build date. The manufacturer continues to be 
subject to the requirement to test two more engines for each failing 
engine, and notify EPA if an engine family fails.
     Require a full test report within 45 days after testing is 
complete for the family. There would be no additional quarterly report 
or annual reports.
     Allow manufacturers to transition to the new test 
requirements by spreading out tests over multiple years if several 
engine families are affected. Small-volume engine manufacturers would 
need to test no more than two engine families in a single model year, 
and other engine manufacturers would need to test no more than four 
engine families in a single model year.
     Allow EPA to withhold approval of a request for 
certification for a family for a given year if PLT work from the 
previous model year is not done.
     Preserve EPA's ability to require an additional test in 
the same model year or a later model year for cause even after there 
was a passing result based on any reasonable suspicion that engines may 
not meet emission standards.
    In our recent rule proposing several regulatory amendments to 
Marine CI provisions in 40 CFR part 1042 (and several other sectors), 
we requested comment on changes to production-line testing that were 
very similar to what we are proposing in this document (85 FR 28140, 
May 12, 2020). That proposed rule referenced a memorandum with draft 
regulatory amendments.\956\ The provisions in this proposal include the 
following adjustments to reflect the input shared by commenters:
---------------------------------------------------------------------------

    \956\ ``Alternative Production-Line Testing Requirements for 
Marine Diesel Engines,'' EPA memorandum from Alan Stout to Docket 
EPA-HQ-OAR-2019-0307, January 23, 2020.
---------------------------------------------------------------------------

     The start of testing must occur within 60 days after 
production starts for a given Category 1 engine family, with an 
accommodation for low-volume families that specifies that the engine 
manufacturer must test the next engine produced if the 60-day time 
frame is not sufficient for selecting a test engine.
     The same provisions apply for selecting a Category 2 
engine for testing, except that the 60-day period for engine selection 
starts after the manufacturer produces the fifth engine from an engine 
family. This approach is reflective of the production volumes that are 
typical for Category 2 engines.
     For the additional testing that is required after failing 
results, we specify a 90-day time frame in case the engine family's 
production volumes are too low to resume testing after producing 15 
engines.
     We are keeping the requirement to randomly select 
production engines for testing, but we are clarifying that (1) the 
fundamental feature of random selection is to ensure that test engines 
have been assembled using the same instructions, procedures, and 
quality-control oversight that applies for other production engines and 
(2) random selection can include preferentially selecting engines 
earlier than we specify. For example, a manufacturer may randomly 
select a test engine for a high-volume Category 1 engine family in the 
first 20 days of production instead of randomly selecting a test engine 
from the first 60 days of production.
     There are no test requirements until after the 
manufacturer starts production for a given engine family.
    The proposal giving us the discretion to require additional testing 
for cause would include a more detailed description to illustrate the 
types of concerns that would lead us to identify the need for 
additional testing. Reporting defects for an engine family would raise 
such a concern. In addition, amending applications for certification 
might also raise concerns.\957\ Decreasing an engine family's Family 
Emission Limit without submitting new emission data would be a concern 
because the manufacturer would appear to be creating credits from what 
was formerly considered a necessary compliance margin. Changing 
suppliers or specifications for critical emission-related components 
would raise concerns about whether the emission controls system is 
continuing to meet performance expectations. Adding a new or modified 
engine configuration always involves a judgment about whether the 
original test data continue to represent the worst-case configuration 
for the expanded family. In any of these cases, we may direct the 
manufacturer to perform an additional test with a production engine to 
confirm that the family meets emission standards. In addition to these 
specific concerns, we expect manufacturers to have a greater vigilance 
in making compliant products if they know that they may need to perform 
additional testing. Conversely, removing the possibility of further 
testing for the entirety of a production run spanning several years 
could substantially weaken our oversight presence to ensure compliance.
---------------------------------------------------------------------------

    \957\ In this context, making the described changes in an 
application for certification applies equally for running changes 
within a model year and for changes that are introduced at the start 
of a new model year.
---------------------------------------------------------------------------

    The net effect of the proposed production-line test changes would 
be a substantial decrease in overall testing. We estimate industry-wide 
testing will decrease by about 30 engines per year. Spreading test 
requirements more widely across the range of engine families should 
allow for a more effective program in spite of the reduced testing 
rate. We acknowledge that some individual companies will test more 
engines under the proposal; however, by limiting default test rates to 
one per engine family, including future years, this would represent a 
small test burden even for the companies with new or additional testing 
requirements.
    We request comment on the timing for starting the transition to the 
new approach, including any appropriate adjustments to the maximum 
annual test rate for small-volume and other engine manufacturers. We 
request comment on adjusting the criteria by which we would treat 
different engine families to be the same for purposes of production-
line testing. We request

[[Page 17638]]

comment on the test schedule, especially for balancing the different 
dynamics that apply for high-volume, low-volume, and seasonal engines. 
We request comment on our attempt to clarify that engines must be 
randomly selected even for the most challenging cases of low-volume 
production and carefully constructed timelines. We request comment on 
the schedule for reporting test results to properly balance the 
interests of timely submissions with the practical realities of 
assembling the information. We request comment on the proposed criteria 
to inform our decision-making for requiring additional testing beyond 
the mandatory first test engine; this may include clarification or 
adjustment of the proposed criteria, and it may include consideration 
of additional criteria that would support a concern for ongoing 
compliance. More generally, we request comment on all aspects of the 
proposed approach for sampling and testing production engines to 
achieve the benefits of EPA's effective compliance oversight at a 
reasonable level of testing for manufacturers.
    We are proposing two additional clarifications related to 
production-line testing. First, we are clarifying that test results 
from the as-built engine are the final results to represent that 
engine. Manufacturers may modify the test engine to develop alternative 
strategies or to better understand the engine's performance; however, 
testing from those modified engines do not represent the engine family 
unless the manufacturer changes their production processes for all 
engines to match those engine modifications. Testing modified engines 
to meet production-line testing obligations would count as a separate 
engine rather than replacing the original test results.
    Second, we are clarifying that Category 3 auxiliary engines 
exempted from EPA certification under part 1042 continue to be subject 
to production-line testing under 40 CFR 1042.305. This question came up 
because we recently amended 40 CFR 1042.650(d) to allow Category 3 
auxiliary engines installed in certain ships to meet Annex VI 
certification requirements instead of EPA certification requirements 
under part 1042 (86 FR 34308, June 29, 2021). As with Category 1 and 
Category 2 engines covered by production-line testing requirements in 
40 CFR 1042.301, these test requirements apply for all engines subject 
to part 1042, even if they are not certified under part 1042.
2. Applying Reporting Requirements to EGR-Equipped Engines
    EPA has received comments suggesting that we apply the SCR-related 
monitoring and reporting requirements in 40 CFR 1042.660(b) to engines 
that instead use exhaust gas recirculation (EGR) to meet Tier 4 
standards. We understand SCR and EGR to be fundamentally different in 
ways that lead us not to propose this suggested change.
i. Maintenance
    There are two principal modes of EGR failure: (1) Failure of the 
valve itself (physically stuck or not able to move or adjust within 
normal range) and (2) EGR cooler fouling. EGR cooler maintenance is 
typically listed in the maintenance instructions provided by engine 
manufacturers to owners. If done according to the prescribed schedule, 
this should prevent fouling of the EGR cooler. Similarly, EGR valves 
typically come with prescribed intervals for inspection and 
replacement. For both components, the intervals are long and occur at 
the time that other maintenance is routinely performed. Under 40 CFR 
1042.125(a)(2), the minimum interval for EGR-related filters and 
coolers is 1500 hours, and the minimum interval for other EGR-related 
components is either 3000 hours or 4500 hours depending on the engine's 
max power.
    In contrast, SCR systems depend on the active, ongoing involvement 
of the operator to maintain an adequate supply of Diesel Exhaust Fluid 
(DEF) as a reductant to keep the catalyst functioning properly. EPA 
does not prescribe the size of DEF storage tanks for vessels, but the 
engine manufacturers provide installation instructions with 
recommendations for tank sizing to ensure that enough DEF is available 
onboard for the duration of a workday or voyages between ports. At the 
frequencies that this fluid needs replenishing, it would not be 
expected that other routine maintenance must also be performed, aside 
from refueling.
    DEF consumption from marine diesel engines is estimated to be 3-8 
percent of diesel fuel consumption. Recommended DEF tank sizes are 
generally about 10 percent of the onboard fuel storage, with the 
expectation that operators would refill DEF tanks during a refueling 
event.
    Another point of contrast is that SCR systems have many failure 
modes in addition to the failure to maintain an adequate supply of 
reductant. For example, dosing could stop due to faulty sensors, 
malfunctions of components in the reductant delivery system, or 
freezing of the reductant.
    Over the years of implementing regulations for which SCR is the 
adopted technology, EPA has produced several guidance documents to 
assist manufacturers in developing approvable SCR engine 
designs.958 959 960 Many of the features implemented to 
assure that SCR systems are properly maintained by vehicle and 
equipment operators are not present with systems on marine vessels. 
Thus, we rely on the reporting provision of 40 CFR 1042.660(b) to 
enhance our assurance that maintenance will occur as prescribed.
---------------------------------------------------------------------------

    \958\ ``Revised Guidance for Certification of Heavy-Duty Diesel 
Engines Using Selective Catalyst Reduction (SCR) Technologies'', EPA 
guidance document CISD-09-04, December 30, 2009.
    \959\ ``Nonroad SCR Certification'', EPA Webinar Presentation, 
July 26, 2011.
    \960\ ``Certification of Nonroad Diesel Engines Equipped with 
SCR Emission Controls'', EPA guidance document CD-14-10, May 12, 
2014.
---------------------------------------------------------------------------

ii. Tampering
    Engine manufacturers and others have asked questions about 
generation of condensate from an EGR-equipped engine. This condensate 
is an acidic liquid waste that must be discharged in accordance with 
water quality standards (and IMO, USCG, local port rules). The Tier 4 
EGR-equipped engines that EPA has certified are believed to generate a 
very small amount of EGR condensate. Larger quantities of condensate 
may be generated from an aftercooler, but that is non-acidic, non-oily 
water that would generally not need to be held onboard or treated. In 
the absence of compelling information to the contrary, we believe that 
the burden of storing, treating, and discharging the EGR condensate is 
not great enough to motivate an operator to tamper with the engine.
    Most EGR-equipped engines have internal valves and components that 
are not readily accessible to operators. In these cases, the controls 
to activate or deactivate EGR are engaged automatically by the engine's 
electronic control module and are not vulnerable to operator tampering. 
Where an engine design has external EGR, even though emission-related 
components may be somewhat accessible to operators, the controls are 
still engaged automatically by the engine's electronic control module 
and continued compliance is ensured if prescribed maintenance is 
performed on schedule and there is no tampering.
    iii. Nature of the Risk
    There are five manufacturers actively producing hundreds of 
certified Category 1 marine diesel engines each year using EGR to 
achieve Tier 3

[[Page 17639]]

emission standards. Nobody has suggested that these EGR controls are 
susceptible to tampering or malmaintenance.
    There is one manufacturer who has certified two Category 3 marine 
diesel engine families using EGR to achieve the Tier 3 emission 
standards for these large engines. If there is any risk with these, 
it's that the ocean-going vessel may not visit an ECA often enough to 
exercise the EGR valve and prevent it from getting corroded or stuck. 
These engines are already subject to other onboard diagnostics and 
reporting requirements, so we expect no need to expand 40 CFR 
1042.660(b) for these engines.
    There is one manufacturer producing Category 2 marine diesel 
engines using EGR to achieve the Tier 4 emission standards. We again do 
not see the need to include them in the reporting scheme in 40 CFR 
1042.660(b).
3. Miscellaneous Amendments for Marine Diesel Engines
    We are proposing the following additional amendments for our marine 
diesel engine program:
     Sections 1042.110 and 1042.205: Revising text to refer to 
``warning lamp'' instead of ``malfunction indicator light'' to prevent 
confusion with conventional onboard diagnostic controls. This aligns 
with changes adopted for land-based nonroad diesel engines in 40 CFR 
part 1039. We are also clarifying that the manufacturers description of 
the diagnostic system in the application for certification should 
identify which communication protocol the engine uses.
     Section 1042.110: Revising text to refer more broadly to 
detecting a proper supply of Diesel Exhaust Fluid to recognize, for 
example, that a closed valve may interrupt the supply (not just an 
empty tank).
     Section 1042.115: Revising provisions related to 
adjustable parameters, as described in Section XII.H.1.
     Section 1042.115: Adding provisions to address concerns 
related to vanadium sublimation, as described in Section XII.B.
     Section 1042.615: Clarifying that engines used to repower 
a steamship may be considered to qualify for the replacement engine 
exemption. This exemption applies relative to EPA standards in 40 CFR 
part 1042. We are also proposing to amend 40 CFR 1043.95 relative to 
the application of MARPOL Annex VI requirements for repowering Great 
Lakes steamships.
     Section 1042.660(b): Revising the instruction for 
reporting related to vessel operation without reductant for SCR-
equipped engines to describe the essential items to be reported, which 
includes the cause, the remedy, and an estimate of the extent of 
operation without reductant. We are also proposing to revise the 
contact information for reporting, and to clarify that the reporting 
requirement applies equally for engines that meet standards under 
MARPOL Annex VI instead of or in addition to meeting EPA standards 
under part 1042. We are also aware that vessel owners may choose to 
voluntarily add SCR systems to engines certified without 
aftertreatment; we propose to clarify that the reporting requirement of 
40 CFR 1042.660(b) does not apply for these uncertified systems. These 
changes are intended to clarify the reporting instructions for 
manufacturers under this provision rather than creating a new reporting 
obligation. We request comment on adjusting these information 
requirements to meet the goal of providing essential information with a 
minimal reporting burden.
     Section 1042.901: Clarifying that the displacement value 
differentiating Category 1 and Category 2 engines subject to Tier 1 and 
Tier 2 standards was 5.0 liters per cylinder, rather than the value of 
7.0 liters per cylinder that applies for engines subject to Tier 3 and 
Tier 4 standards.
     Part 1042, appendix I: Correcting the decimal places to 
properly identify the historical Tier 1 and Tier 2 PM standards for 19-
37 kW engines.
     Section 1043.20: Revising the definition of ``public 
vessel'' to clarify how national security exemptions relate to 
applicability of requirements under MARPOL Annex VI. Specifically, 
vessels with an engine-based national security exemption are exempt 
from NOX standards under MARPOL Annex VI, and vessels with a 
fuel-based national security exemption are exempt from the fuel 
standards under MARPOL Annex VI. Conversely, an engine-based national 
security exemption does not automatically exempt a vessel from the fuel 
standards under MARPOL Annex VI, and a fuel-based national security 
exemption does not automatically exempt a vessel from the 
NOX standards under MARPOL Annex VI. These distinctions are 
most likely to come into play for merchant marine vessels that are 
intermittently deployed for national (noncommercial) service.
     Section 1043.55: Revising text to clarify that U.S. Coast 
Guard is the approving authority for technologies that are equivalent 
to meeting sulfur standards under Regulation 4 of MARPOL Annex VI.
     Section 1043.95: Expanding the Great Lakes steamship 
provisions to allow for engine repowers to qualify for the replacement 
engine exemption in Annex VI, Regulation 13.2.2. This allows EPA to 
approve a ship owner's request to install engines meeting the IMO Tier 
II NOX standard. Since meeting the IMO Tier III 
NOX standard for such a repower project would be cost-
prohibitive, this proposed provision is intended to create an incentive 
for shipowners to upgrade the vessel by replacing the steam boilers 
with IMO Tier II engines, with very substantial expected reductions in 
NOX, PM, and CO2 emissions compared to emission 
rates from continued operation as steamships. We are also proposing to 
simplify the fuel-use exemption for Great Lakes steamships to allow for 
continued use of high-sulfur fuel for already authorized steamships, 
while recognizing that the fuel-use exemption is no longer available 
for additional steamships.

J. Locomotives (40 CFR Part 1033)

    EPA's emission standards and certification requirements for 
locomotives and locomotive engines are in 40 CFR part 1033. This 
proposed rule includes several amendments that affect locomotives, as 
discussed in Sections XI.A and XI.L.
    We are proposing to amend 40 CFR 1033.815 to clarify how penalty 
provisions apply relative to maintenance and remanufacturing 
requirements. We have become aware that the discussion of violations 
and penalties in 40 CFR 1033.815(f) addresses failure to perform 
required maintenance but omits reference to the recordkeeping 
requirements described in that same regulatory section. We originally 
adopted the maintenance and recordkeeping requirements with a statement 
describing that failing to meet these requirements would be considered 
a violation of the tampering prohibition in 40 CFR 1068.101(b)(1). The 
requirement for owners to keep records for the specified maintenance 
are similarly tied to the tampering prohibition, but failing to keep 
required records cannot be characterized as a tampering violation per 
se. As a result, we are proposing to clarify that a failure to keep 
records violates 40 CFR 1068.101(a)(2).
    We are also proposing to amend 40 CFR 1033.815(f) to specifically 
name the tampering prohibition as the relevant provision related to 
maintenance requirements for locomotives, rather than making a more 
general reference to prohibitions in 40 CFR 1068.101.

[[Page 17640]]

    We are also proposing to amend 40 CFR 1033.525 to remove the 
smokemeter requirements and replace them with a reference to 40 CFR 
1065.1125, which we are proposing as the central location for all 
instrument and setup requirements for measuring smoke. We are also 
proposing to add data analysis requirements for locomotives to 40 CFR 
1033.525 that were never migrated over from 40 CFR 92.131; 
manufacturers still use these procedures to analyze and submit smoke 
data for certifying locomotives. It is our understanding is that all 
current smoke testing includes computer-based analysis of measured 
results; we are therefore proposing to remove the references to manual 
or graphical analysis of smoke test data.
    Finally, we are proposing to amend 40 CFR 1033.1 to clarify that 40 
CFR part 1033 applies to engines that were certified under part 92 
before 2008. We are also proposing to remove 40 CFR 1033.102 and revise 
40 CFR 1033.101 and appendix A of part 1033 to more carefully describe 
how locomotives were subject to different standards in the transition 
to the standards currently specified in 40 CFR 1033.101.

K. Stationary Compression-Ignition Engines (40 CFR Part 60, Subpart 
IIII)

    EPA's emission standards and certification requirements for 
stationary compression-ignition engines are in 40 CFR part 60, subpart 
IIII. Section 60.4202 establishes emission standards for stationary 
emergency compression-ignition engines. We are proposing to correct a 
reference in 40 CFR 60.4202 to the Tier 3 standards for marine engines 
contained in 40 CFR part 1042. EPA emission standards for certain 
engine power ratings go directly from Tier 2 to Tier 4. Such engines 
are never subject to Tier 3 standards, so the reference in 40 CFR 
60.4202 is incorrect. Section 60.4202 currently describes the engines 
as those that otherwise ``would be subject to the Tier 4 standards''. 
We propose to amend the regulation to more broadly refer to the 
``previous tier of standards'' instead of naming Tier 3. In most case, 
this would continue to apply the Tier 3 standards for these engines, 
but the Tier 2 standards would apply if there was no applicable Tier 3 
standard.

XIII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is an economically significant regulatory action that 
was submitted to the Office of Management and Budget (OMB) for review. 
Any changes made in response to OMB recommendations have been 
documented in the docket. EPA prepared an analysis of the potential 
costs and benefits associated with this action. This analysis, the 
draft ``Regulatory Impact Analysis--Control of Air Pollution from New 
Motor Vehicles: Heavy-Duty Engine and Vehicle Standards NPRM,'' is 
available in the docket. The analyses contained in this document are 
also summarized in Sections V, VI, VII, VIII, IX, X, and XI of this 
preamble.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the PRA. The Information Collection Request (ICR) document 
that EPA prepared has been assigned EPA ICR Number 2621.01. You can 
find a copy of the ICR in the docket for this rule, and it is briefly 
summarized here.
    The proposed rule builds on existing certification and compliance 
requirements required under title II of the Clean Air Act (42 U.S.C. 
7521 et seq.). Existing requirements are covered under two ICRs: (1) 
EPA ICR Number 1684.20, OMB Control Number 2060-0287, Emissions 
Certification and Compliance Requirements for Nonroad Compression-
ignition Engines and On-highway Heavy Duty Engines; and (2) EPA ICR 
Number 1695.14, OMB Control Number 2060-0338, Certification and 
Compliance Requirements for Nonroad Spark-ignition Engines. Therefore, 
this ICR only covers the incremental burden associated with the updated 
regulatory requirements as described in the proposed rule. The 
resulting burden and costs estimates may be updated in response to 
additional input the Agency receives in comments on the proposed 
regulatory changes and to reflect any updates or revisions in the final 
rule.
     Respondents/affected entities: The entities potentially 
affected by this action are manufacturers of engines and vehicles in 
the heavy-duty on-highway industries, including alternative fuel 
converters, secondary vehicle manufacturers, and electric vehicle 
manufactures. Manufacturers of light-duty vehicles, light-duty trucks, 
marine diesel engines, locomotives, and various types of nonroad 
engines, vehicles, and equipment may be affected to a lesser degree.
     Respondent's obligation to respond: Regulated entities 
must respond to this collection if they wish to sell their products in 
the United States, as prescribed by CAA section 203(a). Participation 
in some programs is voluntary; but once a manufacturer has elected to 
participate, it must submit the required information.
     Estimated number of respondents: Approximately 279 
(total).
     Frequency of response: Annually or On Occasion, depending 
on the type of response.
     Total estimated burden: 24,214 hours per year. Burden is 
defined at 5 CFR 1320.03(b).
     Total estimated cost: $5,694,258 (per year), includes an 
estimated $3,729,550 annualized capital or maintenance and operational 
costs.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the 
accuracy of the provided burden estimates and any suggested methods for 
minimizing respondent burden to EPA using the docket identified at the 
beginning of this rule. You may also send your ICR-related comments to 
OMB's Office of Information and Regulatory Affairs via email to 
[email protected]. Attention: Desk Officer for EPA. Since OMB 
is required to make a decision concerning the ICR between 30 and 60 
days after receipt, OMB must receive comments no later than April 27, 
2022. EPA will respond to any ICR-related comments in the final rule.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. The 
small entities subject to the requirements of this proposed action are 
heavy-duty alternative fuel engine converters, heavy-duty electric 
vehicle manufacturers, a heavy-duty conventional vehicle manufacturer, 
and heavy-duty secondary vehicle manufacturers. While the proposed rule 
also includes regulatory amendments for sectors other than highway 
heavy-duty engines and vehicles, these amendments for other sectors 
correct, clarify, and streamline the regulatory provisions, and there 
is no burden from

[[Page 17641]]

the proposed rule on small entities in these other sectors.
    We identified 265 small entities in the heavy-duty sector that 
would be subject to the proposed rule: Two heavy-duty alternative fuel 
engine converters, 13 electric vehicle manufacturers, one conventional 
vehicle manufacturer, and 249 heavy-duty secondary vehicle 
manufacturers. The Agency has determined that 217 of the 265 small 
entities subject to the rule would experience an impact of less than 1 
percent of annual revenue; 48 small entities would experience an impact 
of 1 to less than 3 percent of annual revenue; and no small entity 
would experience an impact of 3 percent or greater of annual revenue. 
Specifically, the two alternative fuel engine converters, the 13 
electric vehicle manufacturers, the conventional vehicle manufacturer, 
and 201 secondary vehicle manufacturers would experience an impact of 
less than 1 percent of annual revenue, and 48 secondary vehicle 
manufacturers would experience an impact of 1 to less than 3 percent of 
annual revenue. Details of this analysis are presented in Chapter 11 of 
the draft RIA.

D. Unfunded Mandates Reform Act (UMRA)

    This proposed rule contains no federal mandates under UMRA, 2 
U.S.C. 1531-1538, for State, local, or Tribal governments. The proposed 
rule would impose no enforceable duty on any State, local or Tribal 
government. This proposed rule would contain a federal mandate under 
UMRA that may result in expenditures of $100 million or more for the 
private sector in any one year. Accordingly, the costs and benefits 
associated with the proposed rule are discussed in Section IX and in 
the draft RIA, which are in the docket for this rule.
    This action is not subject to the requirements of section 203 of 
UMRA because it contains no regulatory requirements that might 
significantly or uniquely affect small governments.

E. Executive Order 13132: Federalism

    This proposed rule does not have federalism implications. It will 
not have substantial direct effects on states, on the relationship 
between the national government and states, or on the distribution of 
power and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have Tribal implications as specified in 
Executive Order 13175. Thus, Executive Order 13175 does not apply to 
this action. This action does not have substantial direct effects on 
one or more Indian tribes, on the relationship between the Federal 
Government and Indian tribes, or on the distribution of power and 
responsibilities between the Federal Government and Indian tribes. 
However, EPA plans to continue engaging with Tribal stakeholders in the 
development of this rulemaking by offering a Tribal workshop and 
offering government-to-government consultation upon request.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    This action is subject to Executive Order 13045 because it is an 
economically significant regulatory action as defined by Executive 
Order 12866, and EPA believes that the environmental health risks or 
safety risks addressed by this action may have a disproportionate 
effect on children. Accordingly, we have evaluated the environmental 
health or safety effects of air pollutants affected by the proposed 
program on children. The results of this evaluation are described in 
Section II regarding the Need for Additional Emissions Control and 
associated references in Section II.
    Children are more susceptible than adults to many air pollutants 
because of differences in physiology, higher per body weight breathing 
rates and consumption, rapid development of the brain and bodily 
systems, and behaviors that increase chances for exposure. Even before 
birth, the developing fetus may be exposed to air pollutants through 
the mother that affect development and permanently harm the individual.
    Infants and children breathe at much higher rates per body weight 
than adults, with infants under one year of age having a breathing rate 
up to five times that of adults.\961\ In addition, children breathe 
through their mouths more than adults and their nasal passages are less 
effective at removing pollutants, which leads to a higher deposition 
fraction in their lungs.\962\
---------------------------------------------------------------------------

    \961\ U.S. Environmental Protection Agency. (2009). 
Metabolically-derived ventilation rates: A revised approach based 
upon oxygen consumption rates. Washington, DC: Office of Research 
and Development. EPA/600/R-06/129F. https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=202543.
    \962\ Foos, B.; Marty, M.; Schwartz, J.; Bennet, W.; Moya, J.; 
Jarabek, A.M.; Salmon, A.G. (2008) Focusing on children's inhalation 
dosimetry and health effects for risk assessment: An introduction. J 
Toxicol Environ Health 71A: 149-165.
---------------------------------------------------------------------------

    Certain motor vehicle emissions present greater risks to children 
as well. Early lifestages (e.g., children) are thought to be more 
susceptible to tumor development than adults when exposed to 
carcinogenic chemicals that act through a mutagenic mode of 
action.\963\ Exposure at a young age to these carcinogens could lead to 
a higher risk of developing cancer later in life. Section II.B.7 
describes a systematic review and meta-analysis conducted by the U.S. 
Centers for Disease Control and Prevention that reported a positive 
association between proximity to traffic and the risk of leukemia in 
children.
---------------------------------------------------------------------------

    \963\ U.S. Environmental Protection Agency. (2005). Supplemental 
guidance for assessing susceptibility from early-life exposure to 
carcinogens. Washington, DC: Risk Assessment Forum. EPA/630/R-03/
003F. https://www.epa.gov/raf/publications/pdfs/childrens_supplement_final.pdf.
---------------------------------------------------------------------------

    The adverse effects of individual air pollutants may be more severe 
for children, particularly the youngest age groups, than adults. As 
described in Section II.B, the Integrated Science Assessments for a 
number of pollutants affected by this rule, including those for 
NO2, PM, ozone and CO, describe children as a group with 
greater susceptibility. Section II.B.7 discusses a number of childhood 
health outcomes associated with proximity to roadways, including 
evidence for exacerbation of asthma symptoms and suggestive evidence 
for new onset asthma.
    There is substantial evidence that people who live or attend school 
near major roadways are more likely to be of a minority race, Hispanic 
ethnicity, and/or low SES. Within these highly exposed groups, 
children's exposure and susceptibility to health effects is greater 
than adults due to school-related and seasonal activities, behavior, 
and physiological factors.
    Section VI.B of this preamble presents the estimated emissions 
reductions from the proposed rule, including substantial reductions in 
NOX and other criteria and toxic pollutants. Section VII of 
this preamble presents the air quality impacts of the proposed rule. 
The air quality modeling predicts decreases in ambient concentrations 
of air pollutants in 2045 due to the proposed standards, including 
significant improvements in ozone concentrations. Ambient 
PM2.5, NO2 and CO concentrations are also 
predicted to improve in 2045 because of the proposed program.

[[Page 17642]]

    Children are not expected to experience greater ambient 
concentrations of air pollutants than the general population. However, 
because of their greater susceptibility to air pollution and their 
increased time spent outdoors, it is likely that the proposed standards 
would have particular benefits for children's health.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution, or use of energy. In fact, this proposal has an 
incremental positive impact on energy supply and use. Section III.E and 
Section V describe our projected fuel savings due to the proposed 
refueling emissions standards for certain Spark-ignition HDE. These 
refueling emission standards would require manufacturers to implement 
emission control systems to recover evaporative emissions that would 
otherwise be emitted to the ambient air during a refueling event for 
use in those engines. Considering the estimated incremental fuel 
savings from the proposed refueling emissions standards, we have 
concluded that this proposal is not likely to have any adverse energy 
effects.

I. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR 
Part 51

    This action involves technical standards. Except for the standards 
discussed below, the standards included in the regulatory text as 
incorporated by reference were all previously approved for IBR and no 
change is included in this action.
    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference the use of test methods and standards from 
ASTM International (ASTM). The referenced standards and test methods 
may be obtained through the ASTM website (www.astm.org) or by calling 
(610) 832-9585. If ASTM adopts an updated version of the referenced 
standards, we would expect to reference the most recent version. We are 
proposing to incorporate by reference the following ASTM standards:

------------------------------------------------------------------------
   Standard or test method         Regulation              Summary
------------------------------------------------------------------------
ASTM D975-21, Standard        40 CFR 1036.415(c)    Fuel specification
 Specification for Diesel      and 1036.810(a).      needed for
 Fuel''.                                             manufacturer-run
                                                     field-testing
                                                     program. This is a
                                                     newly referenced
                                                     standard.
ASTM D4814-21c, Standard      40 CFR 1036.415(c)    Fuel specification
 Specification for             and 1036.810(a).      needed for
 Automotive Spark-Ignition                           manufacturer-run
 Engine Fuel.                                        field-testing
                                                     program. This is a
                                                     newly referenced
                                                     standard.
ASTM D7467-20a, Standard      40 CFR 1036.415(c)    Fuel specification
 Specification for Diesel      and 1036.810(a).      needed for
 Fuel Oil, Biodiesel Blend                           manufacturer-run
 (B6 to B20).                                        field-testing
                                                     program. This is a
                                                     newly referenced
                                                     standard.
------------------------------------------------------------------------

    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference the use of test methods and standards from 
SAE International. The referenced standards and test methods may be 
obtained through the SAE International website (www.sae.org) or by 
calling (800) 854-7179. We are proposing to incorporate by reference 
the following SAE International standards and test methods:

------------------------------------------------------------------------
   Standard or test method         Regulation              Summary
------------------------------------------------------------------------
SAE J1634, July 2017,         40 CFR 600.011(c),    The procedure
 Battery Electric Vehicle      600.116-12(a),        describes how to
 Energy Consumption and        600.210-12(d), and    measure energy
 Range Test Procedure.         600.311-12(j) and     consumption and
                               (k). 40 CFR           range from electric
                               1066.501(a) and       vehicles. This is
                               1066.1010(b).         an updated version
                                                     of the document
                                                     currently specified
                                                     in the regulation.
SAE J1711, June 2010,         40 CFR 1066.501(a),   The recommended
 Recommended Practice for      1066.1001, and        practice describes
 Measuring the Exhaust         1066.1010(b).         how to measure fuel
 Emissions and Fuel Economy                          economy and
 of Hybrid-Electric                                  emissions from
 Vehicles, Including Plug-In                         light-duty
 Hybrid Vehicles.                                    vehicles, including
                                                     hybrid-electric
                                                     vehicles. This
                                                     proposal cites the
                                                     reference document
                                                     in an additional
                                                     place in the
                                                     regulation.
SAE J1979-2, April 22, 2021,  40 CFR 1036.150(v)    The standard
 E/E Diagnostic Test Modes:    and 1036.810(e).      includes
 OBDonUDS.                                           information
                                                     describing
                                                     interface protocols
                                                     for onboard
                                                     diagnostic systems.
                                                     This is a newly
                                                     referenced
                                                     standard.
SAE J2263, May 2020, Road     40 CFR 1037.528       The procedure
 Load Measurement Using        introductory text,    describes how to
 Onboard Anemometry and        (a), (b), (d), and    perform coastdown
 Coastdown Techniques.         (f), 1037.665(a),     measurements with
                               and 1037.810(e). 40   light-duty and
                               CFR 1066.301(b),      heavy-duty
                               1066.305,             vehicles. This is
                               1066.310(b),          an updated version
                               1066.1010(b).         of the document
                                                     currently specified
                                                     in the regulation.
SAE J2711, May 2020,          40 CFR 1066.501(a)    The recommended
 Recommended Practice for      and 1066.1010(b).     practice describes
 Measuring Fuel Economy and                          how to measure fuel
 Emissions of Hybrid-                                economy and
 Electric and Conventional                           emissions from
 Heavy-Duty Vehicles.                                heavy-duty
                                                     vehicles, including
                                                     hybrid-electric
                                                     vehicles. This is
                                                     an updated version
                                                     of the document
                                                     currently specified
                                                     in the regulation.
SAE J2841, March 2009,        40 CFR 1037.550(a)    The standard
 Utility Factor Definitions    and 1037.810(e).      practice
 for Plug-In Hybrid Electric                         establishes
 Vehicles Using 2001 U.S.                            terminology and
 DOT National Household                              procedures for
 Travel Survey Data.                                 calculating
                                                     emission rates and
                                                     fuel consumption
                                                     for plug-in hybrid
                                                     electric vehicles.
------------------------------------------------------------------------


[[Page 17643]]

    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference the use of test methods and standards from 
the International Organization for Standardization (ISO). This 
reference standard is intended to support proposed changes to labeling 
for heavy-duty engines. We request comment on the need or benefit of 
amending the regulation to cite this same document where we currently 
use an older version of the same reference standard for fuel economy 
labels (see 40 CFR part 600, subpart D). The referenced standards and 
test methods may be obtained through the ISO website (www.iso.org) or 
by calling (41) 22749 0111. We propose to incorporate by reference the 
following ISO standard:

------------------------------------------------------------------------
   Standard or test method         Regulation              Summary
------------------------------------------------------------------------
ISO/IEC 18004:2015(E),        40 CFR 1036.135(c)    The standard
 February 2015, Information    and 1036.810(c).      specifies a
 technology--Automatic                               standardized code
 identification and data                             protocol for
 capture techniques--QR Code                         including on
 bar code symbology                                  engines' emission
 specification, Third                                control information
 Edition.                                            labels. This is a
                                                     newly referenced
                                                     standard.
------------------------------------------------------------------------

    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference the use of test methods and standards from 
the Idaho National Laboratory. The referenced standards and test 
methods may be obtained through the Idaho National Laboratory website 
(www.inl.gov) or by calling (866) 495-7440. We propose to incorporate 
by reference the following test methods:

------------------------------------------------------------------------
   Standard or test method         Regulation              Summary
------------------------------------------------------------------------
U.S. Advanced Battery         40 CFR 1037.552(a)    The referenced
 Consortium, Electric          and 1037.810(f).      procedure describes
 Vehicle Battery Test                                a procedure for
 Procedures Manual, Revision                         preconditioning
 2, January 1996.                                    batteries as part
                                                     of a performance
                                                     demonstration. This
                                                     is a newly
                                                     referenced
                                                     standard.
------------------------------------------------------------------------

    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference the use of test methods and standards from 
the California Air Resources Board (CARB). The referenced standards and 
test methods may be obtained through the CARB website (www.arb.ca.gov) 
or by calling (916) 322-2884. We propose to incorporate by reference 
the following CARB documents:

------------------------------------------------------------------------
   Standard or test method         Regulation              Summary
------------------------------------------------------------------------
CARB's 2019 OBD regulation--  40 CFR 1036.110(b)    The CARB standards
 13 CCR 1968.2, 1968.5, and    and 1036.810(d).      establish
 1971.5.                                             requirements for
                                                     onboard diagnostic
                                                     systems for heavy-
                                                     duty vehicles.
                                                     These are newly
                                                     referenced
                                                     standards.
CARB's 2019 OBD regulation--  40 CFR 1036.110(b)    The CARB standards
 13 CCR 1971.1.                and (c),              establish
                               1036.111(a) and       requirements for
                               (c), and              onboard diagnostic
                               1036.810(d).          systems for heavy-
                                                     duty vehicles. This
                                                     is a newly
                                                     referenced
                                                     standard.
------------------------------------------------------------------------

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    EPA believes that this proposed rule does not have 
disproportionately high and adverse human health or environmental 
effects on minority populations, low-income populations and/or 
indigenous peoples, as specified in Executive Order 12898 (59 FR 7629, 
February 16, 1994). Section II.B.8 of this preamble provides a 
qualitative summary of evidence that communities with environmental 
justice concerns are disproportionately impacted by mobile source 
emissions and would therefore benefit from the emissions reductions 
that would result from this proposal. Section II.B.8 also presents the 
results of new work that shows that, relative to the rest of the 
population, people living near truck routes are more likely to be 
people of color and have lower incomes than the general population.
    With respect to emissions reductions and associated improvements in 
air quality, EPA has determined that this rule would benefit all U.S. 
populations, including minority populations, low-income populations and 
indigenous peoples. Section VI of this preamble presents the estimated 
emissions reductions from the proposed rule, including substantial 
reductions in NOX and other criteria and toxic pollutants. 
Section VII of this preamble presents the air quality impacts of the 
proposed Option 1. The air quality modeling predicts decreases in 
ambient concentrations of air pollutants in 2045 due to the proposed 
standards, including significant improvements in ozone concentrations. 
Ambient PM2.5, NO2 and CO concentrations are also 
predicted to improve in 2045 because of the proposed Option 1 program.
    In terms of benefits to human health, reduced ambient 
concentrations of ozone and PM2.5 would lead to the 
avoidance of many adverse environmental and human health impacts in 
2045, including reductions in premature deaths and many non-fatal 
illnesses. These health benefits, presented in Section VIII of the 
preamble, would accrue to all U.S. populations, including minority 
populations, low-income populations and indigenous peoples.
    EPA also conducted a demographic analysis of air quality modeling 
data in 2045 to examine trends in human exposure to future air quality 
in scenarios both with and without the proposed Option 1 in place. That 
analysis, summarized in Section VII.H of the preamble and presented in 
more detail in draft RIA Chapter 6.3.9, found that in the 2045 
baseline, nearly double the number of people of color live

[[Page 17644]]

within areas with the worst ozone and PM2.5 air quality 
compared to non-Hispanic whites. We also found that the largest 
predicted improvements in both ozone and PM2.5 are estimated 
to occur in areas with the worst baseline air quality. While there 
would be improvements in air quality for people of color, disparities 
in PM2.5 and ozone exposure are projected to remain.

XIV. Statutory Provisions and Legal Authority

    Statutory authority for the requirements proposed in this 
rulemaking can be found in CAA sections 202, 203, 206, 207, 208, 213, 
216, and 301 (42 U.S.C. 7521, 7522, 7525, 7541, 7542, 7547, 7550, and 
7601).

List of Subjects

40 CFR Part 2

    Administrative practice and procedure, Confidential business 
information, Courts, Environmental protection, Freedom of information, 
Government employees

40 CFR Part 59

    Air pollution control, Confidential business information, Labeling, 
Ozone, Reporting and recordkeeping requirements, Volatile organic 
compounds.

40 CFR Part 60

    Administrative practice and procedure, Air pollution control, 
Aluminum, Beverages, Carbon monoxide, Chemicals, Coal, Electric power 
plants, Fluoride, Gasoline, Glass and glass products, Grains, 
Greenhouse gases, Household appliances, Industrial facilities, 
Insulation, Intergovernmental relations, Iron, Labeling, Lead, Lime, 
Metals, Motor vehicles, Natural gas, Nitrogen dioxide, Petroleum, 
Phosphate, Plastics materials and synthetics, Polymers, Reporting and 
recordkeeping requirements, Rubber and rubber products, Sewage 
disposal, Steel, Sulfur oxides, Vinyl, Volatile organic compounds, 
Waste treatment and disposal, Zinc.

40 CFR Part 80

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Diesel fuel, Fuel additives, Gasoline, Imports, 
Oil imports, Petroleum, Renewable fuel.

40 CFR Part 85

    Confidential business information, Greenhouse gases, Imports, 
Labeling, Motor vehicle pollution, Reporting and recordkeeping 
requirements, Research, Warranties.

40 CFR Part 86

    Environmental protection, Administrative practice and procedure, 
Confidential business information, Labeling, Motor vehicle pollution, 
Reporting and recordkeeping requirements.

40 CFR Part 87

    Environmental protection. Air pollution control, Aircraft.

40 CFR Part 600

    Environmental protection, Administrative practice and procedure, 
Electric power, Fuel economy, Incorporation by reference, Labeling, 
Reporting and recordkeeping requirements.

40 CFR Part 1027

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Reporting and recordkeeping requirements.

40 CFR Part 1030

    Environmental protection, Air pollution control, Aircraft, 
Greenhouse gases.

40 CFR Part 1033

    Environmental protection, Administrative practice and procedure, 
Confidential business information, Environmental protection, Labeling, 
Penalties, Railroads, Reporting and recordkeeping requirements.

40 CFR Part 1036

    Environmental protection, Administrative practice and procedure, 
Air pollution control Confidential business information, Greenhouse 
gases, Incorporation by reference, Labeling, Motor vehicle pollution, 
Reporting and recordkeeping requirements, Warranties.

40 CFR Part 1037

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Incorporation 
by reference, Labeling, Motor vehicle pollution, Reporting and 
recordkeeping requirements, Warranties.

40 CFR Part 1039

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Labeling, Penalties, Reporting and recordkeeping requirements, 
Warranties.

40 CFR Part 1042

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Environmental 
protection, Imports, Labeling, Penalties, Reporting and recordkeeping 
requirements, Vessels, Warranties.

40 CFR Part 1043

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Imports, Reporting and recordkeeping 
requirements, Vessels.

40 CFR Parts 1045, 1051, and 1054

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Labeling, Penalties, Reporting and recordkeeping requirements, 
Warranties.

40 CFR Part 1048

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Labeling, Penalties, Reporting and recordkeeping requirements, 
Research, Warranties.

40 CFR Part 1060

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Labeling, Penalties, Reporting and recordkeeping requirements, 
Warranties.

40 CFR Part 1065

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Reporting and recordkeeping requirements, 
Research.

40 CFR Part 1066

    Environmental protection, Air pollution control, Incorporation by 
reference, Reporting and recordkeeping requirements.

40 CFR Part 1068

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Confidential business information, Imports, 
Motor vehicle pollution, Penalties, Reporting and recordkeeping 
requirements, Warranties.

40 CFR Part 1090

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Diesel fuel, Fuel

[[Page 17645]]

additives, Gasoline, Imports, Oil imports, Petroleum, Renewable fuel.

Michael S. Regan,
Administrator.

    For the reasons set out in the preamble, we are amending title 40, 
chapter I of the Code of Federal Regulations as set forth below.

PART 2--PUBLIC INFORMATION

0
1. The authority citation for part 2 continues to read as follows:

    Authority:  5 U.S.C. 552, 552a, 553; 28 U.S.C. 509, 510, 534; 31 
U.S.C. 3717.

0
2. Amend Sec.  2.301 by adding and reserving paragraph (i) and adding 
paragraph (j) to read as follows:


Sec.  2.301  Special rules governing certain information obtained under 
the Clean Air Act.

* * * * *
    (i) [Reserved]
    (j) Requests for or release of information subject to a 
confidentiality determination through rulemaking as specified in 40 CFR 
part 1068. This paragraph (j) describes provisions that apply for a 
wide range of engines, vehicles, and equipment that are subject to 
emission standards and other requirements under the Clean Air Act. This 
includes motor vehicles and motor vehicle engines, nonroad engines and 
nonroad equipment, aircraft and aircraft engines, and stationary 
engines. It also includes portable fuel containers regulated under 40 
CFR part 59, subpart F, and fuel tanks, fuel lines, and related fuel-
system components regulated under 40 CFR part 1060. Regulatory 
provisions related to confidentiality determinations for these products 
are codified broadly in 40 CFR part 1068, with additional detailed 
provisions for specific sectors in the regulatory parts referenced in 
40 CFR 1068.1. References in this paragraph (j) to 40 CFR part 1068 
also include these related regulatory parts.
    (1) Unless noted otherwise, 40 CFR 2.201 through 2.215 do not apply 
for information covered by the confidentiality determinations in 40 CFR 
part 1068 if EPA has determined through rulemaking that information to 
be any of the following pursuant to 42 U.S.C. 7414 or 7542(c) in a 
rulemaking subject to 42 U.S.C. 7607(d):
    (i) Emission data as defined in paragraph (a)(2)(i) of this 
section.
    (ii) Data not entitled to confidential treatment.
    (2) Unless noted otherwise, 40 CFR 2.201 through 2.208 do not apply 
for information covered by the confidentiality determinations in 40 CFR 
part 1068 if EPA has determined through rulemaking that information to 
be entitled to confidential treatment pursuant to 42 U.S.C. 7414 or 
7542(c) in a rulemaking subject to 42 U.S.C. 7607(d). EPA will treat 
such information as confidential in accordance with the provisions of 
Sec.  2.209 through 2.215, subject to paragraph (j)(4) of this section.
    (3) EPA will deny a request for information under 5 U.S.C. 
552(b)(4) if EPA has determined through rulemaking that the information 
is entitled to confidential treatment under 40 CFR part 1068. The 
denial notification will include a regulatory cite to the appropriate 
determination.
    (4) A determination made pursuant to 42 U.S.C. 7414 or 7542 in a 
rulemaking subject to 42 U.S.C. 7607(d) that information specified in 
40 CFR part 1068 is entitled to confidential treatment shall continue 
in effect unless EPA takes one of the following actions to modify the 
determination:
    (i) EPA determines, pursuant to 5 U.S.C. 552(b)(4) and the Clean 
Air Act (42 U.S.C. 7414; 7542(c)) in a rulemaking subject to 42 U.S.C. 
7607(d), that the information is entitled to confidential treatment, or 
that the information is emission data or data that is otherwise not 
entitled to confidential treatment by statute or regulation.
    (ii) EPA determines, pursuant to 5 U.S.C. 552(b)(4) and the Clean 
Air Act (42 U.S.C. 7414; 7542(c)) that the information is emission data 
or data that is otherwise clearly not entitled to confidential 
treatment by statute or regulation under 40 CFR 2.204(d)(2).
    (iii) The Office of General Counsel revisits an earlier 
determination, pursuant to 5 U.S.C. 552(b)(4) and the Clean Air Act (42 
U.S.C. 7414; 7542(c)), that the information is entitled to confidential 
treatment because of a change in the applicable law or newly discovered 
or changed facts. Prior to a revised final determination, EPA shall 
afford the business an opportunity to submit a substantiation on the 
pertinent issues to be considered, including any described in 
Sec. Sec.  2.204(e)(4) or 2.205(b), within 15 days of the receipt of 
the notice to substantiate. If, after consideration of any timely 
comments made by the business in its substantiation, the Office of 
General Counsel makes a revised final determination that the 
information is not entitled to confidential treatment under 42 U.S.C. 
7414 or 7542, EPA will notify the business in accordance with Sec.  
2.205(f)(2).
    (5) The provisions of 40 CFR 2.201 through 2.208 continue to apply 
for the categories of information identified in 40 CFR 1068.11(c) for 
which there is no confidentiality determination in 40 CFR part 1068.

PART 59--NATIONAL VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR 
CONSUMER AND COMMERCIAL PRODUCTS

0
3. The authority citation for part 59 continues to read as follows:

    Authority:  42 U.S.C. 7414 and 7511b(e).

0
4. Revise Sec.  59.695 to read as follows:


Sec.  59.695  What provisions apply to confidential information?

    The provisions of 40 CFR 1068.10 and 1068.11 apply for submitted 
information you claim as confidential information you submit under this 
part.

PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES

0
5. The authority citation for part 60 continues to read as follows:

    Authority:  42 U.S.C. 7401 et seq.

0
6. Amend Sec.  60.4202 by revising paragraph (g) introductory text to 
read as follows:


Sec.  60.4202  What emission standards must I meet for emergency 
engines if I am a stationary CI internal combustion engine 
manufacturer?

* * * * *
    (g) Notwithstanding the requirements in paragraphs (a) through (d) 
of this section, stationary emergency CI ICE identified in paragraphs 
(a) and (c) of this section may be certified to the provisions of 40 
CFR part 1042 for commercial engines that are applicable for the 
engine's model year, displacement, power density, and maximum engine 
power if the engines will be used solely in either or both of the 
locations identified in paragraphs (g)(1) and (2) of this section. 
Engines that would be subject to the Tier 4 standards in 40 CFR part 
1042 that are used solely in either or both of the locations identified 
in paragraphs (g)(1) and (2) of this section may instead continue to be 
certified to the previous tier of standards in 40 CFR part 1042. The 
previous tier is Tier 3 in most cases; however, the previous tier is 
Tier 2 if there are no Tier 3 standards specified for engines of a 
certain size or power rating.
* * * * *
0
7. Revise Sec.  60.4218 to read as follows:

[[Page 17646]]

Sec.  60.4218  What General Provisions and confidential information 
provisions apply to me?

    (a) Table 8 to this subpart shows which parts of the General 
Provisions in Sec. Sec.  60.1 through 60.19 apply to you.
    (b) The provisions of 40 CFR 1068.10 and 1068.11 apply for engine 
manufacturers. For others, the general confidential business 
information (CBI) provisions apply as described in 40 CFR part 2.
0
8. Revise Sec.  60.4246 to read as follows:


Sec.  60.4246  What General Provisions and confidential information 
provisions apply to me?

    (a) Table 3 to this subpart shows which parts of the General 
Provisions in Sec. Sec.  60.1 through 60.19 apply to you.
    (b) The provisions of 40 CFR 1068.10 and 1068.11 apply for engine 
manufacturers. For others, the general confidential business 
information (CBI) provisions apply as described in 40 CFR part 2.

PART 80--REGULATION OF FUELS AND FUEL ADDITIVES

0
9. The authority citation for part 80 continues to read as follows:

    Authority:  42 U.S.C. 7414, 7521, 7542, 7545, and 7601(a).

Subpart B--[Removed and reserved]

0
10. Remove and reserve subpart B.

PART 85--CONTROL OF AIR POLLUTION FROM MOBILE SOURCES

0
11. The authority citation for part 85 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
12. Amend Sec.  85.1501 by revising paragraph (a) to read as follows:


Sec.  85.1501  Applicability.

    (a) Except where otherwise indicated, this subpart is applicable to 
motor vehicles offered for importation or imported into the United 
States for which the Administrator has promulgated regulations under 40 
CFR part 86, subpart D or S, prescribing emission standards, but which 
are not covered by certificates of conformity issued under section 
206(a) of the Clean Air Act (i.e., which are nonconforming vehicles as 
defined in Sec.  85.1502), as amended, and part 86 at the time of 
conditional importation. Compliance with regulations under this subpart 
shall not relieve any person or entity from compliance with other 
applicable provisions of the Clean Air Act. This subpart no longer 
applies for heavy-duty engines certified under 40 CFR part 86, subpart 
A, or 40 CFR part 1036; references in this subpart to ``engines'' 
therefore apply only for replacement engines intended for installation 
in motor vehicles that are subject to this subpart.
* * * * *


Sec.  85.1513  --[Amended]

0
13. Amend Sec.  85.1513 by removing and reserving paragraph (e)(5).
0
14. Revise Sec.  85.1514 to read as follows:


Sec.  85.1514  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this subpart.
0
15. Amend Sec.  85.1515 by revising paragraph (a)(2)(ii)(A) to read as 
follows:


Sec.  85.1515  Emission standards and test procedures applicable to 
imported nonconforming motor vehicles and motor vehicle engines.

    (a) * * *
    (2) * * *
    (ii) * * *
    (A) Exhaust and fuel economy tests. You must measure emissions over 
the FTP driving cycle and the highway fuel economy driving cycle as 
specified in 40 CFR 1066.801 to meet the fuel economy requirements in 
40 CFR part 600 and demonstrate compliance with the exhaust emission 
standards in 40 CFR part 86 (other than PM). Measure exhaust emissions 
and fuel economy with the same test procedures used by the original 
manufacturer to test the vehicle for certification. However, you must 
use an electric dynamometer meeting the requirements of 40 CFR part 
1066, subpart B, unless we approve a different dynamometer based on 
excessive compliance costs. If you certify based on testing with a 
different dynamometer, you must state in the application for 
certification that all vehicles in the emission family will comply with 
emission standards if tested on an electric dynamometer.
* * * * *
0
16. Amend Sec.  85.1701 by revising paragraphs (a)(1), (b), and (c) to 
read as follows:


Sec.  85.1701  General applicability.

    (a) * * *
    (1) Beginning January 1, 2014, the exemption provisions of 40 CFR 
part 1068, subpart C, apply instead of the provisions of this subpart 
for heavy-duty motor vehicle engines and heavy-duty motor vehicles 
regulated under 40 CFR part 86, subpart A, or 40 CFR part 1036 or part 
1037, except that the nonroad competition exemption of 40 CFR 1068.235 
and the nonroad hardship exemption provisions of 40 CFR 1068.245, 
1068.250, and 1068.255 do not apply for motor vehicle engines. Note 
that the provisions for emergency vehicle field modifications in Sec.  
85.1716 continue to apply for heavy-duty engines.
* * * * *
    (b) The provisions of 40 CFR 1068.10 and 1068.11 apply for 
information you submit under this subpart.
    (c) References to engine families and emission control systems in 
this subpart or in 40 CFR part 1068 apply to durability groups and test 
groups as applicable for manufacturers certifying vehicles under the 
provisions of 40 CFR part 86, subpart S.
* * * * *


Sec.  85.1712  --[Removed and Reserved]

0
17. Remove and reserve Sec.  85.1712.
0
18. Revise Sec.  85.1808 to read as follows:


Sec.  85.1808  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this subpart.
0
19. Amend Sec.  85.1901 by revising paragraph (a) to read as follows:


Sec.  85.1901  Applicability.

    (a) The requirements of this subpart shall be applicable to all 
1972 and later model year motor vehicles and motor vehicle engines, 
except that the provisions of 40 CFR 1068.501 apply instead for heavy-
duty motor vehicle engines and heavy-duty motor vehicles certified 
under 40 CFR part 86, subpart A, or 40 CFR part 1036 or 1037 starting 
January 1, 2018.
* * * * *
0
20. Revise Sec.  85.1909 to read as follows:


Sec.  85.1909  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this subpart.

Subpart V--WARRANTY REGULATIONS AND VOLUNTARY AFTERMARKET 
CERTIFICATION PROGRAM

0
21. The heading of subpart V is revised to read as set forth above.
0
22. Amend Sec.  85.2102 by revising paragraphs (a)(1), (2), (4) through 
(6), (10), and (13) to read as follows:


Sec.  85.2102  Definitions.

    (a) * * *
    (1) Act means Part A of Title II of the Clean Air Act, 42 U.S.C. 
7421 et seq.
    (2) Office Director means the Director for the Office of 
Transportation and Air

[[Page 17647]]

Quality in the Office of Air and Radiation of the Environmental 
Protection Agency or other authorized representative of the Office 
Director.
* * * * *
    (4) Emission performance warranty means that warranty given 
pursuant to this subpart and 42 U.S.C. 7541(b).
    (5) Emission warranty means a warranty given pursuant to this 
subpart and 42 U.S.C. 7541(a) or (b).
    (6) Model year means the manufacturer's annual production period as 
described in subpart X of this part.
* * * * *
    (10) Useful life means that period established pursuant to 42 
U.S.C. 7521(d) and regulations promulgated thereunder.
* * * * *
    (13) Written instructions for proper maintenance and use means 
those maintenance and operation instructions specified in the owner's 
manual as being necessary to assure compliance of a vehicle with 
applicable emission standards for the useful life of the vehicle that 
are:
    (i) In accordance with the instructions specified for performance 
on the manufacturer's prototype vehicle used in certification 
(including those specified for vehicles used under special 
circumstances); and
    (ii) In compliance with the requirements of 40 CFR 86.1808; and
    (iii) In compliance with any other EPA regulations governing 
maintenance and use instructions.
* * * * *
0
23. Amend Sec.  85.2103 by revising paragraph (a)(3) to read as 
follows:


Sec.  85.2103  Emission performance warranty.

    (a) * * *
    (3) Such nonconformity results or will result in the vehicle owner 
having to bear any penalty or other sanction (including the denial of 
the right to use the vehicle) under local, State or Federal law, then 
the manufacturer shall remedy the nonconformity at no cost to the 
owner; except that, if the vehicle has been in operation for more than 
24 months or 24,000 miles, the manufacturer shall be required to remedy 
only those nonconformities resulting from the failure of any of the 
specified major emission control components listed in 42 U.S.C. 
7541(i)(2) or components which have been designated by the 
Administrator to be specified major emission control components until 
the vehicle has been in operation for 8 years or 80,000 miles.
* * * * *
0
24. Amend Sec.  85.2104 by revising paragraphs (a) and (h) introductory 
text to read as follows:


Sec.  85.2104  Owners' compliance with instructions for proper 
maintenance and use.

    (a) An emission warranty claim may be denied on the basis of 
noncompliance by a vehicle owner with the written instructions for 
proper maintenance and use.
* * * * *
    (h) In no case may a manufacturer deny an emission warranty claim 
on the basis of--
* * * * *
0
25. Amend Sec.  85.2106 by revising paragraphs (b) introductory text, 
(c), (d) introductory text, (d)(2), and (g) to read as follows:


Sec.  85.2106  Warranty claim procedures.

* * * * *
    (b) A claim under any emission warranty required by 42 U.S.C. 
7541(a) or (b) may be submitted by bringing a vehicle to:
* * * * *
    (c) To the extent required by any Federal or State law, whether 
statutory or common law, a vehicle manufacturer shall be required to 
provide a means for non-franchised repair facilities to perform 
emission warranty repairs.
    (d) The manufacturer of each vehicle to which the warranty is 
applicable shall establish procedures as to the manner in which a claim 
under the emission warranty is to be processed. The procedures shall--
* * * * *
    (2) Require that if the facility at which the vehicle is initially 
presented for repair is unable for any reason to honor the particular 
claim, then, unless this requirement is waived in writing by the 
vehicle owner, the repair facility shall forward the claim to an 
individual or office authorized to make emission warranty 
determinations for the manufacturer.
* * * * *
    (g) The vehicle manufacturer shall incur all costs associated with 
a determination that an emission warranty claim is valid.
0
26. Amend Sec.  85.2107 by revising paragraphs (a) and (b) to read as 
follows:


Sec.  85.2107  Warranty remedy.

    (a) The manufacturer's obligation under the emission warranties 
provided under 42 U.S.C. 7541(a) and (b) shall be to make all 
adjustments, repairs or replacements necessary to assure that the 
vehicle complies with applicable emission standards of the U.S. 
Environmental Protection Agency, that it will continue to comply for 
the remainder of its useful life (if proper maintenance and operation 
are continued), and that it will operate in a safe manner. The 
manufacturer shall bear all costs incurred as a result of the above 
obligation, except that after the first 24 months or 24,000 miles 
(whichever first occurs) the manufacturer shall be responsible only 
for:
    (1) The adjustment, repair or replacement of any of the specified 
major emission control components listed in 42 U.S.C. 7541(i)(2) or 
components which have been designated by the administrator to be 
specified major emission control components until the vehicle has been 
in operation for 8 years or 80,000 miles; and
    (2) All other components which must be adjusted, repaired or 
replaced to enable a component adjusted, repaired, or replaced under 
paragraph (a)(1) of this section to perform properly.
    (b) Manufacturers shall be liable for the total cost of the remedy 
for any vehicle validly presented for repair under an emission warranty 
to any authorized service facility authorized by the vehicle 
manufacturer. State or local limitations as to the extent of the 
penalty or sanction imposed upon an owner of a failed vehicle shall 
have no bearing on this liability.
* * * * *
0
27. Amend Sec.  85.2109 by revising paragraphs (a) introductory text 
and (a)(6) to read as follows:


Sec.  85.2109  Inclusion of warranty provisions in owners' manuals and 
warranty booklets.

    (a) A manufacturer shall furnish with each new motor vehicle, a 
full explanation of the emission warranties required by 42 U.S.C. 
7541(a) and (b), including at a minimum the following information:
* * * * *
    (6) An explanation that an owner may obtain further information 
concerning the emission warranties or that an owner may report 
violations of the terms of the Emission warranties provided under 42 
U.S.C. 7541(a) and (b) by contacting the Director, Compliance Division, 
Environmental Protection Agency, 2000 Traverwood Dr, Ann Arbor, MI 
48105 (Attention: Warranty) or email to: [email protected].
* * * * *
0
28. Amend Sec.  85.2111 by revising the introductory text and 
paragraphs (b) introductory text, (c), and (d) to read as follows:

[[Page 17648]]

Sec.  85.2111  Warranty enforcement.

    The following acts are prohibited and may subject a manufacturer to 
a civil penalty as described in paragraph (d) of this section:
* * * * *
    (b) Failing or refusing to comply with the terms and conditions of 
the emission warranties provided under 42 U.S.C. 7541(a) and (b) with 
respect to any vehicle to which this subpart applies. Acts constituting 
such a failure or refusal shall include, but are not limited to, the 
following:
* * * * *
    (c) To provide directly or indirectly in any communication to the 
ultimate purchaser or any subsequent purchaser that emission warranty 
coverage is conditioned upon the use of any name brand component, or 
system or upon service (other than a component or service provided 
without charge under the terms of the purchase agreement), unless the 
communication is made pursuant to a written waiver by the Office 
Director.
    (d) The maximum penalty value is $37,500 for each offense that 
occurs after November 2, 2015. Maximum penalty limits may be adjusted 
based on the Consumer Price Index as described at 40 CFR part 19.
* * * * *
0
29. Revise Sec.  85.2123 to read as follows:


Sec.  85.2123  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this subpart.

PART 86--CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES 
AND ENGINES

0
30. The authority citation for part 86 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
31. Amend Sec.  86.007-11 by revising paragraphs (f) and (g) 
introductory text to read as follows:


Sec.  86.007-11  Emission standards and supplemental requirements for 
2007 and later model year diesel heavy-duty engines and vehicles.

* * * * *
    (f) Model year 2007 and later diesel-fueled heavy-duty engines and 
vehicles for sale in Guam, American Samoa, or the Commonwealth of the 
Northern Mariana Islands may be subject to alternative standards under 
40 CFR 1036.655.
    (g) Model years 2018 through 2026 engines at or above 56 kW that 
will be installed in specialty vehicles as allowed by 40 CFR 1037.605 
may meet alternate emission standards as follows:
* * * * *
0
32. Amend Sec.  86.008-10 by revising paragraph (g) introductory text 
to read as follows:


Sec.  86.008-10  Emission standards for 2008 and later model year Otto-
cycle heavy-duty engines and vehicles.

* * * * *
    (g) Model years 2018 through 2026 engines that will be installed in 
specialty vehicles as allowed by 40 CFR 1037.605 may meet alternate 
emission standards as follows:
* * * * *
0
33. Amend Sec.  86.010-18 by:
0
a. Revising paragraph (a) introductory text.
0
b. Removing and reserving paragraph (o)
    The revision reads as follows:


Sec.  86.010-18  On-board Diagnostics for engines used in applications 
greater than 14,000 pounds GVWR.

    (a) General. Heavy-duty engines intended for use in a heavy-duty 
vehicle weighing more than 14,000 pounds GVWR must be equipped with an 
on-board diagnostic (OBD) system capable of monitoring all emission-
related engine systems or components during the life of the engine. The 
OBD requirements of 40 CFR 1036.110 apply starting in model year 2027. 
In earlier model years, manufacturers may meet the requirements of this 
section or the requirements of 40 CFR 1036.110. Note that 40 CFR 
1036.150(u) allows for an alternative communication protocol before 
model year 2027. The OBD system is required to detect all malfunctions 
specified in paragraphs (g), (h), and (i) of this section even though 
the OBD system is not required to use a unique monitor to detect each 
of those malfunctions.
* * * * *
0
34. Amend Sec.  86.016-1 by:
0
a. Revising paragraphs (a) introductory text, (d) introductory text, 
and (d)(4).
0
b. Adding and reserving paragraph (i).
0
c. Adding paragraph (j).
    The revisions and additions read as follows:


Sec.  86.016-1  General applicability.

    (a) Applicability. The provisions of this subpart apply for certain 
types of new heavy-duty engines and vehicles as described in this 
section. As described in paragraph (j) of this section, most of this 
subpart no longer applies starting with model year 2027. Note that this 
subpart does not apply for light-duty vehicles, light-duty trucks, 
medium-duty passenger vehicles, or vehicles at or below 14,000 pounds 
GVWR that have no propulsion engine, such as electric vehicles; see 
subpart S of this part for requirements that apply for those vehicles. 
In some cases, manufacturers of heavy-duty engines and vehicles can 
choose to meet the requirements of this subpart or the requirements of 
subpart S of this part; those provisions are therefore considered 
optional, but only to the extent that manufacturers comply with the 
other set of requirements. In cases where a provision applies only for 
a certain vehicle group based on its model year, vehicle class, motor 
fuel, engine type, or other distinguishing characteristics, the limited 
applicability is cited in the appropriate section. The provisions of 
this subpart apply for certain heavy-duty engines and vehicles as 
follows:
* * * * *
    (d) Non-petroleum fueled vehicles. Standards and requirements apply 
to model year 2016 and later non-petroleum fueled motor vehicles as 
follows:
* * * * *
    (4) The standards and requirements of 40 CFR part 1037 apply for 
vehicles above 14,000 pounds GVWR that have no propulsion engine, such 
as electric vehicles. Electric heavy-duty vehicles may not generate PM 
emission credits. Electric heavy-duty vehicles may not generate 
NOX emission credits except as allowed under 40 CFR part 
1037.
* * * * *
    (i) [Reserved]
    (j) Transition to 40 CFR parts 1036 and 1037. Except for Sec.  
86.010-38(j), this subpart no longer applies starting with model year 
2027. Individual provisions in 40 CFR parts 1036 and 1037 apply instead 
of the provisions of this subpart before model year 2027 as specified 
in this subpart and 40 CFR parts 1036 and 1037.
0
35. Amend Sec.  86.090-5 by adding paragraph (b)(4) to read as follows.


Sec.  86.090-5  General standards; increase in emissions; unsafe 
conditions.

* * * * *
    (b) * * *
    (4) Manufacturers of engines equipped with vanadium-based SCR 
catalysts must design the engine and its emission controls to prevent 
vanadium sublimation and protect the catalyst from high temperatures as 
described in 40 CFR 1036.115(g)(2).
0
36. Amend Sec.  86.117-96 by revising paragraph (d)(1) introductory 
text and adding paragraphs (d)(1)(iii) and (iv) to read as follows.

[[Page 17649]]

Sec.  86.117-96  Evaporative emission enclosure calibrations.

* * * * *
    (d) * * *
    (1) The calculation of net methanol and hydrocarbon mass change is 
used to determine enclosure background and leak rate. It is also used 
to check the enclosure volume measurements. The methanol mass change is 
calculated from the initial and final methanol samples, the net 
withdrawn methanol (in the case of diurnal emission testing with fixed-
volume enclosures), and initial and final temperature and pressure 
according to the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.013

* * * * *
    (iii) TE = temperature of sample withdrawn, R.
    (iv) TSHED = temperature of SHED, R.
* * * * *
0
37. Add Sec.  86.450 to subpart E to read as follows:


Sec.  86.450  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this subpart.

Subpart I--[Removed and Reserved]

0
38. Subpart I, consisting of Sec. Sec.  86.1101-87 through 86.1116-87, 
is removed and reserved.
0
39. Add Sec.  86.1117 to subpart L to read as follows:


Sec.  86.1117  Labeling.

    (a) Light-duty trucks and heavy-duty vehicles and engines for which 
nonconformance penalties are to be paid in accordance with Sec.  
86.1113-87(b) must have information printed on the emission control 
information label or a supplemental label as follows.
    (1) The manufacturer must begin labeling production engines or 
vehicles within 10 days after the completion of the PCA.
    (2) This statement shall read: ``The manufacturer of this [engine 
or vehicle, as applicable] will pay a nonconformance penalty to be 
allowed to introduce it into U.S. commerce at an emission level higher 
than the applicable emission standard. The [compliance level or 
alternative emission standard] for this engine/vehicle is [insert the 
applicable pollutant and compliance level calculated in accordance with 
Sec.  86.1112-87(a)].''
    (3) If a manufacturer introduces an engine or vehicle into U.S. 
commerce prior to the compliance level determination of Sec.  86.1112-
87(a), it must provide the engine or vehicle owner with a label as 
described in paragraph (a)(2) of this section to be affixed in a 
location in proximity to the emission control information label within 
30 days of the completion of the PCA.
    (b) The Administrator may approve in advance other label content 
and formats, provided the alternative label contains information 
consistent with this section.
0
40. Revise Sec.  86.1301 to read as follows:


Sec.  86.1301  Scope; applicability.

    (a) This subpart specifies gaseous emission test procedures for 
Otto-cycle and diesel heavy-duty engines, and particulate emission test 
procedures for diesel heavy-duty engines.
    (b) You may optionally demonstrate compliance with the emission 
standards of this part by testing hybrid engines and hybrid powertrains 
using the test procedures in 40 CFR part 1036, rather than testing the 
engine alone. If you choose this option, you may meet the supplemental 
emission test (SET) requirements by using the SET duty cycle specified 
in either Sec.  86.1362 or 40 CFR 1036.505. Except as specified, 
provisions of this subpart and subpart A of this part that reference 
engines apply equally to hybrid engines and hybrid powertrains.
    (c) The abbreviations and acronyms from subpart A of this part 
apply to this subpart.

Sec.  Sec.  86.1302-84, 86.1303-84, and 86.1304--[Removed]

0
41. Remove Sec. Sec.  86.1302-84, 86.1303-84, and 86.1304.
0
42. Amend Sec.  86.1362 by revising paragraph (b) to read as follows:


Sec.  86.1362  Steady-state testing with a ramped-modal cycle.

* * * * *
    (b) Measure emissions by testing the engine on a dynamometer with 
the following ramped-modal duty cycle to determine whether it meets the 
applicable steady-state emission standards in this part and 40 CFR part 
1036:

[[Page 17650]]



                                                                                           Table 1 of Sec.   86.1362--Ramped-Modal Duty Cycle
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                   Engine testing                                                                        Hybrid powertrain testing
                                ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
            RMC mode              Time in                                                                                                         Road-grade coefficients \4\                                             CO2weighting
                                    mode     Engine speed \1\    Torque (percent)   Vehicle speed (mi/ ----------------------------------------------------------------------------------------------------------------   (percent) \5\
                                 (seconds)          \2\               \2\ \3\             hr) \4\             a             b             c             d             e             f             g             h
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1a Steady-state................        170  Warm Idle.........  0.................  0.................             0             0             0             0             0             0             0             0               6
1b Transition..................         20  Linear Transition.  Linear Transition.  Linear Transition.    -1.898E-08    -5.895E-07     3.780E-05     4.706E-03     6.550E-04    -2.679E-02    -1.027E+00     1.542E+01  ................
2a Steady-state................        173  A.................  100...............  vrefA.............    -1.235E-08    -5.506E-07     3.954E-05     1.248E-03     5.287E-04    -3.117E-02    -3.263E-01     1.627E+01               9
2b Transition..................         20  Linear Transition.  Linear Transition.  Linear Transition.    -1.640E-09    -4.899E-07     2.493E-05     5.702E-04     4.768E-04    -2.389E-02    -2.712E-01     1.206E+01  ................
3a Steady-state................        219  B.................  50................  vrefB.............     8.337E-09    -4.758E-07     1.291E-05     2.874E-04     4.528E-04    -1.803E-02    -1.830E-01     8.808E+00              10
3b Transition..................         20  B.................  Linear Transition.  vrefB.............     4.263E-09    -5.102E-07     2.010E-05     3.703E-04     4.852E-04    -2.242E-02    -2.068E-01     1.074E+01  ................
4a Steady-state................        217  B.................  75................  vrefB.............     1.686E-10    -5.226E-07     2.579E-05     5.521E-04     5.005E-04    -2.561E-02    -2.393E-01     1.285E+01              10
4b Transition..................         20  Linear Transition.  Linear Transition.  Linear Transition.     6.556E-10    -4.971E-07     2.226E-05     5.293E-04     4.629E-04    -2.185E-02    -1.819E-01     1.086E+01  ................
5a Steady-state................        103  A.................  50................  vrefA.............     3.833E-09    -4.343E-07     1.369E-05     4.755E-04     4.146E-04    -1.605E-02    -1.899E-01     8.200E+00              12
5b Transition..................         20  A.................  Linear Transition.  vrefA.............    -7.526E-11    -4.680E-07     2.035E-05     7.214E-04     4.478E-04    -2.012E-02    -2.306E-01     1.043E+01  ................
6a Steady-state................        100  A.................  75................  vrefA.............    -4.195E-09    -4.855E-07     2.624E-05     8.345E-04     4.669E-04    -2.338E-02    -2.547E-01     1.215E+01              12
6b Transition..................         20  A.................  Linear Transition.  vrefA.............     3.185E-09    -4.545E-07     1.549E-05     6.220E-04     4.308E-04    -1.724E-02    -2.093E-01     8.906E+00  ................
7a Steady-state................        103  A.................  25................  vrefA.............     1.202E-08    -3.766E-07     6.943E-07     1.107E-04     3.579E-04    -8.468E-03    -1.243E-01     4.195E+00              12
7b Transition..................         20  Linear Transition.  Linear Transition.  Linear Transition.     1.481E-09    -5.004E-07     2.151E-05     6.028E-04     4.765E-04    -2.197E-02    -2.669E-01     1.109E+01  ................
8a Steady-state................        194  B.................  100...............  vrefB.............    -8.171E-09    -5.682E-07     3.880E-05     8.171E-04     5.462E-04    -3.315E-02    -2.957E-01     1.689E+01               9
8b Transition..................         20  B.................  Linear Transition.  vrefB.............     3.527E-09    -5.294E-07     2.221E-05     4.955E-04     4.976E-04    -2.363E-02    -2.253E-01     1.156E+01  ................
9a Steady-state................        218  B.................  25................  vrefB.............     1.665E-08    -4.288E-07    -1.393E-07     2.170E-05     4.062E-04    -1.045E-02    -1.266E-01     4.762E+00               9
9b Transition..................         20  Linear Transition.  Linear Transition.  Linear Transition.     7.236E-09    -5.497E-07     1.998E-05     1.381E-04     5.110E-04    -2.333E-02    -2.154E-01     1.024E+01  ................
10a Steady-state...............        171  C.................  100...............  vrefC.............    -7.509E-10    -5.928E-07     3.454E-05     5.067E-04     5.670E-04    -3.353E-02    -2.648E-01     1.649E+01               2
10b Transition.................         20  C.................  Linear Transition.  vrefC.............     1.064E-08    -5.343E-07     1.678E-05     2.591E-04     5.101E-04    -2.331E-02    -2.017E-01     1.119E+01  ................
11a Steady-state...............        102  C.................  25................  vrefC.............     2.235E-08    -4.756E-07    -2.078E-06    -6.006E-05     4.509E-04    -1.213E-02    -1.261E-01     5.090E+00               1
11b Transition.................         20  C.................  Linear Transition.  vrefC.............     1.550E-08    -5.417E-07     1.114E-05     8.438E-05     5.051E-04    -2.005E-02    -1.679E-01     8.734E+00  ................
12a Steady-state...............        100  C.................  75................  vrefC.............     7.160E-09    -5.569E-07     2.234E-05     3.107E-04     5.301E-04    -2.644E-02    -2.177E-01     1.266E+01               1
12b Transition.................         20  C.................  Linear Transition.  vrefC.............     9.906E-09    -5.292E-07     1.694E-05     2.460E-04     5.058E-04    -2.304E-02    -1.990E-01     1.103E+01  ................
13a Steady-state...............        102  C.................  50................  vrefC.............     1.471E-08    -5.118E-07     9.881E-06     1.002E-04     4.864E-04    -1.904E-02    -1.678E-01     8.738E+00               1
13b Transition.................         20  Linear Transition.  Linear Transition.  Linear Transition.    -1.482E-09    -1.992E-06     6.475E-05    -1.393E-02     1.229E-03    -3.967E-02     1.135E+00    -7.267E+00  ................

[[Page 17651]]

 
14 Steady-state................        168  Warm Idle.........  0.................  0.................             0             0             0             0             0             0             0             0               6
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Engine speed terms are defined in 40 CFR part 1065.
\2\ Advance from one mode to the next within a 20 second transition phase. During the transition phase, command a linear progression from the settings of the current mode to the settings of the next mode.
\3\ The percent torque is relative to maximum torque at the commanded engine speed.
\4\ See 40 CFR 1036.505(c) for a description of powertrain testing with the ramped-modal cycle, including the equation that uses the road-grade coefficients.
\5\ Use the specified weighting factors to calculate composite emission results for CO2 as specified in 40 CFR 1036.501.


[[Page 17652]]

0
43. Amend Sec.  86.1372 by revising paragraph (a) introductory text to 
read as follows:


Sec.  86.1372  Measuring smoke emissions within the NTE zone.

* * * * *
    (a) For steady-state or transient smoke testing using full-flow 
opacimeters, equipment meeting the requirements of 40 CFR part 1065, 
subpart L, or ISO/DIS-11614 ``Reciprocating internal combustion 
compression-ignition engines--Apparatus for measurement of the opacity 
and for determination of the light absorption coefficient of exhaust 
gas'' is required. ISO/DIS-11614 is incorporated by reference (see 
Sec.  86.1).
* * * * *
0
44. Amend Sec.  86.1801-12 by revising paragraphs (a)(2) introductory 
text, (a)(2)(iii), (a)(3) introductory text, and (g) to read as 
follows:


Sec.  86.1801-12  Applicability.

    (a) * * *
    (2) The provisions of this subpart apply for medium-duty passenger 
vehicles and all vehicles at or below 14,000 pounds GVWR that have no 
propulsion engine, such as electric vehicles. The provisions of this 
subpart also apply for other complete heavy-duty vehicles at or below 
14,000 pounds GVWR, except as follows:
* * * * *
    (iii) The provisions of this subpart are optional for diesel-fueled 
Class 3 heavy-duty vehicles in a given model year if those vehicles are 
equipped with engines certified to the appropriate standards in Sec.  
86.007-11 or 40 CFR 1036.104 for which less than half of the engine 
family's sales for the model year in the United States are for complete 
Class 3 heavy-duty vehicles. This includes engines sold to all vehicle 
manufacturers. If you are the original manufacturer of the engine and 
the vehicle, base this showing on your sales information. If you 
manufacture the vehicle but are not the original manufacturer of the 
engine, you must use your best estimate of the original manufacturer's 
sales information.
    (3) The provisions of this subpart generally do not apply to 
incomplete heavy-duty vehicles or to complete vehicles above 14,000 
pounds GVWR (see Sec.  86.016-1 and 40 CFR parts 1036 and 1037). 
However, this subpart applies to such vehicles in the following cases:
* * * * *
    (g) Complete and incomplete vehicles. Several provisions in this 
subpart, including the applicability provisions described in this 
section, are different for complete and incomplete vehicles. We 
differentiate these vehicle types as described in 40 CFR 1037.801.
* * * * *
0
45. Amend Sec.  86.1810-17 by adding paragraph (j) to read as follows:


Sec.  86.1810-17  General requirements.

* * * * *
    (j) Small-volume manufacturers that modify a vehicle already 
certified by a different company may recertify that vehicle under this 
subpart S based on the vehicle supplier's compliance with fleet average 
standards for criteria exhaust emissions, evaporative emissions, and 
greenhouse gas emissions as follows:
    (1) The recertifying manufacturer must certify the vehicle at bin 
levels and family emission limits that are the same as or more 
stringent than the corresponding bin levels and family emission limits 
for the vehicle supplier.
    (2) The recertifying manufacturer must meet all the standards and 
requirements described in this subpart S, except for the fleet average 
standards for criteria exhaust emissions, evaporative emissions, and 
greenhouse gas emissions.
    (3) The vehicle supplier must send the small-volume manufacturer a 
written statement accepting responsibility to include the subject 
vehicles in the vehicle supplier's exhaust and evaporative fleet 
average calculations in Sec. Sec.  86.1860-17, 86.1864-10, and 86.1865-
12.
    (4) The small-volume manufacturer must describe in the application 
for certification how the two companies are working together to 
demonstrate compliance for the subject vehicles. The application must 
include the statement from the vehicle supplier described in paragraph 
(j)(3) of this section.
    (5) The vehicle supplier must include a statement that the vehicle 
supplier is including the small volume manufacturer's sales volume and 
emissions levels in the vehicle supplier's fleet average reports under 
Sec. Sec.  86.1860-17, 86.1864-10, and 86.1865-12.


Sec.  86.1819  [Removed]

0
46. Remove Sec.  86.1819.
0
47. Amend Sec.  86.1819-14 by revising paragraph (d)(12)(i) to read as 
follows:


Sec.  86.1819-14  Greenhouse gas emission standards for heavy-duty 
vehicles.

* * * * *
    (d) * * *
    (12) * * *
    (i) Configuration means a subclassification within a test group 
based on engine code, transmission type and gear ratios, final drive 
ratio, and other parameters we designate. Engine code means the 
combination of both ``engine code'' and ``basic engine'' as defined for 
light-duty vehicles in 40 CFR 600.002.
* * * * *
0
48. Amend Sec.  86.1823-08 by:
0
a. Revising paragraph (c)(1)(iv)(A).
0
b. Adding paragraph (m) introductory text.
0
c. Revising paragraph (m)(1).
    The addition and revisions read as follows:


Sec.  86.1823-08  Durability demonstration procedures for exhaust 
emissions.

* * * * *
    (c) * * *
    (1) * * *
    (iv) * * *
    (A) The simulated test weight will be the equivalent test weight 
specified in Sec.  86.129 using a weight basis of the loaded vehicle 
weight for light-duty vehicles and light light-duty trucks, and ALVW 
for all other vehicles.
* * * * *
    (m) Durability demonstration procedures for vehicles subject to the 
greenhouse gas exhaust emission standards specified in Sec.  86.1818. 
Determine a deterioration factor for each exhaust constituent as 
described in this paragraph (m) and in 40 CFR 600.113-12(h) through (m) 
to calculate the composite CREE DF value.
    (1) CO2. (i) Unless otherwise specified under paragraph (m)(1)(ii) 
or (iii) of this section, manufacturers may use a multiplicative 
CO2 deterioration factor of one or an additive deterioration 
factor of zero to determine full useful life emissions for the FTP and 
HFET tests.
    (ii) Based on an analysis of industry-wide data, EPA may 
periodically establish and/or update the deterioration factor for 
CO2 emissions, including air conditioning and other credit-
related emissions. Deterioration factors established and/or updated 
under this paragraph (m)(1)(ii) will provide adequate lead time for 
manufacturers to plan for the change.
    (iii) For plug-in hybrid electric vehicles and any other vehicle 
model the manufacturer determines will experience increased 
CO2 emissions over the vehicle's useful life, consistent 
with good engineering judgment, manufacturers must either install aged 
components on test vehicles as provided in paragraph (f)(2) of this 
section, determine a deterioration factor based on testing, or provide 
an engineering analysis that the vehicle is designed such that 
CO2 emissions will not increase over the vehicle's useful 
life. Manufacturers may test using the whole-vehicle mileage 
accumulation

[[Page 17653]]

procedures in Sec.  86.1823-08 (c) or (d)(1), or manufacturers may 
request prior EPA approval for an alternative durability procedure 
based on good engineering judgment. For the testing option, each FTP 
test performed on the durability data vehicle selected under Sec.  
86.1822 must also be accompanied by an HFET test, and combined FTP/HFET 
CO2 results determined by averaging the city (FTP) and 
highway (HFET) CO2 values, weighted 0.55 and 0.45 
respectively. The deterioration factor will be determined for this 
combined CO2 value. Calculated multiplicative deterioration 
factors that are less than one shall be set to equal one, and 
calculated additive deterioration factors that are less than zero shall 
be set to zero.
* * * * *
0
49. Amend Sec.  86.1843-01 by revising paragraph (f)(2) and adding 
paragraph (i) to read as follows:


Sec.  86.1843-01  General information requirements.

* * * * *
    (f) * * *
    (2) The manufacturer must submit a final update to Part 1 and Part 
2 of the Application by May 1 following the end of the model year to 
incorporate any applicable running changes or corrections which 
occurred between January 1 of the applicable model year and the end of 
the model year. A manufacturer may request an extension for submitting 
the final update. The request must clearly indicate the circumstances 
necessitating the extension.
* * * * *
    (i) Confidential information. The provisions of 40 CFR 1068.10 and 
1068.11 apply for information you submit under this subpart.
0
50. Amend Sec.  86.1869-12 by revising paragraph (d)(2)(i) to read as 
follows:


Sec.  86.1869-12  CO2 credits for off-cycle CO2 reducing technologies.

* * * * *
    (d) * * *
    (2) Notice and opportunity for public comment. (i) The 
Administrator will publish a notice of availability in the Federal 
Register notifying the public of a manufacturer's proposed alternative 
off-cycle credit calculation methodology. The notice will include 
details regarding the proposed methodology but will not include any 
Confidential Business Information (see 40 CFR 1068.10 and 1068.11). The 
notice will include instructions on how to comment on the methodology. 
The Administrator will take public comments into consideration in the 
final determination and will notify the public of the final 
determination. Credits may not be accrued using an approved methodology 
until the first model year for which the Administrator has issued a 
final approval.
* * * * *

PART 87--CONTROL OF AIR POLLUTION FROM AIRCRAFT AND AIRCRAFT 
ENGINES

0
51. The authority citation for part 87 continues to read as follows:

    Authority:  42 U.S.C. 7401 et seq.

0
52. Revise Sec.  87.4 to read as follows:


Sec.  87.4  Treatment of confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.


Sec.  87.42  [Amended]

0
53. Amend Sec.  87.42 by removing and reserving paragraph (d).

PART 600--FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF 
MOTOR VEHICLES

0
54. The authority citation for part 600 continues to read as follows:

    Authority: 49 U.S.C. 32901-23919q, Pub. L. 109-58.

0
55. Amend Sec.  600.001 by removing the paragraph heading from 
paragraph (e) and adding paragraph (f) to read as follows:


Sec.  600.001  General applicability.

* * * * *
    (f) Unless we specify otherwise, send all reports and requests for 
approval to the Designated Compliance Officer (see Sec.  600.002).
0
56. Amend Sec.  600.002 by adding a definition for ``Designated 
Compliance Officer'' in alphabetical order and revising the definitions 
for ``Engine code'', ``SC03'', and ``US06'' to read as follows:


Sec.  600.002  Definitions.

* * * * *
    Designated Compliance Officer means the Director, Light-Duty 
Vehicle Center, U.S. Environmental Protection Agency, 2000 Traverwood 
Drive, Ann Arbor, MI 48105; [email protected]; www.epa.gov/ve-certification.
* * * * *
    Engine code means one of the following:
    (1) For LDV, LDT, and MDPV, engine code means a unique combination, 
within a test group (as defined in Sec.  86.1803 of this chapter), of 
displacement, fuel injection (or carburetion or other fuel delivery 
system), calibration, distributor calibration, choke calibration, 
auxiliary emission control devices, and other engine and emission 
control system components specified by the Administrator. For electric 
vehicles, engine code means a unique combination of manufacturer, 
electric traction motor, motor configuration, motor controller, and 
energy storage device.
    (2) For HDV, engine code has the meaning given in Sec.  86.1819-
14(d)(12) of this chapter.
* * * * *
    SC03 means the test procedure specified in 40 CFR 1066.801(c)(2).
* * * * *
    US06 means the test procedure as described in 40 CFR 
1066.801(c)(2).
* * * * *
0
57. Amend Sec.  600.011 by revising paragraphs (a) and (c)(2) to read 
as follows:


Sec.  600.011  Incorporation by reference.

    (a) Certain material is incorporated by reference into this part 
with the approval of the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other 
than that specified in this section, the Environmental Protection 
Agency (EPA) must publish a document in the Federal Register and the 
material must be available to the public. All approved material is 
available for inspection at the EPA and at the National Archives and 
Records Administration (NARA). Contact EPA at: U.S. EPA, Air and 
Radiation Docket and Information Center, 1301 Constitution Ave. NW, 
Room B102, EPA West Building, Washington, DC 20460, www.epa.gov/dockets, (202) 202-1744. For information on the availability of this 
material at NARA, email: [email protected], or go to: 
www.archives.gov/federal-register/cfr/ibr-locations.html. The material 
may be obtained from the sources in the following paragraphs of this 
section.
* * * * *
    (c) * * *
    (2) SAE J1634, Battery Electric Vehicle Energy Consumption and 
Range Test Procedure, revised July 2017; IBR approved for Sec. Sec.  
600.116-12(a); 600.210-12(d); 600.311-12(j) and (k).
* * * * *


Sec. Sec.  600.106-08, 600.108-08, 600.109-08, and 600.110-
08  [Removed]

0
58. Amend subpart B by removing the following sections: Sec. Sec.  
600.106-08, 600.108-08, 600.109-08, and 600.110-08.

[[Page 17654]]

0
59. Amend Sec.  600.111-08 by revising the introductory text to read as 
follows:


Sec.  600.111-08  Test procedures.

    This section describes test procedures for the FTP, highway fuel 
economy test (HFET), US06, SC03, and the cold temperature FTP tests. 
See 40 CFR 1066.801(c) for an overview of these procedures. Perform 
testing according to test procedures and other requirements contained 
in this part 600 and in 40 CFR part 1066. This testing includes 
specifications and procedures for equipment, calibrations, and exhaust 
sampling. Manufacturers may use data collected according to previously 
published test procedures for model years through 2021. In addition, we 
may approve the use of previously published test procedures for later 
model years as an alternative procedure under 40 CFR 1066.10(c). 
Manufacturers must comply with regulatory requirements during the 
transition as described in 40 CFR 86.101 and 86.201.
* * * * *


Sec.  600.112-08  [Removed]

0
60. Remove Sec.  600.112-08.
0
61. Amend Sec.  600.113-12 by revising paragraphs (a)(1), (b) through 
(d), and (e)(1) to read as follows:


Sec.  600.113-12  Fuel economy, CO2 emissions, and carbon-
related exhaust emission calculations for FTP, HFET, US06, SC03 and 
cold temperature FTP tests.

* * * * *
    (a) * * *
    (1) Calculate the weighted grams/mile values for the FTP test for 
CO2, HC, and CO, and where applicable, CH3OH, 
C2H5OH, C2H4O, HCHO, NMHC, 
N2O, and CH4 as specified in 40 CFR 1066.605. 
Measure and record the test fuel's properties as specified in paragraph 
(f) of this section.
* * * * *
    (b) Calculate the HFET fuel economy as follows:
    (1) Calculate the mass values for the highway fuel economy test for 
HC, CO, and CO2, and where applicable, CH3OH, 
C2H5OH, C2H4O, HCHO, NMHC, 
N2O, and CH4 as specified in 40 CFR 1066.605. 
Measure and record the test fuel's properties as specified in paragraph 
(f) of this section.
    (2) Calculate the grams/mile values for the highway fuel economy 
test for HC, CO, and CO2, and where applicable 
CH3OH, C2H5OH, 
C2H4O, HCHO, NMHC, N2O, and 
CH4 by dividing the mass values obtained in paragraph (b)(1) 
of this section, by the actual driving distance, measured in miles, as 
specified in 40 CFR 1066.840.
    (c) Calculate the cold temperature FTP fuel economy as follows:
    (1) Calculate the weighted grams/mile values for the cold 
temperature FTP test for HC, CO, and CO2, and where 
applicable, CH3OH, C2H5OH, 
C2H4O, HCHO, NMHC, N2O, and 
CH4 as specified in 40 CFR 1066.605.
    (2) Calculate separately the grams/mile values for the cold 
transient phase, stabilized phase and hot transient phase of the cold 
temperature FTP test as specified in 40 CFR 1066.605.
    (3) Measure and record the test fuel's properties as specified in 
paragraph (f) of this section.
    (d) Calculate the US06 fuel economy as follows:
    (1) Calculate the total grams/mile values for the US06 test for HC, 
CO, and CO2, and where applicable, CH3OH, 
C2H5OH, C2H4O, HCHO, NMHC, 
N2O, and CH4 as specified in 40 CFR 1066.605.
    (2) Calculate separately the grams/mile values for HC, CO, and 
CO2, and where applicable, CH3OH, 
C2H5OH, C2H4O, HCHO, NMHC, 
N2O, and CH4, for both the US06 City phase and 
the US06 Highway phase of the US06 test as specified in 40 CFR 1066.605 
and 1066.831. In lieu of directly measuring the emissions of the 
separate city and highway phases of the US06 test according to the 
provisions of 40 CFR 1066.831, the manufacturer may optionally, with 
the advance approval of the Administrator and using good engineering 
judgment, analytically determine the grams/mile values for the city and 
highway phases of the US06 test. To analytically determine US06 City 
and US06 Highway phase emission results, the manufacturer shall 
multiply the US06 total grams/mile values determined in paragraph 
(d)(1) of this section by the estimated proportion of fuel use for the 
city and highway phases relative to the total US06 fuel use. The 
manufacturer may estimate the proportion of fuel use for the US06 City 
and US06 Highway phases by using modal CO2, HC, and CO 
emissions data, or by using appropriate OBD data (e.g., fuel flow rate 
in grams of fuel per second), or another method approved by the 
Administrator.
    (3) Measure and record the test fuel's properties as specified in 
paragraph (f) of this section.
    (e) * * *
    (1) Calculate the grams/mile values for the SC03 test for HC, CO, 
and CO2, and where applicable, CH3OH, 
C2H5OH, C2H4O, HCHO, NMHC, 
N2O, and CH4 as specified in 40 CFR 1066.605.
* * * * *
0
62. Amend Sec.  600.115-11 by revising the introductory text to read as 
follows:


Sec.  600.115-11  Criteria for determining the fuel economy label 
calculation method.

    This section provides the criteria to determine if the derived 5-
cycle method for determining fuel economy label values, as specified in 
Sec.  600.210-08(a)(2) or (b)(2) or Sec.  600.210-12(a)(2) or (b)(2), 
as applicable, may be used to determine label values. Separate criteria 
apply to city and highway fuel economy for each test group. The 
provisions of this section are optional. If this option is not chosen, 
or if the criteria provided in this section are not met, fuel economy 
label values must be determined according to the vehicle-specific 5-
cycle method specified in Sec.  600.210-08(a)(1) or (b)(1) or Sec.  
600.210-12(a)(1) or (b)(1), as applicable. However, dedicated 
alternative-fuel vehicles (other than battery electric vehicles), dual 
fuel vehicles when operating on the alternative fuel, MDPVs, and 
vehicles imported by Independent Commercial Importers may use the 
derived 5-cycle method for determining fuel economy label values 
whether or not the criteria provided in this section are met. 
Manufacturers may alternatively account for this effect for battery 
electric vehicles, fuel cell vehicles, and plug-in hybrid electric 
vehicles (when operating in the charge-depleting mode) by multiplying 
2-cycle fuel economy values by 0.7 and dividing 2-cycle CO2 
emission values by 0.7.
* * * * *
0
63. Amend Sec.  600.116-12 by revising paragraph (a) to read as 
follows:


Sec.  600.116-12  Special procedures related to electric vehicles and 
hybrid electric vehicles.

    (a) Determine fuel economy values for electric vehicles as 
specified in Sec. Sec.  600.210 and 600.311 using the procedures of SAE 
J1634 (incorporated by reference in Sec.  600.011). Use the procedures 
of SAE J1634, Section 8, with the following clarifications and 
modifications for using this and other sections of SAE J1634:
    (1) Vehicles that cannot complete the Multi-Cycle Range and Energy 
Consumption Test (MCT) because they are unable travel the distance 
required to complete the test with a fully charged battery, or they are 
unable to achieve the maximum speed on either the UDDS or HFEDS 
(Highway Fuel Economy Drive Cycle also known as the HFET) cycle should 
seek Administrator approval to use the procedures outlined in SAE J1634 
Section 7 Single Cycle Range and Energy Consumption Test (SCT).
    (2) The MCT includes the following key-on soak times and key-off 
soak periods:

[[Page 17655]]

    (i) As noted in SAE J1634 Section 8.3.4, a 15 second key-on pause 
is required between UDDS1 and HFEDS1, and 
UDDS3 and HFEDS2. The key-on pause is considered 
a part of the HFEDS1 and HFEDS2 drive cycle.
    (ii) As noted in SAE J1634 Section 8.3.4, a 10 minute key-off soak 
period is required between HFEDS1 and UDDS2, and 
HFEDS2 and UDDS4.
    (iii) A 5-minute minimum key-off soak period is required between 
UDDS2 and the first phase of the mid-test constant speed 
cycle, and UDDS4 and the first phase of the end-of-test 
constant speed cycle.
    (iv) If multiple phases are required during either the mid-test 
constant speed cycle or the end-of-test constant speed cycle there must 
be a minimum 5-minute key-off soak period between each constant speed 
phase. The key-off soak periods between the constant speed phases may 
last for up to a maximum of 30 minutes.
    (3) As noted in SAE J1634 Section 8.3.4, during all `key-off' soak 
periods, the key or power switch must be in the ``off'' position, the 
hood must be closed, the test cell fan(s) must be off, and the brake 
pedal not depressed. For vehicles which do not have a key or power 
switch the vehicle must be placed in the `mode' the manufacturer 
recommends when the vehicle is to be parked and the occupants exit the 
vehicle.
    (4) Either Method 1 or Method 2 described in Appendix A of SAE 
J1634 may be used to estimate the mid-test constant speed cycle 
distance (dM). The mid-test constant speed cycle distance 
calculation needs to be performed prior to beginning the test and 
should not use data from the test being performed. If Method 2 is used, 
multiply the result determined by the Method 2 equation by 0.8 to 
determine the mid-test constant speed cycle distance (dM).
    (5) Divide the mid-test constant speed cycle distance 
(dM) by 65 mph to determine the total time required for the 
mid-test constant speed cycle. If the time required is one-hour or less 
the mid-test constant speed cycle can be performed with no key-off soak 
periods. If the time required is greater than one-hour the mid-test 
constant speed cycle must be separated into phases such that no phase 
exceeds more than one-hour. At the conclusion of each mid-test constant 
speed phase a minimum 5-minute key-off soak will be performed.
    (6) Using good engineering judgment determine the end-of-test 
constant speed cycle distance so that it does not exceed 20% of the 
total distance driven during the MCT as described in SAE J1634 Section 
8.3.3.
    (7) Divide the end-of-test constant speed cycle distance 
(dE) by 65 mph to determine the total time required for the 
end-of-test constant speed cycle. If the time required is one-hour or 
less the end-of-test constant speed cycle can be performed with no key-
off soak periods. If the time required is greater than one-hour the 
end-of-test constant speed cycle must be separated into phases such 
that no phase exceeds more than one-hour. At the conclusion of each 
end-of-test constant speed phase a minimum 5-minute key-off soak will 
be performed.
    (8) SAE J634 Section 3.13 defines useable battery energy (UBE) as 
the total DC discharge energy (Edctotal), measured in DC watt-hours for 
a full discharge test. The total DC discharge energy is the sum of all 
measured phases of a test inclusive of all drive cycle types. As key-
off soak periods are not considered part of the test phase, the 
discharge energy that occurs during the key-off soak periods is not 
included in the useable battery energy.
    (9) Recharging the vehicle's battery must start within three hours 
after the end of testing.
    (10) At the request of a manufacturer, the Administrator may 
approve the use of an earlier version of SAE J1634 when a manufacturer 
is carrying over data for vehicles tested using a prior version of SAE 
J1634.
    (11) All label values related to fuel economy, energy consumption, 
and range must be based on 5-cycle testing or on values adjusted to be 
equivalent to 5-cycle results. Prior to performing testing to generate 
a 5-cycle adjustment factor, manufacturers must request Administrator 
approval to use SAE J1634 Appendices B and C for determining a 5-cycle 
adjustment factor with the following modifications, clarifications, and 
attestations:
    (i) The 20 [deg]F charge-depleting UDDS must be performed with a 
minimum 10-minute key-off soak period between each UDDS cycle. Key-off 
soak periods of up to 30 minutes are allowed. During all `key-off' soak 
periods, the key or power switch must be in the ``off'' position, the 
hood must be closed, the test cell fan(s) must be off, and the brake 
pedal not depressed. For vehicles which do not have a key or power 
switch the vehicle must be placed in the `mode' the manufacturer 
recommends when the vehicle is to be parked and the occupants exit the 
vehicle.
    (ii) Prior to performing the 20 [deg]F charge-depleting UDDS the 
vehicle must soak for a minimum of 12 hours and a maximum of 36 hours 
at a temperature of 20 [deg]F. Prior to beginning the 12 to 36 hour 
cold soak at 20 [deg]F the vehicle must be fully charged, the charging 
can take place at test laboratory ambient temperatures (68 to 86 
[deg]F) or at 20 [deg]F. During the 12 to 36 hour cold soak period the 
vehicle may not be connected to a charger nor is the vehicle cabin or 
battery to be preconditioned during the 20 [deg]F soak period.
    (iii) Beginning with the 2024 model year the 20 [deg]F UDDS charge-
depleting UDDS test will be replaced with a 20 [deg]F UDDS test 
consisting of 2 UDDS cycles performed with a 10-minute key-off soak 
between the two UDDS cycles. The data from the two UDDS cycles will be 
used to calculate the five-cycle adjustment factor, instead of using 
the results from the entire charge-depleting data set. Manufacturers 
that have submitted and used the average data from 20 [deg]F charge-
depleting UDDS data sets will be required to revise their 5-cycle 
adjustment factor calculation and re-label vehicles using the data from 
the first two UDDS cycles only. Manufacturers, at their discretion, 
would also be allowed to re-run the 20 [deg]F UDDS test with the 
battery charged to a state-of-charge (SoC) determined by the 
manufacturer. The battery does not need to be at 100% SoC before the 20 
[deg]F cold soak.
    (iv) Manufacturers must submit a written attestation to the 
Administrator at the completion of testing with the following 
information:
    (A) A statement noting the SoC level of the rechargeable energy 
storage system (RESS) prior to beginning the 20[deg]F cold soak for 
testing performed beginning with model year 2024.
    (B) A statement confirming the vehicle was not charged or 
preconditioned during the 12 to 36 hour 20 [deg]F soak period before 
starting the 20 [deg]F UDDS cycle.
    (C) A summary of all the 5-cycle test results and the calculations 
used to generate the 5-cycle adjustment factor, including all of the 20 
[deg]F UDDS cycles, the distance travelled during each UDDS and the 
measured DC discharge energy during each UDDS phase. Beginning in model 
year 2024, the 20 [deg]F UDDS test results will consist of only two 
UDDS cycles.
    (D) Beginning in model year 2024 the RunningFC equation used to 
calculate the City Fuel Economy found on Page 30 in Appendix C of J1634 
should be replaced with the following equation when calculating City 
Fuel Economy:

[[Page 17656]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.014

    (E) A description of each test group and configuration which will 
use the 5-cycle adjustment factor, including the battery capacity of 
the vehicle used to generate the 5-cycle adjustment factor and the 
battery capacity of all the configurations to which it will be applied.
    (v) At the conclusion of the manufacturers testing and after 
receiving the attestations from the manufacturer regarding the 
performance of the 20 [deg]F UDDS test processes, the 5-cycle test 
results, and the summary of vehicles to which the manufacturer proposes 
applying the 5-cycle adjustment factor, the Administrator will review 
the submittals and inform the manufacturer in writing if the 
Administrator concurs with the manufacturer's proposal. If not, the 
Administrator will describe the rationale to the manufacturer for not 
approving their request.
* * * * *
0
64. Amend Sec.  600.210-12 by revising paragraphs (a) introductory 
text, (a)(2)(iii), and (d) to read as follows:


Sec.  600.210-12  Calculation of fuel economy and CO2 emission values 
for labeling.

    (a) General labels. Except as specified in paragraphs (d) and (e) 
of this section, fuel economy and CO2 emissions for general 
labels may be determined by one of two methods. The first is based on 
vehicle-specific model-type 5-cycle data as determined in Sec.  
600.209-12(b). This method is available for all vehicles and is 
required for vehicles that do not qualify for the second method as 
described in Sec.  600.115 (other than electric vehicles). The second 
method, the derived 5-cycle method, determines fuel economy and 
CO2 emissions values from the FTP and HFET tests using 
equations that are derived from vehicle-specific 5-cycle model type 
data, as determined in paragraph (a)(2) of this section. Manufacturers 
may voluntarily lower fuel economy (MPG) values and raise 
CO2 values if they determine that the label values from any 
method are not representative of the in-use fuel economy and 
CO2 emissions for that model type, but only if the 
manufacturer changes both the MPG values and the CO2 value 
and revises any other affected label value accordingly for a model type 
(including but not limited to the fuel economy 1-10 rating, greenhouse 
gas 1-10 rating, annual fuel cost, 5-year fuel cost information). 
Similarly, for any electric vehicles and plug-in hybrid electric 
vehicles, manufacturers may voluntarily lower the fuel economy (MPGe) 
and raise the energy consumption (kW-hr/100 mile) values if they 
determine that the label values are not representative of the in-use 
fuel economy, energy consumption, and CO2 emissions for that 
model type, but only if the manufacturer changes both the MPGe and the 
energy consumption value and revises any other affected label value 
accordingly for a model type. Manufacturers may voluntarily lower the 
value for electric driving range if they determine that the label 
values are not representative of the in-use electric driving range.
* * * * *
    (2) * * *
    (iii) Unless and until superseded by written guidance from the 
Administrator, the following intercepts and slopes shall be used in the 
equations in paragraphs (a)(2)(i) and (ii) of this section:
    City Intercept = 0.004091.
    City Slope = 1.1601.
    Highway Intercept = 0.003191.
    Highway Slope = 1.2945.
* * * * *
    (d) Calculating combined fuel economy, CO2 emissions, and driving 
range. (1) If the criteria in Sec.  600.115-11(a) are met for a model 
type, both the city and highway fuel economy and CO2 
emissions values must be determined using the vehicle-specific 5-cycle 
method. If the criteria in Sec.  600.115-11(b) are met for a model 
type, the city fuel economy and CO2 emissions values may be 
determined using either method, but the highway fuel economy and 
CO2 emissions values must be determined using the vehicle-
specific 5-cycle method (or modified 5-cycle method as allowed under 
Sec.  600.114-12(b)(2)).
    (2) If the criteria in Sec.  600.115 are not met for a model type, 
the city and highway fuel economy and CO2 emission label 
values must be determined by using the same method, either the derived 
5-cycle or vehicle-specific 5-cycle.
    (3) Manufacturers may use one of the following methods to determine 
5-cycle values for fuel economy, CO2 emissions, and driving 
range for electric vehicles:
    (i) Generate 5-cycle data as described in paragraph (a)(1) of this 
section using the procedures of SAE J1634 (incorporated by reference in 
Sec.  600.011) with amendments and revisions as described in Sec.  
600.116-12(a).
    (ii) Multiply 2-cycle fuel economy values and driving range by 0.7 
and divide 2-cycle CO2 emission values by 0.7.
    (iii) Manufacturers may ask the Administrator to approve adjustment 
factors for deriving 5-cycle fuel economy results from 2-cycle test 
data based on operating data from their in-use vehicles. Such data 
should be collected from multiple vehicles with different drivers over 
a range of representative driving routes and conditions. The 
Administrator may approve such an adjustment factor for any of the 
manufacturer's vehicle models that are properly represented by the 
collected data.
* * * * *
0
65. Amend Sec.  600.311-12 by revising paragraphs (j)(2), (j)(4) 
introductory text, and (j)(4)(i) to read as follows:


Sec.  600.311-12  Determination of values for fuel economy labels.

* * * * *
    (j) * * *
    (2) For electric vehicles, determine the vehicle's overall driving 
range as described in Section 8 of SAE J1634 (incorporated by reference 
in Sec.  600.011), with amendments and revisions as described in Sec.  
600.116. Determine separate range values for FTP-based city and HFET-
based highway driving. Adjust these values to reflect actual in-use 
driving conditions, then calculate a combined value by arithmetically

[[Page 17657]]

averaging the two values, weighted 0.55 and 0.45 respectively, and 
rounding to the nearest whole number.
* * * * *
    (4) For plug-in hybrid electric vehicles, determine the adjusted 
charge-depleting (Rcda) driving range, the adjusted all electric 
driving range (if applicable), and overall adjusted driving range as 
described in SAE J1711 (incorporated by reference in Sec.  600.011), as 
described in Sec.  600.116, as follows:
    (i) Determine the vehicle's Actual Charge-Depleting Range, 
Rcda, and adjust these values to reflect actual in-use 
driving conditions. Determine separate range values for FTP-based city 
and HFET-based highway driving, then calculate a combined value by 
arithmetically averaging the two values, weighted 0.55 and 0.45 
respectively, and rounding to the nearest whole number. Precondition 
the vehicle as needed to minimize engine operation for consuming stored 
fuel vapors in evaporative canisters; for example, you may purge the 
evaporative canister or time a refueling event to avoid engine starting 
related to purging the canister. For vehicles that use combined power 
from the battery and the engine before the battery is fully discharged, 
also use this procedure to establish an all electric range by 
determining the distance the vehicle drives before the engine starts, 
rounded to the nearest mile. You may represent this as a range of 
values. We may approve adjustments to these procedures if they are 
necessary to properly characterize a vehicle's all electric range.
* * * * *
0
66. Amend Sec.  600.510-12 by revising the entry defining the term 
``AFE'' in paragraph (e) to read as follows:


Sec.  600.510-12  Calculation of average fuel economy and average 
carbon-related exhaust emissions.

* * * * *
    (e) * * *
    AFE = Average combined fuel economy as calculated in paragraph 
(c)(2) of this section, rounded to the nearest 0.0001 mpg;
* * * * *
0
67. Amend Sec.  600.512-12 by adding paragraph (a)(3) and revising 
paragraph (b) to read as follows:


Sec.  600.512-12  Model year report.

    (a) * * *
    (3) Separate reports shall be submitted for passenger automobiles 
and light trucks (as identified in Sec.  600.510-12).
    (b) The model year report shall be in writing, signed by the 
authorized representative of the manufacturer and shall be submitted no 
later than May 1 following the end of the model year. A manufacturer 
may request an extension for submitting the model year report if that 
is needed to provide all additional required data as determined in 
Sec.  600.507-12. The request must clearly indicate the circumstances 
necessitating the extension.
* * * * *

PART 1027--FEES FOR VEHICLE AND ENGINE COMPLIANCE PROGRAMS

0
68. The authority citation for part 1027 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.

0
69. Amend Sec.  1027.101 by revising paragraph (a)(1) to read as 
follows:


Sec.  1027.101  To whom do these requirements apply?

    (a) * * *
    (1) Motor vehicles and motor vehicle engines we regulate under 40 
CFR part 86 or 1036. This includes light-duty vehicles, light-duty 
trucks, medium-duty passenger vehicles, highway motorcycles, and heavy-
duty highway engines and vehicles.
* * * * *

PART 1030--CONTROL OF GREENHOUSE GAS EMISSIONS FROM ENGINES 
INSTALLED ON AIRPLANES

0
70. The authority citation for part 1030 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.

0
71. Revise Sec.  1030.98 to read as follows:


Sec.  1030.98  Confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.

PART 1033--CONTROL OF EMISSIONS FROM LOCOMOTIVES

0
72. The authority citation for part 1033 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.

0
73. Amend Sec.  1033.1 by revising paragraph (e) to read as follows:


Sec.  1033.1  Applicability.

* * * * *
    (e) This part applies for locomotives that were certified as 
freshly manufactured or remanufactured locomotives under 40 CFR part 
92.


Sec.  1033.5  [Amended]

0
74. Amend Sec.  1033.5 by removing and reserving paragraph (c).
0
75. Amend Sec.  1033.101 by revising the introductory text to read as 
follows:


Sec.  1033.101  Exhaust emission standards.

    See appendix A of this part to determine how emission standards 
apply before 2023.
* * * * *


Sec.  1033.102  Removed]

0
76. Remove Sec.  1033.102.
0
77. Amend Sec.  1033.115 by revising paragraphs (b) introductory text 
and (c) to read as follows:


Sec.  1033.115  Other requirements.

* * * * *
    (b) Adjustable parameters. Locomotives that have adjustable 
parameters must meet all the requirements of this part for any 
adjustment in the approved adjustable range. General provisions for 
adjustable parameters apply as specified in 40 CFR 1068.50. You must 
specify in your application for certification the adjustable range of 
each adjustable parameter on a new locomotive or new locomotive engine 
to--
* * * * *
    (c) Prohibited controls. (1) General provisions. You may not design 
or produce your locomotives with emission control devices, systems, or 
elements of design that cause or contribute to an unreasonable risk to 
public health, welfare, or safety while operating. For example, a 
locomotive may not emit a noxious or toxic substance it would otherwise 
not emit that contributes to such an unreasonable risk.
    (2) Vanadium sublimation in SCR catalysts. For engines equipped 
with vanadium-based SCR catalysts, you must design the engine and its 
emission controls to prevent vanadium sublimation and protect the 
catalyst from high temperatures. We will evaluate your engine design 
based on the following information that you must include in your 
application for certification:
    (i) Identify the threshold temperature for vanadium sublimation for 
your specified SCR catalyst formulation as described in 40 CFR 
1065.1113 through 1065.1121.
    (ii) Describe how you designed your engine to prevent catalyst 
inlet temperatures from exceeding the temperature you identify in 
paragraph (c)(2)(i) of this section, including consideration of engine 
wear through the useful life. Also describe your design for catalyst 
protection in case catalyst temperatures exceed the specified 
temperature. In your description, include how you considered elevated 
catalyst temperature resulting from sustained high-load engine 
operation, catalyst

[[Page 17658]]

exotherms, particulate filter regeneration, and component failure 
resulting in unburned fuel in the exhaust stream.
* * * * *
0
78. Amend Sec.  1033.120 by revising paragraph (c) to read as follows:


Sec.  1033.120  Emission-related warranty requirements.

* * * * *
    (c) Components covered. The emission-related warranty covers all 
components whose failure would increase a locomotive's emissions of any 
regulated pollutant. This includes components listed in 40 CFR part 
1068, appendix A, and components from any other system you develop to 
control emissions. The emission-related warranty covers the components 
you sell even if another company produces the component. Your emission-
related warranty does not need to cover components whose failure would 
not increase a locomotive's emissions of any regulated pollutant. For 
remanufactured locomotives, your emission-related warranty is required 
to cover only those parts that you supply or those parts for which you 
specify allowable part manufacturers. It does not need to cover used 
parts that are not replaced during the remanufacture.
* * * * *
0
79. Amend Sec.  1033.205 by revising paragraph (d)(6) to read as 
follows:


Sec.  1033.205  Applying for a certificate of conformity.

* * * * *
    (d) * * *
    (6) A description of injection timing, fuel rate, and all other 
adjustable operating parameters, including production tolerances. For 
any operating parameters that do not qualify as adjustable parameters, 
include a description supporting your conclusion (see 40 CFR 
1068.50(c)). Include the following in your description of each 
adjustable parameter:
    (i) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, the 
limits or stops used to limit adjustable ranges, and production 
tolerances of the limits or stops used to establish each physically 
adjustable range. Also include information showing why the physical 
limits, stops or other means of limiting adjustment, are effective in 
preventing adjustment of parameters on in-use engines to settings 
outside your intended physically adjustable ranges.
    (ii) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
80. Amend Sec.  1033.245 by adding paragraph (f) to read as follows:


Sec.  1033.245  Deterioration factors.

* * * * *
    (f) You may alternatively determine and verify deterioration 
factors based on bench-aged aftertreatment as described in 40 CFR 
1036.245 and 1036.246, with the following exceptions:
    (1) Apply the percentage of useful life from Table 1 of 40 CFR 
1036.246 based on hours of operation rather than vehicle mileage.
    (2) Perform verification testing as described in subpart F of this 
part rather than 40 CFR 1036.520. The provisions of 40 CFR 
1036.246(d)(2) and (3) do not apply. Perform testing consistent with 
the original certification to determine whether tested locomotives meet 
the duty-cycle emission standards in Sec.  1033.101.
    (3) Apply infrequent regeneration adjustment factors as specified 
in Sec.  1033.535 rather than 40 CFR 1036.522.
0
81. Revise Sec.  1033.525 to read as follows:


Sec.  1033.525  Smoke opacity testing.

    Analyze exhaust opacity test data as follows:
    (a) Measure exhaust opacity using the procedures specified in 40 
CFR 1065.1125. Perform the opacity test with a continuous digital 
recording of smokemeter response identified by notch setting over the 
entire locomotive test cycle specified in Sec.  1033.515(c)(4) or Sec.  
1033.520(e)(4). Measure smokemeter response in percent opacity to 
within one percent resolution.
    (b) Calibrate the smokemeter as follows:
    (1) Calibrate using neutral density filters with approximately 10, 
20, and 40 percent opacity. Confirm that the opacity values for each of 
these reference filters are NIST-traceable within 185 days of testing, 
or within 370 days of testing if you consistently protect the reference 
filters from light exposure between tests.
    (2) Before each test, remove the smokemeter from the exhaust 
stream, if applicable, and calibrate as follows:
    (i) Zero. Adjust the smokemeter to give a zero response when there 
is no detectable smoke.
    (ii) Linearity. Insert each of the qualified reference filters in 
the light path perpendicular to the axis of the light beam and adjust 
the smokemeter to give a result within 1 percentage point of the named 
value for each reference filter.
    (c) Use computer analysis to evaluate percent opacity for each 
notch setting. Treat the start of the first idle mode as the start of 
the test. Each mode ends when operator demand changes for the next mode 
(or for the end of the test). Analyze the opacity trace using the 
following procedure:
    (1) 3 second peak. Identify the highest opacity value over the test 
and integrate the highest 3 second average including that highest 
value.
    (2) 30 second peak. Divide the test into a series of 30 second 
segments, advancing each segment in 1 second increments. Determine the 
opacity value for each segment and identify the highest opacity value 
from all the 30 second segments.
    (3) Steady-state. Calculate the average of second-by-second values 
between 120 and 180 seconds after the start of each mode. For RMC modes 
that are less than 180 seconds, calculate the average over the last 60 
seconds of the mode. Identify the highest of those steady-state values 
from the different modes.
    (d) Determine values of standardized percent opacity, [kappa]std, 
by correcting to a reference optical path length of 1 meter for 
comparing to the standards using the following equation:

[[Page 17659]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.015

0
82. Amend Sec.  1033.630 by revising paragraph (b)(1) to read as 
follows:


Sec.  1033.630  Staged-assembly and delegated assembly exemptions.

* * * * *
    (b) * * *
    (1) In cases where an engine has been assembled in its certified 
configuration, properly labeled, and will not require an aftertreatment 
device to be attached when installed in the locomotive, no exemption is 
needed to ship the engine. You do not need an exemption to ship engines 
without specific components if they are not emission-related components 
identified in appendix A of 40 CFR part 1068.
0
83. Amend Sec.  1033.815 by revising paragraph (f) to read as follows:


Sec.  1033.815  Maintenance, operation, and repair.

* * * * *
    (f) Failure to perform required maintenance is a violation of the 
tampering prohibition in 40 CFR 1068.101(b)(1). Failure of any person 
to comply with the recordkeeping requirements of this section is a 
violation of 40 CFR 1068.101(a)(2).
0
84. Amend Sec.  1033.901 by revising the definition of ``Designated 
Compliance Officer'' to read as follows:


Sec.  1033.901  Definitions.

* * * * *
    Designated Compliance Officer means the Director, Diesel Engine 
Compliance Center, U.S. Environmental Protection Agency, 2000 
Traverwood Drive, Ann Arbor, MI 48105; [email protected]; 
www.epa.gov/ve-certification.
* * * * *
0
85. Redesignate appendix I to part 1033 as appendix A to part 1033 and 
revise newly redesignated appendix A to read as follows:

Appendix A to Part 1033--Original Standards for Tier 0, Tier 1 and Tier 
2 Locomotives

    (a) Locomotives were originally subject to Tier 0, Tier 1, and 
Tier 2 emission standards described in paragraph (b) of this 
appendix as follows:
    (1) The Tier 0 and Tier 1 standards in paragraph (b) of this 
appendix applied instead of the Tier 0 and Tier 1 standards of Sec.  
1033.101 for locomotives manufactured and remanufactured before 
January 1, 2010. For example, a locomotive that was originally 
manufactured in 2004 and remanufactured on April 10, 2011 was 
subject to the original Tier 1 standards specified in paragraph (b) 
of this appendix and became subject to the Tier 1 standards of Sec.  
1033.101 when it was remanufactured on April 10, 2011.
    (2) The Tier 2 standards in paragraph (b) of this appendix 
applied instead of the Tier 2 standards of Sec.  1033.101 for 
locomotives manufactured and remanufactured before January 1, 2013.
    (b) The following NOX and PM standards applied before 
the dates specified in paragraph (a) of this appendix:

                          Table 1 to Appendix A--Original Locomotive Emission Standards
----------------------------------------------------------------------------------------------------------------
                                                                               Standards (g/bhp-hr)
                               Year of original                  -----------------------------------------------
      Type of standard           manufacture           Tier                                        PM-alternate
                                                                        NOX         PM-primary          \1\
----------------------------------------------------------------------------------------------------------------
Line-haul...................          1973-1992  Tier 0.........             9.5            0.60            0.30
                                      1993-2004  Tier 1.........             7.4            0.45            0.22
                                      2005-2011  Tier 2.........             5.5            0.20            0.10
Switch......................          1973-1992  Tier 0.........            14.0            0.72            0.36
                                      1993-2004  Tier 1.........            11.0            0.54            0.27
                                      2005-2011  Tier 2.........             8.1            0.24            0.12
----------------------------------------------------------------------------------------------------------------
 \1\Locomotives certified to the alternate PM standards are also subject to alternate CO standards of 10.0 for
  the line-haul cycle and 12.0 for the switch cycle.


[[Page 17660]]

    (c) The original Tier 0, Tier 1, and Tier 2 standards for HC and 
CO emissions and smoke are the same standards identified in Sec.  
1033.101.

PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVY-DUTY 
HIGHWAY ENGINES

0
86. Revise part 1036 to read as follows:

PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVY-DUTY 
HIGHWAY ENGINES

Sec.
Subpart A--Overview and Applicability
1036.1 Applicability.
1036.2 Compliance responsibility.
1036.5 Excluded engines.
1036.10 Organization of this part.
1036.15 Other applicable regulations.
1036.30 Submission of information.
Subpart B--Emission Standards and Related Requirements
1036.101 Overview of exhaust emission standards.
1036.104 Criteria pollutant emission standards--NOX, HC, 
PM, and CO.
1036.108 Greenhouse gas emission standards--CO2, 
CH4, and N2O.
1036.110 Diagnostic controls.
1036.111 Inducements related to SCR.
1036.115 Other requirements.
1036.120 Emission-related warranty requirements.
1036.125 Maintenance instructions and allowable maintenance.
1036.130 Installation instructions for vehicle manufacturers.
1036.135 Labeling.
1036.140 Primary intended service class and engine cycle.
1036.150 Interim provisions.
Subpart C--Certifying Engine Families
1036.201 General requirements for obtaining a certificate of 
conformity.
1036.205 Requirements for an application for certification.
1036.210 Preliminary approval before certification.
1036.225 Amending applications for certification.
1036.230 Selecting engine families.
1036.235 Testing requirements for certification.
1036.240 Demonstrating compliance with criteria pollutant emission 
standards.
1036.241 Demonstrating compliance with greenhouse gas emission 
standards.
1036.245 Deterioration factors for exhaust emission standards.
1036.246 Verifying deterioration factors.
1036.250 Reporting and recordkeeping for certification.
1036.255 EPA oversight on certificates of conformity.
Subpart D--Testing Production Engines and Hybrid Powertrains
1036.301 Measurements related to GEM inputs in a selective 
enforcement audit.
Subpart E--In-use Testing
1036.401 Testing requirements for in-use engines.
1036.405 Overview of the manufacturer-run field-testing program.
1036.410 Selecting and screening vehicles and engines for testing.
1036.415 Preparing and testing engines.
1036.420 Pass criteria for individual engines.
1036.425 Pass criteria for engine families.
1036.430 Reporting requirements.
1036.435 Recordkeeping requirements.
1036.440 Warranty obligations related to in-use testing.
Subpart F--Test Procedures
1036.501 General testing provisions.
1036.503 Engine data and information to support vehicle 
certification.
1036.505 Supplemental Emission Test.
1036.510 Federal Test Procedure.
1036.512 Low Load Cycle.
1036.514 Clean Idle test.
1036.515 Test procedures for off-cycle testing.
1036.520 Test procedures to verify deterioration factors.
1036.522 Infrequently regenerating aftertreatment devices.
1036.527 Powertrain system rated power determination.
1036.530 Calculating greenhouse gas emission rates.
1036.535 Determining steady-state engine fuel maps and fuel 
consumption at idle.
1036.540 Determining cycle-average engine fuel maps.
1036.543 Carbon balance error verification.
Subpart G--Special Compliance Provisions
1036.601 Overview of compliance provisions.
1036.605 Alternate emission standards for engines used in specialty 
vehicles.
1036.610 Off-cycle technology credits and adjustments for reducing 
greenhouse gas emissions.
1036.615 Engines with Rankine cycle waste heat recovery and hybrid 
powertrains.
1036.620 Alternate CO2 standards based on model year 2011 
compression-ignition engines.
1036.625 In-use compliance with CO2 family emission 
limits (FELs).
1036.630 Certification of engine greenhouse gas emissions for 
powertrain testing.
1036.635 --[Reserved]
1036.655 Special provisions for diesel-fueled engines sold in 
American Samoa or the Commonwealth of the Northern Mariana Islands.
Subpart H--Averaging, Banking, and Trading for Certification
1036.701 General provisions.
1036.705 Generating and calculating emission credits.
1036.710 Averaging.
1036.715 Banking.
1036.720 Trading.
1036.725 Required information for certification.
1036.730 ABT reports.
1036.735 Recordkeeping.
1036.740 Restrictions for using emission credits.
1036.741 Using emission credits from electric vehicles and hydrogen 
fuel-cell vehicles.
1036.745 End-of-year CO2 credit deficits.
1036.750 Consequences for noncompliance.
1036.755 Information provided to the Department of Transportation.
Subpart I--Definitions and Other Reference Information
1036.801 Definitions.
1036.805 Symbols, abbreviations, and acronyms.
1036.810 Incorporation by reference.
1036.815 Confidential information.
1036.820 Requesting a hearing.
1036.825 Reporting and recordkeeping requirements.

Appendix A of Part 1036--Summary of Previous Emission Standards

Appendix B of Part 1036--Transient Duty Cycles

Appendix C of Part 1036--Default Engine Fuel Maps for Sec.  1036.540

    Authority:  42 U.S.C. 7401-7671q.

Subpart A--Overview and Applicability


Sec.  1036.1  Applicability.

    (a) Except as specified in Sec.  1036.5, the provisions of this 
part apply for engines that will be installed in heavy-duty vehicles 
(including glider vehicles).
    (b) Heavy-duty engines produced before model year 2027 are subject 
to greenhouse gas emission standards and related provisions under this 
part as specified in Sec.  1036.108; these engines are subject to 
exhaust emission standards for HC, CO, NOX, and PM and 
related provisions under 40 CFR part 86, subpart A, instead of this 
part, except as follows:
    (1) The provisions of Sec. Sec.  1036.115, 1036.501(f), and 
1036.601 apply.
    (2) 40 CFR parts 85 and 86 may specify that certain provisions 
apply.
    (3) This part describes how several individual provisions are 
optional or mandatory before model year 2027. For example, Sec.  
1036.150(a) describes how you may generate emission credits by meeting 
the standards of this part before model year 2027.
    (c) The provisions of this part also apply for fuel conversions of 
all engines described in paragraph (a) of this section as described in 
40 CFR 85.502.
    (d) Gas turbine heavy-duty engines and other heavy-duty engines not 
meeting the definition compression-ignition or spark-ignition are 
deemed to be compression-ignition engines for purposes of this part.
    (e) For the purpose of applying the provisions of this part, 
engines include all emission-related components and any components or 
systems that should be identified in your application for

[[Page 17661]]

certification, such as hybrid components for engines that are certified 
as hybrid engines or hybrid powertrains.


Sec.  1036.2  Compliance responsibility.

    The regulations in this part contain provisions that affect both 
engine manufacturers and others. However, the requirements of this part 
are generally addressed to the engine manufacturer(s). The term ``you'' 
generally means the engine manufacturer(s), especially for issues 
related to certification. Additional requirements and prohibitions 
apply to other persons as specified in subpart G of this part and 40 
CFR part 1068.


Sec.  1036.5  Excluded engines.

    (a) The provisions of this part do not apply to engines used in 
medium-duty passenger vehicles or other heavy-duty vehicles that are 
subject to regulation under 40 CFR part 86, subpart S, except as 
specified in 40 CFR part 86, subpart S, and Sec.  1036.150(j). For 
example, this exclusion applies for engines used in vehicles certified 
to the standards of 40 CFR 86.1818 and 86.1819.
    (b) An engine installed in a heavy-duty vehicle that is not used to 
propel the vehicle is not a heavy-duty engine. The provisions of this 
part therefore do not apply to these engines. Note that engines used to 
indirectly propel the vehicle (such as electrical generator engines 
that provide power to batteries for propulsion) are subject to this 
part. See 40 CFR part 1039, 1048, or 1054 for other requirements that 
apply for these auxiliary engines. See 40 CFR part 1037 for 
requirements that may apply for vehicles using these engines, such as 
the evaporative emission requirements of 40 CFR 1037.103.
    (c) The provisions of this part do not apply to aircraft or 
aircraft engines. Standards apply separately to certain aircraft 
engines, as described in 40 CFR part 87.
    (d) The provisions of this part do not apply to engines that are 
not internal combustion engines, except as specified in Sec.  1036.741. 
For example, the provisions of this part generally do not apply to fuel 
cells. Note that gas turbine engines are internal combustion engines.
    (e) The provisions of this part do not apply for model year 2013 
and earlier heavy-duty engines unless they were:
    (1) Voluntarily certified to this part.
    (2) Installed in a glider vehicle subject to 40 CFR part 1037.


Sec.  1036.10  Organization of this part.

    This part is divided into the following subparts:
    (a) Subpart A of this part defines the applicability of this part 
and gives an overview of regulatory requirements.
    (b) Subpart B of this part describes the emission standards and 
other requirements that must be met to certify engines under this part. 
Note that Sec.  1036.150 describes certain interim requirements and 
compliance provisions that apply only for a limited time.
    (c) Subpart C of this part describes how to apply for a certificate 
of conformity.
    (d) Subpart D of this part addresses testing of production engines.
    (e) Subpart E of this part describes provisions for testing in-use 
engines.
    (f) Subpart F of this part describes how to test your engines 
(including references to other parts of the Code of Federal 
Regulations).
    (g) Subpart G of this part describes requirements, prohibitions, 
and other provisions that apply to engine manufacturers, vehicle 
manufacturers, owners, operators, rebuilders, and all others.
    (h) Subpart H of this part describes how you may generate and use 
emission credits to certify your engines.
    (i) Subpart I of this part contains definitions and other reference 
information.


Sec.  1036.15  Other applicable regulations.

    (a) Parts 85 and 86 of this chapter describe additional provisions 
that apply to engines that are subject to this part. See Sec.  
1036.601.
    (b) Part 1037 of this chapter describes requirements for 
controlling evaporative emissions and greenhouse gas emissions from 
heavy-duty vehicles, whether or not they use engines certified under 
this part.
    (c) Part 1065 of this chapter describes procedures and equipment 
specifications for testing engines to measure exhaust emissions. 
Subpart F of this part describes how to apply the provisions of part 
1065 of this chapter to determine whether engines meet the exhaust 
emission standards in this part.
    (d) The requirements and prohibitions of part 1068 of this chapter 
apply as specified in Sec.  1036.601 to everyone, including anyone who 
manufactures, imports, installs, owns, operates, or rebuilds any of the 
engines subject to this part, or vehicles containing these engines. See 
Sec.  1036.601 to determine how to apply the part 1068 regulations for 
heavy-duty engines. The issues addressed by these provisions include 
these seven areas:
    (1) Prohibited acts and penalties for engine manufacturers, vehicle 
manufacturers, and others.
    (2) Rebuilding and other aftermarket changes.
    (3) Exclusions and exemptions for certain engines.
    (4) Importing engines.
    (5) Selective enforcement audits of your production.
    (6) Recall.
    (7) Procedures for hearings.
    (e) Other parts of this chapter apply if referenced in this part.


Sec.  1036.30  Submission of information.

    Unless we specify otherwise, send all reports and requests for 
approval to the Designated Compliance Officer (see Sec.  1036.801). See 
Sec.  1036.825 for additional reporting and recordkeeping provisions.

Subpart B--Emission Standards and Related Requirements


Sec.  1036.101  Overview of exhaust emission standards.

    (a) You must show that engines meet the following exhaust emission 
standards:
    (1) Criteria pollutant standards for NOX, HC, PM, and CO 
apply as described in Sec.  1036.104.
    (2) Greenhouse gas (GHG) standards for CO2, 
CH4, and N2O apply as described in Sec.  
1036.108.
    (b) You may optionally demonstrate compliance with the emission 
standards of this part by testing hybrid engines and hybrid 
powertrains, rather than testing the engine alone. Except as specified, 
provisions of this part that reference engines apply equally to hybrid 
engines and hybrid powertrains.


Sec.  1036.104  Criteria pollutant emission standards--NOX, HC, PM, and 
CO.

    This section describes the applicable NOX, HC, CO, and 
PM standards for model years 2027 and later. These standards apply 
equally for all primary intended service classes unless otherwise 
noted.
    (a) Emission standards. Exhaust emissions may not exceed the 
standards in this section for the specified duty cycle, as follows:
    (1) Measure emissions over the specified duty cycles using the test 
procedures described in subpart F of this part.
    (2) The following emission standards apply over the FTP and SET 
duty cycles:

[[Page 17662]]



                 Table 1 to Paragraph (a)(2) of Sec.   1036.104--FTP and SET Emission Standards
----------------------------------------------------------------------------------------------------------------
                                                     NOX (mg/         HC (mg/         PM (mg/         CO (g/
                   Model year                      hp[middot]hr)   hp[middot]hr)   hp[middot]hr)   hp[middot]hr)
----------------------------------------------------------------------------------------------------------------
2027-2030.......................................              35              60               5             6.0
2031 and later..................................          \a\ 20              40               5             6.0
----------------------------------------------------------------------------------------------------------------
\a\ The NO standard identified for Heavy HDE applies for an intermediate useful life of 435,000 miles, 10 years,
  or 22,000 hours, whichever comes first. A standard of 40 mg/hp[middot]hr applies for the rest of the useful
  life.

    (3) The following emission standards apply for compression-ignition 
engines over the Low Load Cycle:

                Table 2 to Paragraph (a)(3) of Sec.   1036.104--Low Load Cycle Emission Standards
----------------------------------------------------------------------------------------------------------------
                                                     NOX (mg/         HC (mg/         PM (mg/         CO (g/
                   Model Year                      hp[middot]hr)   hp[middot]hr)   hp[middot]hr)   hp[middot]hr)
----------------------------------------------------------------------------------------------------------------
2027-2030.......................................              90             140               5             6.0
2031 and later..................................          \a\ 50              60               5             6.0
----------------------------------------------------------------------------------------------------------------
\a\ The NOX standard identified for Heavy HDE applies for an intermediate useful life of 435,000 miles, 10
  years, or 22,000 hours, whichever comes first. A standard of 100 mg/hp[middot]hr applies for the rest of the
  useful life.

    (4) Off-cycle emission standards apply for compression-ignition 
engines using the procedures specified in Sec.  1036.515. For the idle 
bin, the NOX off-cycle emission standard is 10.0 g/hr 
starting in model years 2027 through 2030 and 7.5 g/hr starting in 
model year 2031. Additional off-cycle emission standards apply as 
described in the following table:

  Table 3 to Paragraph (a)(4) of Sec.   1036.104--Off-Cycle Emission Standards for Compression-Ignition Engines
----------------------------------------------------------------------------------------------------------------
                                                     NOX (mg/         HC (mg/         PM (mg/         CO (g/
          Model year                   Bin         hp[middot]hr)   hp[middot]hr)   hp[middot]hr)   hp[middot]hr)
----------------------------------------------------------------------------------------------------------------
2027-2030.....................  Low load........             180             280              10            12.0
                                Medium/high load              70             120              10            12.0
2031 and later................  Low load........          \a\ 75              90               8             9.0
                                Medium/high load          \a\ 30              60               8             9.0
----------------------------------------------------------------------------------------------------------------
\a\ The low load and medium/high load NOX standards identified for Heavy HDE apply for an intermediate useful
  life of 435,000 miles, 10 years, or 22,000 hours, whichever comes first. A low load bin standard of 150 mg/
  hp[middot]hr and a medium/high load bin standard of 60 mg/hp[middot]hr apply for the rest of the useful life.

    (b) Clean Idle. You may optionally certify compression-ignition 
engines to the Clean Idle NOX emission standard using the 
Clean Idle test specified in Sec.  1036.514. The optional Clean Idle 
NOX emission standard is 30.0 g/h before model year 2024, 
10.0 g/h for model years 2024 through 2026, and 5.0 g/hr for model year 
2027 and later. The mass emission rate of HC, CO, and PM in g/hr during 
the Clean Idle test may not exceed the emission results from the idle 
modes of the SET duty cycle as described in Sec.  1036.505(h) or the 
idle segments of the FTP duty cycle as described in Sec.  1036.510(g). 
The standard applies separately to each mode of the Clean Idle test. If 
you certify an engine family to the Clean Idle standards, it is subject 
to all these voluntary standards as if they were mandatory.
    (c) Averaging, banking, and trading. You may generate or use 
emission credits under the averaging, banking, and trading (ABT) 
program described in subpart H of this part for demonstrating 
compliance with NOX emission standards in paragraph (a) of 
this section. You must meet the PM, HC, and CO emission standards in 
Sec.  1036.104(a) without generating or using emission credits.
    (1) To generate or use emission credits, you must specify a family 
emission limit for each engine family. Declare the family emission 
limit corresponding to full useful life for engine operation over the 
FTP duty cycle, FELFTP, expressed to the same number of 
decimal places as the emission standard. Use FELFTP to 
calculate emission credits in subpart H of this part.
    (2) The following NOX FEL caps are the maximum values 
you may specify for FELFTP:
    (i) 150 mg/hp[middot]hr for model year 2027 through 2030 Spark-
ignition HDE, Light HDE, Medium HDE, and Heavy HDE.
    (ii) 50 mg/hp[middot]hr for model year 2031 and later Spark-
ignition HDE, Light HDE, and Medium HDE.
    (iii) 70 mg/hp[middot]hr for model year 2031 and later Heavy HDE.
    (3) Calculate the NOX family emission limit, 
FEL[cycle]NOX, that applies for each duty-cycle or off-cycle 
standard using the following equation, noting that you must also use 
this approach to determine the FEL for each cycle that applies for 
Heavy HDE at intermediate useful life:

[[Page 17663]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.016

    (4) The family emission limits in this paragraph (c) serve as the 
emission standards for compliance testing instead of the standards 
specified in this section.
    (d) Fuel types. The exhaust emission standards in this section 
apply for engines using the fuel type on which the engines in the 
engine family are designed to operate. You must meet the numerical 
emission standards for HC in this section based on the following types 
of hydrocarbon emissions for engines powered by the following fuels:
    (1) Alcohol-fueled engines: NMHCE emissions.
    (2) Gaseous-fueled engines: NMNEHC emissions.
    (3) Other engines: NMHC emissions.
    (e) Useful life. The exhaust emission standards of this section 
apply for the useful life, expressed in vehicle miles, or hours of 
engine operation, or years in service, whichever comes first, as 
follows:

           Table 4 to Paragraph (e) of Sec.   1036.104--Useful Life by Primary Intended Service Class
----------------------------------------------------------------------------------------------------------------
                                                   Model year 2027 through 2030      Model year 2031 and later
         Primary intended service class          ---------------------------------------------------------------
                                                       Miles           Years           Miles           Years
----------------------------------------------------------------------------------------------------------------
Spark-ignition HDE..............................         155,000              12         200,000              15
Light HDE.......................................         190,000              12         270,000              15
Medium HDE......................................         270,000              11         350,000              12
Heavy HDE \a\...................................         600,000              11        800,000b              12
----------------------------------------------------------------------------------------------------------------
\a\ Useful life for Heavy HDE is also expressed as 32,000 operating hours for model year 2027 through 2030, and
  40,000 operating hours for model year 2031 and later. For an individual engine, the useful life is no shorter
  than 10 years or 100,000 miles, whichever occurs first, regardless of operating hours.
\b\ Additional standards apply for Heavy HDE during an intermediate useful life of 435,000 miles, 10 years, or
  22,000 hours, whichever comes first.

    (f) Applicability for testing. The emission standards in this 
subpart apply to all testing, including certification, selective 
enforcement audits, and in-use testing. For selective enforcement 
audits, we may require you to perform the appropriate duty-cycle 
testing as specified in Sec. Sec.  1036.505, 1036.510, and 1036.512. 
The off-cycle standards in this section apply for duty-cycle testing 
you perform for a selective enforcement audit. We may direct you to do 
additional testing to show that your engines meet the off-cycle 
standards.


Sec.  1036.108  Greenhouse gas emission standards--CO2, CH4, and N2O.

    This section contains standards and other regulations applicable to 
the emission of the air pollutant defined as the aggregate group of six 
greenhouse gases: Carbon dioxide, nitrous oxide, methane, 
hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. This 
section describes the applicable CO2, N2O, and 
CH4 standards for engines.
    (a) Emission standards. Emission standards apply for engines and 
optionally powertrains measured using the test procedures specified in 
subpart F of this part as follows:
    (1) CO2 emission standards in this paragraph (a)(1) 
apply based on testing as specified in subpart F of this part. The 
applicable test cycle for measuring CO2 emissions differs 
depending on the engine family's primary intended service class and the 
extent to which the engines will be (or were designed to be) used in 
tractors. For Medium HDE and Heavy HDE certified as tractor engines, 
measure CO2 emissions using the SET

[[Page 17664]]

steady-state duty cycle specified in Sec.  1036.505. This testing with 
the SET duty cycle is intended for engines designed to be used 
primarily in tractors and other line-haul applications. Note that the 
use of some SET-certified tractor engines in vocational applications 
does not affect your certification obligation under this paragraph 
(a)(1); see other provisions of this part and 40 CFR part 1037 for 
limits on using engines certified to only one cycle. For Medium HDE and 
Heavy HDE certified as both tractor and vocational engines, measure 
CO2 emissions using the SET duty cycle specified in Sec.  
1036.505 and the FTP transient duty cycle specified in Sec.  1036.510. 
Testing with both SET and FTP duty cycles is intended for engines that 
are designed for use in both tractor and vocational applications. For 
all other engines (including Spark-ignition HDE), measure 
CO2 emissions using the FTP transient duty cycle specified 
in Sec.  1036.510.
    (i) The CO2 standard is 627 g/hp[middot]hr for all 
spark-ignition engines for model years 2016 through 2020. This standard 
continues to apply in later model years for all spark-ignition engines 
that are not Heavy HDE.
    (ii) The following CO2 standards apply for compression-
ignition engines (in g/hp[middot]hr):

 Table 1 to Paragraph (a)(1)(ii) of Sec.   1036.108--Compression-Ignition Engine Standards for Model Years 2014-
                                                      2020
----------------------------------------------------------------------------------------------------------------
                                                   Medium heavy-   Heavy heavy-
           Model years             Light heavy-        duty-           duty-       Medium heavy-   Heavy heavy-
                                       duty         vocational      vocational     duty- tractor   duty- tractor
----------------------------------------------------------------------------------------------------------------
2014-2016.......................             600             600             567             502             475
2017-2020.......................             576             576             555             487             460
----------------------------------------------------------------------------------------------------------------

    (iii) The following CO2 standards apply for compression-
ignition engines and all Heavy HDE (in g/hp[middot]hr):

 Table 2 to Paragraph (a)(1)(iii) of Sec.   1036.108--Compression-Ignition Engine Standards for Model Years 2021
                                                    and Later
----------------------------------------------------------------------------------------------------------------
                                                   Medium heavy-   Heavy heavy-
           Model years             Light heavy-        duty-           duty-       Medium heavy-   Heavy heavy-
                                       duty         vocational      vocational     duty- tractor   duty- tractor
----------------------------------------------------------------------------------------------------------------
2021-2023.......................             563             545             513             473             447
2024-2026.......................             555             538             506             461             436
2027 and later..................             552             535             503             457             432
----------------------------------------------------------------------------------------------------------------

    (iv) You may certify spark-ignition engines to the compression-
ignition standards for the appropriate model year under this paragraph 
(a). If you do this, those engines are treated as compression-ignition 
engines for all the provisions of this part.
    (2) The CH4 emission standard is 0.10 g/hp[middot]hr 
when measured over the applicable transient duty cycle specified in 
Sec.  1036.510. This standard begins in model year 2014 for 
compression-ignition engines and in model year 2016 for spark-ignition 
engines. Note that this standard applies for all fuel types just like 
the other standards of this section.
    (3) The N2O emission standard is 0.10 g/hp[middot]hr 
when measured over the transient duty cycle specified in Sec.  
1036.510. This standard begins in model year 2014 for compression-
ignition engines and in model year 2016 for spark-ignition engines.
    (b) Family Certification Levels. You must specify a CO2 
Family Certification Level (FCL) for each engine family. The FCL may 
not be less than the certified emission level for the engine family. 
The CO2 Family Emission Limit (FEL) for the engine family is 
equal to the FCL multiplied by 1.03.
    (c) Averaging, banking, and trading. You may generate or use 
emission credits under the averaging, banking, and trading (ABT) 
program described in subpart H of this part for demonstrating 
compliance with CO2 emission standards. Credits (positive 
and negative) are calculated from the difference between the FCL and 
the applicable emission standard. As described in Sec.  1036.705, you 
may use CO2 credits to certify your engine families to FELs 
for N2O and/or CH4, instead of the 
N2O/CH4 standards of this section that otherwise 
apply. Except as specified in Sec. Sec.  1036.150 and 1036.705, you may 
not generate or use credits for N2O or CH4 
emissions.
    (d) Useful life. The exhaust emission standards of this section 
apply for the useful life, expressed as vehicle miles, or hours of 
engine operation, or years in service, whichever comes first, as 
follows:

   Table 3 to Paragraph (d) of Sec.   1036.108--Useful Life by Primary
          Intended Service Class for Model Year 2021 and Later
------------------------------------------------------------------------
     Primary intended service class            Miles           Years
------------------------------------------------------------------------
Spark-ignition HDE......................         150,000              15
Light HDE...............................         150,000              15
Medium HDE..............................         185,000              10

[[Page 17665]]

 
Heavy HDE \a\...........................         435,000              10
------------------------------------------------------------------------
\a\ Useful life for Heavy HDE is also expressed as 22,000 operating
  hours. For an individual engine, the useful life is no shorter than 10
  years or 100,000 miles, whichever occurs first, regardless of
  operating hours.

    (e) Applicability for testing. The emission standards in this 
subpart apply as specified in this paragraph (e) to all duty-cycle 
testing (according to the applicable test cycles) of testable 
configurations, including certification, selective enforcement audits, 
and in-use testing. The CO2 FCLs serve as the CO2 
emission standards for the engine family with respect to certification 
and confirmatory testing instead of the standards specified in 
paragraph (a)(1) of this section. The FELs serve as the emission 
standards for the engine family with respect to all other duty-cycle 
testing. See Sec. Sec.  1036.235 and 1036.241 to determine which engine 
configurations within the engine family are subject to testing. Note 
that engine fuel maps and powertrain test results also serve as 
standards as described in Sec. Sec.  1036.535, 1036.540, and 1036.630 
and 40 CFR 1037.550.


Sec.  1036.110  Diagnostic controls.

    Onboard diagnostic (OBD) systems must generally detect malfunctions 
in the emission control system, store trouble codes corresponding to 
detected malfunctions, and alert operators appropriately. Starting in 
model year 2027, new engines must have OBD systems as described in this 
section. You may optionally comply with any or all of the requirements 
of this section instead of 40 CFR 86.010-18 in earlier model years.
    (a) Chassis-based OBD requirements apply instead of the 
requirements of this section for certain engines as follows:
    (1) Heavy-duty engines intended to be installed in heavy duty 
vehicles at or below 14,000 pounds GVWR must meet the requirements in 
40 CFR 86.1806.
    (2) Heavy-duty spark-ignition engines intended to be installed in 
heavy-duty vehicles above 14,000 pounds GVWR may meet the requirements 
in 40 CFR 86.1806 if the engines share essential design characteristics 
with engines that the engine manufacturer also installs in vehicles 
certified under 40 CFR part 86, subpart S.
    (b) Engines must comply with the 2019 heavy-duty OBD requirements 
adopted for California as described in this paragraph (b). California's 
2019 heavy-duty OBD requirements are part of 13 CCR 1968.2, 1968.5, 
1971.1, and 1971.5 (incorporated by reference in Sec.  1036.810). We 
may approve your request to certify an OBD system meeting alternative 
specifications if you demonstrate that it meets the intent of this 
section. For example, we may approve your request for a system that 
meets a later version of California's OBD requirements if you 
demonstrate that it meets the intent of this section. To demonstrate 
that your engine meets the intent of this section, the OBD system 
meeting alternative specifications must address all the provisions 
described in this paragraph (b) and in paragraph (c) of this section. 
The following clarifications and exceptions apply for engines certified 
under this part:
    (1) We may approve a small manufacturer's request to delay 
complying with the requirements of this section for up to three model 
years if that manufacturer has not certified those engines or other 
comparable engines in California for those model years.
    (2) For engines not certified in California, references to vehicles 
meeting certain California Air Resources Board emission standards are 
understood to refer to the corresponding EPA emission standards for a 
given family, where applicable. Use good engineering judgment to 
correlate the specified standards with the EPA standards that apply 
under this part. You must describe in your application for 
certification how you will perform testing to demonstrate compliance 
with OBD requirements to represent all your engine families over five 
or fewer model years.
    (3) Engines must comply with OBD requirements throughout the useful 
life as specified in Sec.  1036.104.
    (4) The purpose and applicability statements in 13 CCR 1971.1(a) 
and (b) do not apply.
    (5) Compression-ignition engines are subject to a NOX 
threshold of 0.40 g/hp-hr and a PM threshold of 0.03 g/hp-hr for 
operation on the FTP and SET duty cycles. Spark-ignition engines are 
subject to the following thresholds:
    (i) 0.015 g/hp-hr for PM emissions.
    (ii) 0.30 g/hp-hr for monitors detecting a malfunction before 
NOX emissions exceed 1.5 times the applicable standard.
    (iii) 0.35 g/hp-hr for monitors detecting a malfunction before 
NOX emissions exceed 1.75 times the applicable standard.
    (iv) 0.60 g/hp-hr for monitors detecting a malfunction before 
NOX emissions exceed 3.0 times the applicable standard.
    (6) The testing and reporting requirements in 13 CCR 1971.1(i)(2.3) 
and (2.4) do not apply.
    (7) The deficiency provisions described in paragraph (d) of this 
section apply instead of 13 CCR 1971.1(k).
    (8) Capture the following elements as freeze frame data:
    (i) Data parameters specified in 13 CCR 1971.1(h)(4.2) and (4.3).
    (ii) System health monitor parameters specified in paragraph (c)(3) 
of this section.
    (9) Design compression-ignition engines to make the following 
parameters available for reading with a generic scan tool, if so 
equipped:
    (i) Engine and vehicle parameters. Status of parking brake, neutral 
switch, brake switch, and clutch switch, wastegate control solenoid 
output, wastegate position (commanded and actual), speed and output 
shaft torque consistent with Sec.  1036.115(d).
    (ii) Diesel oxidation catalyst parameters. Include inlet and outlet 
pressure and temperature for the diesel oxidation catalyst.
    (iii) Particulate filter parameters. Include filter soot load and 
ash load for all installed particulate filters.
    (iv) EGR parameters. Include differential pressure for exhaust gas 
recirculation.
    (v) SCR parameters. Include DEF quality-related signals, output of 
aftertreatment doser system (pump and injectors), DEF coolant control 
valve position (commanded and actual), DEF tank temperature, DEF system 
pressure, DEF pump commanded percentage, DEF doser control status, DEF 
line heater control outputs.
    (vi) Additional parameters. Include any additional parameters if 
they are related to engine derating or other inducements under Sec.  
1036.111 or Sec.  1036.125.
    (10) Design spark-ignition engines to make the following additional

[[Page 17666]]

parameters available for reading with a generic scan tool, if 
appliable:
    (i) Air/fuel enrichment parameters. Percent of time in enrichment, 
both for each trip (key-on to key-off) and as a cumulative lifetime 
value. Track values separately for enrichment based on throttle, engine 
protection, and catalyst protection.
    (ii) Component temperature parameters. Include component 
temperatures (measured and modeled, if applicable) used for catalyst 
protection.
    (11) If you have an approved Executive order from the California 
Air Resources Board for a given engine family, we may rely on that 
Executive order to evaluate whether you meet federal OBD requirements 
for that same engine family or an equivalent engine family. Engine 
families are equivalent if they are identical in all aspects material 
to emission characteristics. EPA would count two equivalent engines 
families as one for the purposes of determining OBD demonstration 
testing requirements. Send us the following information:
    (i) You must submit additional information as needed to demonstrate 
that you meet the requirements of this section that are not covered by 
the California Executive order.
    (ii) Send us results from any testing you performed for certifying 
engine families (including equivalent engine families) with the 
California Air Resources Board, including the results of any testing 
performed under 13 CCR 1971.1(i)(2.3) and (2.4), 13 CCR 1971.1(l), and 
13 CCR 1971.5(b).
    (iii) We may require that you send us additional information if we 
need it to evaluate whether you meet the requirements of this section. 
This may involve sending us copies of documents you send to the 
California Air Resources Board.
    (c) The following additional provisions apply:
    (1) Design the diagnostic system to display the following 
information in the cab:
    (i) The health monitoring information specified in paragraph (c)(3) 
of this section.
    (ii) The information related to inducements as specified in Sec.  
1036.111(f).
    (2) Diagnostic testing to measure the effectiveness of DEF dosing 
must be made available for use with either a generic scan tool or an 
equivalent alternative method (such as an option commanded through a 
vehicle system menu).
    (3) The following provisions related to system health monitors 
apply:
    (i) Provide the following information related to particulate 
filters:
    (A) An indicator of general system wear, such as the total number 
of regeneration events that have taken place since installing the 
current particulate filter.
    (B) Indicator of historical and current active and passive 
regeneration frequency.
    (C) The estimated mileage until the particulate filter needs 
cleaning to remove accumulated ash.
    (D) Information describing any disabled regeneration if this is 
accompanied by engine derating. Also include the reason for disabling.
    (ii) Provide the following information related to SCR:
    (A) An indicator of historical and current DEF consumption.
    (B) Information describing any disabled DEF dosing if this is 
accompanied by engine derating. Also include the reason for disabling.
    (C) Information describing any detected flow obstruction in DEF 
lines or dosing valve in anticipation of triggering an inducement under 
Sec.  1036.111(b)(2).
    (iii) Provide an indication of EGR valve health, such as by 
comparing commanded and actual EGR position.
    (iv) Provide an indicator of EGR cooler performance, such as by 
displaying parameters described in 13 CCR 1971.1(e)(3.2.5).
    (v) Provide current data under paragraphs (c)(3)(i) and (ii) of 
this section based on a default method of updating or resetting 
collected data. For example, the current data may include information 
from the Active 100-Hour Array or Stored 100-Hour Array. The system 
must allow the operator to perform a manual reset to start collecting 
new data on demand.
    (d) You may ask us to accept as compliant an engine that does not 
fully meet specific requirements under this section. The following 
provisions apply regarding OBD system deficiencies:
    (1) We will not approve a deficiency for gasoline-fueled or diesel-
fueled engines if it involves the complete lack of a major diagnostic 
monitor, such as monitors related to exhaust aftertreatment devices, 
oxygen sensors, air-fuel ratio sensors, NOX sensors, engine 
misfire, evaporative leaks, and diesel EGR (if applicable). We may 
approve such deficiencies for engines using other fuels if you 
demonstrate that the alternative fuel causes these monitors to be 
unreliable.
    (2) We will approve a deficiency only if you show us that full 
compliance is infeasible or unreasonable considering any relevant 
factors, such as the technical feasibility of a given monitor, or the 
lead time and production cycles of vehicle designs and programmed 
computing upgrades.
    (3) Our approval for a given deficiency applies only for a single 
model year, though you may continue to ask us to extend a deficiency 
approval in renewable one-year increments. We may approve an extension 
if you demonstrate an acceptable level of progress toward compliance 
and you show that the necessary hardware or software modifications 
would pose an unreasonable burden. We will approve a deficiency for 
more than two years only if you further demonstrate that you need the 
additional lead time to make substantial changes to engine hardware.
    (4) We will not approve deficiencies retroactively.


Sec.  1036.111  Inducements related to SCR.

    Engines using SCR to control emissions depend on a constant supply 
of diesel exhaust fluid (DEF). This section describes how manufacturers 
must design their engines to derate power output to induce operators to 
take appropriate actions to ensure the SCR system is working properly. 
The requirements of this section apply starting in model year 2027, 
though you may comply with the requirements of this section in earlier 
model years.
    (a) General provisions. The following terms and general provisions 
apply under this section:
    (1) As described in Sec.  1036.110, this section relies on terms 
and requirements specified for OBD systems by California ARB in 13 CCR 
1971.1 (incorporated by reference in Sec.  1036.810).
    (2) The provisions of this section apply differently for low-speed 
vehicles. A low-speed vehicle is one whose OBD system has recorded an 
average speed below 20 miles per hour for the preceding 30 hours of 
non-idle engine operation. Non-idle engine operation includes all 
operating conditions except those that qualify as idle based on OBD 
system controls as specified in 13 CCR 1971.1(h)(5.4.10).
    (3) An inducement drive cycle consists of four hours of continuous 
engine operation, without regard to engine starting.
    (b) Fault conditions. Create derate strategies that monitor for and 
trigger an inducement based on the following conditions:
    (1) DEF supply falling to a level corresponding to three hours of 
engine operation, based on available information on DEF consumption 
rates.
    (2) Blocked DEF lines or dosing valves.

[[Page 17667]]

    (3) DEF quality failing to meet your concentration specifications.
    (4) Open circuit faults related to the following: DEF tank level 
sensor, DEF pump, DEF quality sensor, SCR wiring harness, 
NOX sensors, DEF dosing valve, DEF tank heater and 
aftertreatment control module.
    (5) Monitor for a missing catalyst.
    (c) NOX override. Reset the Active 100 Hour Array in the 
OBD system when the engine detects a fault condition identified in 
paragraph (b) of this section (but do not reset the Active 100 Hour 
Array if an additional fault occurs before the fault condition is 
resolved). Use NOX sensor data to override engine derates as 
described in this paragraph (c) after the engine detects the fault 
condition. Override the onset of derating associated with a fault 
condition if the NOX conversion efficiency in the Active 100 
Hour Array is within 10 percent of the NOX conversion 
efficiency stored in the lifetime array for OBD REAL Bin 13 and 14. The 
Active 100 Hour Array and the Lifetime Array are referenced in 13 CCA 
1971.1(h)(5.3.2)(A) and (C), respectively. Calculate the NOX 
conversion efficiency relative to the lifetime value using the 
following equation and override inducements if the calculated override 
factor is at or below 0.10:
[GRAPHIC] [TIFF OMITTED] TP28MR22.017

    (d) Derate schedule. Engines must follow the derate schedule 
described in this paragraph (d) if the engine detects a fault condition 
identified in paragraphs (b) and (c) of this section. The derate takes 
the form of a maximum drive speed for the vehicle. This maximum drive 
speed decreases over time based on hours of engine operation without 
regard to engine starting or mode of operation. Apply speed-limiting 
derates according to the following schedule:

    Table 1 to Paragraph (d) of Sec.   1036.111--Derate Schedule for
                             Detected Faults
------------------------------------------------------------------------
                                                           Maximum speed
                                              Default      for low-speed
 Non-idle hours of engine operation-\a\    maximum speed   vehicles (mi/
                                              (mi/hr)           hr)
------------------------------------------------------------------------
0.......................................              65              50
6.......................................              60              45
12......................................              55              40
60......................................              50              35
------------------------------------------------------------------------
\a\ Hours start counting when the engine detects a fault condition
  specified in paragraph (b) of this section and the override factor for
  NOX conversion efficiency is above 0.10. For DEF supply, you may
  program the engine to reset the timer to three hours when the engine
  detects an empty DEF tank.

    (e) Multiple and continuing faults. The following provisions apply 
if the engine detects fault conditions after starting with the derate 
schedule specified in paragraph (d) of this section:
    (1) The determination to qualify a low-speed vehicle in paragraph 
(a)(2) of this section applies at the point that the engine first 
detects a fault condition and continues to apply until the fault 
condition is fully resolved, as specified in paragraph (g) of this 
section.
    (2) Apply the provisions of this section independently for each 
fault, except as specified in this section.
    (f) In-cab display. The in-cab display required in Sec.  
1036.110(c)(1) must indicate the condition that triggered the pending 
or active derate. The display must indicate ``inducement pending'' as 
long as the system is evaluating NOX conversion efficiency 
without finding that the override factor is above 0.10. Once calculated 
NOX conversion efficiency confirms the fault condition, the 
display must identify the current stage of derating and show a 
countdown timer to estimate the time or distance remaining before the 
next stage.
    (g) Deactivating derates. Once the override factor for 
NOX conversion efficiency confirms a detected fault 
condition, do not use it alone to deactivate derates. Rather, program 
the engine to deactivate derates as follows:
    (1) Evaluate whether the detected fault condition continues to 
apply and reset the Active 100 Hour Array in the OBD system when the 
fault condition no longer exists. Deactivate derates if the engine 
confirms that the fault condition is resolved and the override factor 
for NOX conversion efficiency is at or below 0.10 for a full 
inducement drive schedule.
    (2) Allow a generic scan tool to tentatively deactivate inducement-
related fault codes while the vehicle is not in motion. Reactivate the 
derate at the same point in the derate schedule if the engine detects 
the same fault condition during a full inducement drive schedule.
    (3) Treat any fault condition that recurs within 80 hours of engine 
operation as the same triggering condition, which would restart the 
derate at the same point that the system last deactivated the derate.


Sec.  1036.115  Other requirements.

    Engines that are required to meet the emission standards of this 
part must meet the following requirements, except as noted elsewhere in 
this part:
    (a) Crankcase emissions. Crankcase emissions may not be discharged 
directly into the ambient atmosphere from any engine throughout its 
useful life. For purposes of this paragraph (a), crankcase emissions 
that are routed to the exhaust upstream of exhaust aftertreatment 
during all operation are not considered to be discharged directly into 
the ambient atmosphere.
    (b) Fuel mapping. You must perform fuel mapping for your engine as 
described in Sec.  1036.510(b).
    (c) Evaporative emissions. You must design and produce your engines 
to comply with evaporative emission standards as follows:
    (1) For complete heavy-duty vehicles you produce, you must certify 
the vehicles to emission standards as specified in 40 CFR 1037.103.

[[Page 17668]]

    (2) For incomplete heavy-duty vehicles, and for engines used in 
vehicles you do not produce, you do not need to certify your engines to 
evaporative emission standards or otherwise meet those standards. 
However, vehicle manufacturers certifying their vehicles with your 
engines may depend on you to produce your engines according to their 
specifications. Also, your engines must meet applicable exhaust 
emission standards in the installed configuration.
    (d) Torque broadcasting. Electronically controlled engines must 
broadcast their speed and output shaft torque (in newton-meters). 
Engines may alternatively broadcast a surrogate value for determining 
torque. Engines must broadcast engine parameters such that they can be 
read with a remote device or broadcast them directly to their 
controller area networks. This information is necessary for testing 
engines in the field (see Sec.  1036.515).
    (e) EPA access to broadcast information. If we request it, you must 
provide us any hardware, tools, and information we would need to 
readily read, interpret, and record all information broadcast by an 
engine's on-board computers and electronic control modules. If you 
broadcast a surrogate parameter for torque values, you must provide us 
what we need to convert these into torque units. We will not ask for 
hardware or tools if they are readily available commercially.
    (f) Adjustable parameters. Engines that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range.
    (1) We may require that you set adjustable parameters to any 
specification within the adjustable range during any testing, including 
certification testing, selective enforcement auditing, or in-use 
testing.
    (2) General provisions apply for adjustable parameters as specified 
in 40 CFR 1068.50.
    (3) DEF supply and DEF quality are adjustable parameters. The 
physically adjustable range includes any amount or quality of DEF that 
the engine's diagnostic system does not trigger inducement provisions 
under Sec.  1036.111.
    (g) Prohibited controls. (1) General provisions. You may not design 
your engines with emission control devices, systems, or elements of 
design that cause or contribute to an unreasonable risk to public 
health, welfare, or safety while operating. For example, this would 
apply if the engine emits a noxious or toxic substance it would 
otherwise not emit that contributes to such an unreasonable risk.
    (2) Vanadium sublimation in SCR catalysts. For engines equipped 
with vanadium-based SCR catalysts, you must design the engine and its 
emission controls to prevent vanadium sublimation and protect the 
catalyst from high temperatures. We will evaluate your engine design 
based on the following information that you must include in your 
application for certification:
    (i) Identify the threshold temperature for vanadium sublimation for 
your specified SCR catalyst formulation as described in 40 CFR 
1065.1113 through 1065.1121.
    (ii) Describe how you designed your engine to prevent catalyst 
inlet temperatures from exceeding the temperature you identify in 
paragraph (g)(2)(i) of this section, including consideration of engine 
wear through the useful life. Also describe your design for catalyst 
protection in case catalyst temperatures exceed the specified 
temperature. In your description, include how you considered elevated 
catalyst temperature resulting from sustained high-load engine 
operation, catalyst exotherms, particulate filter regeneration, and 
component failure resulting in unburned fuel in the exhaust stream.
    (h) Defeat devices. You may not equip your engines with a defeat 
device. A defeat device is an auxiliary emission control device (AECD) 
that reduces the effectiveness of emission controls under conditions 
that may reasonably be expected in normal operation and use. This does 
not apply to auxiliary emission control devices you identify in your 
application for certification if any of the following is true:
    (1) The conditions of concern were substantially included in the 
applicable procedure for duty-cycle testing as described in subpart F 
of this part.
    (2) You show your design is necessary to prevent engine (or 
vehicle) damage or accidents.
    (3) The reduced effectiveness applies only to starting the engine.
    (4) The AECD applies only for engines that will be installed in 
emergency vehicles, and the need is justified in terms of preventing 
the engine from losing speed, torque, or power due abnormal conditions 
of the emission control system, or in terms of preventing such abnormal 
conditions from occurring, during operation related to emergency 
response. Examples of such abnormal conditions may include excessive 
exhaust backpressure from an overloaded particulate trap, and running 
out of diesel exhaust fluid for engines that rely on urea-based 
selective catalytic reduction.
    (i) DEF tanks. Diesel exhaust fluid tanks must be sized to require 
refilling no more frequently than the vehicle operator will need to 
refill the fuel tank, even for worst-case assumptions related to fuel 
efficiency and refueling volumes.
    (j) Special provisions for spark-ignition engines. The following 
provisions apply for spark-ignition engines starting with model year 
2027:
    (1) Catalyst bed temperature may not fall below 350 [deg]C during 
extended idle. Describe how you designed your engine to meet this 
requirement in your application for certification. You may ask us to 
approve alternative strategies to prevent emissions from increasing 
during idle.
    (2) You may use modeled exhaust component temperatures to protect 
the catalyst instead of designing the engine to continuously monitor 
exhaust component temperatures as described in this paragraph (j)(2). 
Measure and record component temperatures during engine mapping and 
during emission measurements with each required duty cycle. You may use 
modeled exhaust temperatures under this paragraph (j)(2) only if all 
modeled and actual temperatures differ by 5 [deg]C or less. Submit a 
second-by-second comparison of the modeled and actual component 
temperatures as part of your application for certification.


Sec.  1036.120  Emission-related warranty requirements.

    (a) General requirements. You must warrant to the ultimate 
purchaser and each subsequent purchaser that the new engine, including 
all parts of its emission control system, meets two conditions:
    (1) It is designed, built, and equipped so it conforms at the time 
of sale to the ultimate purchaser with the requirements of this part.
    (2) It is free from defects in materials and workmanship that may 
keep it from meeting these requirements.
    (b) Warranty period. Your emission-related warranty must be valid 
for at least as long as the minimum warranty periods listed in this 
paragraph (b) in vehicle miles, or hours of engine operation, or years 
in service, whichever comes first. You may offer an emission-related 
warranty more generous than we require. The emission-related warranty 
for the engine may not be shorter than any published warranty you offer 
with or without charge for the engine. Similarly, the emission-related 
warranty for any component may not be shorter than any published 
warranty you offer

[[Page 17669]]

without charge for that component. If an extended warranty requires 
owners to pay for a portion of repairs, those terms apply in the same 
manner to the emission-related warranty. The warranty period begins 
when the vehicle is placed into service. The following minimum warranty 
periods apply:

           Table 1 to Paragraph (b) of Sec.   1036.120--Warranty by Primary Intended Service Class \a\
----------------------------------------------------------------------------------------------------------------
                                    Model year     Model year  2027 through 2030    Model year  2031 and later
                                     2026 and    ---------------------------------------------------------------
 Primary intended service class       earlier
                                 ----------------     Mileage          Hours          Mileage          Hours
                                      Mileage
----------------------------------------------------------------------------------------------------------------
Spark-Ignition HDE..............          50,000         110,000           6,000         160,000           8,000
Light HDE.......................          50,000         150,000           7,000         210,000          10,000
Medium HDE......................         100,000         220,000          11,000         280,000          14,000
Heavy HDE.......................         100,000         450,000          22,000         600,000          30,000
----------------------------------------------------------------------------------------------------------------
\a\ Warranty period is also expressed as 5 years for model years 2026 and earlier, 7 years for model years 2027
  through 2030, and 10 years for model years 2031 and later.

    (c) Components covered. The emission-related warranty covers all 
components whose failure would increase an engine's emissions of any 
regulated pollutant, including components listed in 40 CFR part 1068, 
appendix A, and components from any other system you develop to control 
emissions. The emission-related warranty covers these components even 
if another company produces the component.
    (d) Limited applicability. You may deny warranty claims under this 
section if the operator caused the problem through improper maintenance 
or use, subject to the provisions in Sec.  1036.125 and 40 CFR 
1068.115.
    (e) Owners manual. Describe in the owners manual the emission-
related warranty provisions from this section that apply to the engine.


Sec.  1036.125  Maintenance instructions and allowable maintenance.

    Maintenance includes any inspection, adjustment, cleaning, repair, 
or replacement of components and is classified as either emission-
related or nonemission-related and each of these can be classified as 
either scheduled or unscheduled. Further, some emission-related 
maintenance is also classified as critical emission-related 
maintenance. Give the ultimate purchaser of each new engine written 
instructions for maintaining and using the engine. As described in 
paragraph (h) of this section, these instructions must identify how 
owners properly maintain and use engines for applying regulatory 
requirements such as emission-related warranty and defect reporting.
    (a) Critical emission-related maintenance. Critical emission-
related maintenance includes any adjustment, cleaning, repair, or 
replacement of components listed in paragraph (a)(2) of this section. 
This may also include other maintenance that you determine is critical, 
including maintenance on other critical emission-related components as 
defined in 40 CFR part 1068, if we approve it in advance. You may 
perform scheduled critical emission-related maintenance during service 
accumulation on your emission-data engines at the intervals you 
specify.
    (1) Maintenance demonstration. You must demonstrate that the 
maintenance is reasonably likely to be done at the recommended 
intervals on in-use engines. We will accept DEF replenishment and other 
SCR-related maintenance as reasonably likely to occur if your engine 
meets the specifications in Sec.  1036.111. We will accept other 
scheduled maintenance as reasonably likely to occur if you satisfy any 
of the following conditions:
    (i) You present data showing that, if a lack of maintenance 
increases emissions, it also unacceptably degrades the engine's 
performance.
    (ii) You design and produce your engines with a system we approve 
that displays a visible signal to alert drivers that maintenance is 
due, either as a result of component failure or the appropriate degree 
of engine or vehicle operation. The signal must clearly display 
``maintenance needed'', ``check engine'', or a similar message that we 
approve. The signal must be continuous while the engine is operating 
and not be easily eliminated without performing the specified 
maintenance. Your maintenance instructions must specify resetting the 
signal after completing the specified maintenance. We must approve the 
method for resetting the signal. You may not design the system to be 
less effective at the end of the useful life or after any other degree 
of operation. If others install your engine in their vehicle, you may 
rely on installation instructions to ensure proper mounting and 
operation of the display. Disabling or improperly resetting the system 
for displaying these maintenance-related signals without performing the 
indicated maintenance violates the tampering prohibition in 42 U.S.C. 
7522(a)(3).
    (iii) You present survey data showing that at least 80 percent of 
engines in the field get the maintenance you specify at the recommended 
intervals.
    (iv) You provide the maintenance free of charge and clearly say so 
in your maintenance instructions.
    (v) You otherwise show us that the maintenance is reasonably likely 
to be done at the recommended intervals.
    (2) Minimum scheduled maintenance intervals. You may not schedule 
replacement of catalyst beds or particulate filters during an engine's 
useful life. You may not schedule other critical emission-related 
maintenance more frequently than the minimum intervals specified in 
Table 1 and Table 2 of this section or otherwise allowed in this 
paragraph (a). The minimum intervals specified for each component 
applies to actuators, sensors, tubing, valves, and wiring associated 
with that component, except as specified.

[[Page 17670]]



     Table 1 to Paragraph (a)(2) of Sec.   1036.125--Minimum Scheduled Maintenance Intervals for Replacement
----------------------------------------------------------------------------------------------------------------
                                                       Accumulated miles (hours) for components
                                     ---------------------------------------------------------------------------
              Component                 Spark-Ignition
                                             HDE             Light HDE          Medium HDE         Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs.........................       25,000 (750)                 NA                 NA                 NA
DEF filters.........................                 NA    100,000 (3,000)    120,000 (3,600)    175,000 (5,250)
Crankcase ventilation valves and         60,000 (1,800)     60,000 (1,800)     60,000 (1,800)     60,000 (1,800)
 filters............................
Ignition wires......................    100,000 (3,000)                 NA                 NA                 NA
Oxygen sensors......................     80,000 (2,400)                 NA                 NA                 NA
Air injection system components.....    110,000 (3,300)                 NA                 NA                 NA
Particulate filtration system (other    100,000 (3,000)    100,000 (3,000)    250,000 (7,500)    250,000 (7,500)
 than filters)......................
Catalyst systems (other than            110,000 (3,300)    110,000 (3,300)    185,000 (5,550)   435,000 (13,050)
 catalyst beds).....................
Fuel injectors......................
Electronic control modules..........
Evaporative emission canisters......
Turbochargers.......................
EGR system components (including
 filters and coolers)...............
----------------------------------------------------------------------------------------------------------------


    Table 2 to Paragraph (a)(2) of Sec.   1036.125--Minimum Scheduled Maintenance Intervals for Adjustment or
                                                    Cleaning
----------------------------------------------------------------------------------------------------------------
                                                       Accumulated miles (hours) for components
                                     ---------------------------------------------------------------------------
              Component                 Spark-Ignition
                                             HDE             Light HDE          Medium HDE         Heavy HDE
----------------------------------------------------------------------------------------------------------------
Spark plugs.........................       25,000 (750)                 NA                 NA                 NA
EGR-related filters and coolers.....     50,000 (1,500)     50,000 (1,500)     50,000 (1,500)     50,000 (1,500)
Fuel injectors......................
Crankcase ventilation valves and
 filters............................
DEF filters.........................                 NA     50,000 (1,500)     50,000 (1,500)     50,000 (1,500)
Ignition wires......................     50,000 (1,500)                 NA                 NA                 NA
Idle mixture........................
Oxygen sensors......................     80,000 (2,400)                 NA                 NA                 NA
Air injection system components.....    100,000 (3,000)                 NA                 NA                 NA
Catalyst system components..........    100,000 (3,000)    100,000 (3,000)    150,000 (4,500)    150,000 (4,500)
EGR system components (other than
 filters or coolers)................
Particulate filtration system
 components.........................
Turbochargers.......................
----------------------------------------------------------------------------------------------------------------

    (3) New technology. You may ask us to approve scheduled critical 
emission-related maintenance of components not identified in paragraph 
(a)(2) of this section that is a direct result of the implementation of 
new technology not used in model year 2020 or earlier engines, subject 
to the following provisions:
    (i) Your request must include your recommended maintenance 
interval, including data to support the need for the maintenance, and a 
demonstration that the maintenance is likely to occur at the 
recommended interval using one of the conditions specified in paragraph 
(a)(1) of this section.
    (ii) For any such new technology, we will publish a Federal 
Register notice based on information you submit and any other available 
information to announce that we have established new allowable minimum 
maintenance intervals. Any manufacturer objecting to our decision may 
ask for a hearing (see Sec.  1036.820).
    (b) Recommended additional maintenance. You may recommend any 
amount of maintenance that is additional to what we approve for 
critical emission-related components in paragraph (a) of this section 
for those components, as long as you state clearly that the recommended 
additional maintenance steps are not necessary to keep the emission-
related warranty valid. If operators do the maintenance specified in 
paragraph (a) of this section, but not the recommended additional 
maintenance, this does not allow you to disqualify those engines from 
in-use testing or deny a warranty claim. Do not take these maintenance 
steps during service accumulation on your emission-data engines.
    (c) Special maintenance. You may specify more frequent maintenance 
to address problems related to special situations, such as atypical 
engine operation. You must clearly state that this special maintenance 
is associated with the special situation you are addressing. We may 
disapprove your maintenance instructions if we determine that you have 
specified special maintenance steps to address engine operation that is 
not atypical, or that the maintenance is unlikely to occur in use. If 
we determine that certain maintenance items do not qualify as special 
maintenance under this paragraph (c), you may identify them as 
recommended additional maintenance under paragraph (b) of this section.
    (d) Noncritical emission-related maintenance. You may specify any 
amount of emission-related inspection or other maintenance that is not 
approved critical emission-related maintenance under paragraph (a) of 
this section, subject to the provisions of this paragraph (d). 
Noncritical emission-related maintenance generally includes maintenance 
on the components we specify in 40 CFR part 1068, appendix A, that is 
not covered in paragraph (a) of this section. You must state in the 
owners manual that these steps are not necessary to keep the emission-
related

[[Page 17671]]

warranty valid. If operators fail to do this maintenance, this does not 
allow you to disqualify those engines from in-use testing or deny a 
warranty claim. Do not take these inspection or other maintenance steps 
during service accumulation on your emission-data engines.
    (e) Nonemission-related maintenance. You may schedule any amount of 
maintenance unrelated to emission controls that is needed for proper 
functioning of the engine. This might include adding engine oil; 
changing air, fuel, or oil filters; servicing engine-cooling systems; 
adjusting idle speed, governor, engine bolt torque, valve lash, 
injector lash, timing, or tension of air pump drive belts; and 
lubricating the heat control valve in the exhaust manifold. You may 
perform nonemission-related maintenance during service accumulation on 
your emission-data engines at the least frequent intervals that you 
recommend to the ultimate purchaser (but not the intervals recommended 
for special situations).
    (f) Source of parts and repairs. State clearly on the first page of 
your written maintenance instructions that a repair shop or person of 
the owner's choosing may maintain, replace, or repair emission control 
devices and systems. Your instructions may not require components or 
service identified by brand, trade, or corporate name. Also, do not 
directly or indirectly condition your warranty on a requirement that 
the engine be serviced by your franchised dealers or any other service 
establishments with which you have a commercial relationship. You may 
disregard the requirements in this paragraph (f) if you do one of two 
things:
    (1) Provide a component or service without charge under the 
purchase agreement.
    (2) Get us to waive this prohibition in the public's interest by 
convincing us the engine will work properly only with the identified 
component or service.
    (g) Payment for scheduled maintenance. Owners are responsible for 
properly maintaining their engines, which generally includes paying for 
scheduled maintenance. However, you may commit to paying for scheduled 
maintenance as described in paragraph (a)(1)(iv) of this section to 
demonstrate that the maintenance will occur. You may also schedule 
maintenance not otherwise allowed by paragraph (a)(2) of this section 
if you pay for it. You must pay for scheduled maintenance on any 
component during the useful life if it meets all the following 
conditions:
    (1) Each affected component was not in general use on similar 
engines before 1980.
    (2) The primary function of each affected component is to reduce 
emissions.
    (3) The cost of the scheduled maintenance is more than 2 percent of 
the price of the engine.
    (4) Failure to perform the maintenance would not cause clear 
problems that would significantly degrade the engine's performance.
    (h) Owners manual. Include the following information in the owners 
manual to clarify maintenance instructions and the owner's 
responsibilities:
    (1) Clearly describe the scheduled maintenance steps, consistent 
with the provisions of this section, using nontechnical language as 
much as possible. Include a list of components for which you will cover 
scheduled replacement costs.
    (2) Identify steps owners must take to qualify their engines as 
properly maintained, consistent with the requirements of this section. 
Also identify types of engine operation that would not qualify their 
engines as being properly used. Describe what documentation you 
consider appropriate for making these demonstrations. Note that you may 
identify failure to repair critical emission-related components as 
improper maintenance if the repairs are related to an observed defect.
    (3) Describe how the owner can access the OBD system to 
troubleshoot problems and find emission-related diagnostic information 
and codes stored in onboard monitoring systems as described in Sec.  
1036.110(b) and (c). For example, the instructions should identify the 
communication protocol and any other information the owner would need 
to read and understand stored codes.
    (4) Include a general description of how the emission control 
systems operate.
    (5) Include one or more diagrams of the engine and its emission-
related components with the following information:
    (i) The flow path for intake air and exhaust gas.
    (ii) The flow path of evaporative and refueling emissions for 
spark-ignition engines, and DEF for compression-ignition engines, as 
applicable.
    (iii) The flow path of engine coolant if it is part of the emission 
control system described in the application for certification.
    (iv) The identity, location, and arrangement of relevant sensors, 
wiring, and other emission-related components in the diagram. 
Terminology to identify components must be consistent with codes you 
use for the OBD system.
    (v) Expected pressures at the particulate filter and exhaust 
temperatures throughout the aftertreatment system.
    (6) Include exploded-view drawings to allow the owner to identify 
the part numbers and basic assembly requirements for turbochargers, 
aftercoolers, and all components required for proper functioning of EGR 
and aftertreatment devices. Include enough detail to allow a mechanic 
to replace any of those components.
    (7) Include basic wiring diagrams for aftertreatment-related 
components. Include enough detail to allow a mechanic to detect 
improper functioning of those components.
    (8) Include the following statement: ``Technical service bulletins 
and other information for your engine may be available at 
www.nhtsa.gov/recalls.''
    (9) Include a troubleshooting guide to address warning signals 
related to DEF dosing and particulate filter regeneration that would be 
displayed in the cab or in a generic scan tool. The troubleshooting 
guide must describe the fault condition, the potential causes, the 
remedy, and the consequence of continuing to operate without remedy, 
this would include a list of all codes that cause derate or inducement 
(e.g., list SPN/FMI combinations) and associated operating restrictions 
(e.g., percent torque derate).
    (10) Note that Sec.  1036.135(c)(10) requires the owners manual for 
an engine to be accessible electronically from a QR Code on the 
emission control information label.
    (11) Include the following information for engines with particulate 
filters:
    (i) Instructions on removing the particulate filter for cleaning.
    (ii) Criteria for establishing that a particulate filter has been 
cleaned, including maximum clean filter weight and pressure drop across 
the filter. We recommend that you also specify a pre-installation 
filter weight to represent a like-new configuration.
    (iii) A statement that particulate filter inlet and outlet 
pressures are available with a generic scan tool.
    (iv) Suggested maintenance practices to prevent damage to 
particulate filters.


Sec.  1036.130  Installation instructions for vehicle manufacturers.

    (a) If you sell an engine for someone else to install in a vehicle, 
give the engine installer instructions for installing it consistent 
with the requirements of this part. Include all

[[Page 17672]]

information necessary to ensure that an engine will be installed in its 
certified configuration.
    (b) Make sure these instructions have the following information:
    (1) Include the heading: ``Emission-related installation 
instructions''.
    (2) State: ``Failing to follow these instructions when installing a 
certified engine in a heavy-duty motor vehicle violates federal law, 
subject to fines or other penalties as described in the Clean Air 
Act.''
    (3) Provide all instructions needed to properly install the exhaust 
system and any other components.
    (4) Describe any necessary steps for installing any diagnostic 
system required under Sec.  1036.110.
    (5) Describe how your certification is limited for any type of 
application. For example, if you certify Heavy HDE to the CO2 standards 
using only transient FTP testing, you must make clear that the engine 
may not be installed in tractors.
    (6) Describe any other instructions to make sure the installed 
engine will operate according to design specifications in your 
application for certification. This may include, for example, 
instructions for installing aftertreatment devices when installing the 
engines.
    (7) Give the following instructions if you do not ship diesel 
exhaust fluid tanks with your engines:
    (i) Specify that vehicle manufacturers must install diesel exhaust 
fluid tanks meeting the specifications of Sec.  1036.115(i).
    (ii) Describe how vehicle manufacturers must install diesel exhaust 
fluid tanks with sensors as needed to meet the requirements of 
Sec. Sec.  1036.110 and 1036.111.
    (8) State: ``If you install the engine in a way that makes the 
engine's emission control information label hard to read during normal 
engine maintenance, you must place a duplicate label on the vehicle, as 
described in 40 CFR 1068.105.''
    (c) Give the vehicle manufacturer fuel map results as described in 
Sec.  1036.503(b).
    (d) You do not need installation instructions for engines that you 
install in your own vehicles.
    (e) Provide instructions in writing or in an equivalent format. For 
example, you may post instructions on a publicly available website for 
downloading or printing. If you do not provide the instructions in 
writing, explain in your application for certification how you will 
ensure that each installer is informed of the installation 
requirements.


Sec.  1036.135  Labeling.

    (a) Assign each engine a unique identification number and 
permanently affix, engrave, or stamp it on the engine in a legible way.
    (b) At the time of manufacture, affix a permanent and legible label 
identifying each engine. The label must meet the requirements of 40 CFR 
1068.45.
    (c) The label must--
    (1) Include the heading ``EMISSION CONTROL INFORMATION''.
    (2) Include your full corporate name and trademark. You may 
identify another company and use its trademark instead of yours if you 
comply with the branding provisions of 40 CFR 1068.45.
    (3) Include EPA's standardized designation for the engine family.
    (4) Identify the primary intended service class.
    (5) State the engine's displacement (in liters); however, you may 
omit this from the label if all the engines in the engine family have 
the same per-cylinder displacement and total displacement.
    (6) State the date of manufacture [DAY (optional), MONTH, and 
YEAR]; however, you may omit this from the label if you stamp, engrave, 
or otherwise permanently identify it elsewhere on the engine, in which 
case you must also describe in your application for certification where 
you will identify the date on the engine.
    (7) State the FEL(s) to which the engines are certified if 
certification depends on the ABT provision of subpart H of this part.
    (8) State: ``THIS ENGINE COMPLIES WITH U.S. EPA REGULATIONS FOR 
[MODEL YEAR] HEAVY-DUTY HIGHWAY ENGINES.''
    (9) Identify any limitations on your certification. For example, if 
you certify Heavy HDE to the CO2 standards using only 
steady-state testing, include the statement ``TRACTORS ONLY''. 
Similarly, for engines with one or more approved AECDs for emergency 
vehicle applications under Sec.  1036.115(h)(4), the statement: ``THIS 
ENGINE IS FOR INSTALLATION IN EMERGENCY VEHICLES ONLY''.
    (10) Include a field on the label to allow for accessing 
interactive information with mobile electronic devices. To do this, 
include an image of a QR code that will direct mobile electronic 
devices to a public Web site that you maintain. Generate the QR code as 
specified in ISO/IEC 18004 (incorporated by reference in Sec.  
1036.810). To the left of the QR code, include the vertically oriented 
caption ``Smartphone QR CodeTM''. The website associated with the QR 
code for a given engine must include a link to a public copy of the 
owners manual and the following information for that engine:
    (i) Include EPA's standardized designation for the engine family. 
This may include multiple engine families in a given model year and it 
may include multiple model years for those families as long as the 
appropriate information is available for each engine.
    (ii) Identify the emission control system. Use terms and 
abbreviations as described in 40 CFR 1068.45.
    (iii) Identify any requirements for fuel and lubricants that do not 
involve fuel-sulfur levels.
    (d) You may add information to the emission control information 
label as follows:
    (1) You may identify other emission standards that the engine meets 
or does not meet. You may add the information about the other emission 
standards to the statement we specify, or you may include it in a 
separate statement.
    (2) You may add other information to ensure that the engine will be 
properly maintained and used.
    (3) You may add appropriate features to prevent counterfeit labels. 
For example, you may include the engine's unique identification number 
on the label.
    (e) You may ask us to approve modified labeling requirements in 
this part if you show that it is necessary or appropriate. We will 
approve your request if your alternate label is consistent with the 
requirements of this part. We may also specify modified labeling 
requirements to be consistent with the intent of 40 CFR part 1037.
    (f) If you obscure the engine label while installing the engine in 
the vehicle such that the label cannot be read during normal 
maintenance, you must place a duplicate label on the vehicle. If others 
install your engine in their vehicles in a way that obscures the engine 
label, we require them to add a duplicate label on the vehicle (see 40 
CFR 1068.105); in that case, give them the number of duplicate labels 
they request and keep the following records for at least five years:
    (1) Written documentation of the request from the vehicle 
manufacturer.
    (2) The number of duplicate labels you send for each engine family 
and the date you sent them.


Sec.  1036.140  Primary intended service class and engine cycle.

    You must identify a single primary intended service class for each 
engine family that best describes vehicles for which you design and 
market the engine, as follows:
    (a) Divide compression-ignition engines into primary intended 
service

[[Page 17673]]

classes based on the following engine and vehicle characteristics:
    (1) Light HDE includes engines that are not designed for rebuild 
and do not have cylinder liners. Vehicle body types in this group might 
include any heavy-duty vehicle built from a light-duty truck chassis, 
van trucks, multi-stop vans, and some straight trucks with a single 
rear axle. Typical applications would include personal transportation, 
light-load commercial delivery, passenger service, agriculture, and 
construction. The GVWR of these vehicles is normally at or below 19,500 
pounds.
    (2) Medium HDE includes engines that may be designed for rebuild 
and may have cylinder liners. Vehicle body types in this group would 
typically include school buses, straight trucks with single rear axles, 
city tractors, and a variety of special purpose vehicles such as small 
dump trucks, and refuse trucks. Typical applications would include 
commercial short haul and intra-city delivery and pickup. Engines in 
this group are normally used in vehicles whose GVWR ranges from 19,501 
to 33,000 pounds.
    (3) Heavy HDE includes engines that are designed for multiple 
rebuilds and have cylinder liners. Vehicles in this group are normally 
tractors, trucks, straight trucks with dual rear axles, and buses used 
in inter-city, long-haul applications. These vehicles normally exceed 
33,000 pounds GVWR.
    (b) Divide spark-ignition engines into primary intended service 
classes as follows:
    (1) Spark-ignition engines that are best characterized by paragraph 
(a)(1) or (2) of this section are in a separate Spark-ignition HDE 
primary intended service class.
    (2) Spark-ignition engines that are best characterized by paragraph 
(a)(3) of this section are included in the Heavy HDE primary intended 
service class along with compression-ignition engines. Gasoline-fueled 
engines are presumed not to be characterized by paragraph (a)(3) of 
this section; for example, vehicle manufacturers may install some 
number of gasoline-fueled engines in Class 8 trucks without causing the 
engine manufacturer to consider those to be Heavy HDE.
    (c) References to ``spark-ignition standards'' in this part relate 
only to the spark-ignition engines identified in paragraph (b)(1) of 
this section. References to ``compression-ignition standards'' in this 
part relate to compression-ignition engines, to spark-ignition engines 
optionally certified to standards that apply to compression-ignition 
engines, and to all engines identified under paragraph (b)(2) of this 
section as Heavy HDE.


Sec.  1036.150  Interim provisions.

    The provisions in this section apply instead of other provisions in 
this part. This section describes when these interim provisions expire, 
if applicable.
    (a) Transitional and early credits for NOX emissions. You may 
generate and use transitional and early credits for NOX 
emissions according to Sec.  1036.104(c) and subpart H of this part 
subject to the following provisions:
    (1) Transitional credits. Model year 2024 through 2026 engines may 
generate transitional credits that can be used to certify model year 
2027 and later engines as follows:
    (i) Calculate transitional credits as described in Sec.  
1036.705(b) relative to the NOX emission standard for FTP 
testing in 40 CFR 86.007-11 or 86.008-10 using the useful life mileages 
of 40 CFR 86.004-2.
    (ii) Engines must also comply with NOX family emission 
limits for each duty-cycle standard other than the FTP duty cycle in 
Sec.  1036.104(a) using the test procedures in subpart F of this part. 
Calculate these NOX family emission limits, 
FEL[cycle]NOX, using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.018

    (iii) The family emission limits in this paragraph (a)(1) serve as 
the emission standards to determine compliance for all testing instead 
of the standards specified in 40 CFR 86.007-11 or 86.008-10.
    (iv) Record PM, HC, and CO emission levels during all testing. 
Demonstrate that you comply with applicable PM, HC, and CO emission 
standards in 40 CFR 86.007-11 or 86.008-10.
    (2) Early credits. Model year 2024 and later engines may generate 
early credits under this paragraph (a)(2) only if they

[[Page 17674]]

comply with all the requirements that apply under this part for the 
model year to which you are certifying. Calculate early credits as 
described in Sec.  1036.705(b) with the following adjustments and 
clarifications:
    (i) Calculate early credits for all model year 2030 and earlier 
engines relative to the NOX standard for FTP testing in 40 
CFR 86.007-11 or 86.008-10 or Sec.  1036.104 that applies for an engine 
family's model year.
    (ii) Replace the FL term in Eq. 1036.705-1 with:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.019
    
    (3) Limitations on using banked emission credits in model years 
2027 and later. You must use one of the methods described in paragraphs 
(a)(1) and (2) of this section for using NOX emission 
credits generated by model year 2026 and earlier engines when 
certifying model year 2027 and later engines. Similarly, you must use 
the method described in paragraph (a)(2) of this section for using 
NOX emission credits generated by model year 2027 through 
2030 engines when certifying model year 2031 and later engines.
    (b) Model year 2014 N2O standards. In model year 2014 and earlier, 
manufacturers may show compliance with the N2O standards using an 
engineering analysis. This allowance also applies for later families 
certified using carryover CO2 data from model 2014 consistent with 
Sec.  1036.235(d).
    (c) Engine cycle classification. Through model year 2020, engines 
meeting the definition of spark-ignition, but regulated as compression-
ignition engines under Sec.  1036.140, must be certified to the 
requirements applicable to compression-ignition engines under this 
part. Such engines are deemed to be compression-ignition engines for 
purposes of this part. Similarly, through model year 2020, engines 
meeting the definition of compression-ignition, but regulated as Otto-
cycle under 40 CFR part 86 must be certified to the requirements 
applicable to spark-ignition engines under this part. Such engines are 
deemed to be spark-ignition engines for purposes of this part. See 
Sec.  1036.140 for provisions that apply for model year 2021 and later.
    (d) Small manufacturers. The greenhouse gas standards of this part 
apply on a delayed schedule for manufacturers meeting the small 
business criteria specified in 13 CFR 121.201. Apply the small business 
criteria for NAICS code 336310 for engine manufacturers with respect to 
gasoline-fueled engines and 333618 for engine manufacturers with 
respect to other engines; the employee limits apply to the total number 
employees together for affiliated companies. Qualifying small 
manufacturers are not subject to the greenhouse gas emission standards 
in Sec.  1036.108 for engines with a date of manufacture on or after 
November 14, 2011 but before January 1, 2022. In addition, qualifying 
small manufacturers producing engines that run on any fuel other than 
gasoline, E85, or diesel fuel may delay complying with every later 
standard under this part by one model year. Small manufacturers may 
certify their engines and generate emission credits under this part 
before standards start to apply, but only if they certify their entire 
U.S.-directed production volume within that averaging set for that 
model year. Note that engines not yet subject to standards must 
nevertheless supply fuel maps to vehicle manufacturers as described in 
paragraph (n) of this section. Note also that engines produced by small 
manufacturers are subject to criteria pollutant standards.
    (e) Alternate phase-in standards for greenhouse gas emissions. 
Where a manufacturer certifies all of its model year 2013 compression-
ignition engines within a given primary intended service class to the 
applicable alternate standards of this paragraph (e), its compression-
ignition engines within that primary intended service class are subject 
to the standards of this paragraph (e) for model years 2013 through 
2016. This means that once a manufacturer chooses to certify a primary 
intended service class to the standards of this paragraph (e), it is 
not allowed to opt out of these standards.

[[Page 17675]]



                    Table 1 to Paragraph (e) of Sec.   1036.150--Alternate Phase-In Standards
----------------------------------------------------------------------------------------------------------------
          Vehicle type                Model years         LHD engines         MHD engines         HHD engines
----------------------------------------------------------------------------------------------------------------
Tractors........................  2013-2015.........  NA................  512 g/hp[middot]hr  485 g/
                                                                                               hp[middot]hr.
2016 and later a................  NA................  487 g/hp[middot]hr  460 g/
                                                                           hp[middot]hr..
Vocational......................  2013-2015.........  618 g/hp[middot]hr  618 g/hp[middot]hr  577 g/
                                                                                               hp[middot]hr.
                                  2016 through 2020   576 g/hp[middot]hr  576 g/hp[middot]hr  555 g/
                                   \a\.                                                        hp[middot]hr.
----------------------------------------------------------------------------------------------------------------
 \a\Note: These alternate standards for 2016 and later are the same as the otherwise applicable standards for
  2017 through 2020.

    (f) [Reserved]
    (g) Default deterioration factors for greenhouse gas standards. You 
may use default deterioration factors (DFs) without performing your own 
durability emission tests or engineering analysis as follows:
    (1) You may use a default additive DF of 0.0 g/hp[middot]hr for 
CO2 emissions from engines that do not use advanced or off-
cycle technologies. If we determine it to be consistent with good 
engineering judgment, we may allow you to use a default additive DF of 
0.0 g/hp[middot]hr for CO2 emissions from your engines with 
advanced or off-cycle technologies.
    (2) You may use a default additive DF of 0.010 g/hp[middot]hr for 
N2O emissions from any engine through model year 2021, and 
0.020 g/hp-hr for later model years.
    (3) You may use a default additive DF of 0.020 g/hp[middot]hr for 
CH4 emissions from any engine.
    (h) Advanced-technology credits. If you generate CO2 
credits from model year 2020 and earlier engines certified for advanced 
technology, you may multiply these credits by 1.5.
    (i) CO2 credits for low N2O emissions. If you certify your model 
year 2014, 2015, or 2016 engines to an N2O FEL less than 
0.04 g/hp[middot]hr (provided you measure N2O emissions from 
your emission-data engines), you may generate additional CO2 
credits under this paragraph (i). Calculate the additional 
CO2 credits from the following equation instead of the 
equation in Sec.  1036.705:
[GRAPHIC] [TIFF OMITTED] TP28MR22.020

    (j) Alternate standards under 40 CFR part 86. This paragraph (j) 
describes alternate emission standards for loose engines certified 
under 40 CFR 86.1819-14(k)(8). The standards of Sec.  1036.108 do not 
apply for these engines. The standards in this paragraph (j) apply for 
emissions measured with the engine installed in a complete vehicle 
consistent with the provisions of 40 CFR 86.1819-14(k)(8)(vi). The only 
requirements of this part that apply to these engines are those in this 
paragraph (j), Sec. Sec.  1036.115 through 1036.135, 1036.535, and 
1036.540.
    (k) [Reserved]
    (l) Credit adjustment for spark-ignition engines and light heavy-
duty compression-ignition engines. For greenhouse gas emission credits 
generated from model year 2020 and earlier spark-ignition and light 
heavy-duty engines, multiply any banked CO2 credits that you 
carry forward to demonstrate compliance with model year 2021 and later 
standards by 1.36.
    (m) Infrequent regeneration. For model year 2020 and earlier, you 
may invalidate any test interval with respect to CO2 
measurements if an infrequent regeneration event occurs during the test 
interval. Note that Sec.  1036.522 specifies how to apply infrequent 
regeneration adjustment factors for later model years.
    (n) Supplying fuel maps. Engine manufacturers not yet subject to 
standards under Sec.  1036.108 in model year 2021 must supply vehicle 
manufacturers with fuel maps (or powertrain test results) as described 
in Sec.  1036.130 for those engines.
    (o) Engines used in glider vehicles. For purposes of recertifying a 
used engine for installation in a glider vehicle, we may allow you to 
include in an existing certified engine family those engines you modify 
(or otherwise demonstrate) to be identical to engines already covered 
by the certificate. We would base such an approval on our review of any 
appropriate documentation. These engines must have emission control 
information labels that accurately describe their status.
    (p) Transition to Phase 2 CO2 standards. If you certify all your 
model year 2020 engines within an averaging set to the model year 2021 
FTP and SET standards and requirements, you may apply the provisions of 
this paragraph (p) for enhanced generation and use of emission credits. 
These provisions apply separately for Medium HDE and Heavy HDE.
    (1) Greenhouse gas emission credits you generate with model year 
2018 through 2024 engines may be used through model year 2030, instead 
of being limited to a five-year credit life as specified in Sec.  
1036.740(d).
    (2) You may certify your model year 2024 through 2026 engines to 
the following alternative standards:

     Table 2 to Paragraph (p)(2) of Sec.   1036.150--Alternative Standards for Model Years 2024 Through 2026
----------------------------------------------------------------------------------------------------------------
                                               Medium heavy-     Heavy heavy-    Medium heavy-     Heavy heavy-
                 Model years                  duty-vocational  duty-vocational    duty-tractor     duty-tractor
----------------------------------------------------------------------------------------------------------------
2024-2026...................................             542              510              467              442
----------------------------------------------------------------------------------------------------------------

    (q) Confirmatory testing of fuel maps defined in Sec.  1036.503(b). 
For model years 2021 and later, where the results from Eq. 1036.235-1 
for a confirmatory test are at or below 2.0%, we will not replace the 
manufacturer's fuel maps.
    (r) [Reserved]
    (s) Greenhouse gas compliance testing. Select duty cycles and 
measure

[[Page 17676]]

emissions to demonstrate compliance with greenhouse gas emission 
standards before model year 2027 as follows:
    (1) For model years 2016 through 2020, measure emissions using the 
FTP duty cycle specified in Sec.  1036.510 and SET duty cycle specified 
in 40 CFR 86.1362, as applicable.
    (2) The following provisions apply for model years 2021 through 
2026:
    (i) Determine criteria pollutant emissions during any testing used 
to demonstrate compliance with greenhouse gas emission standards; 
however, the duty-cycle standards of Sec.  1036.104 apply for measured 
criteria pollutant emissions only as described in subpart F of this 
part.
    (ii) You may demonstrate compliance with SET-based greenhouse gas 
emission standards in Sec.  1036.108(a)(1) using the SET duty cycle 
specified in 40 CFR 86.1362 if you collect emissions with continuous 
sampling. Integrate the test results by mode to establish separate 
emission rates for each mode (including the transition following each 
mode, as applicable). Apply the CO2 weighting factors specified in 40 
CFR 86.1362 to calculate a composite emission result.
    (t) [Reserved]
    (u) Crankcase emissions. Through model year 2026, compression-
ignition engines may discharge crankcase emissions to the ambient 
atmosphere if the emissions are added to the exhaust emissions (either 
physically or mathematically) during all emission testing. If you take 
advantage of this exception, you must do the following things:
    (1) Manufacture the engines so that all crankcase emissions can be 
routed into the applicable sampling systems specified in 40 CFR part 
1065.
    (2) Account for deterioration in crankcase emissions when 
determining exhaust deterioration factors.
    (v) OBD communication protocol. For model year 2026 and earlier 
engines, we may approve the alternative communication protocol 
specified in SAE J1979-2 (incorporated by reference in Sec.  1036.810) 
if the protocol is approved by the California Air Resources Board. The 
alternative protocol would apply instead of SAE J1939 and SAE J1979 as 
specified in 40 CFR 86.010-18(k)(1).
    (w) Greenhouse gas warranty. For model year 2027 and later engines, 
you may ask us to approve the model year 2026 warranty periods 
specified in Sec.  1036.120 for components or systems needed to comply 
with greenhouse gas emission standards if those components or systems 
do not play a role in complying with criteria pollutant standards.
    (x) Schedule for migrating provisions from 40 CFR part 86. This 
part included provisions that applied uniquely for complying with 
greenhouse gas standards before [the effective date of the final rule]. 
The following provisions apply through model year 2026:
    (1) Subpart F of this part applies except as specified in this 
section; otherwise, you may continue to comply with the earlier version 
of the provisions of this part if those provisions are modified to 
apply for complying with both criteria pollutant standards and 
greenhouse gas standards.
    (2) Engines exempted from the applicable standards of 40 CFR part 
86 under the provisions of 40 CFR part 1068 are exempt from the 
standards of this part without request.
    (y) Powertrain testing for criteria pollutants. You may apply the 
powertrain testing provisions of Sec.  1036.101(b) for demonstrating 
compliance with criteria pollutant emission standards in 40 CFR part 86 
before model year 2027.

Subpart C--Certifying Engine Families


Sec.  1036.201  General requirements for obtaining a certificate of 
conformity.

    (a) You must send us a separate application for a certificate of 
conformity for each engine family. A certificate of conformity is valid 
from the indicated effective date until December 31 of the model year 
for which it is issued.
    (b) The application must contain all the information required by 
this part and must not include false or incomplete statements or 
information (see Sec.  1036.255).
    (c) We may ask you to include less information than we specify in 
this subpart, as long as you maintain all the information required by 
Sec.  1036.250.
    (d) You must use good engineering judgment for all decisions 
related to your application (see 40 CFR 1068.5).
    (e) An authorized representative of your company must approve and 
sign the application.
    (f) See Sec.  1036.255 for provisions describing how we will 
process your application.
    (g) We may require you to deliver your test engines to a facility 
we designate for our testing (see Sec.  1036.235(c)). Alternatively, 
you may choose to deliver another engine that is identical in all 
material respects to the test engine, or another engine that we 
determine can appropriately serve as an emission-data engine for the 
engine family.
    (h) For engines that become new after being placed into service, 
such as rebuilt engines installed in new vehicles, we may specify 
alternate certification provisions consistent with the intent of this 
part. See 40 CFR 1068.120(h) and the definition of ``new motor vehicle 
engine'' in Sec.  1036.801.


Sec.  1036.205  Requirements for an application for certification.

    This section specifies the information that must be in your 
application, unless we ask you to include less information under Sec.  
1036.201(c). We may require you to provide additional information to 
evaluate your application.
    (a) Identify the engine family's primary intended service class and 
describe the engine family's specifications and other basic parameters 
of the engine's design and emission controls with respect to compliance 
with the requirements of this part. List the fuel type on which your 
engines are designed to operate (for example, gasoline, diesel fuel, or 
natural gas). For engines that can operate on multiple fuels, identify 
whether they are dual-fuel or flexible-fuel engines; also identify the 
range of mixtures for operation on blended fuels, if applicable. List 
each distinguishable engine configuration in the engine family. List 
the rated power for each engine configuration.
    (b) Explain how the emission control system operates. Describe in 
detail all system components for controlling greenhouse gas and 
criteria pollutant emissions, including all auxiliary emission control 
devices (AECDs) and all fuel-system components you will install on any 
production or test engine. Identify the part number of each component 
you describe. For this paragraph (b), treat as separate AECDs any 
devices that modulate or activate differently from each other. Include 
all the following:
    (1) Give a general overview of the engine, the emission control 
strategies, and all AECDs.
    (2) Describe each AECD's general purpose and function.
    (3) Identify the parameters that each AECD senses (including 
measuring, estimating, calculating, or empirically deriving the 
values). Include engine-based parameters and state whether you simulate 
them during testing with the applicable procedures.
    (4) Describe the purpose for sensing each parameter.
    (5) Identify the location of each sensor the AECD uses.
    (6) Identify the threshold values for the sensed parameters that 
activate the AECD.

[[Page 17677]]

    (7) Describe the parameters that the AECD modulates (controls) in 
response to any sensed parameters, including the range of modulation 
for each parameter, the relationship between the sensed parameters and 
the controlled parameters and how the modulation achieves the AECD's 
stated purpose. Use graphs and tables, as necessary.
    (8) Describe each AECD's specific calibration details. This may be 
in the form of data tables, graphical representations, or some other 
description.
    (9) Describe the hierarchy among the AECDs when multiple AECDs 
sense or modulate the same parameter. Describe whether the strategies 
interact in a comparative or additive manner and identify which AECD 
takes precedence in responding, if applicable.
    (10) Explain the extent to which the AECD is included in the 
applicable test procedures specified in subpart F of this part.
    (11) Do the following additional things for AECDs designed to 
protect engines or vehicles:
    (i) Identify any engine and vehicle design limits that make 
protection necessary and describe any damage that would occur without 
the AECD.
    (ii) Describe how each sensed parameter relates to the protected 
components' design limits or those operating conditions that cause the 
need for protection.
    (iii) Describe the relationship between the design limits/
parameters being protected and the parameters sensed or calculated as 
surrogates for those design limits/parameters, if applicable.
    (iv) Describe how the modulation by the AECD prevents engines and 
vehicles from exceeding design limits.
    (v) Explain why it is necessary to estimate any parameters instead 
of measuring them directly and describe how the AECD calculates the 
estimated value, if applicable.
    (vi) Describe how you calibrate the AECD modulation to activate 
only during conditions related to the stated need to protect components 
and only as needed to sufficiently protect those components in a way 
that minimizes the emission impact.
    (c) Explain in detail how the engine diagnostic system works, 
describing especially the engine conditions (with the corresponding 
diagnostic trouble codes) that cause the malfunction indicator to go 
on. Propose the conditions under which the diagnostic system should 
disregard trouble codes as described in Sec.  1036.110.
    (d) Describe the engines you selected for testing and the reasons 
for selecting them.
    (e) Describe any test equipment and procedures that you used, 
including any special or alternate test procedures you used (see Sec.  
1036.501).
    (f) Describe how you operated the emission-data engine before 
testing, including the duty cycle and the number of engine operating 
hours used to stabilize emission levels. Explain why you selected the 
method of service accumulation. Describe any scheduled maintenance you 
did.
    (g) List the specifications of the test fuel to show that it falls 
within the required ranges we specify in 40 CFR part 1065.
    (h) Identify the engine family's useful life.
    (i) Include the maintenance instructions and warranty statement you 
will give to the ultimate purchaser of each new engine (see Sec. Sec.  
1036.120 and 1036.125).
    (j) Include the emission-related installation instructions you will 
provide if someone else installs your engines in their vehicles (see 
Sec.  1036.130).
    (k) Describe your emission control information label (see Sec.  
1036.135). We may require you to include a copy of the label.
    (l) Identify the duty-cycle emission standards from Sec. Sec.  
1036.104(a) and (b) and 1036.108(a) that apply for the engine family. 
Also identify FELs and FCLs as follows:
    (1) Identify the NOX FEL over the FTP for the engine 
family.
    (2) Identify the CO2 FCLs for the engine family; also 
identify any FELs that apply for CH4 and N2O. The 
actual U.S.-directed production volume of configurations that have 
CO2 emission rates at or below the FCL and CH4 
and N2O emission rates at or below the applicable standards 
or FELs must be at least one percent of your actual (not projected) 
U.S.-directed production volume for the engine family. Identify 
configurations within the family that have emission rates at or below 
the FCL and meet the one percent requirement. For example, if your 
U.S.-directed production volume for the engine family is 10,583 and the 
U.S.-directed production volume for the tested rating is 75 engines, 
then you can comply with this provision by setting your FCL so that one 
more rating with a U.S.-directed production volume of at least 31 
engines meets the FCL. Where applicable, also identify other testable 
configurations required under Sec.  1036.230(f)(2)(ii).
    (m) Identify the engine family's deterioration factors and describe 
how you developed them (see Sec. Sec.  1036.240 and 1036.241). Present 
any test data you used for this.
    (n) State that you operated your emission-data engines as described 
in the application (including the test procedures, test parameters, and 
test fuels) to show you meet the requirements of this part.
    (o) Present emission data from all valid tests on an emission-data 
engine to show that you meet emission standards. Note that Sec.  
1036.235 allows you to submit an application in certain cases without 
new emission data. Present emission data as follows:
    (1) For hydrocarbons (such as NMHC or NMHCE), NOX, PM, 
and CO, as applicable, show your engines meet the applicable exhaust 
emission standards we specify in Sec.  1036.104. Show emission figures 
for duty-cycle exhaust emission standards before and after applying 
adjustment factors for regeneration and deterioration factors for each 
engine.
    (2) For CO2, CH4, and NO2, show 
that your engines meet the applicable emission standards we specify in 
Sec.  1036.108. Show emission figures before and after applying 
deterioration factors for each engine. In addition to the composite 
results, show individual measurements for cold-start testing and hot-
start testing over the transient test cycle. For each of these tests, 
also include the corresponding exhaust emission data for criteria 
emissions.
    (3) If we specify more than one grade of any fuel type (for 
example, a summer grade and winter grade of gasoline), you need to 
submit test data only for one grade, unless the regulations of this 
part specify otherwise for your engine.
    (p) State that all the engines in the engine family comply with the 
off-cycle emission standards we specify in Sec.  1036.104 for all 
normal operation and use when tested as specified in Sec.  1036.515. 
Describe any relevant testing, engineering analysis, or other 
information in sufficient detail to support your statement.
    (q) We may ask you to send information to confirm that the emission 
data you submitted were from valid tests meeting the requirements of 
this part and 40 CFR part 1065. You must indicate whether there are 
test results from invalid tests or from any other tests of the 
emission-data engine, whether or not they were conducted according to 
the test procedures of subpart F of this part. We may require you to 
report these additional test results.
    (r) Describe all adjustable operating parameters (see Sec.  
1036.115(f)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a

[[Page 17678]]

description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
    (s) Provide the information to read, record, and interpret all the 
information broadcast by an engine's onboard computers and ECMs as 
described in Sec.  1036.115(d). State that, upon request, you will give 
us any hardware, software, or tools we would need to do this.
    (t) Confirm that your emission-related installation instructions 
specify how to ensure that sampling of exhaust emissions will be 
possible after engines are installed in equipment and placed in 
service. If this cannot be done by simply adding a 20-centimeter 
extension to the exhaust pipe, show how to sample exhaust emissions in 
a way that prevents diluting the exhaust sample with ambient air.
    (u) State whether your certification is limited for certain 
engines. For example, you might certify engines only for use in 
tractors, in emergency vehicles, or in vehicles with hybrid 
powertrains. If this is the case, describe how you will prevent use of 
these engines in vehicles for which they are not certified.
    (v) Unconditionally certify that all the engines in the engine 
family comply with the requirements of this part, other referenced 
parts of the CFR, and the Clean Air Act. Note that Sec.  1036.235 
specifies which engines to test to show that engines in the entire 
family comply with the requirements of this part.
    (w) Include good-faith estimates of U.S.-directed production 
volumes. Include a justification for the estimated production volumes 
if they are substantially different than actual production volumes in 
earlier years for similar models.
    (x) Include the information required by other subparts of this 
part. For example, include the information required by Sec.  1036.725 
if you participate in the ABT program.
    (y) Include other applicable information, such as information 
specified in this part or 40 CFR part 1068 related to requests for 
exemptions.
    (z) Name an agent for service located in the United States. Service 
on this agent constitutes service on you or any of your officers or 
employees for any action by EPA or otherwise by the United States 
related to the requirements of this part.
    (aa) For imported engines, identify the following:
    (1) Describe your normal practice for importing engines. For 
example, this may include identifying the names and addresses of any 
agents you have authorized to import your engines. Engines imported by 
nonauthorized agents are not covered by your certificate.
    (2) The location of a test facility in the United States where you 
can test your engines if we select them for testing under a selective 
enforcement audit, as specified in 40 CFR part 1068, subpart E.
    (bb) Include information needed to certify vehicles to greenhouse 
gas standards under 40 CFR part 1037 as described in Sec.  1036.503.


Sec.  1036.210  Preliminary approval before certification.

    If you send us information before you finish the application, we 
may review it and make any appropriate determinations, especially for 
questions related to engine family definitions, auxiliary emission 
control devices, adjustable parameters, deterioration factors, testing 
for service accumulation, and maintenance. Decisions made under this 
section are considered to be preliminary approval, subject to final 
review and approval. We will generally not reverse a decision where we 
have given you preliminary approval, unless we find new information 
supporting a different decision. If you request preliminary approval 
related to the upcoming model year or the model year after that, we 
will make best-efforts to make the appropriate determinations as soon 
as practicable. We will generally not provide preliminary approval 
related to a future model year more than two years ahead of time.


Sec.  1036.225  Amending applications for certification.

    Before we issue you a certificate of conformity, you may amend your 
application to include new or modified engine configurations, subject 
to the provisions of this section. After we have issued your 
certificate of conformity, you may send us an amended application any 
time before the end of the model year requesting that we include new or 
modified engine configurations within the scope of the certificate, 
subject to the provisions of this section. You must also amend your 
application if any changes occur with respect to any information that 
is included or should be included in your application.
    (a) You must amend your application before you take any of the 
following actions:
    (1) Add an engine configuration to an engine family. In this case, 
the engine configuration added must be consistent with other engine 
configurations in the engine family with respect to the design aspects 
listed in Sec.  1036.230.
    (2) Change an engine configuration already included in an engine 
family in a way that may affect emissions, or change any of the 
components you described in your application for certification. This 
includes production and design changes that may affect emissions any 
time during the engine's lifetime.
    (3) Modify an FEL or FCL for an engine family as described in 
paragraph (f) of this section.
    (b) To amend your application for certification, send the relevant 
information to the Designated Compliance Officer.
    (1) Describe in detail the addition or change in the engine model 
or configuration you intend to make.
    (2) Include engineering evaluations or data showing that the 
amended engine family complies with all applicable requirements. You 
may do this by showing that the original emission-data engine is still 
appropriate for showing that the amended family complies with all 
applicable requirements.
    (3) If the original emission-data engine for the engine family is 
not appropriate to show compliance for the new or modified engine 
configuration, include new test data showing that the new or modified 
engine configuration meets the requirements of this part.
    (4) Include any other information needed to make your application 
correct and complete.
    (c) We may ask for more test data or engineering evaluations. You 
must give us these within 30 days after we request them.
    (d) For engine families already covered by a certificate of 
conformity, we will determine whether the existing certificate of 
conformity covers your newly added or modified engine. You may ask for 
a hearing if we deny your request (see Sec.  1036.820).
    (e) The amended application applies starting with the date you 
submit the amended application, as follows:
    (1) For engine families already covered by a certificate of 
conformity,

[[Page 17679]]

you may start producing a new or modified engine configuration any time 
after you send us your amended application and before we make a 
decision under paragraph (d) of this section. However, if we determine 
that the affected engines do not meet applicable requirements in this 
part, we will notify you to cease production of the engines and may 
require you to recall the engines at no expense to the owner. Choosing 
to produce engines under this paragraph (e) is deemed to be consent to 
recall all engines that we determine do not meet applicable emission 
standards or other requirements in this part and to remedy the 
nonconformity at no expense to the owner. If you do not provide 
information required under paragraph (c) of this section within 30 days 
after we request it, you must stop producing the new or modified 
engines.
    (2) [Reserved]
    (f) You may ask us to approve a change to your FEL in certain cases 
after the start of production, but before the end of the model year. If 
you change an FEL for CO2, your FCL for CO2 is 
automatically set to your new FEL divided by 1.03. The changed FEL may 
not apply to engines you have already introduced into U.S. commerce, 
except as described in this paragraph (f). You may ask us to approve a 
change to your FEL in the following cases:
    (1) You may ask to raise your FEL for your engine family at any 
time. In your request, you must show that you will still be able to 
meet the emission standards as specified in subparts B and H of this 
part. Use the appropriate FELs/FCLs with corresponding production 
volumes to calculate emission credits for the model year, as described 
in subpart H of this part.
    (2) You may ask to lower the FEL for your engine family only if you 
have test data from production engines showing that emissions are below 
the proposed lower FEL (or below the proposed FCL for CO2). 
The lower FEL/FCL applies only to engines you produce after we approve 
the new FEL/FCL. Use the appropriate FEL/FCL with corresponding 
production volumes to calculate emission credits for the model year, as 
described in subpart H of this part.
    (g) You may produce engines or modify in-use engines as described 
in your amended application for certification and consider those 
engines to be in a certified configuration. Modifying a new or in-use 
engine to be in a certified configuration does not violate the 
tampering prohibition of 40 CFR 1068.101(b)(1), as long as this does 
not involve changing to a certified configuration with a higher family 
emission limit.


Sec.  1036.230  Selecting engine families.

    (a) For purposes of certification to the standards of this part, 
divide your product line into families of engines that are expected to 
have similar characteristics for criteria emissions throughout the 
useful life as described in this section. Your engine family is limited 
to a single model year.
    (b) Group engines in the same engine family if they are the same in 
all the following design aspects:
    (1) The combustion cycle and fuel. See paragraph (g) of this 
section for special provisions that apply for dual-fuel and flexible-
fuel engines.
    (2) The cooling system (water-cooled vs. air-cooled).
    (3) Method of air aspiration, including the location of intake and 
exhaust valves or ports and the method of intake-air cooling, if 
applicable.
    (4) The number, location, volume, and composition of catalytic 
converters or other aftertreatment devices.
    (5) Cylinder arrangement (such as in-line vs. vee configurations), 
number of cylinders, and bore center-to-center dimensions.
    (6) Method of control for engine operation other than governing 
(i.e., mechanical or electronic).
    (7) The numerical level of the applicable criteria emission 
standards. For example, an engine family may not include engines 
certified to different family emission limits for criteria emission 
standards, though you may change family emission limits without 
recertifying as specified in Sec.  1036.225(f).
    (c) You may subdivide a group of engines that is identical under 
paragraph (b) of this section into different engine families if you 
show the expected criteria emission characteristics are different 
during the useful life.
    (d) In unusual circumstances, you may group engines that are not 
identical with respect to the design aspects listed in paragraph (b) of 
this section in the same engine family if you show that their criteria 
emission characteristics during the useful life will be similar.
    (e) Engine configurations certified as hybrid engines or hybrid 
powertrains may not be included in an engine family with engines that 
have nonhybrid powertrains. Note that this does not prevent you from 
including engines in a nonhybrid family if they are used in hybrid 
vehicles, as long as you certify them based on engine testing.
    (f) You must certify your engines to the greenhouse gas standards 
of Sec.  1036.108 using the same engine families you use for criteria 
pollutants. The following additional provisions apply with respect to 
demonstrating compliance with the standards in Sec.  1036.108:
    (1) You may subdivide an engine family into subfamilies that have a 
different FCL for CO2 emissions. These subfamilies do not 
apply for demonstrating compliance with criteria standards in Sec.  
1036.104.
    (2) If you certify engines in the family for use as both vocational 
and tractor engines, you must split your family into two separate 
subfamilies.
    (i) Calculate emission credits relative to the vocational engine 
standard for the number of engines sold into vocational applications 
and relative to the tractor engine standard for the number of engines 
sold into non-vocational tractor applications. You may assign the 
numbers and configurations of engines within the respective subfamilies 
at any time before submitting the end-of-year report required by Sec.  
1036.730. If the family participates in averaging, banking, or trading, 
you must identify the type of vehicle in which each engine is 
installed; we may alternatively allow you to use statistical methods to 
determine this for a fraction of your engines. Keep records to document 
this determination.
    (ii) If you restrict use of the test configuration for your split 
family only to tractors, or only to vocational vehicles, you must 
identify a second testable configuration for the other type of vehicle 
(or an unrestricted configuration). Identify this configuration in your 
application for certification. The FCL for the engine family applies 
for this configuration as well as the primary test configuration.
    (3) If you certify both engine fuel maps and powertrain fuel maps 
for an engine family, you may split the engine family into two separate 
subfamilies. Indicate this in your application for certification, and 
identify whether one or both of these sets of fuel maps applies for 
each group of engines. If you do not split your family, all engines 
within the family must conform to the engine fuel maps, including any 
engines for with the powertrain maps also apply.
    (4) If you certify in separate engine families engines that could 
have been certified in vocational and tractor engine subfamilies in the 
same engine family, count the two families as one family for purposes 
of determining your obligations with respect to the OBD requirements 
and in-use testing requirements. Indicate in the applications for 
certification that the two engine families are covered by this 
paragraph (f)(4).

[[Page 17680]]

    (5) Except as described in this paragraph (f), engine 
configurations within an engine family must use equivalent greenhouse 
gas emission controls. Unless we approve it, you may not produce 
nontested configurations without the same emission control hardware 
included on the tested configuration. We will only approve it if you 
demonstrate that the exclusion of the hardware does not increase 
greenhouse gas emissions.
    (g) You may certify dual-fuel or flexible-fuel engines in a single 
engine family. You may include dedicated-fuel versions of this same 
engine model in the same engine family, as long as they are identical 
to the engine configuration with respect to that fuel type for the 
dual-fuel or flexible-fuel version of the engine. For example, if you 
produce an engine that can alternately run on gasoline and natural gas, 
you can include the gasoline-only and natural gas-only versions of the 
engine in the same engine family as the dual-fuel engine if engine 
operation on each fuel type is identical with or without installation 
of components for operating on the other fuel.


Sec.  1036.235  Testing requirements for certification.

    This section describes the emission testing you must perform to 
show compliance with the emission standards in Sec. Sec.  1036.104 and 
1036.108.
    (a) Select and configure a single emission-data engine from each 
engine family.
    (1) For criteria pollutant emission testing, select the engine 
configuration most likely to exceed (or have emissions nearer to) an 
applicable emission standard or FEL identified in Sec.  1036.205(l)(1). 
To the extent we allow it for establishing deterioration factors, 
select for testing those engine components or subsystems whose 
deterioration represents the deterioration of in-use engines.
    (2) For greenhouse gas emission testing, the standards of this part 
apply only with respect to emissions measured from this tested 
configuration and other configurations identified in Sec.  
1036.205(l)(2). Note that configurations identified in Sec.  
1036.205(l)(2) are considered to be ``tested configurations'' whether 
or not you test them for certification. However, you must apply the 
same (or equivalent) emission controls to all other engine 
configurations in the engine family. In other contexts, the tested 
configuration is sometimes referred to as the ``parent configuration'', 
although the terms are not synonymous.
    (b) Test your emission-data engines using the procedures and 
equipment specified in subpart F of this part. In the case of dual-fuel 
and flexible-fuel engines, measure emissions when operating with each 
type of fuel for which you intend to certify the engine.
    (1) For criteria pollutant emission testing, measure 
NOX, PM, CO, and NMHC emissions using each duty cycle 
specified in Sec.  1036.104.
    (2) For greenhouse gas emission testing, measure CO2, 
CH4, and N2O emissions; the following provisions 
apply regarding test cycles for demonstrating compliance with tractor 
and vocational standards:
    (i) If you are certifying the engine for use in tractors, you must 
measure CO2 emissions using the applicable SET specified in 
Sec.  1036.505, taking into account the interim provisions in Sec.  
1036.150(s), and measure CH4 and N2O emissions 
using the specified transient cycle.
    (ii) If you are certifying the engine for use in vocational 
applications, you must measure CO2, CH4, and 
N2O emissions using the specified transient duty cycle, 
including cold-start and hot-start testing as specified in Sec.  
1036.510.
    (iii) You may certify your engine family for both tractor and 
vocational use by submitting CO2 emission data from both SET 
and transient cycle testing and specifying FCLs for both duty cycles.
    (iv) Some of your engines certified for use in tractors may also be 
used in vocational vehicles, and some of your engines certified for use 
in vocational may be used in tractors. However, you may not knowingly 
circumvent the intent of this part (to reduce in-use emissions of 
CO2) by certifying engines designed for tractors or 
vocational vehicles (and rarely used in the other application) to the 
wrong cycle. For example, we would generally not allow you to certify 
all your engines to the SET without certifying any to the transient 
cycle.
    (c) We may perform confirmatory testing by measuring emissions from 
any of your emission-data engines. If your certification includes 
powertrain testing as specified in Sec.  1036.630, this paragraph (c) 
also applies for the powertrain test results.
    (1) We may decide to do the testing at your plant or any other 
facility. If we do this, you must deliver the engine to a test facility 
we designate. The engine you provide must include appropriate 
manifolds, aftertreatment devices, ECMs, and other emission-related 
components not normally attached directly to the engine block. If we do 
the testing at your plant, you must schedule it as soon as possible and 
make available the instruments, personnel, and equipment we need.
    (2) If we measure emissions on your engine, the results of that 
testing become the official emission results for the engine as 
specified in this paragraph (c). Unless we later invalidate these data, 
we may decide not to consider your data in determining if your engine 
family meets applicable requirements in this part.
    (3) Before we test one of your engines, we may set its adjustable 
parameters to any point within the physically adjustable ranges (see 
Sec.  1036.115(f)).
    (4) Before we test one of your engines, we may calibrate it within 
normal production tolerances for anything we do not consider an 
adjustable parameter. For example, we may calibrate it within normal 
production tolerances for an engine parameter that is subject to 
production variability because it is adjustable during production, but 
is not considered an adjustable parameter (as defined in Sec.  
1036.801) because it is permanently sealed. For parameters that relate 
to a level of performance that is itself subject to a specified range 
(such as maximum power output), we will generally perform any 
calibration under this paragraph (c)(4) in a way that keeps performance 
within the specified range.
    (5) For greenhouse gas emission testing, we may use our emission 
test results for steady-state, idle, cycle-average and powertrain fuel 
maps defined in Sec.  1036.503(b) as the official emission results. We 
will not replace individual points from your fuel map.
    (i) We will determine fuel masses, mfuel[cycle], and 
mean idle fuel mass flow rates, mifuelidle, if applicable, 
using both direct and indirect measurement. We will determine the 
result for each test point based on carbon balance error verification 
as described in Sec.  1036.535(g)(3)(i) and (ii).
    (ii) We will perform this comparison using the weighted results 
from GEM, using vehicles that are appropriate for the engine under 
test. For example, we may select vehicles that the engine went into for 
the previous model year.
    (iii) If you supply cycle-average engine fuel maps for the highway 
cruise cycles instead of generating a steady-state fuel map for these 
cycles, we may perform a confirmatory test of your engine fuel maps for 
the highway cruise cycles by either of the following methods:
    (A) Directly measuring the highway cruise cycle-average fuel maps.
    (B) Measuring a steady-state fuel map as described in this 
paragraph (c)(5) and using it in GEM to create our own cycle-

[[Page 17681]]

average engine fuel maps for the highway cruise cycles.
    (iv) We will replace fuel maps as a result of confirmatory testing 
as follows:
    (A) Weight individual duty cycle results using the vehicle 
categories determined in paragraph (c)(5)(i) of this section and 
respective weighting factors in 40 CFR 1037.510(c) to determine a 
composite CO2 emission value for each vehicle configuration; then 
repeat the process for all the unique vehicle configurations used to 
generate the manufacturer's fuel maps.
    (B) The average percent difference between fuel maps is calculated 
using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.021


Where:

i = an indexing variable that represents one individual weighted 
duty cycle result for a vehicle configuration.
N = total number of vehicle configurations.
eCO2compEPAi = unrounded composite mass of CO2 
emissions in g/ton-mile for vehicle configuration i for the EPA 
test.
eCO2compManui = unrounded composite mass of 
CO2 emissions in g/ton-mile for vehicle configuration i 
for the manufacturer-declared map.

    (C) Where the unrounded average percent difference between our 
composite weighted fuel map and the manufacturer's is at or below 0%, 
we will not replace the manufacturer's maps, and we will consider an 
individual engine to have passed the fuel map.
    (6) We may perform confirmatory testing with an engine dynamometer 
to simulate normal engine operation to determine whether your emission-
data engine meets off-cycle emission standards. The accuracy margins 
described in Sec.  1036.420(a) do not apply for such laboratory 
testing.
    (d) You may ask to use carryover emission data from a previous 
model year instead of doing new tests, but only if all the following 
are true:
    (1) The engine family from the previous model year differs from the 
current engine family only with respect to model year, items identified 
in Sec.  1036.225(a), or other characteristics unrelated to emissions. 
We may waive this criterion for differences we determine not to be 
relevant.
    (2) The emission-data engine from the previous model year remains 
the appropriate emission-data engine under paragraph (a) of this 
section.
    (3) The data show that the emission-data engine would meet all the 
requirements that apply to the engine family covered by the application 
for certification. If the useful life for a new engine certification is 
longer than the useful life for the model year corresponding to the 
original testing, you must demonstrate that you meet the requirements 
of Sec. Sec.  1036.245 and 1036.246 in a way that accounts for the 
longer useful life for the new model year. For example, you may use 
carryover bench-aged deterioration factors in model year 2030 only if 
you originally performed bench-aging based on the useful life values 
for model year 2030 or if you supplement your original bench-aging 
procedures with additional bench-aging and emission measurements 
corresponding to the longer useful life that applies for model year 
2030.
    (e) We may require you to test a second engine of the same 
configuration in addition to the engines tested under paragraph (a) of 
this section.
    (f) If you use an alternate test procedure under 40 CFR 1065.10 and 
later testing shows that such testing does not produce results that are 
equivalent to the procedures specified in subpart F of this part, we 
may reject data you generated using the alternate procedure.
    (g) We may evaluate or test your engines to determine whether they 
have a defeat device before or after we issue a certificate of 
conformity. We may test or require testing on any vehicle or engine at 
a designated location, using driving cycles and conditions that may 
reasonably be expected in normal operation and use to investigate a 
potential defeat device. If we designate an engine's AECD as a possible 
defeat device, you must demonstrate to us that that the AECD does not 
reduce emission control effectiveness when the engine operates under 
conditions that may reasonably be expected in normal operation and use, 
unless one of the specific exceptions described in Sec.  1036.115(h) 
applies.


Sec.  1036.240  Demonstrating compliance with criteria pollutant 
emission standards.

    (a) For purposes of certification, your engine family is considered 
in compliance with the emission standards in Sec.  1036.104 if all 
emission-data engines representing that family have test results 
showing official emission results and deteriorated emission levels at 
or below these standards (including all corrections and adjustments). 
This also applies for all test points for emission-data engines within 
the family used to establish deterioration factors. Note that your FELs 
are considered to be the applicable emission standards with which you 
must comply if you participate in the ABT program in subpart H of this 
part.
    (b) Your engine family is deemed not to comply if any emission-data 
engine representing that family has test results showing an official 
emission result or a deteriorated emission level for any pollutant that 
is above an applicable emission standard (including all corrections and 
adjustments). Similarly, your engine family is deemed not to comply if 
any emission-data engine representing that family has test results 
showing any emission level above the applicable off-cycle emission 
standard for any pollutant. This also applies for all test points for 
emission-data engines within the family used to establish deterioration 
factors.
    (c) To compare emission levels from the emission-data engine with 
the applicable duty-cycle emission standards, apply deterioration 
factors to the measured emission levels for each pollutant. Section 
1036.245 specifies how to test your engine to develop deterioration 
factors that represent the deterioration expected in emissions over 
your engines' useful life (or intermediate useful life, as applicable). 
Your deterioration factors must take into account any available data 
from in-use testing with similar engines. Small manufacturers may use 
assigned deterioration factors that we establish. Apply deterioration 
factors as follows:
    (1) Additive deterioration factor for exhaust emissions. Except as 
specified in paragraph (c)(2) of this section, use an additive 
deterioration factor for exhaust emissions. An additive deterioration 
factor is the difference

[[Page 17682]]

between exhaust emissions at the end of the useful life and exhaust 
emissions at the low-hour test point. In these cases, adjust the 
official emission results for each tested engine at the selected test 
point by adding the factor to the measured emissions. If the factor is 
less than zero, use zero. Additive deterioration factors must be 
specified to one more decimal place than the applicable standard.
    (2) Multiplicative deterioration factor for exhaust emissions. Use 
a multiplicative deterioration factor if good engineering judgment 
calls for the deterioration factor for a pollutant to be the ratio of 
exhaust emissions at the end of the useful life to exhaust emissions at 
the low-hour test point. For example, if you use aftertreatment 
technology that controls emissions of a pollutant proportionally to 
engine-out emissions, it is often appropriate to use a multiplicative 
deterioration factor. Adjust the official emission results for each 
tested engine at the selected test point by multiplying the measured 
emissions by the deterioration factor. If the factor is less than one, 
use one. A multiplicative deterioration factor may not be appropriate 
in cases where testing variability is significantly greater than 
engine-to-engine variability. Multiplicative deterioration factors must 
be specified to one more significant figure than the applicable 
standard.
    (3) Sawtooth and other nonlinear deterioration patterns. The 
deterioration factors described in paragraphs (c)(1) and (2) of this 
section assume that the highest useful life emissions occur either at 
the end of useful life or at the low-hour test point. The provisions of 
this paragraph (c)(3) apply where good engineering judgment indicates 
that the highest useful life emissions will occur between these two 
points. For example, emissions may increase with service accumulation 
until a certain maintenance step is performed, then return to the low-
hour emission levels and begin increasing again. Such a pattern may 
occur with battery-based electric hybrid engines. Base deterioration 
factors for engines with such emission patterns on the difference 
between (or ratio of) the point at which the highest emissions occur 
and the low-hour test point. Note that this applies for maintenance-
related deterioration only where we allow such critical emission-
related maintenance.
    (4) Dual-fuel and flexible-fuel engines. In the case of dual-fuel 
and flexible-fuel engines, apply deterioration factors separately for 
each fuel type. You may accumulate service hours on a single emission-
data engine using the type of fuel or the fuel mixture expected to have 
the highest combustion and exhaust temperatures; you may ask us to 
approve a different fuel mixture if you demonstrate that a different 
criterion is more appropriate.
    (d) Determine the official emission result for each pollutant to at 
least one more decimal place than the applicable standard. Apply the 
deterioration factor to the official emission result, as described in 
paragraph (c) of this section, then round the adjusted figure to the 
same number of decimal places as the emission standard. Compare the 
rounded emission levels to the emission standard for each emission-data 
engine.


Sec.  1036.241  Demonstrating compliance with greenhouse gas emission 
standards.

    (a) For purposes of certification, your engine family is considered 
in compliance with the emission standards in Sec.  1036.108 if all 
emission-data engines representing the tested configuration of that 
engine family have test results showing official emission results and 
deteriorated emission levels at or below the standards. Note that your 
FCLs are considered to be the applicable emission standards with which 
you must comply for certification.
    (b) Your engine family is deemed not to comply if any emission-data 
engine representing the tested configuration of that engine family has 
test results showing an official emission result or a deteriorated 
emission level for any pollutant that is above an applicable emission 
standard (generally the FCL). Note that you may increase your FCL if 
any certification test results exceed your initial FCL.
    (c) Apply deterioration factors to the measured emission levels for 
each pollutant to show compliance with the applicable emission 
standards. Your deterioration factors must take into account any 
available data from in-use testing with similar engines. Apply 
deterioration factors as follows:
    (1) Additive deterioration factor for greenhouse gas emissions. 
Except as specified in paragraphs (c)(2) and (3) of this section, use 
an additive deterioration factor for exhaust emissions. An additive 
deterioration factor is the difference between the highest exhaust 
emissions (typically at the end of the useful life) and exhaust 
emissions at the low-hour test point. In these cases, adjust the 
official emission results for each tested engine at the selected test 
point by adding the factor to the measured emissions. If the factor is 
less than zero, use zero. Additive deterioration factors must be 
specified to one more decimal place than the applicable standard.
    (2) Multiplicative deterioration factor for greenhouse gas 
emissions. Use a multiplicative deterioration factor for a pollutant if 
good engineering judgment calls for the deterioration factor for that 
pollutant to be the ratio of the highest exhaust emissions (typically 
at the end of the useful life) to exhaust emissions at the low-hour 
test point. Adjust the official emission results for each tested engine 
at the selected test point by multiplying the measured emissions by the 
deterioration factor. If the factor is less than one, use one. A 
multiplicative deterioration factor may not be appropriate in cases 
where testing variability is significantly greater than engine-to-
engine variability. Multiplicative deterioration factors must be 
specified to one more significant figure than the applicable standard.
    (3) Sawtooth and other nonlinear deterioration patterns. The 
deterioration factors described in paragraphs (c)(1) and (2) of this 
section assume that the highest useful life emissions occur either at 
the end of useful life or at the low-hour test point. The provisions of 
this paragraph (c)(3) apply where good engineering judgment indicates 
that the highest useful life emissions will occur between these two 
points. For example, emissions may increase with service accumulation 
until a certain maintenance step is performed, then return to the low-
hour emission levels and begin increasing again. Such a pattern may 
occur with battery-based electric hybrid engines. Base deterioration 
factors for engines with such emission patterns on the difference 
between (or ratio of) the point at which the highest emissions occur 
and the low-hour test point. Note that this applies for maintenance-
related deterioration only where we allow such critical emission-
related maintenance.
    (4) [Reserved]
    (5) Dual-fuel and flexible-fuel engines. In the case of dual-fuel 
and flexible-fuel engines, apply deterioration factors separately for 
each fuel type by measuring emissions with each fuel type at each test 
point. You may accumulate service hours on a single emission-data 
engine using the type of fuel or the fuel mixture expected to have the 
highest combustion and exhaust temperatures; you may ask us to approve 
a different fuel mixture if you demonstrate that a different criterion 
is more appropriate.
    (d) Calculate emission data using measurements to at least one more 
decimal place than the applicable standard. Apply the deterioration 
factor to the official emission result, as described in paragraph (c) 
of this section, then round the adjusted figure

[[Page 17683]]

to the same number of decimal places as the emission standard. Compare 
the rounded emission levels to the emission standard for each emission-
data engine.
    (e) If you identify more than one configuration in Sec.  
1036.205(l)(2), we may test (or require you to test) any of the 
identified configurations. We may also require you to provide an 
engineering analysis that demonstrates that untested configurations 
listed in Sec.  1036.205(l)(2) comply with their FCL.


Sec.  1036.245  Deterioration factors for exhaust emission standards.

    This section describes how to determine deterioration factors, 
either with an engineering analysis, with pre-existing test data, or 
with new emission measurements. Apply these deterioration factors to 
determine whether your engines will meet the duty-cycle emission 
standards as described in Sec.  1036.240. These standards generally 
apply throughout the useful life; a separate deterioration factor 
applies starting in model year 2031 for intermediate useful life for 
Heavy HDE. The provisions of this section and Sec.  1036.246 apply for 
all engine families starting in model year 2027; you may optionally use 
these provisions to determine and verify deterioration factors for 
earlier model years.
    (a) You may ask us to approve deterioration factors for an engine 
family based on an engineering analysis of emission measurements from 
similar highway or nonroad engines if you have already given us these 
data for certifying the other engines in the same or earlier model 
years. Use good engineering judgment to decide whether the two engines 
are similar. We will approve your request if you show us that the 
emission measurements from other engines reasonably represent in-use 
deterioration for the engine family for which you have not yet 
determined deterioration factors.
    (b) If you are unable to determine deterioration factors for an 
engine family under paragraph (a) of this section, select engines, 
subsystems, or components for testing. Determine deterioration factors 
based on service accumulation and related testing to represent the 
deterioration expected from in-use engines over the useful life. You 
may perform maintenance on emission-data engines as described in Sec.  
1036.125 and 40 CFR part 1065, subpart E. Use good engineering judgment 
for all aspects of the effort to establish deterioration factors under 
this paragraph (b). Send us your test plan for our preliminary approval 
under Sec.  1036.210. You may apply deterioration factors based on 
testing under this paragraph (b) to multiple engine families, 
consistent with the provisions in paragraph (a) of this section. 
Determine deterioration factors using one of the following procedures:
    (1) Operate the emission-data engine in the certified configuration 
on an engine dynamometer to represent the useful life.
    (i) You may accelerate the service accumulation using higher-load 
operation based on equivalent total fuel flow. However, the engine 
operation for service accumulation must also include light-load 
operation (or alternating light-load and high-load operation) 
representing in-use behavior that may contribute to aging of 
aftertreatment devices or systems.
    (ii) Calculate deterioration factors by comparing exhaust emissions 
at the end of the useful life and exhaust emissions at the low-hour 
test point. For Heavy HDE starting in model year 2031, also calculate 
deterioration factors by comparing exhaust emissions at the end of 
intermediate useful life and exhaust emissions at the low-hour test 
point. Create a linear curve fit if testing includes intermediate test 
points. Calculate deterioration factors based on measured values, 
without extrapolation.
    (2) Determine deterioration factors based on bench-aged 
aftertreatment. If you use this option, you must verify deterioration 
factors based on emission measurements with in-use engines as described 
in Sec.  1036.246.
    (i) Perform bench aging of aftertreatment devices in a way that 
accounts for thermal and chemical degradation to represent normal 
engine operation over the useful life. For Heavy HDE starting in model 
year 2031, also account for thermal and chemical degradation to 
represent normal engine operation over the intermediate useful life. 
Use an EPA-approved bench-aging procedure or propose an equivalent 
procedure. For example, this might involve testing consistent with the 
analogous procedures that apply for light-duty vehicles under 40 CFR 
part 86, subpart S.
    (ii) After bench-aging aftertreatment devices, install or reinstall 
those aftertreatment devices and systems on an emission-data engine 
that has been stabilized without aftertreatment (or an equivalent 
engine). Ensure that the engine is in an appropriate certified 
configuration to represent the engine family.
    (iii) Measure all criteria pollutants after operating the engine 
with the bench-aged aftertreatment devices to stabilize emission 
controls for at least 100 hours on an engine dynamometer.
    (iv) Calculate deterioration factors by comparing exhaust emissions 
with the bench-aged aftertreatment at the useful life and exhaust 
emissions at the low-hour test point. For Heavy HDE starting in model 
year 2031, also calculate deterioration factors by comparing exhaust 
emissions with the bench-aged aftertreatment at the intermediate useful 
life and exhaust emissions at the low-hour test point. Create a linear 
curve fit if testing includes intermediate test points. Calculate 
deterioration factors based on measured values, without extrapolation.
    (c) If you determine deterioration factors as described in 
paragraph (b)(2) of this section, you may apply those deterioration 
factors in later years for engine families that qualify for carryover 
certification as described in Sec.  1036.235(d), subject to the 
conditions described in Sec.  1036.246. You may also apply those 
deterioration factors for additional engine families as described in 
paragraph (a) of this section.
    (d) Include the following information in your application for 
certification:
    (1) If you use test data from a different engine family, explain 
why this is appropriate and include all the emission measurements on 
which you base the deterioration factors. If the deterioration factors 
for the new engine family are not identical to the deterioration 
factors for the different engine family, describe your engineering 
analysis to justify the revised values and state that all your data, 
analyses, evaluations, and other information are available for our 
review upon request.
    (2) If you determined deterioration factors based on testing under 
paragraph (b)(1) of this section, describe your procedure for service 
accumulation, including a supporting rationale for any accelerated 
aging.
    (3) If you determined deterioration factors under paragraph (b)(2) 
of this section, include the following information in the first year 
that you use those deterioration factors:
    (i) Describe your bench aging or other procedures to represent 
full-life service accumulation for the engine's emission controls. Also 
describe how you prepared the test engine before and after installing 
aftertreatment systems to determine deterioration factors. Identify the 
power rating of the emission-data engine used to determine 
deterioration factors.
    (ii) Describe your plan for verification testing under Sec.  
1036.246. Include at least the following information:
    (A) Identify whether you intend to test using procedures specified 
in Sec.  1036.246(d)(1), (2), or (3).

[[Page 17684]]

    (B) Describe how you intend to identify candidate vehicles for 
testing, including consideration of how you will identify or prioritize 
specific vehicle types and vehicle applications to represent the engine 
family.
    (C) Describe your intended schedule for recruiting and testing 
vehicles.
    (D) Describe any steps you will take to ensure that selected 
vehicles have been properly maintained and used.
    (4) If you determined deterioration factors under paragraph (b)(2) 
of this section, include the following information in any later year 
that you use those deterioration factors:
    (i) Identify any changes or updates to your verification test plan 
that you have made in your most recent testing, or that you plan to 
make for later years.
    (ii) Submit a report to describe any verification testing you have 
performed under Sec.  1036.246 as described in Sec.  1036.246(e). 
Include previously submitted results in addition to information related 
to new testing you performed for the current submission.


Sec.  1036.246  Verifying deterioration factors.

    This section describes how to perform in-use testing to verify that 
your deterioration factors are appropriate. This applies for 
deterioration factors you determine based on testing with bench-aged 
aftertreatment devices or other procedures as described in Sec.  
1036.245(b)(2). You may continue to use those deterioration factors for 
later model years with carryover engines if in-use engines meet the 
verification requirements of this section.
    (a) Paragraph (d) of this section describes three different 
verification procedures you may use for measuring emissions. We may 
also approve your request to use an alternative verification procedure 
if you demonstrate that it is at least as effective as one of the 
specified verification procedures.
    (b) Verify deterioration factors based on bench-aged aftertreatment 
as follows:
    (1) You may use the original deterioration factors for the original 
model year and one additional model year, prior to the start of the 
year three production verification, without restriction.
    (2) You must verify the original deterioration factors with testing 
that starts in the third year of production and continues in later 
production years up to and including the eighth year of production.
    (3) As long as your verification test has a passing result, you may 
continue to use the original deterioration factors for the upcoming 
model year without restriction.
    (4) The provisions of paragraph (h) of this section apply if your 
verification testing has a fail result.
    (c) Select and prepare in-use engines for verification testing 
under this section as follows:
    (1) You may recruit candidate engines any time before testing. This 
may involve creating a pool of candidate engines and vehicles in 
coordination with vehicle manufacturers and vehicle purchasers to 
ensure availability and to confirm a history of proper maintenance. You 
may meet the testing requirements of this section by repeating tests on 
a given engine as it ages, or you may test different engines over the 
course of verification testing; however, you may not choose whether to 
repeat tests on a given engine at a later stage based on its measured 
emission levels. This generally requires that you describe your plan 
for selecting engines in advance and justify any departures from that 
plan.
    (2) Selected vehicles must come from independent sources, unless we 
approve your request to select vehicles that you own or manage. In your 
request, you must describe how you will ensure that the vehicle 
operator will drive in a way that represents normal in-use operation 
for the engine family.
    (3) Select vehicles with installed engines from the same engine 
family and with the same power rating as the emission-data engine used 
to determine the deterioration factors. You may ask for our approval to 
modify engines in selected vehicles by reflashing the ECM or replacing 
parts to change the engines to be in a different certified 
configuration for proper testing. We may approve your request to modify 
the engines or we may waive test specifications to allow you to test in 
the as-received condition.
    (4) You may exclude selected engines from testing if you determine 
that they have not been properly maintained or used. Selected engines 
may not have maintenance exceeding your instructions for the 
maintenance items specified in Sec.  1036.125(a). Selected engines must 
have their original aftertreatment components and be in a certified 
configuration. Do not perform verification testing with an engine if 
its critical emission-related components had a major repair other than 
what we allow under Sec.  1036.125(a). You may ask us to approve 
replacing a critical emission-related component with an equivalent part 
that has undergone a comparable degree of aging.
    (5) Select vehicles meeting the mileage specifications specified in 
Table 1 of this paragraph (c)(5) for each stage of the verification 
testing program. If you are unable to find enough test vehicles that 
meet the mileage specifications, perform testing as described in this 
section using vehicles with the highest available mileage and describe 
how you will attempt to test properly qualified vehicles for later 
years. If this occurs in the eighth year, continue testing in future 
years until all tested vehicles have mileage that is at least 85 
percent of the engine's useful life.

Table 1 to paragraph (c)(5) of Sec.   1036.246--Minimum Age Required for
                        Obtaining In-use Engines
------------------------------------------------------------------------
                                                              Minimum
                                                            mileage for
                                                             selected
Year of production following the initial model year that   vehicles as a
           relied on the deterioration factors             percentage of
                                                           the engine's
                                                            useful life
------------------------------------------------------------------------
1.......................................................              --
2.......................................................              --
3.......................................................             35%
4.......................................................              45
5.......................................................              55
6.......................................................              65
7.......................................................              75
8.......................................................              85
------------------------------------------------------------------------

    (6) You may accelerate the testing schedule specified in paragraph 
(c)(5) of this section if all your test vehicles in a given year meet 
the mileage specifications for a later year of testing.
    (d) Perform verification testing each year with one of the 
following procedures:
    (1) Engine dynamometer testing. Measure emissions from engines 
equipped with in-use aftertreatment systems on an engine dynamometer as 
follows:
    (i) Test at least two engines using the procedures specified in 
subpart F of this part and 40 CFR part 1065. Install the aftertreatment 
system from the selected in-use vehicle, including all associated 
wiring, sensors, and related hardware and software, on one of the 
following partially complete engines:
    (A) The in-use engine from the same vehicle.
    (B) The emission-data engine used to determine the deterioration 
factors.
    (C) A different emission-data engine from the same engine family 
that has been stablized as described in 40 CFR 1065.405(c).
    (ii) Perform testing on all duty cycles with brake-specific 
emission standards (g/hp[middot]hr) to determine whether the engine 
meets all the duty-cycle emission standards for criteria pollutants. 
Apply

[[Page 17685]]

infrequent regeneration adjustment factors as specified in Sec.  
1036.522.
    (iii) Evaluate verification testing for each pollutant 
independently. You pass the verification test if at least 70 percent of 
tested engines meet standards for each pollutant over all duty cycles. 
You fail the verification test if 70 percent or fewer engines meet 
standards for a given pollutant over all duty cycles.
    (2) PEMS testing. Measure emissions using PEMS with in-use engines 
that remain installed in selected vehicles as follows:
    (i) Test at least five engines using the procedures specified in 
Sec.  1036.520 and 40 CFR part 1065, subpart J.
    (ii) Measure emissions of NOX, HC, and CO as the test 
vehicle's normal operator drives over a regular shift-day to determine 
whether the engine meets all the off-cycle emission standards that 
applied for the engine's original certification. Apply infrequent 
regeneration adjustment factors as specified in Sec.  1036.522. For 
Spark-ignition HDE, calculate off-cycle emission standards for purposes 
of this subpart by multiplying the FTP duty-cycle standards in Sec.  
1036.104(a) by 2.0 in model years 2027 through 2030 and by 1.5 in model 
years 2031 and later, and rounding to the same number of decimal 
places.
    (iii) Evaluate verification testing for each pollutant 
independently. You pass the verification test if at least 70 percent of 
tested engines meet standards for each pollutant. You fail the 
verification test if 70 percent or fewer engines do not meet standards 
for a given pollutant.
    (iv) You may reverse a fail determination under paragraph 
(d)(2)(iii) of this section by restarting and successfully completing 
the verification test for that year using the procedures specified in 
paragraph (d)(1) of this section. If you do this, you must use the 
verification testing procedures specified in paragraph (d)(1) of this 
section for all remaining years of the verification testing program.
    (3) Onboard NOX measurement. Collect on-board NOX data 
from in-use engines that remain installed in selected vehicles as 
follows:
    (i) Test at least 50 percent of engines produced using the 
procedures specified in Sec.  1036.520 and 40 CFR part 1065, subpart J. 
Perform the overall verification of your onboard NOX 
measurement system as described in 40 CFR 1065.920(b) using an engine 
that emits NOX at levels at or below the off-cycle 
NOX emission standard that applied for the engine's original 
certification. The onboard NOX measurement system must be 
functional within 100 seconds of engine starting and must remain 
functional over the entire shift-day.
    (ii) Collect NOX data as the test vehicle's normal 
operator drives over a regular shift-day to determine whether the 
engine meets the off-cycle NOX emission standards that 
applied for the engine's original certification. Apply infrequent 
regeneration adjustment factors as specified in Sec.  1036.522. For 
Spark-ignition HDE, calculate off-cycle emission standards as described 
in paragraph (d)(2)(ii) of this section.
    (iii) You pass the verification test if at least 70 percent of 
tested engines meet the off-cycle NOX emission standard. You 
fail the verification test if 70 percent or fewer engines do not meet 
standards for a given pollutant.
    (iv) You may reverse a fail determination under paragraph 
(d)(3)(iii) of this section by restarting and successfully completing 
the verification test for that year using the procedures specified in 
paragraph (d)(1) of this section. If you do this, you must use the 
verification testing procedures specified in paragraph (d)(1) of this 
section for all remaining years of the verification testing program.
    (e) You may stop testing before you meet all the requirements of 
this section in the following circumstances:
    (1) In a given year, you may discontinue the verification test 
program and concede a fail result before you meet all the testing 
requirements of this section. However, we may require you to do more 
testing before we approve revised deterioration factors under paragraph 
(h)(2) of this section.
    (2) You may stop testing before the eight-year period specified in 
paragraph (c)(5) of this section if you meet all the requirements with 
vehicles that had mileage accumulation representing at least 85 percent 
of the engine family's useful life.
    (f) Prepare a report to describe your verification testing each 
year. Include at least the following information:
    (1) Identify whether you tested using the procedures specified in 
Sec.  1036.246(d)(1), (2), or (3).
    (2) Describe how the test results support a pass or fail decision 
for the verification test. For in-field measurements, include 
continuous 1 Hz data collected over the shift-day and binned emission 
values determined under Sec.  1036.515.
    (3) If your testing included invalid test results, describe the 
reasons for invalidating the data. Give us the invalid test results if 
we ask for them.
    (4) Describe the types of vehicles selected for testing. If you 
determined that any selected vehicles with enough mileage accumulation 
were not suitable for testing, describe why you chose not to test them.
    (5) For each tested engine, identify the vehicle's VIN, the 
engine's serial number, the engine's power rating, and the odometer 
reading and the engine's lifetime operating hours at the start of 
testing (or engine removal).
    (6) State that the tested engines have been properly maintained and 
used and describe any noteworthy aspects of each vehicle's maintenance 
history. Describe the steps you took to prepare the engines for 
testing.
    (7) For testing with engines that remain installed in vehicles, 
identify the date and location of testing. Also describe the ambient 
conditions and the driving route over the course of the shift-day.
    (g) Send electronic reports to the Designated Compliance Officer 
using an approved information format. If you want to use a different 
format, send us a written request with justification.
    (1) You may send us reports as you complete testing for an engine 
instead of waiting until you complete testing for all engines.
    (2) We may ask you to send us less information in your reports than 
we specify in this section.
    (3) We may require you to send us more information to evaluate 
whether your engine family meets the requirements of this part.
    (4) Once you send us information under this section, you need not 
send that information again in later reports.
    (5) We will review your test report to evaluate the results of the 
verification testing at each stage. We will notify you if we disagree 
with your conclusions, if we need additional information, or if you 
need to revise your testing plan for future testing.
    (h) The following provisions apply if your verification test has a 
fail result for any deterioration factor:
    (1) You may certify affected engine families for one additional 
model year based on the original deterioration factors. We may require 
you to certify with family emission limits that are at the maximum 
values we allow in Sec.  1036.104(c)(2), or at some lower value 
corresponding to your measured emission results. You may not generate 
emission credits from affected engine families for any pollutant. We 
may require you to apply the revised family emission limits to 
recalculate emission credits and credit balances from previous model 
years based on your test results.
    (2) You may ask us to approve revised deterioration factors for 
future model years based on your measured emission results. You may use 
such revised

[[Page 17686]]

deterioration factors and continue verification testing under this 
section if the engine family still meets emission standards (or family 
emission limits) after applying the revised deterioration factors to 
the low-hour test results from an emission-data engine.
    (3) Unless we approve revised deterioration factors under paragraph 
(h)(2) of this section, you must do new testing to establish 
deterioration factors after the one additional model year described in 
paragraph (h)(1) of this section.
    (4) The provisions of this paragraph (h) apply for all engine 
families relying on the deterioration factors that failed to pass 
verification testing.


Sec.  1036.250  Reporting and recordkeeping for certification.

    (a) By September 30 following the end of the model year, send the 
Designated Compliance Officer a report including the total U.S.-
directed production volume of engines you produced in each engine 
family during the model year (based on information available at the 
time of the report). Report the production by serial number and engine 
configuration. You may combine this report with reports required under 
subpart H of this part. We may waive the reporting requirements of this 
paragraph (a) for small manufacturers.
    (b) Organize and maintain the following records:
    (1) A copy of all applications and any summary information you send 
us.
    (2) Any of the information we specify in Sec.  1036.205 that you 
were not required to include in your application.
    (3) A detailed history of each emission-data engine. For each 
engine, describe all of the following:
    (i) The emission-data engine's construction, including its origin 
and buildup, steps you took to ensure that it represents production 
engines, any components you built specially for it, and all the 
components you include in your application for certification.
    (ii) How you accumulated engine operating hours (service 
accumulation), including the dates and the number of hours accumulated.
    (iii) All maintenance, including modifications, parts changes, and 
other service, and the dates and reasons for the maintenance.
    (iv) All your emission tests, including documentation on routine 
and standard tests, as specified in part 40 CFR part 1065, and the date 
and purpose of each test.
    (v) All tests to diagnose engine or emission control performance, 
giving the date and time of each and the reasons for the test.
    (vi) Any other significant events.
    (4) Production figures for each engine family divided by assembly 
plant.
    (5) Engine identification numbers for all the engines you produce 
under each certificate of conformity.
    (c) Keep routine data from emission tests required by this part 
(such as test cell temperatures and relative humidity readings) for one 
year after we issue the associated certificate of conformity. Keep all 
other information specified in this section for eight years after we 
issue your certificate.
    (d) Store these records in any format and on any media, as long as 
you can promptly send us organized, written records in English if we 
ask for them. You must keep these records readily available. We may 
review them at any time.


Sec.  1036.255  EPA oversight on certificates of conformity.

    (a) If we determine an application is complete and shows that the 
engine family meets all the requirements of this part and the Act, we 
will issue a certificate of conformity for the engine family for that 
model year. We may make the approval subject to additional conditions.
    (b) We may deny an application for certification if we determine 
that an engine family fails to comply with emission standards or other 
requirements of this part or the Clean Air Act. We will base our 
decision on all available information. If we deny an application, we 
will explain why in writing.
    (c) In addition, we may deny your application or suspend or revoke 
a certificate of conformity if you do any of the following:
    (1) Refuse to comply with any testing or reporting requirements in 
this part.
    (2) Submit false or incomplete information. This includes doing 
anything after submitting an application that causes submitted 
information to be false or incomplete.
    (3) Cause any test data to become inaccurate.
    (4) Deny us from completing authorized activities (see 40 CFR 
1068.20). This includes a failure to provide reasonable assistance.
    (5) Produce engines for importation into the United States at a 
location where local law prohibits us from carrying out authorized 
activities.
    (6) Fail to supply requested information or amend an application to 
include all engines being produced.
    (7) Take any action that otherwise circumvents the intent of the 
Act or this part.
    (d) We may void a certificate of conformity if you fail to keep 
records, send reports, or give us information as required under this 
part or the Act. Note that these are also violations of 40 CFR 
1068.101(a)(2).
    (e) We may void a certificate of conformity if we find that you 
intentionally submitted false or incomplete information. This includes 
doing anything after submitting an application that causes submitted 
information to be false or incomplete after submission.
    (f) If we deny an application or suspend, revoke, or void a 
certificate, you may ask for a hearing (see Sec.  1036.820).

Subpart D--Testing Production Engines and Hybrid Powertrains


Sec.  1036.301  Measurements related to GEM inputs in a selective 
enforcement audit.

    (a) Selective enforcement audits apply for engines as specified in 
40 CFR part 1068, subpart E. This section describes how this applies 
uniquely in certain circumstances.
    (b) Selective enforcement audit provisions apply with respect to 
your fuel maps as follows:
    (1) A selective enforcement audit for an engine with respect to 
fuel maps would consist of performing measurements with production 
engines to determine fuel-consumption rates as declared for GEM 
simulations, and running GEM for the vehicle configurations specified 
in paragraph (b)(2) of this section based on those measured values. The 
engine is considered passing for a given configuration if the new 
modeled emission result for each applicable duty cycle is at or below 
the modeled emission result corresponding to the declared GEM inputs. 
The engine is considered failing if it is determined that its fuel map 
test result is above the modeled emission result corresponding to the 
result using the manufacturer-declared fuel maps, as specified in Sec.  
1036.235(c)(5).
    (2) If the audit includes fuel-map testing in conjunction with 
engine testing relative to exhaust emission standards, the fuel-map 
simulations for the whole set of vehicles and duty cycles counts as a 
single test result for purposes of evaluating whether the engine family 
meets the pass-fail criteria under 40 CFR 1068.420.
    (c) If your certification includes powertrain testing as specified 
in 40 CFR 1036.630, these selective enforcement audit provisions apply 
with respect to powertrain test results as specified in 40 CFR part 
1037, subpart D, and 40 CFR 1037.550. We may allow manufacturers to 
instead perform the

[[Page 17687]]

engine-based testing to simulate the powertrain test as specified in 40 
CFR 1037.551.
    (d) We may suspend or revoke certificates for any appropriate 
configurations within one or more engine families based on the outcome 
of a selective enforcement audit.

Subpart E--In-Use Testing


Sec.  1036.401  Testing requirements for in-use engines.

    (a) We may perform in-use testing of any engine family subject to 
the standards of this part, consistent with the Clean Air Act and the 
provisions of Sec.  1036.235.
    (b) This subpart describes a manufacturer-run field-testing program 
that applies for model year 2027 and later compression-ignition 
engines. Note that the testing requirements of 40 CFR part 86, subpart 
T, continue to apply for model year 2026 and earlier engines.
    (c) In-use test procedures for spark-ignition engines apply as 
described in Sec.  1036.515. We won't require routine manufacturer-run 
field testing for spark-ignition engines, but the procedures of this 
subpart describe how to use field-testing procedures to measure 
emissions from engines installed in vehicles. Use good engineering 
judgment to apply the measurement procedures for fuels other than 
gasoline.
    (d) We may void your certificate of conformity for an engine family 
if you do not meet your obligations under this subpart. We may also 
void individual tests and require you to retest those vehicles or take 
other appropriate measures in instances where you have not performed 
the testing in accordance with the requirements described in this 
subpart.


Sec.  1036.405  Overview of the manufacturer-run field-testing program.

    (a) You must test in-use engines from the families we select. We 
may select the following number of engine families for testing, except 
as specified in paragraph (b) of this section:
    (1) We may select up to 25 percent of your engine families in any 
calendar year, calculated by dividing the number of engine families you 
certified in the model year corresponding to the calendar year by four 
and rounding to the nearest whole number. We will consider only engine 
families with annual U.S.-directed production volumes above 1,500 units 
in calculating the number of engine families subject to testing each 
calendar year under the annual 25 percent engine family limit. If you 
have only three or fewer families that each exceed an annual U.S.-
directed production volume of 1,500 units, we may select one engine 
family per calendar year for testing.
    (2) Over any four-year period, we will not select more than the 
average number of engine families that you have certified over that 
four-year period (the model year when the selection is made and the 
preceding three model years), based on rounding the average value to 
the nearest whole number.
    (3) We will not select engine families for testing under this 
subpart from a given model year if your total U.S.-directed production 
volume was less than 100 engines.
    (b) If there is clear evidence of a nonconformity with regard to an 
engine family, we may select that engine family without counting it as 
a selected engine family under paragraph (a) of this section. For 
example, there may be clear evidence of a nonconformity if you certify 
an engine family using carryover data after reaching a fail decision 
under this subpart in an earlier model year without modifying the 
engine to remedy the problem.
    (c) We may select any individual engine family for testing, 
regardless of its production volume, as long as we do not select more 
than the number of engine families described in paragraph (a) of this 
section. We may select an engine family from model year 2027 or any 
later model year.
    (d) You must complete all the required testing and reporting under 
this subpart (for all ten test engines, if applicable), within 18 
months after we approve your proposed plan for recruiting, screening, 
and selecting vehicles. We will typically select engine families for 
testing and notify you in writing by June 30 of the applicable calendar 
year. If you request it, we may allow additional time to send us this 
information.
    (e) If you make a good-faith effort to access enough test vehicles 
to complete the testing requirements under this subpart for an engine 
family, but are unable to do so, you must ask us either to modify the 
testing requirements for the selected engine family or to select a 
different engine family.
    (f) We may select an engine family for repeat testing in a later 
calendar year. Such a selection for repeat testing would count as an 
additional engine family for that year under paragraph (a) of this 
section.
    (g) You may ask for approval to meet requirements under this 
subpart for an engine family based on information from onboard 
NOX sensors that have been shown to comply with the on-board 
NOX measurement system verification described in 40 CFR 
1065.920(b) using an engine that emits NOX at levels at or 
below the applicable standard. Any on-board NOX measurement 
system must be functional within 100 seconds of engine starting and 
must remain functional during the entire shift-day. An alternative test 
program would need to rely on telematic methods to collect 
NOX emission values broadly from engines in the fleet to 
evaluate whether emission controls are working properly across a wide 
range of engine operation. The alternative test program must include 
PEMS field-testing of at least two engines as described in this 
subpart, including measurement of all regulated pollutants. In your 
request, you must show us that the alternative program gives comparable 
assurance that your engines meet the NOX standards of this 
part. We may waive some or all of this subpart's requirements for the 
engine family if we approve your alternative test program.


Sec.  1036.410  Selecting and screening vehicles and engines for 
testing.

    (a) Send us your proposed plan for recruiting, screening, and 
selecting vehicles. Identify the types of vehicles, location, and any 
other relevant criteria. We will approve your plan if it supports the 
objective of measuring emissions to represent a broad range of 
operating characteristics.
    (b) Select vehicles and engines for testing that meet the following 
criteria:
    (1) The vehicles come from at least two independent sources.
    (2) Powertrain, drivetrain, emission controls, and other key 
vehicle and engine systems have been properly maintained and used. See 
Sec.  1036.125.
    (3) The engines have not been tampered with, rebuilt, or undergone 
major repair that could be expected to affect emissions.
    (4) The engines have not been misfueled. Do not consider engines 
misfueled if they have used fuel meeting the specifications of Sec.  
1036.415(c).
    (5) The vehicles are likely to operate for at least three hours of 
non-idle operation over a complete shift-day, as described in Sec.  
1036.415(f).
    (6) The vehicles have not exceeded the applicable useful life, in 
miles, hours, or years; you may otherwise not exclude engines from 
testing based on their age or mileage.
    (7) The vehicle has appropriate space for safe and proper mounting 
of the portable emission measurement system (PEMS) equipment.
    (c) You must notify us before disqualifying any vehicle based on 
the owner declining to participate, illuminated MIL or stored OBD 
trouble

[[Page 17688]]

codes as described in Sec.  1036.415(b)(2), or for any other reasons 
not specified in paragraph (b) of this section. For example, notify us 
if you disqualify any vehicle because the engine does not represent the 
engine family or the vehicle's usage is atypical for the particular 
application.


Sec.  1036.415  Preparing and testing engines.

    (a) You must limit maintenance to what is in the owners manual for 
engines with that amount of service and age. For anything we consider 
an adjustable parameter (see Sec.  1036.115(f)), you may adjust that 
parameter only if it is outside its adjustable range. You must then set 
the adjustable parameter to your recommended setting or the mid-point 
of its adjustable range, unless we approve your request to do 
otherwise. You must get our approval before adjusting anything not 
considered an adjustable parameter. You must keep records of all 
maintenance and adjustments, as required by Sec.  1036.435. You must 
send us these records, as described in Sec.  1036.430(a)(2)(ix), unless 
we instruct you not to send them.
    (b) You may treat a vehicle with an illuminated MIL or stored 
trouble code as follows:
    (1) If a candidate vehicle has an illuminated MIL or stored trouble 
code, either test the vehicle as received or repair the vehicle before 
testing. You may disqualify the vehicle only if MIL illumination or 
trouble code storage exceeds 12 hours. Once testing is initiated on the 
vehicle, you accept that the vehicle has been properly maintained and 
used.
    (2) If a MIL illuminates or a trouble code appears on a test 
vehicle during a field test, stop the test and repair the vehicle. 
Determine test results as specified in Sec.  1036.515 using one of the 
following options:
    (i) Restart the testing and use only the portion of the full test 
results without the MIL illuminated or trouble code set.
    (ii) Initiate a new test and use only the post-repair test results.
    (3) If you determine that repairs are needed but they cannot be 
completed in a timely manner, you may disqualify the vehicle and 
replace it with another vehicle.
    (c) Use appropriate fuels for testing, as follows:
    (1) You may use any diesel fuel that meets the specifications for 
S15 in ASTM D975 (incorporated by reference in Sec.  1036.810). You may 
use any commercially available biodiesel fuel blend that meets the 
specifications for ASTM D975 or ASTM D7467 (incorporated by reference 
in Sec.  1036.810). You may use any gasoline fuel that meets the 
specifications in ASTM D4814 (incorporated by reference in Sec.  
1036.810). For other fuel types, you may use any commercially available 
fuel.
    (2) You may drain test vehicles' fuel tanks and refill them with 
diesel fuel conforming to the specifications in paragraph (c)(1) of 
this section.
    (3) Any fuel that is added to a test vehicle's fuel tanks must be 
purchased at a local retail establishment near the site of vehicle 
recruitment or screening, or along the test route. Alternatively, the 
fuel may be drawn from a central fueling source, as long as the fuel 
represents commercially available fuel in the area of testing.
    (4) No post-refinery fuel additives are allowed, except that 
specific fuel additives may be used during field testing if you can 
document that the test vehicle has a history of normally using the fuel 
treatments and they are not prohibited in the owners manual or in your 
published fuel-additive recommendations.
    (5) You may take fuel samples from test vehicles to ensure that 
appropriate fuels were used during field testing. If a vehicle fails 
the vehicle-pass criteria and you can show that an inappropriate fuel 
was used during the failed test, that particular test may be voided. 
You may drain vehicles' fuel tanks and refill them with diesel fuel 
conforming to the specifications described in paragraph (c)(1) of this 
section. You must report any fuel tests that are the basis of voiding a 
test in your report under Sec.  1036.430.
    (d) You must test the selected engines using the test procedure 
described in Sec.  1036.515 while they remain installed in the vehicle. 
Testing consists of characterizing emission rates for moving average 
300 second windows while driving, with those windows divided into bins 
representing different types of engine operation over a shift-day. Use 
one of the following methods to measure emissions:
    (1) Perform all testing with PEMS and field-testing procedures 
referenced in 40 CFR part 1065, subpart J. Measure emissions of HC, CO, 
NOX, PM, and CO2. You may determine HC emissions 
by any method specified in 40 CFR 1065.660(b).
    (2) [Reserved]
    (e) Operate the test vehicle under conditions reasonably expected 
during normal operation. For the purposes of this subpart, normal 
operation generally includes the vehicle's normal routes and loads 
(including auxiliary loads such as air conditioning in the cab), normal 
ambient conditions, and the normal driver.
    (f) Once an engine is set up for testing, test the engine for at 
least one shift-day. To complete a shift-day's worth of testing, start 
sampling at the beginning of a shift and continue sampling for the 
whole shift, subject to the calibration requirements of the PEMS. A 
shift-day is the period of a normal workday for an individual employee. 
Evaluate the emission data as described in Sec.  1036.420 and include 
the data in the reporting and record keeping requirements specified in 
Sec. Sec.  1036.430 and 1036.435.
    (g) You may ask us to waive testing relative to one or more 
emission standards if you can show that field testing for such 
emissions is not necessary.


Sec.  1036.420  Pass criteria for individual engines.

    Perform the following steps to determine whether an engine meets 
the binned emission standards in Sec.  1036.104(a)(4):
    (a) Determine the binned or shift-day emission standard, as 
applicable, for each regulated pollutant by adding the following 
accuracy margins for PEMS to the off-cycle standards in Sec.  
1036.104(a)(4):
    (1) HC: 10 mg/hp[middot]hr.
    (2) CO: 0.025 g/hp[middot]hr.
    (3) PM: 6 mg/hp[middot]hr.
    (4) NOX: 10% of the standard.
    (b) Calculate the mass emission rate for each pollutant as 
specified in 40 CFR part 1065, subpart G, for use in the calculations 
in Sec.  1036.515.
    (c) For compression-ignition engines, determine the number of 
windows in each bin. A bin is valid under this section only if it has 
more than 2,400 windows. If the 2,400 valid windows in any bin is not 
achieved, continue testing additional shift-days as necessary to 
achieve the minimum window requirements for each bin. You may idle the 
engine anytime during the shift day to increase the number of windows 
in the idle bin.
    (d) An engine passes if the result for each valid bin is at or 
below the standard determined in paragraph (a) of this section. An 
engine fails if the result for any valid bin for any pollutant is above 
the standard determined in paragraph (a) of this section. Having no 
valid bins for a bin category over a shift-day does not disqualify an 
engine from pass-fail determinations under this paragraph (d).


Sec.  1036.425  Pass criteria for engine families.

    For testing with PEMS under Sec.  1036.415(d)(1), determine the 
number of engines you must test from each selected engine family and 
the family pass criteria as follows:

[[Page 17689]]

    (a) Start by measuring emissions from five engines using the 
procedures described in this subpart E and Sec.  1036.515. If all five 
engines comply fully with the off-cycle bin standards, the engine 
family passes, and you may stop testing.
    (b) If only one of the engines tested under paragraph (a) of this 
section does not comply fully with the off-cycle bin standards, test 
one more engine. If this additional engine complies fully with the off-
cycle bin standards, the engine family passes, and you may stop 
testing.
    (c) If two or more engines tested under paragraphs (a) and (b) of 
this section do not comply fully with the off-cycle bin standards, test 
additional engines until you have tested a total of ten engines. 
Calculate the arithmetic mean of the sum-over-sum emissions from the 
ten engine tests as specified in Sec.  1036.515(g) for each pollutant. 
If the results are at or below the off-cycle bin standards, the engine 
family passes. If the result for any pollutant is above an off-cycle 
bin standard, the engine family fails.


Sec.  1036.430  Reporting requirements.

    (a) Report content. Prepare test reports as follows:
    (1) Include the following for each engine family:
    (i) Describe how you recruited vehicles. Describe how you used any 
criteria or thresholds to narrow your search or to screen individual 
vehicles.
    (ii) Include a summary of the vehicles you have disqualified and 
the reasons you disqualified them, whether you base the 
disqualification on the criteria in Sec.  1036.410(b) or anything else. 
If you disqualified a vehicle due to misfueling, include the results of 
any fuel sample tests. If you reject a vehicle due to tampering, 
describe how you determined that tampering occurred.
    (iii) Identify how many engines you have tested from the applicable 
engine family and how many engines still need to be tested. Identify 
how many tested engines have passed or failed under Sec.  1036.420.
    (iv) After the final test, report the results and state the outcome 
of testing for the engine family based on the criteria in Sec.  
1036.425.
    (v) Describe any incomplete or invalid tests that were conducted 
under this subpart.
    (2) Include the following information for the test vehicle:
    (i) The EPA engine-family designation, and the engine's model 
number, total displacement, and power rating.
    (ii) The date EPA selected the engine family for testing.
    (iii) The vehicle's make and model and the year it was built.
    (iv) The vehicle identification number and engine serial number.
    (v) The vehicle's type or application (such as delivery, line haul, 
or dump truck). Also, identify the type of trailer, if applicable.
    (vi) The vehicle's maintenance and use history.
    (vii) The known status history of the vehicle's OBD system and any 
actions taken to address OBD trouble codes or MIL illumination over the 
vehicle's lifetime.
    (viii) Any OBD codes or MIL illumination that occur after you 
accept the vehicle for field testing under this subpart.
    (ix) Any steps you take to maintain, adjust, modify, or repair the 
vehicle or its engine to prepare for or continue testing, including 
actions to address OBD trouble codes or MIL illumination. Include any 
steps you took to drain and refill the vehicle's fuel tank(s) to 
correct misfueling, and the results of any fuel test conducted to 
identify misfueling.
    (3) Include the following data and measurements for each test 
vehicle:
    (i) The date and time of testing, and the test number.
    (ii) Number of shift-days of testing (see Sec.  1036.415(f)).
    (iii) Route and location of testing. You may base this description 
on the output from a global-positioning system (GPS).
    (iv) The steps you took to ensure that vehicle operation during 
testing was consistent with normal operation and use, as described in 
Sec.  1036.415(e).
    (v) Fuel test results, if fuel was tested under Sec.  1036.410 or 
Sec.  1036.415.
    (vi) The vehicle's mileage at the start of testing. Include the 
engine's total lifetime hours of operation, if available.
    (vii) The number of windows in each bin (see Sec.  1036.420(c)).
    (viii) The bin emission value per vehicle for each pollutant. 
Describe the method you used to determine HC as specified in 40 CFR 
1065.660(b).
    (ix) Recorded 1 Hz test data for at least the following parameters, 
noting that gaps in the 1 Hz data file over the shift-day are only 
allowed during analyzer zero and span verifications:
    (A) Ambient temperature.
    (B) Ambient pressure.
    (C) Ambient humidity.
    (D) Altitude.
    (E) Emissions of HC, CO, CO2, and NOX. Report 
results for PM if it was measured in a manner that provides 1 Hz test 
data.
    (F) Differential backpressure of any PEMS attachments to vehicle 
exhaust.
    (G) Exhaust flow.
    (H) Exhaust aftertreatment temperatures.
    (I) Engine speed.
    (J) Engine brake torque.
    (K) Engine coolant temperature
    (L) Intake manifold temperature.
    (M) Intake manifold pressure.
    (N) Throttle position.
    (O) Any parameter sensed or controlled to modulate the emission 
control system or fuel-injection timing.
    (4) Include the following summary information after you complete 
testing with each engine:
    (i) State whether the engine meets the off-cycle standards for each 
bin for each pollutant as described in Sec.  1036.420(d).
    (ii) Describe if any testing or evaluations were conducted to 
determine why a vehicle failed the off-cycle emission standards 
described in Sec.  1036.420.
    (iii) Describe the purpose of any diagnostic procedures you 
conduct.
    (iv) Describe any instances in which the OBD system illuminated the 
MIL or set trouble codes. Also describe any actions taken to address 
the trouble codes or MIL.
    (v) Describe any instances of misfueling, the approved actions 
taken to address the problem, and the results of any associated fuel 
sample testing.
    (b) Submission. Send electronic reports to the Designated 
Compliance Officer using an approved information format. If you want to 
use a different format, send us a written request with justification.
    (1) You may send us reports as you complete testing for an engine 
instead of waiting until you complete testing for all engines.
    (2) We may ask you to send us less information in your reports than 
we specify in this section.
    (3) We may require you to send us more information to evaluate 
whether your engine family meets the requirements of this part.
    (4) Once you send us information under this section, you need not 
send that information again in later reports.
    (c) Additional notifications. Notify the Designated Compliance 
Officer describing progress toward completing the required testing and 
reporting under this subpart, as follows:
    (1) Notify us once you complete testing for an engine.
    (2) Notify us if your review of the test data for an engine family 
indicates that two of the first five tested engines have failed to 
comply with the vehicle-pass criteria in Sec.  1036.420(d).
    (3) Notify us if your review of the test data for an engine family 
indicates that the engine family does not comply with the family-pass 
criteria in Sec.  1036.425(c).
    (4) Describe any voluntary vehicle/engine emission evaluation 
testing you

[[Page 17690]]

intend to conduct with PEMS on the same engine families that are being 
tested under this subpart, from the time that engine family was 
selected for field testing under Sec.  1036.405 until the final results 
of all testing for that engine family are reported to us under this 
section.


Sec.  1036.435  Recordkeeping requirements.

    Keep the following paper or electronic records of your field 
testing for five years after you complete all the testing required for 
an engine family:
    (a) Keep a copy of the reports described in Sec.  1036.430.
    (b) Keep any additional records, including forms you create, 
related to any of the following:
    (1) The recruitment, screening, and selection process described in 
Sec.  1036.410, including the vehicle owner's name, address, phone 
number, and email address.
    (2) Pre-test maintenance and adjustments to the engine performed 
under Sec.  1036.415.
    (3) Test results for all void, incomplete, and voluntary testing 
described in Sec.  1036.430.
    (4) Evaluations to determine why a vehicle failed any of the bin 
standards described in Sec.  1036.420.
    (c) Keep a copy of the relevant calibration results required by 40 
CFR part 1065.


Sec.  1036.440  Warranty obligations related to in-use testing.

    Testing under this subpart that finds an engine exceeding emission 
standards under this subpart is not by itself sufficient to show a 
breach of warranty under 42 U.S.C. 7541(a)(1). A breach of warranty 
would also require one of the following:
    (a) That the engine or vehicle, as designed, built, and equipped at 
the time of sale, does not conform in all material respects reasonably 
related to emission controls to the engine as described in the 
application for certification and covered by the certificate.
    (b) A defect in a component's materials or workmanship causes the 
vehicle or engine to fail to conform to the applicable regulations for 
its useful life.

Subpart F--Test Procedures


Sec.  1036.501  General testing provisions.

    (a) Use the equipment and procedures specified in this subpart and 
40 CFR part 1065 to determine whether engines meet the emission 
standards in Sec. Sec.  1036.104 and 1036.108.
    (b) You may use special or alternate procedures to the extent we 
allow them under 40 CFR 1065.10.
    (c) This subpart is addressed to you as a manufacturer, but it 
applies equally to anyone who does testing for you, and to us when we 
perform testing to determine if your engines meet emission standards.
    (d) For engines that use aftertreatment technology with infrequent 
regeneration events, apply infrequent regeneration adjustment factors 
as described in Sec.  1036.522.
    (e) Determine engine fuel maps as described in Sec.  1036.503(b).
    (f) If your engine is intended for installation in a vehicle 
equipped with stop-start technology, you may turn the engine off during 
idle portions of the duty cycle to represent in-use operation. We 
recommend installing a production engine starter motor and allowing the 
engine's ECM to manipulate the starter motor to control the engine stop 
and start events.


Sec.  1036.503  Engine data and information to support vehicle 
certification.

    You must give vehicle manufacturers information as follows so they 
can certify their vehicles to greenhouse gas emission standards under 
40 CFR part 1037:
    (a) Identify engine make, model, fuel type, combustion type, engine 
family name, calibration identification, and engine displacement. Also 
identify whether the engines meet CO2 standards for 
tractors, vocational vehicles, or both.
    (b) This paragraph (b) describes four different methods to generate 
engine fuel maps. For engines without hybrid components and for mild 
hybrid engines where you do not include hybrid components in the test, 
generate fuel maps using either paragraph (b)(1) or (2) of this 
section. For other hybrid engines, generate fuel maps using paragraph 
(b)(3) of this section. For powertrains and for vehicles where the 
transmission is not automatic, automated manual, manual, or dual-
clutch, generate fuel maps using paragraph (b)(4) of this section.
    (1) Determine steady-state engine fuel maps as described in Sec.  
1036.535(b). Determine fuel consumption at idle as described in Sec.  
1036.535(c). Determine cycle-average engine fuel maps as described in 
Sec.  1036.540, excluding cycle-average fuel maps for highway cruise 
cycles.
    (2) Determine steady-state fuel maps as described in either Sec.  
1036.535(b) or (d). Determine fuel consumption at idle as described in 
Sec.  1036.535(c). Determine cycle-average engine fuel maps as 
described in Sec.  1036.540, including cycle-average engine fuel maps 
for highway cruise cycles. We may do confirmatory testing by creating 
cycle-average fuel maps from steady-state fuel maps created in 
paragraph (b)(1) of this section for highway cruise cycles. In Sec.  
1036.540 we define the vehicle configurations for testing; we may add 
more vehicle configurations to better represent your engine's operation 
for the range of vehicles in which your engines will be installed (see 
40 CFR 1065.10(c)(1)).
    (3) Determine fuel consumption at idle as described in Sec.  
1036.535(c) and (d), and determine cycle-average engine fuel maps as 
described in 40 CFR 1037.550, including cycle-average engine fuel maps 
for highway cruise cycles.
    (4) Generate powertrain fuel maps as described in 40 CFR 1037.550 
instead of fuel mapping under Sec.  1036.535 or Sec.  1036.540. Note 
that the option in 40 CFR 1037.550(b)(2) is allowed only for hybrid 
engine testing.
    (c) Provide the following information if you generate engine fuel 
maps using either paragraph (b)(1), (2), or (3) of this section:
    (1) Full-load torque curve for installed engines and the full-load 
torque curve of the engine (parent engine) with the highest fueling 
rate that shares the same engine hardware, including the turbocharger, 
as described in 40 CFR 1065.510. You may use 40 CFR 1065.510(b)(5)(i) 
for Spark-ignition HDE. Measure the torque curve for hybrid engines 
that have an RESS as described in 40 CFR 1065.510(g)(2) with the hybrid 
system active. Test hybrid engines with no RESS as described in 40 CFR 
1065.510(b)(5)(ii).
    (2) Motoring torque curve as described in 40 CFR 1065.510(c)(2) and 
(5) for conventional and hybrid engines, respectively. For engines with 
a low-speed governor, remove data points where the low-speed governor 
is active. If you don't know when the low-speed governor is active, we 
recommend removing all points below 40 r/min above the warm low-idle 
speed.
    (3) Declared engine idle speed. For vehicles with manual 
transmissions, this is the engine speed with the transmission in 
neutral. For all other vehicles, this is the engine's idle speed when 
the transmission is in drive.
    (4) The engine idle speed during the transient cycle-average fuel 
map.
    (5) The engine idle torque during the transient cycle-average fuel 
map.
    (d) If you generate powertrain fuel maps using paragraph (b)(4) of 
this section, determine the system continuous rated power according to 
Sec.  1036.527.

[[Page 17691]]

Sec.  1036.505  Supplemental Emission Test.

    (a) Measure emissions using the steady-state SET duty cycle as 
described in this section. Note that the SET duty cycle is operated as 
a ramped-modal cycle rather than discrete steady-state test points.
    (b) Perform SET testing with one of the following procedures:
    (1) For testing nonhybrid engines, the SET duty cycle is based on 
normalized speed and torque values relative to certain maximum values. 
Denormalize speed as described in 40 CFR 1065.512. Denormalize torque 
as described in 40 CFR 1065.610(d).
    (2) Test hybrid engines and hybrid powertrains as described in 40 
CFR 1037.550, except as specified in this paragraph (b)(2). Do not 
compensate the duty cycle for the distance driven as described in 40 
CFR 1037.550(g)(4). For hybrid engines, select the transmission from 
Table 1 of Sec.  1036.540, substituting ``engine'' for ``vehicle'' and 
``highway cruise cycle'' for ``SET''. Disregard duty cycles in 40 CFR 
1037.550(j). For cycles that begin with idle, leave the transmission in 
neutral or park for the full initial idle segment. Place the 
transmission into drive no earlier than 5 seconds before the first 
nonzero vehicle speed setpoint. For SET testing only, place the 
transmission into park or neutral when the cycle reaches the final idle 
segment. Use the following vehicle parameters instead of those in 40 
CFR 1037.550 to define the vehicle model in 40 CFR 1037.550(a)(3):
    (i) Determine the vehicle test mass, M, as follows:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.022
    
Where:

Pcontrated = the continuous rated power of the hybrid 
system determined in Sec.  1036.527.

Example:

Pcontrated = 350.1 kW
M = 15.1[middot]350.1\1.31\ = 32499 kg

[[Page 17692]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.023


[[Page 17693]]



Example:

Mrotating = 0.07 [middot] 11833 = 828.3 kg

    (vii) Select a drive axle ratio, ka, that represents the 
worst-case combination of final gear ratio, drive axle ratio, and tire 
size for CO2 expected for vehicles in which the hybrid 
powertrain or hybrid engine will be installed. This is typically the 
highest axle ratio.
    (viii) Select a tire radius, r, that represents the worst-case pair 
of tire size and drive axle ratio for CO2 expected for 
vehicles in which the hybrid powertrain or hybrid engine will be 
installed. This is typically the smallest tire radius.
    (ix) If you are certifying a hybrid engine, use a default 
transmission efficiency of 0.95 and create the vehicle model along with 
its default transmission shift strategy as described in 40 CFR 
1037.550(a)(3)(ii). Use the transmission parameters defined in Table 1 
of Sec.  1036.540 to determine transmission type and gear ratio. For 
Light HDV and Medium HDV, use the Light HDV and Medium HDV parameters 
for FTP, LLC, and SET duty cycles. For Tractors and Heavy HDVs, use the 
Tractor and Heavy HDV transient cycle parameters for the FTP and LLC 
duty cycles and the Tractor and Heavy HDV highway cruise cycle 
parameters for the SET duty cycle.
    (c) Measure emissions using the SET duty cycle shown in Table 1 of 
this section to determine whether engines meet the steady-state 
compression-ignition standards specified in subpart B of this part. 
Table 1 of this section specifies test settings, as follows:
    (1) The duty cycle for testing engines (including hybrid engines) 
involves a schedule of normalized engine speed and torque values.
    (2) The duty cycle for testing hybrid powertrains involves a 
schedule of vehicle speeds and road grade as follows:
    (i) Determine road grade at each point based on the continuous 
rated power of the hybrid powertrain system, Pcontrated, in 
kW determined in Sec.  1036.527, the vehicle speed (A, B, or C) in mi/
hr for a given SET mode, vref[speed], and the specified 
road-grade coefficients using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.024

Example for SET mode 3a in Table 1 of this section:

Pcontrated = 345.2 kW
vrefB = 59.3 mi/hr
Road grade = 8.296 [middot] 10-9 [middot] 345.23 
+ (-4.752 [middot] 10-7) [middot] 345.22 [middot] 
59.3 + 1.291 [middot] 10-5 + 2.88 [middot] 10-4 
[middot] 59.32 + 4.524 [middot] 10-4 [middot] 
345.2 [middot] 59.3 + (-1.802 [middot] 10-2) [middot] 345.2 
+ (-1.83 [middot] 10-1) [middot] 59.3 + 8.81 = 0.53%

    (ii) Use the vehicle C speed determined in Sec.  1036.527. 
Determine vehicle A and B speeds as follows:
    (A) Determine vehicle A speed using the following equation:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.025
    
    (B) Determine vehicle B speed using the following equation:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.026
    
    (3) Table 1 follows:

[[Page 17694]]



                                                                               Table 1 to Paragraph (c)(3) of Sec.   1036.505--Supplemental Emission Test
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Engine testing                                                                               Hybrid powertrain testing
                                     ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
              SET mode                 Time in                                                                                                                        Road-grade coefficients
                                         mode      Engine speed \a\ \b\    Torque  (percent) \b\  Vehicle speed  (mi/hr) ---------------------------------------------------------------------------------------------------------------
                                      (seconds)                                     \c\                                         a             b             c             d             e             f             g             h
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1a Steady-state.....................        124  Warm Idle..............  0.....................  0.....................             0             0             0             0             0             0             0             0
1b Transition.......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....    -1.898E-08    -5.895E-07     3.780E-05     4.706E-03     6.550E-04    -2.679E-02    -1.027E+00     1.542E+01
2a Steady-state.....................        196  A......................  100...................  vrefA.................    -1.227E-08    -5.504E-07     3.946E-05     1.212E-03     5.289E-04    -3.116E-02    -3.227E-01     1.619E+01
2b Transition.......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....    -2.305E-09    -4.873E-07     2.535E-05     8.156E-04     4.730E-04    -2.383E-02    -2.975E-01     1.277E+01
3a Steady-state.....................        220  B......................  50....................  vrefB.................     8.296E-09    -4.752E-07     1.291E-05     2.880E-04     4.524E-04    -1.802E-02    -1.830E-01     8.810E+00
3b Transition.......................         20  B......................  Linear Transition.....  vrefB.................     4.642E-09    -5.143E-07     1.991E-05     3.556E-04     4.873E-04    -2.241E-02    -2.051E-01     1.068E+01
4a Steady-state.....................        220  B......................  75....................  vrefB.................     1.818E-10    -5.229E-07     2.579E-05     5.575E-04     5.006E-04    -2.561E-02    -2.399E-01     1.287E+01
4b Transition.......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....     5.842E-10    -4.992E-07     2.244E-05     4.700E-04     4.659E-04    -2.203E-02    -1.761E-01     1.072E+01
5a Steady-state.....................        268  A......................  50....................  vrefA.................     3.973E-09    -4.362E-07     1.365E-05     4.846E-04     4.158E-04    -1.606E-02    -1.908E-01     8.206E+00
5b Transition.......................         20  A......................  Linear Transition.....  vrefA.................    -2.788E-10    -4.226E-07     1.812E-05     6.591E-04     4.158E-04    -1.846E-02    -2.201E-01     1.001E+01
6a Steady-state.....................        268  A......................  75....................  vrefA.................    -4.216E-09    -4.891E-07     2.641E-05     8.796E-04     4.692E-04    -2.348E-02    -2.595E-01     1.226E+01
6b Transition.......................         20  A......................  Linear Transition.....  vrefA.................     3.979E-09    -4.392E-07     1.411E-05     2.079E-04     4.203E-04    -1.658E-02    -1.655E-01     7.705E+00
7a Steady-state.....................        268  A......................  25....................  vrefA.................     1.211E-08    -3.772E-07     6.209E-07     1.202E-04     3.578E-04    -8.420E-03    -1.248E-01     4.189E+00
7b Transition.......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....     1.659E-09    -4.954E-07     2.103E-05     4.849E-04     4.776E-04    -2.194E-02    -2.551E-01     1.075E+01
8a Steady-state.....................        196  B......................  100...................  vrefB.................    -8.232E-09    -5.707E-07     3.900E-05     8.150E-04     5.477E-04    -3.325E-02    -2.956E-01     1.689E+01
8b Transition.......................         20  B......................  Linear Transition.....  vrefB.................     4.286E-09    -5.150E-07     2.070E-05     5.214E-04     4.882E-04    -2.291E-02    -2.271E-01     1.157E+01
9a Steady-state.....................        196  B......................  25....................  vrefB.................     1.662E-08    -4.261E-07    -2.705E-07     2.098E-05     4.046E-04    -1.037E-02    -1.263E-01     4.751E+00
9b Transition.......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....     7.492E-09    -5.451E-07     1.950E-05     2.243E-04     5.114E-04    -2.331E-02    -2.270E-01     1.062E+01
10a Steady-state....................         28  C......................  100...................  vrefC.................    -1.073E-09    -5.904E-07     3.477E-05     5.069E-04     5.647E-04    -3.354E-02    -2.648E-01     1.651E+01
10b Transition......................         20  C......................  Linear Transition.....  vrefC.................     9.957E-09    -5.477E-07     1.826E-05     2.399E-04     5.196E-04    -2.410E-02    -2.010E-01     1.128E+01
11a Steady-state....................          4  C......................  25....................  vrefC.................     1.916E-08    -5.023E-07     3.715E-06     3.634E-05     4.706E-04    -1.539E-02    -1.485E-01     6.827E+00
11b Transition......................         20  C......................  Linear Transition.....  vrefC.................     1.474E-08    -5.176E-07     1.027E-05     1.193E-04     4.911E-04    -1.937E-02    -1.713E-01     8.872E+00
12a Steady-state....................          4  C......................  75....................  vrefC.................     6.167E-09    -5.577E-07     2.354E-05     3.524E-04     5.319E-04    -2.708E-02    -2.253E-01     1.313E+01
12b Transition......................         20  C......................  Linear Transition.....  vrefC.................     1.039E-08    -5.451E-07     1.756E-05     2.257E-04     5.165E-04    -2.366E-02    -1.978E-01     1.106E+01
13a Steady-state....................          4  C......................  50....................  vrefC.................     6.209E-09    -5.292E-07     2.126E-05     3.475E-04     5.132E-04    -2.552E-02    -2.212E-01     1.274E+01
13b Transition......................         20  Linear Transition......  Linear Transition.....  Linear Transition.....     4.461E-09    -6.452E-07     1.301E-05     1.420E-03     5.779E-04    -1.564E-02     1.949E-01     7.998E+00
14 Steady-state.....................        144  Warm Idle..............  0.....................  0.....................             0             0             0             0             0             0             0             0
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Engine speed terms are defined in 40 CFR part 1065.
\b\ Advance from one mode to the next within a 20 second transition phase. During the transition phase, command a linear progression from the settings of the current mode to the settings of the next mode.
\c\ The percent torque is relative to maximum torque at the commanded engine speed.


[[Page 17695]]

    (d) Determine criteria pollutant emissions for plug-in hybrid 
engines and powertrains as follows:
    (1) Precondition the engine or powertrain in charge-sustaining 
mode. Perform testing as described in this section for hybrid engines 
and hybrid powertrains in charge-sustaining mode.
    (2) Carry out a charge-depleting test as described in paragraph 
(d)(1) of this section, except as follows:
    (i) Fully charge the RESS after preconditioning.
    (ii) Operate the hybrid engine or powertrain continuously over 
repeated SET duty cycles until you reach the end-of-test criterion 
defined in 40 CFR 1066.501(a)(3).
    (iii) Calculate emission results for each SET duty cycle. Figure 1 
of this section provides an example of a charge-depleting test sequence 
where there are two test intervals that contain engine operation.
    (3) Report the highest emission result for each criteria pollutant 
from all tests in paragraphs (d)(1) and (2) of this section, even if 
those individual results come from different test intervals.
    (4) Figure 1 follows:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.027
    
    (e) Determine greenhouse gas pollutant emissions for plug-in hybrid 
engines and powertrains using the emissions results for all the SET 
test intervals for both charge-depleting and charge-sustaining 
operation from paragraph (d)(2) of this section. Calculate the utility 
factor-weighted composite mass of emissions from the charge-depleting 
and charge-sustaining test results, eUF[emission]comp, using 
the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.028


Where:

i = an indexing variable that represents one test interval.
N = total number of charge-depleting test intervals.
e[emission][int]CDi = total mass of emissions in the 
charge-depleting portion of the test for each test interval, i, 
starting from i = 1, including the test interval(s) from the 
transition phase.
UFDCDi = utility factor fraction at distance DCDi from 
Eq. 1036.505-11, as determined by interpolating the approved utility 
factor curve for each test interval, i, starting from i = 1. Let 
UFDCD0 = 0.
j = an indexing variable that represents one test interval.
M = total number of charge-sustaining test intervals.
e[emission][int]CSj = total mass of emissions in the 
charge-sustaining portion of the test for each test interval, j, 
starting from j = 1.
UFRCD = utility factor fraction at the full charge-
depleting distance, RCD, as determined by interpolating the approved 
utility factor curve. RCD is the cumulative distance driven over N 
charge-depleting test intervals.
[GRAPHIC] [TIFF OMITTED] TP28MR22.029


Where:

k = an indexing variable that represents one recorded velocity 
value.
Q = total number of measurements over the test interval.
v = vehicle velocity at each time step, k, starting from k = 1. For 
tests completed under this section, v is the vehicle

[[Page 17696]]

velocity from the vehicle model in 40 CFR 1037.550. Note that this 
should include charge-depleting test intervals that start when the 
engine is not yet operating.
[Delta]t = 1/frecord
frecord = the record rate.

Example using the charge-depletion test in Figure 1 of Sec.  
1036.505 for the SET for CO2 emission determination:
Q = 24000
v1 = 0 mi/hr
v2 = 0.8 mi/hr
v3 = 1.1 mi/hr
frecord = 10 Hz
[Delta]t = 1/10 Hz = 0.1 s
[GRAPHIC] [TIFF OMITTED] TP28MR22.030

DCD2 = 30.0 mi
DCD3 = 30.1 mi
DCD4 = 30.2 mi
DCD5 = 30.1 mi
N = 5
UFDCD1 = 0.11
UFDCD2 = 0.23
UFDCD3 = 0.34
UFDCD4 = 0.45
UFDCD5 = 0.53
eCO2SETCD1 = 0 g/hp[middot]hr
eCO2SETCD2 = 0 g/hp[middot]hr
eCO2SETCD3 = 0 g/hp[middot]hr
eCO2SETCD4 = 0 g/hp[middot]hr
eCO2SETCD5 = 174.4 g/hp[middot]hr
M = 1
eCO2SETCS = 428.1 g/hp[middot]hr
UFRCD = 0.53

[GRAPHIC] [TIFF OMITTED] TP28MR22.031

    (f) Calculate and evaluate cycle statistics as specified in 40 CFR 
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines 
and hybrid powertrains.
    (g) Calculate cycle work for powertrain testing using system power, 
Psys. Determine Psys, using Sec.  1036.527(e).
    (h) If you certify to the clean idle standard in Sec.  1036.104(b), 
determine the mean mass emission rate, mI[emission], in g/hr 
over the combined warm idle modes 1a and 14 of the SET duty cycle for 
HC, CO, and PM by calculating the total emission mass 
m[emission] and dividing by the total time. Note that this 
requires creating composite emission values from separate samples for 
CO and PM. These values for mI[emission] serve as emission 
standards for testing over the Clean Idle test in Sec.  1036.514. 
(Note: For plug-in hybrid engines and powertrains, use the SET results 
from the charge-sustaining or charge-depleting tests that have the 
highest emission values.)


Sec.  1036.510  Federal Test Procedure.

    (a) Measure emissions using the transient Federal Test Procedure 
(FTP) as described in this section to determine whether engines meet 
the emission standards in subpart B of this part. Operate the engine or 
hybrid powertrain over one of the following transient duty cycles:
    (1) For engines subject to spark-ignition standards, use the 
transient duty cycle described in paragraph (b) of appendix B of this 
part.
    (2) For engines subject to compression-ignition standards, use the 
transient duty cycle described in paragraph (c) of appendix B of this 
part.
    (b) The following procedures apply differently for testing engines 
and hybrid powertrains:
    (1) The transient duty cycles for nonhybrid engine testing are 
based on normalized speed and torque values. Denormalize speed as 
described in 40 CFR 1065.512. Denormalize torque as described in 40 CFR 
1065.610(d).
    (2) Test hybrid engines and hybrid powertrains as described in 
Sec.  1036.505(b)(2), with the following exceptions:
    (i) Replace Pcontrated with Prated, which is 
the peak rated power determined in Sec.  1036.527.
    (ii) Keep the transmission in drive for all idle segments after the 
initial idle segment.
    (iii) For hybrid engines, select the transmission from Table 1 of 
Sec.  1036.540, substituting ``engine'' for ``vehicle''.
    (iv) For hybrid engines, you may request to change the engine-
commanded torque at idle to better represent curb idle transmission 
torque (CITT).
    (v) For plug-in hybrid engines and powertrains, test over the FTP 
in both charge-sustaining and charge-depleting operation for both 
criteria and greenhouse gas pollutant determination.
    (c) The FTP duty cycle consists of an initial run through the 
transient duty cycle from a cold start as described in 40 CFR part 
1065, subpart F, followed by a (20 1) minute hot soak with 
no engine operation, and then a final hot start run through the same 
transient duty cycle. Engine starting is part of both the cold-start 
and hot-start test intervals. Calculate the total emission mass of each 
constituent, m, and the total work, W, over each test interval as 
described in 40 CFR 1065.650. Calculate total work over each test 
interval for powertrain testing using system power, Psys. 
Determine Psys using Sec.  1036.527(e). For powertrains with 
automatic transmissions, account for and include the work produced by 
the engine from the CITT load. Calculate the official transient 
emission result from the cold-start and hot-start test intervals using 
the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.032


[[Page 17697]]


    (d) Determine criteria pollutant emissions for plug-in hybrid 
engines and powertrains as follows:
    (1) Precondition the engine or powertrain in charge-sustaining 
mode. Perform testing as described in this section for hybrid engines 
and hybrid powertrains in charge-sustaining mode.
    (2) Carry out a charge-depleting test as described in paragraph 
(d)(1) of this section, except as follows:
    (i) Fully charge the battery after preconditioning.
    (ii) Operate the hybrid engine or powertrain over one FTP duty 
cycle followed by alternating repeats of a 20-minute soak and a hot 
start test interval until you reach the end-of-test criteria defined in 
40 CFR 1066.501.
    (iii) Calculate emission results for each successive pair of test 
intervals. Calculate the emission result by treating the first of the 
two test intervals as a cold-start test. Figure 1 of this section 
provides an example of a charge-depleting test sequence where there are 
three test intervals with engine operation for two overlapping FTP duty 
cycles.
    (3) Report the highest emission result for each criteria pollutant 
from all tests in paragraphs (d)(1) and (2) of this section, even if 
those individual results come from different test intervals.
    (4) Figure 1 follows:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.033
    
    (e) Determine greenhouse gas pollutant emissions for plug-in hybrid 
engines and powertrains using the emissions results for all the 
transient duty cycle test intervals described in either paragraph (b) 
or (c) of appendix B of this part for both charge-depleting and charge-
sustaining operation from paragraph (d)(2) of this section. Calculate 
the utility factor weighted composite mass of emissions from the 
charge-depleting and charge-sustaining test results, 
eUF[emission]comp, as described in Sec.  1036.505(e), 
replacing occurances of ``SET'' with ``transient test interval''. Note 
this results in composite FTP GHG emission results for plug-in hybrid 
engines and powertrains without the use of the cold-start and hot-start 
test interval weighting factors in Eq. 1036.510-1.
    (f) Calculate and evaluate cycle statistics as specified in 40 CFR 
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines 
and hybrid powertrains.
    (g) If you certify to the clean idle standard in Sec.  1036.104(b), 
determine the mean mass emission rate, mI[emission], in g/hr 
over the idle segments of the FTP duty cycle for HC, CO, and PM by 
calculating the total emission mass m[emission] and dividing 
by the total time. Note that this requires creating composite emission 
values from separate samples for CO and PM. These values for 
mI[emission] serve as emission standards for testing over 
the Clean Idle test in Sec.  1036.514. (Note: For plug-in hybrid 
engines and powertrains, use the FTP results from the charge-sustaining 
or charge-depleting tests that have the highest emission values.)


Sec.  1036.512  Low Load Cycle.

    (a) Measure emissions using the transient Low Load Cycle (LLC) as 
described in this section to determine whether engines meet the LLC 
emission standards in Sec.  1036.104.
    (b) The operating profile for the LLC is in paragraph (d) of 
appendix B of this part. The following procedures apply differently for 
testing engines and hybrid powertrains:
    (1) For engine testing, the duty cycle is based on normalized speed 
and torque values.
    (i) Denormalize speed as described in 40 CFR 1065.512. Denormalize 
torque as described in 40 CFR 1065.610(d).
    (ii) For idle segments more than 200 seconds, set reference torques 
to zero instead of CITT. This is to represent shifting the transmission 
to park or neutral at the start of the idle segment. Change the 
reference torque to CITT no earlier than 5 seconds before the end of 
the idle segment. This is to represent shifting the transmission to 
drive.
    (2) Test hybrid powertrains as described in Sec.  1036.505(b)(2), 
with the following exceptions:
    (i) Replace Pcontrated with Prated, which is 
the peak rated power determined in Sec.  1036.527.
    (ii) Keep the transmission in drive for all idle segments 200 
seconds or less. For idle segments more than 200 seconds, place the 
transmission in park or neutral at the start of the idle segment and 
place the transmission into drive

[[Page 17698]]

again no earlier than 5 seconds before the first nonzero vehicle speed 
setpoint.
    (3) For gaseous-fueled engine testing with a single-point fuel 
injection system, you may apply all the statistical criteria in Sec.  
1036.540(d)(3) to validate the LLC.
    (c) Set dynamometer torque demand such that vehicle power 
represents an accessory load for all idle operation as described in 
Table 1 of paragraph (c)(4) of this section for each primary intended 
service class. Additional provisions related to accessory load apply 
for the following special cases:
    (1) For engines with stop-start technology, account for accessory 
load during engine-off conditions by determining the total engine-off 
power demand over the test interval and distributing that load over the 
engine-on portions of the test interval based on calculated average 
power. You may determine the engine-off time by running practice cycles 
or through engineering analysis.
    (2) Apply accessory loads for hybrid powertrain testing that 
includes the transmission either as a mechanical or electrical load.
    (3) You may apply the following deviations from specified torque 
settings for smoother idle (other than idle that includes motoring), or 
you may develop different procedures for adjusting accessory load at 
idle consistent with good engineering judgment:
    (i) Set the reference torque to correspond to the applicable 
accessory load for all points with normalized speed at or below zero 
percent and reference torque from zero up to the torque corresponding 
to the accessory load.
    (ii) Change the reference torques to correspond to the applicable 
accessory load for consecutive points with reference torques from zero 
up to the torque corresponding to the accessory load that immediately 
precedes or follows idle points.
    (4) Table 1 follows:

 Table 1 to Paragraph (c)(4) of Sec.   1036.512--Accessory Load at Idle
------------------------------------------------------------------------
                                                               Power
                                                           representing
             Primary intended service class               accessory load
                                                               (kW)
------------------------------------------------------------------------
Light HDE...............................................             1.5
Medium HDE..............................................             2.5
Heavy HDE...............................................             3.5
------------------------------------------------------------------------

    (d) The transient test sequence consists of preconditioning the 
engine by running one or two FTPs with each FTP followed by (20 1) minutes with no engine operation and running the LLC. You may 
start any preconditioning FTP with a hot engine. Perform testing as 
described in 40 CFR 1065.530 for a test interval that includes engine 
starting. Calculate the total emission mass of each constituent, m, and 
the total work, W, as described in 40 CFR 1065.650.
    (e) Determine criteria pollutant and greenhouse gas emissions for 
plug-in hybrid engines and powertrains as described in Sec.  
1036.505(d) and (e), replacing ``SET'' with ``LLC''.
    (f) Calculate and evaluate cycle statistics as specified in 40 CFR 
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines 
and hybrid powertrains.


Sec.  1036.514  Clean Idle test.

    Measure emissions using the procedures described in this section to 
determine whether engines and hybrid powertrains meet the clean idle 
emission standards in Sec.  1036.104(b). For plug-in hybrid engines and 
powertrains, perform the test with the hybrid function disabled.
    (a) The clean idle test consists of two separate test intervals as 
follows:
    (1) Mode 1 consists of engine operation with a speed setpoint at 
your recommended warm idle speed. Set the dynamometer torque demand 
corresponding to vehicle power requirements at your recommended warm 
idle speed that represent in-use operation.
    (2) Mode 2 consists of engine operation with a speed setpoint at 
1100 r/min. Set the dynamometer torque demand to account for the sum of 
the following power loads:
    (i) Determine power requirements for idling at 1100 r/min.
    (ii) Apply a power demand of 2 kW to account for appliances and 
accessories the vehicle operator may use during rest periods.
    (3) Determine torque demand for testing under this paragraph (a) 
based on an accessory load that includes the engine cooling fan, 
alternator, coolant pump, air compressor, engine oil and fuel pumps, 
and any other engine accessory that operates at the specific test 
condition. Also include the accessory load from the air conditioning 
compressor operating at full capacity for Mode 2. Do not include any 
other load for air conditioning or other cab or vehicle accessories 
except as specified.
    (b) Perform the Clean Idle test as follows:
    (1) Warm up the engine by operating it over the FTP or SET duty 
cycle, or by operating it at any speed above peak-torque speed and at 
(65 to 85) % of maximum mapped power. The warm-up is complete when the 
engine thermostat controls engine temperature or when the engine 
coolant's temperature is within 2% of its mean value for at least 2 
minutes.
    (2) Start operating the engine in Mode 1 as soon as practical after 
the engine warm-up is complete.
    (3) Start sampling emissions 10 minutes after reaching the speed 
and torque setpoints and continue emission sampling and engine 
operation at those setpoints. Stop emission sampling after 1200 seconds 
to complete the test interval.
    (4) Linearly ramp the speed and torque setpoints over 5 seconds to 
start operating the engine in Mode 2. Sample emissions during Mode 2 as 
described in paragraph (b)(3) of this section.
    (c) Verify that the test speed stays within 50 r/min of 
the speed setpoint throughout the test. The torque tolerance is 2 percent of the maximum mapped torque at the test speed. Verify 
that measured torque meets the torque tolerance relative to the torque 
setpoint throughout the test.
    (d) Calculate the mean mass emission rate of NOX, HC, 
CO, and PM, mi[emission] over each test interval by 
calculating the total emission mass m[emission] and dividing 
by the total time.


Sec.  1036.515  Test procedures for off-cycle testing.

    (a) General. This section describes the measurement and calculation 
procedures to perform field testing under subpart E of this part. Use 
good engineering judgment if you use these procedures to simulate 
vehicle operation in the laboratory.
    (b) Emission measurement. Set up the vehicle for testing with a 
portable emissions measurement system (PEMS) as specified in 40 CFR 
part 1065, subpart J. Measure emissions over one or more shift-days as 
specified in subpart E of this part. Collect data using moving average 
windows as follows:
    (1) Start the engine at the beginning of the shift-day only after 
confirming that engine coolant temperature is at or below 30 [deg]C and 
that all measurement systems are activated as described in 40 CFR 
1065.935(c)(3). Start emission sampling just before starting the 
engine.
    (2) Determine the test interval as follows:
    (i) For Light HDE, Medium HDE, and Heavy HDE, establish a test 
interval for every 300 second moving average window until key-off. 
Create each new window starting 1 second after the start of the 
previous window. Note that most 1 Hz data points will be included in 
300 windows.

[[Page 17699]]

    (ii) For Spark-ignition HDE, your test interval is the entire 
shift-day except for data excluded under paragraph (c) of this section.
    (3) For Light HDE, Medium HDE, and Heavy HDE, create windows as 
follows if you exclude data under paragraph (c) of this section:
    (i) For excluded blocks of data that are less than 300 seconds 
long, create 300 second moving average windows that include operation 
before and after the excluded portion. The resulting windows might 
include multiple interruptions less than 300 seconds long that may 
total more than 300 seconds.
    (ii) For excluded blocks of data that are 300 seconds or longer, 
discontinue windows at the start of the excluded portion. Create new 
300 second moving average windows following the excluded portion, like 
at the start of the shift-day.
    (c) Exclusions. Exclude the following shift-day data:
    (1) Data collected during the PEMS zero and span drift checks or 
zero and span calibrations. Emissions analyzers are not available to 
measure emissions during that time and these checks/calibrations are 
needed to ensure the robustness of the data.
    (2) Data collected where the engine is off, including engine off 
due to automated start/stop.
    (3) Data collected during infrequent regeneration events. The data 
collected for the test order may not collect enough operation during 
the infrequent regeneration to properly weight the emissions rates 
during an infrequent regeneration event with emissions that occur 
without an infrequent regeneration event.
    (4) Data collected where the instantaneous ambient air temperature 
is below -7 [deg]C or above the value in degrees Celsius calculated 
using Eq. 1036.515-1. Colder temperatures can significantly inhibit the 
engine's ability to maintain aftertreatment temperature above the 
minimum operating temperature of the SCR catalyst while high 
temperature conditions at altitude can adversely affect (limit) the 
mass airflow through the engine, which can affect the engine's ability 
to reduce engine out NOX through the use of EGR. In addition 
to affecting EGR, the air-fuel ratio of the engine can decrease under 
high load, which can increase exhaust temperatures above the condition 
where the SCR catalyst is most efficient at reducing NOX.
[GRAPHIC] [TIFF OMITTED] TP28MR22.034

Where:

h = instantaneous altitude in feet above sea level (h is negative 
for altitudes below sea-level).

    (5) Data collected where the altitude more than 5,500 feet above 
sea level for the same reasons given for the high temperature at 
altitude exclusion in paragraph (c)(4) of this section.
    (6) If your engine family includes engines with one or more 
approved AECDs for emergency vehicle applications under Sec.  
1036.115(h)(4), any data where these AECDs are active because the 
engines are allowed to exceed the emission standards when these AECDs 
are active. Do not exclude data for any other AECDs.
    (d) Mean mass percent of CO2 from normalized CO2 rate. For Light 
HDE, Medium HDE, and Heavy HDE, determine the mean mass percent of 
CO2 of a window, wCO2win, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.035

Where:

miCO2win = mean mass rate of CO2 over the 
valid window.
mCO2max = eCO2FTPFCL [middot] Pmax
eCO2FTPFCL = the engine's FTP FCL CO2 emission 
value.
Pmax = the engine family's maximum power determined 
according to the torque mapping test procedure defined in 40 CFR 
1065.510.

Example:

miCO2win = 13.16 g/s = 47368 g/hr
eCO2FTPFCL = 428.2 g/hp[middot]hr
Pmax = 406.5 hp
mCO2max = 428.2 [middot] 406.5 = = 174063 g/hr
[GRAPHIC] [TIFF OMITTED] TP28MR22.036

    (e) Binning. For Light HDE, Medium HDE, and Heavy HDE, segregate 
test results from each 300 second window over the shift-day based on 
its mean mass percent of CO2 into one of the following bins:

 Table 1 to paragraph (e) of Sec.   1036.515--Criteria for Off-Cycle Bin
                                  Types
------------------------------------------------------------------------
                    Bin                       Mean mass percent of CO2
------------------------------------------------------------------------
Idle......................................  wCO2win <= 6%.
Low load..................................  6% < wCO2win <= 20%.
Medium/high load..........................  wCO2win > 20%.
------------------------------------------------------------------------

    (f) Window emission values. For Light HDE, Medium HDE, and Heavy 
HDE, determine the emission mass for a given window, 
m[emission]win, for CO2 and other measured 
emissions using the following equation:

[[Page 17700]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.037

Where:

i = an indexing variable that represents one recorded emission 
value.
N = total number of measurements in the window.
m[emission] = mass emission rate at a point in time 
within a given window.
[Delta]t = 1/[fnof]record
[fnof]record = the record rate.

Example:

N = 300
mNOx1 = 0.0179 g/s
mNOx2 = 0.0181 g/s
[fnof]record = 1 Hz
[Delta]t = 1/1 Hz = 1 s
mNOxwin = (0.0179 + 0.0181+ . . . +mNOx300) 
[middot] 1 = 5.46 g

    (g) Bin emission values. For Light HDE, Medium HDE, and Heavy HDE, 
determine the emission value for each bin, which may include 
measurement windows from multiple vehicles.
    (1) Determine the sum of the NOX emissions from each 
window for the idle bin, eNOxidle, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.038

Where:

i = an indexing variable that represents one window.
N = total number of windows in the bin.
mNOxidlewin = total mass of NOX emissions for 
a given window as determined in paragraph (f) of this section.
ti = duration for a given window = 300 seconds.

Example:

N = 10114
mNOxidlewin1 = 0.021 g
mNOxidlewin2 = 0.025 g
t1 = 300 s
t2 = 300 s

[GRAPHIC] [TIFF OMITTED] TP28MR22.039

    (2) Determine the sum of mass emissions from each window over the 
sum of CO2 emissions from each window for the low load and 
medium high load bins, esos[emission][bin], for each 
measured pollutant using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.040

Where:

i = an indexing variable that represents mass emissions from one 
window.
N = total number of windows in the bin.
m[emission][bin]win = sum of mass for each emission for a 
given window and bin as determined in paragraph (f) of this section.
mCO2[bin]win = sum of mass for CO2 for a given 
window and bin as determined in paragraph (f) of this section.
eCO2FTPFCL = the FCL value for CO2 emissions 
over the FTP duty cycle identified in the engine family's 
application for certification.

Example:

    N = 15439
mNOxmediumhighloadwin1 = 0.546 g
mNOxmediumhighloadwin2 = 0.549 g
mCO2mediumhighloadwin1 = 10950.2 g
mCO2mediumhighloadwin2 = 10961.3 g
eCO2 FTPFCL = 428.1 g/hp[middot]hr
[GRAPHIC] [TIFF OMITTED] TP28MR22.041

    (h) Shift-day emission values for spark-ignition engines. For 
spark-ignition engines, determine the shift-day emission values as 
follows:
    (1) Determine the emission mass for a shift-day, 
m[emission]shift, for each measured pollutant and 
CO2 using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.042


[[Page 17701]]


Where:

i = an indexing variable that represents one recorded emission 
value.
N = total number of measurements in the shift-day.
m[emission] = mass emission rate at a point in time 
within a given shift-day.
    [Delta]t = 1/[fnof]record
    [fnof]record = the record rate.

Example:

N = 24543
mNOx1 = 0.0187 g/s
mNOx2 = 0.0191 g/s
[fnof]record = 1 Hz
[Delta]t = 1/1 Hz = 1 s
mNOxshift = (0.0187 + 0.0191 + . . . + 
mNOX24543)= [middot] 1 = 1.337 g

    (2) Determine the sum of mass emissions from the shift day over the 
sum of CO2 emissions from the shift day, 
esos[emission]shift, for each measured pollutant using the 
following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.043

Where:

m[emission]shift = sum of mass for each emission for the 
shift day as determined in paragraph (h)(1) of this section.
mCO2shift = sum of mass for CO2 for the shift 
day as determined in paragraph (h)(1) of this section.
    eCO2FTPFCL = the FCL value for CO2 
emissions over the FTP duty cycle identified in the engine family's 
application for certification.

Example:

mNOxshift = 1.337 g
mCO2shift = 18778 g
eCO2 FTPFCL = 505.1 g/hp[middot]hr
[GRAPHIC] [TIFF OMITTED] TP28MR22.044

Sec.  1036.520  Test procedures to verify deterioration factors.

    Sections 1036.240 through 1036.246 describe certification 
procedures to determine, verify, and apply deterioration factors. This 
section describes the measurement procedures for verifying 
deterioration factors using PEMS or onboard NOX sensors with 
in-use vehicles.
    (a) Use PEMS or onboard NOX sensors to collect 1 Hz data 
throughout a shift-day of driving. Collect all the data elements needed 
to determine brake-specific emissions. Calculate emission results using 
moving average windows as described in Sec.  1036.515.
    (b) Collect data as needed to perform the calculations specified in 
paragraph (a) of this section and to submit the test report specified 
in Sec.  1036.246(f).


Sec.  1036.522  Infrequently regenerating aftertreatment devices.

    For engines using aftertreatment technology with infrequent 
regeneration events that may occur during testing, take one of the 
following approaches to account for the emission impact of regeneration 
on criteria pollutant and greenhouse gas emissions:
    (a) You may use the calculation methodology described in 40 CFR 
1065.680 to adjust measured emission results. Do this by developing an 
upward adjustment factor and a downward adjustment factor for each 
pollutant based on measured emission data and observed regeneration 
frequency as follows:
    (1) Adjustment factors should generally apply to an entire engine 
family, but you may develop separate adjustment factors for different 
configurations within an engine family. Use the adjustment factors from 
this section for all testing for the engine family.
    (2) You may use carryover data to establish adjustment factors for 
an engine family as described in Sec.  1036.235(d), consistent with 
good engineering judgment.
    (3) Identify the value of F[cycle] in each application 
for the certification for which it applies.
    (4) Calculate separate adjustment factors for each required duty 
cycle.
    (b) You may ask us to approve an alternate methodology to account 
for regeneration events. We will generally limit approval to cases 
where your engines use aftertreatment technology with extremely 
infrequent regeneration and you are unable to apply the provisions of 
this section.
    (c) You may choose to make no adjustments to measured emission 
results if you determine that regeneration does not significantly 
affect emission levels for an engine family (or configuration) or if it 
is not practical to identify when regeneration occurs. You may omit 
adjustment factors under this paragraph (c) for N2O, 
CH4, or other individual pollutants under this paragraph (c) 
as appropriate. If you choose not to make adjustments under paragraph 
(a) or (b) of this section, your engines must meet emission standards 
for all testing, without regard to regeneration.


Sec.  1036.527  Powertrain system rated power determination.

    This section describes how to determine the peak and continuous 
rated power of conventional and hybrid powertrain systems and the 
vehicle speed for carrying out testing according to Sec. Sec.  1036.505 
and 1036.510 and 40 CFR 1037.550.
    (a) Set up the powertrain according to 40 CFR 1037.550, but use the 
vehicle parameters in Sec.  1036.505(b)(2), except replace 
Pcontrated with the manufacturer declared system peak power 
and use applicable automatic transmission for the engine. Note that if 
you repeat the system rated power determination as described in 
paragraph (f)(4) of this section, use the measured system peak power in 
place of Pcontrated.
    (b) Prior to the start of each test interval verify the following:
    (1) The state-of-charge of the rechargeable energy storage system 
(RESS) is >= 90% of the operating range between the minimum and maximum 
RESS energy levels specified by the manufacturer.
    (2) The conditions of all hybrid system components are within their 
normal operating range as declared by the manufacturer.
    (3) RESS restrictions (e.g., power limiting, thermal limits, etc.) 
are not active.
    (c) Carry out the test as follows:
    (1) Warm up the powertrain by operating it. We recommend operating 
the powertrain at any vehicle speed and road grade that achieves 
approximately 75% of its expected maximum power.

[[Page 17702]]

Continue the warm-up until the engine coolant, block, or head absolute 
temperature is within 2% of its mean value for at least 2 
min or until the engine thermostat controls engine temperature.
    (2) Once warmup is complete, bring the vehicle speed to 0 mi/hr and 
start the test by operating the powertrain at 0 mi/hr for 50 seconds.
    (3) Set maximum driver demand for a full load acceleration at 6% 
road grade with an initial vehicle speed of 0 mi/hr. After 268 seconds, 
linearly ramp the grade from 6% down to 0% over 300 seconds. Stop the 
test after the vehicle speed has reached a maximum value.
    (d) Record the powertrain system angular speed and torque values 
measured at the dynamometer at 100 Hz and use these in conjunction with 
the vehicle model to calculate Psys,vehicle.
    (e) Calculate the system power, Psys, for each data 
point as follows:
    (1) For testing with the speed and torque measurements at the 
transmission input shaft, Psysi is equal to the calculated 
vehicle system power, Psysi,vehicle, determined 
in paragraphs (c) and (d) of this section.
    (2) For testing with the speed and torque measurements at the axle 
input shaft or the wheel hubs, determine Psys for each data 
point using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.045

    (f) The system peak rated power, Prated, is the highest 
calculated Psys where the coefficient of variation (COV) 
<2%. The COV is determined as follows:
    (1) Calculate the standard deviation, [sigma](t).
    [GRAPHIC] [TIFF OMITTED] TP28MR22.046
    

Where:

N = the number of measurement intervals = 20.
Psysi = the N samples of Psys in the 100 Hz 
signal previously used to calculate the respective 
Psys(t) values at the time step t.
Psys(t) = the power vector from the results of each test 
run that is determined by a moving averaging of 20 consecutive 
samples of Psys in the 100 Hz that converts 
Psys(t) to a 5 Hz signal.

    (2) The resulting 5 Hz power and covariance signals are used to 
determine system rated power.
    (3) The coefficient of variation COV(t) shall be calculated as the 
ratio of the standard deviation, [sigma](t), to the mean value of 
power,Psys(t), for each time step t.
[GRAPHIC] [TIFF OMITTED] TP28MR22.047

    (4) If the determined system peak rated power is not within 3% of the system peak rated power as declared by the 
manufacturer, you must repeat the procedure in paragraphs (a) through 
(f)(3) of this section using the measured system peak rated power 
determined in this paragraph (f) instead of the manufacturer declared 
value. The result from this repeat is the final determined system peak 
rated power.
    (5) If the determined system peak rated power is within 3% of the system peak rated power as declared by the

[[Page 17703]]

manufacturer, the declared system peak rated power shall be used.
    (g) Determine continuous rated power as follows:
    (1) For conventional powertrains, Pcontrated equals 
Prated.
    (2) For hybrid powertrains, continuous rated power, 
Pcontrated, is the maximum measured power from the data 
collected in paragraph (c)(3) of this section that meets the 
requirements in paragraph (f) of this section.
    (h) Vehicle C speed, vrefC, is determined as follows:
    (1) For powertrains where Psys is greater than 
0.98[middot]Pcontrated in top gear at more than one vehicle 
speed, vrefC is the average of the minimum and maximum 
vehicle speeds from the data collected in paragraph (c)(3) of this 
section that meets the requirements in paragraph (f) of this section.
    (2) For powertrains where Psys is less than 
0.98[middot]Pcontrated in top gear at more than one vehicle 
speed, vrefC is the maximum vehicle speed from the data 
collected in paragraph (c)(3) of this section that meets the 
requirements in paragraph (f) of this section where Psys is 
greater than 0.98[middot]Pcontrated.


Sec.  1036.530  Calculating greenhouse gas emission rates.

    This section describes how to calculate official emission results 
for CO2, CH4, and N2O.
    (a) Calculate brake-specific emission rates for each applicable 
duty cycle as specified in 40 CFR 1065.650. Apply infrequent 
regeneration adjustment factors as described in Sec.  1036.522.
    (b) Adjust CO2 emission rates calculated under paragraph 
(a) of this section for measured test fuel properties as specified in 
this paragraph (b). This adjustment is intended to make official 
emission results independent of differences in test fuels within a fuel 
type. Use good engineering judgment to develop and apply testing 
protocols to minimize the impact of variations in test fuels.
    (1) Determine your test fuel's mass-specific net energy content, 
Emfuelmeas, also known as lower heating value, in MJ/kg, 
expressed to at least three decimal places. Determine 
Emfuelmeas as follows:
    (i) For liquid fuels, determine Emfuelmeas according to 
ASTM D4809 (incorporated by reference in Sec.  1036.810). Have the 
sample analyzed by at least three different labs and determine the 
final value of your test fuel's Emfuelmeas as the median all 
of the lab results you obtained. If you have results from three 
different labs, we recommend you screen them to determine if additional 
observations are needed. To perform this screening, determine the 
absolute value of the difference between each lab result and the 
average of the other two lab results. If the largest of these three 
resulting absolute value differences is greater than 0.297 MJ/kg, we 
recommend you obtain additional results prior to determining the final 
value of Emfuelmeas.
    (ii) For gaseous fuels, determine Emfuelmeas according 
to ASTM D3588 (incorporated by reference in Sec.  1036.810).
    (2) Determine your test fuel's carbon mass fraction, wC, 
as described in 40 CFR 1065.655(d), expressed to at least three decimal 
places; however, you must measure fuel properties rather than using the 
default values specified in Table 1 of 40 CFR 1065.655.
    (i) For liquid fuels, have the sample analyzed by at least three 
different labs and determine the final value of your test fuel's 
wC as the median of all of the lab results you obtained. If 
you have results from three different labs, we recommend you screen 
them to determine if additional observations are needed. To perform 
this screening, determine the absolute value of the difference between 
each lab result and the average of the other two lab results. If the 
largest of these three resulting absolute value differences is greater 
than 1.56 percent carbon, we recommend you obtain additional results 
prior to determining the final value of wC.
    (ii) For gaseous fuels, have the sample analyzed by a single lab 
and use that result as your test fuel's wC.
    (3) If, over a period of time, you receive multiple fuel deliveries 
from a single stock batch of test fuel, you may use constant values for 
mass-specific energy content and carbon mass fraction, consistent with 
good engineering judgment. To use these constant values, you must 
demonstrate that every subsequent delivery comes from the same stock 
batch and that the fuel has not been contaminated.
    (4) Correct measured CO2 emission rates as follows:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.048
    

Where:

eCO2 = the calculated CO2 emission result.
Emfuelmeas = the mass-specific net energy content of the 
test fuel as determined in paragraph (b)(1) of this section. Note 
that dividing this value by wCmeas (as is done in this 
equation) equates to a carbon-specific net energy content having the 
same units as EmfuelCref.
EmfuelCref = the reference value of carbon-mass-specific 
net energy content for the appropriate fuel type, as determined in 
Table 1 in this section.
wCmeas = carbon mass fraction of the test fuel (or 
mixture of test fuels) as determined in paragraph (b)(2) of this 
section.

Example:
eCO2 = 630.0 g/hp[middot]hr
Emfuelmeas = 42.528 MJ/kg
EmfuelCref = 49.3112 MJ/kgC
wCmeas = 0.870

[GRAPHIC] [TIFF OMITTED] TP28MR22.049

eCO2cor = 624.5 g/hp[middot]hr

                    Table 1 to Paragraph (b)(4) of Sec.   1036.530--Reference Fuel Properties
----------------------------------------------------------------------------------------------------------------
                                                                 Reference fuel carbon-
                                                                   mass-specific net      Reference fuel carbon
                         Fuel type \a\                              energy  content,       mass fraction, wCref
                                                                 EmfuelCref, (MJ/kgC) b            \b\
 
----------------------------------------------------------------------------------------------------------------
Diesel fuel...................................................                  49.3112                    0.874
Gasoline......................................................                  50.4742                    0.846
Natural Gas...................................................                  66.2910                    0.750
LPG...........................................................                  56.5218                    0.820
Dimethyl Ether................................................                  55.3886                    0.521
High-level ethanol-gasoline blends............................                  50.3211                    0.576
----------------------------------------------------------------------------------------------------------------
\a\ For fuels that are not listed, you must ask us to approve reference fuel properties.
\b\ For multi-fuel streams, such as natural gas with diesel fuel pilot injection, use good engineering judgment
  to determine blended values for EmfuelCref and wCref using the values in this table.


[[Page 17704]]

    (c) Your official emission result for each pollutant equals your 
calculated brake-specific emission rate multiplied by all applicable 
adjustment factors, other than the deterioration factor.


Sec.  1036.535  Determining steady-state engine fuel maps and fuel 
consumption at idle.

    The procedures in this section describe how to determine an 
engine's steady-state fuel map and fuel consumption at idle for model 
year 2021 and later vehicles; these procedures apply as described in 
Sec.  1036.503. Vehicle manufacturers may need these values to 
demonstrate compliance with emission standards under 40 CFR part 1037.
    (a) General test provisions. Perform fuel mapping using the 
procedure described in paragraph (b) of this section to establish 
measured fuel-consumption rates at a range of engine speed and load 
settings. Measure fuel consumption at idle using the procedure 
described in paragraph (c) of this section. Paragraph (d) of this 
section describes how to apply the steady-state mapping from paragraph 
(b) of this section for the special case of cycle-average mapping for 
highway cruise cycles as described in Sec.  1036.540. Use these 
measured fuel-consumption values to declare fuel-consumption rates for 
certification as described in paragraph (g) of this section.
    (1) Map the engine's torque curve and declare engine idle speed as 
described in Sec.  1036.503(c)(1) and (3). Perform emission 
measurements as described in 40 CFR 1065.501 and 1065.530 for discrete-
mode steady-state testing. This section uses engine parameters and 
variables that are consistent with 40 CFR part 1065.
    (2) Measure NOX emissions as described in paragraph (f) 
of this section. Include these measured NOX values any time 
you report to us your fuel consumption values from testing under this 
section.
    (3) You may use shared data across engine configurations to the 
extent that the fuel-consumption rates remain valid.
    (4) The provisions related to carbon balance error verification in 
Sec.  1036.543 apply for all testing in this section. These procedures 
are optional, but we will perform carbon balance error verification for 
all testing under this section.
    (5) Correct fuel mass flow rate to a mass-specific net energy 
content of a reference fuel as described in paragraph (e) of this 
section.
    (b) Steady-state fuel mapping. Determine steady-state fuel-
consumption rates for each engine configuration over a series of paired 
engine speed and torque setpoints as described in this paragraph (b). 
For example, if you test a high-output (parent) configuration and 
create a different (child) configuration that uses the same fueling 
strategy but limits the engine operation to be a subset of that from 
the high-output configuration, you may use the fuel-consumption rates 
for the reduced number of mapped points for the low-output 
configuration, as long as the narrower map includes at least 70 points. 
Perform fuel mapping as follows:
    (1) Generate the fuel-mapping sequence of engine speed and torque 
setpoints as follows:
    (i) Select the following required speed setpoints: Warm idle speed, 
fnidle the highest speed above maximum power at which 70% of 
maximum power occurs, nhi, and eight (or more) equally 
spaced points between fnidle and nhi. (See 40 CFR 
1065.610(c)). For engines with adjustable warm idle speed, replace 
fnidle with minimum warm idle speed fnidlemin.
    (ii) Determine the following default torque setpoints at each of 
the selected speed setpoints: Zero (T = 0), maximum mapped torque, 
Tmax mapped, and eight (or more) equally spaced points 
between T = 0 and Tmax mapped. Select the maximum torque 
setpoint at each speed to conform to the torque map as follows:
    (A) Calculate 5 percent of Tmax mapped. Subtract this 
result from the mapped torque at each speed setpoint, Tmax.
    (B) Select Tmax at each speed setpoint as a single 
torque value to represent all the default torque setpoints above the 
value determined in paragraph (b)(1)(ii)(A) of this section. All the 
default torque setpoints less than Tmax at a given speed 
setpoint are required torque setpoints.
    (iii) You may select any additional speed and torque setpoints 
consistent with good engineering judgment. For example you may need to 
select additional points if the engine's fuel consumption is nonlinear 
across the torque map. Avoid creating a problem with interpolation 
between narrowly spaced speed and torque setpoints near 
Tmax. For each additional speed setpoint, we recommend 
including a torque setpoint of Tmax; however, you may select 
torque setpoints that properly represent in-use operation. Increments 
for torque setpoints between these minimum and maximum values at an 
additional speed setpoint must be no more than one-ninth of 
Tmax,mapped. Note that if the test points were added for the 
child rating, they should still be reported in the parent fuel map. We 
will test with at least as many points as you. If you add test points 
to meet testing requirements for child ratings, include those same test 
points as reported values for the parent fuel map. For our testing, we 
will use the same normalized speed and torque test points you use, and 
we may select additional test points.
    (iv) Start fuel-map testing at the highest speed setpoint and 
highest torque setpoint, followed by decreasing torque setpoints at the 
highest speed setpoint. Continue testing at the next lowest speed 
setpoint and the highest torque setpoint at that speed setpoint, 
followed by decreasing torque setpoints at that speed setpoint. Follow 
this pattern through all the speed and torque points, ending with the 
lowest speed (fnidle or fnidlemin) and torque 
setpoint (T = 0). The following figure illustrates an array of test 
points and the corresponding run order.

[[Page 17705]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.050

    (v) The highest torque setpoint for each speed setpoint is an 
optional reentry point to restart fuel mapping after an incomplete test 
run.
    (vi) The lowest torque setpoint at each speed setpoint is an 
optional exit point to interrupt testing. Paragraph (b)(7) of this 
section describes how to interrupt testing at other times.
    (2) If the engine's warm idle speed is adjustable, set it to its 
minimum value, fnidlemin.
    (3) The measurement at each unique combination of speed and torque 
setpoints constitutes a test interval. Unless we specify otherwise, you 
may program the dynamometer to control either speed or torque for a 
given test interval, with operator demand controlling the other 
parameter. Control speed and torque so that all recorded speed points 
are within 1% of nhi from the target speed and 
all recorded engine torque points are within 5% of 
Tmax mapped from the target torque during each test 
interval, except as follows:
    (i) For steady-state engine operating points that cannot be 
achieved, and the operator demand stabilizes at minimum; program the 
dynamometer to control torque and let the engine govern speed (see 40 
CFR 1065.512(b)(1)). Control torque so that all recorded engine torque 
points are within 25 N[middot]m from the target torque. The 
specified speed tolerance does not apply for the test interval.
    (ii) For steady-state engine operating points that cannot be 
achieved and the operator demand stabilizes at maximum and the speed 
setpoint is below 90% of nhi even with maximum operator 
demand, program the dynamometer to control speed and let the engine 
govern torque (see 40 CFR 1065.512(b)(2)). The specified torque 
tolerance does not apply for the test interval.
    (iii) For steady-state engine operating points that cannot be 
achieved and the operator demand stabilizes at maximum and the speed 
setpoint is at or above 90% of nhi even with maximum 
operator demand, program the dynamometer to control torque and let the 
engine govern speed (see 40 CFR 1065.512(b)(1)). The specified speed 
tolerance does not apply for the test interval.
    (iv) For the steady-state engine operating points at the minimum 
speed setpoint and maximum torque setpoint, you may program the 
dynamometer to control speed and let the engine govern torque. The 
specified torque tolerance does not apply for this test interval if 
operator demand stabilizes at its maximum or minimum limit.
    (4) Record measurements using direct and/or indirect measurement of 
fuel flow as follows:
    (i) Direct fuel-flow measurement. Record speed and torque and 
measure fuel consumption with a fuel flow meter for (30  1) 
seconds. Determine the corresponding mean values for the test interval. 
Use of redundant direct fuel-flow measurements require prior EPA 
approval.
    (ii) Indirect fuel-flow measurement. Record speed and torque and 
measure emissions and other inputs needed to run the chemical balance 
in 40 CFR 1065.655(c) for (30  1) seconds. Determine the 
corresponding mean values for the test interval. Use of redundant 
indirect fuel-flow measurements require prior EPA approval. Measure 
background concentration as described in 40 CFR 1065.140, except that 
you may use one of the following methods to apply a

[[Page 17706]]

single background reading to multiple test intervals:
    (A) For batch sampling, you may sample periodically into the bag 
over the course of multiple test intervals and read them as allowed in 
paragraph (b)(7)(i) of this section. You must determine a single 
background reading for all affected test intervals if you use the 
method described in this paragraph (b)(4)(ii)(A).
    (B) You may measure background concentration by sampling from the 
dilution air during the interruptions allowed in paragraph (b)(7)(i) of 
this section or at other times before or after test intervals. Measure 
background concentration within 30 minutes before the first test 
interval and within 30 minutes before each reentry point. Measure the 
corresponding background concentration within 30 minutes after each 
exit point and within 30 minutes after the final test interval. You may 
measure background concentration more frequently. Correct measured 
emissions for test intervals between a pair of background readings 
based on the average of those two values. Once the system stabilizes, 
collect a background sample over an averaging period of at least 30 
seconds.
    (5) Warm up the engine as described in 40 CFR 1065.510(b)(2). 
Within 60 seconds after concluding the warm-up, linearly ramp the speed 
and torque setpoints over 5 seconds to the starting test point from 
paragraph (b)(1) of this section.
    (6) Stabilize the engine by operating at the specified speed and 
torque setpoints for (70  1) seconds and then start the 
test interval. Record measurements during the test interval. Measure 
and report NOX emissions over each test interval as 
described in paragraph (f) of this section.
    (7) After completing a test interval, linearly ramp the speed and 
torque setpoints over 5 seconds to the next test point.
    (i) You may interrupt the fuel-mapping sequence before a reentry 
point as noted in paragraphs (b)(1)(v) and (vi) of this section. If you 
zero and span analyzers, read and evacuate background bag samples, or 
sample dilution air for a background reading during the interruption, 
the maximum time to stabilize in paragraph (b)(6) of this section does 
not apply. If you shut off the engine, restart with engine warm-up as 
described in paragraph (b)(5) of this section.
    (ii) You may interrupt the fuel-mapping sequence at a given speed 
setpoint before completing measurements at that speed. If this happens, 
you may measure background concentration and take other action as 
needed to validate test intervals you completed before the most recent 
reentry point. Void all test intervals after the last reentry point. 
Restart testing at the appropriate reentry point in the same way that 
you would start a new test. Operate the engine long enough to stabilize 
aftertreatment thermal conditions, even if it takes more than 70 
seconds. In the case of an infrequent regeneration event, interrupt the 
fuel-mapping sequence and allow the regeneration event to finish with 
the engine operating at a speed and load that allows effective 
regeneration.
    (iii) If you void any one test interval, all the testing at that 
speed setpoint is also void. Restart testing by repeating the fuel-
mapping sequence as described in this paragraph (b);

include all voided speed setpoints and omit testing at speed setpoints 
that already have a full set of valid results.
    (8) If you determine fuel-consumption rates using emission 
measurements from the raw or diluted exhaust, calculate the mean fuel 
mass flow rate, mifuel, for each point in the fuel map using 
the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.051

Where:

mifuel = mean fuel mass flow rate for a given fuel map 
setpoint, expressed to at least the nearest 0.001 g/s.
MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of test 
fuels) as determined in 40 CFR 1065.655(d), except that you may not 
use the default properties in Table 2 of 40 CFR 1065.655 to 
determine [alpha], [beta], and wC. You may not account 
for the contribution to [alpha], [beta], [gamma], and [delta] of 
diesel exhaust fluid or other non-fuel fluids injected into the 
exhaust.
niexh = the mean raw exhaust molar flow rate from which 
you measured emissions according to 40 CFR 1065.655.
xCcombdry = the mean concentration of carbon from fuel 
and any injected fluids in the exhaust per mole of dry exhaust as 
determined in 40 CFR 1065.655(c).
xH2Oexhdry = the mean concentration of H2O in 
exhaust per mole of dry exhaust as determined in 40 CFR 1065.655(c).
miCO2DEF = the mean CO2 mass emission rate 
resulting from diesel exhaust fluid decomposition as determined in 
paragraph (b)(9) of this section. If your engine does not use diesel 
exhaust fluid, or if you choose not to perform this correction, set 
miCO2DEF equal to 0.
MCO2 = molar mass of carbon dioxide.

Example:

MC = 12.0107 g/mol
wCmeas = 0.869
niexh = 25.534 mol/s
xCcombdry = 0.002805 mol/mol
xH2Oexhdry = 0.0353 mol/mol
miCO2DEF = 0.0726 g/s
MCO2 = 44.0095 g/mol
[GRAPHIC] [TIFF OMITTED] TP28MR22.052

    (9) If you determine fuel-consumption rates using emission 
measurements with engines that utilize diesel exhaust fluid for 
NOX control and you correct for the mean CO2 mass 
emission rate resulting from diesel exhaust fluid decomposition as 
described in paragraph (b)(8) of this section, perform this correction 
at each fuel map setpoint using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.053

Where:

miDEF = the mean mass flow rate of injected urea solution 
diesel exhaust fluid for a

[[Page 17707]]

given sampling period, determined directly from the ECM, or measured 
separately, consistent with good engineering judgment.
MCO2 = molar mass of carbon dioxide.
wCH4N2O = mass fraction of urea in diesel exhaust fluid 
aqueous solution. Note that the subscript ``CH4N2O'' refers to urea 
as a pure compound and the subscript ``DEF'' refers to the aqueous 
urea diesel exhaust fluid as a solution of urea in water. You may 
use a default value of 32.5% or use good engineering judgment to 
determine this value based on measurement.
MCH4N2O = molar mass of urea.

Example:

miDEF = 0. 304 g/s
MCO2 = 44.0095 g/mol
wCH4N2O = 32.5% = 0.325
MCH4N2O = 60.05526 g/mol
[GRAPHIC] [TIFF OMITTED] TP28MR22.054

    (c) Fuel consumption at idle. Determine fuel-consumption rates at 
idle for each engine configuration that is certified for installation 
in vocational vehicles. Determine fuel-consumption rates at idle by 
testing engines over a series of paired engine speed and torque 
setpoints as described in this paragraph (c). Perform measurements as 
follows:
    (1) The idle test sequence consists of measuring fuel consumption 
at four test points representing each combination of the following 
speed and torque setpoints in any order.
    (i) Speed setpoints for engines with adjustable warm idle speed are 
minimum warm idle speed, fnidlemin, and maximum warm idle 
speed, fnidlemax. Speed setpoints for engines with no 
adjustable warm idle speed (with zero torque on the primary output 
shaft) are fnidle and 1.15 times fnidle.
    (ii) Torque setpoints are 0 and 100 N [middot] m.
    (2) Control speed and torque as follows:
    (i) Adjustable warm idle speed. Set the engine's warm idle speed to 
the next speed setpoint any time before the engine reaches the next 
test point. Control both speed and torque when the engine is warming up 
and when it is transitioning to the next test point. Start to control 
both speed and torque. At any time prior to reaching the next engine-
idle operating point, set the engine's adjustable warm idle speed 
setpoint to the speed setpoint of the next engine-idle operating point 
in the sequence. This may be done before or during the warm-up or 
during the transition. Near the end of the transition period control 
speed and torque as described in paragraph (b)(3)(i) of this section 
shortly before reaching each test point. Once the engine is operating 
at the desired speed and torque setpoints, set the operator demand to 
minimum; control torque so that all recorded engine torque points are 
within 25 N[middot]m from the target torque.
    (ii) Nonadjustable warm idle speed. For the lowest speed setpoint, 
control speed and torque as described in paragraph (c)(2)(i) of this 
section, except for adjusting the warm idle speed. For the second-
lowest speed setpoint, control speed and torque so that all recorded 
speed points are within 1% of nhi from the 
target speed and engine torque within 5% of 
Tmax mapped from the target torque.
    (3) Record measurements using direct and/or indirect measurement of 
fuel flow as follows:
    (i) Direct fuel flow measurement. Record speed and torque and 
measure fuel consumption with a fuel flow meter for (600 1) 
seconds. Determine the corresponding mean values for the test interval. 
Use of redundant direct fuel-flow measurements require prior EPA 
approval.
    (ii) Indirect fuel flow measurement. Record speed and torque and 
measure emissions and other inputs needed to run the chemical balance 
in 40 CFR 1065.655(c) for (600 1) seconds. Determine the 
corresponding mean values for the test interval. Use of redundant 
indirect fuel-flow measurements require prior EPA approval. Measure 
background concentration as described in paragraph (b)(4)(ii) of this 
section. We recommend setting the CVS flow rate as low as possible to 
minimize background, but without introducing errors related to 
insufficient mixing or other operational considerations. Note that for 
this testing 40 CFR 1065.140(e) does not apply, including the minimum 
dilution ratio of 2:1 in the primary dilution stage.
    (4) Warm up the engine as described in 40 CFR 1065.510(b)(2). 
Within 60 seconds after concluding the warm-up, linearly ramp the speed 
and torque over 20 seconds to the first speed and torque setpoint.
    (5) The measurement at each unique combination of speed and torque 
setpoints constitutes a test interval. Operate the engine at the 
selected speed and torque set points for (180 1) seconds, 
and then start the test interval. Record measurements during the test 
interval. Measure and report NOX emissions over each test 
interval as described in paragraph (f) of this section.
    (6) After completing each test interval, repeat the steps in 
paragraphs (c)(4) and (5) of this section for all the remaining engine-
idle test points.
    (7) Each test point represents a stand-alone measurement. You may 
therefore take any appropriate steps between test intervals to process 
collected data and to prepare engines and equipment for further 
testing. Note that the allowances for combining background in paragraph 
(b)(4)(ii)(B) of this section do not apply. If an infrequent 
regeneration event occurs, allow the regeneration event to finish; void 
the test interval if the regeneration starts during a measurement.
    (8) Correct the measured or calculated mean fuel mass flow rate, at 
each of the engine-idle operating points to account for mass-specific 
net energy content as described in paragraph (e) of this section.
    (d) Steady-state fuel maps used for cycle-average fuel mapping of 
the highway cruise cycles. Determine steady-state fuel-consumption 
rates for each engine configuration over a series of paired engine 
speed and torque setpoints near idle as described in this paragraph 
(d). Perform fuel mapping as described in paragraph (b) of this section 
with the following exceptions:
    (1) Select speed setpoints to cover a range of values to represent 
in-use operation at idle. Speed setpoints for engines with adjustable 
warm idle speed must include at least minimum warm idle speed, 
fnidlemin, and a speed at or above maximum warm idle speed, 
fnidlemax. Speed setpoints for engines with no adjustable 
idle speed must include at least warm idle speed (with zero torque on 
the primary output shaft), fnidle, and a speed at or above 
1.15 [middot] fnidle.
    (2) Select the following torque setpoints at each speed setpoint to 
cover a range of values to represent in-use operation at idle:
    (i) The minimum torque setpoint is zero.
    (ii) Choose a maximum torque setpoint that is at least as large as 
the

[[Page 17708]]

value determined by the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.055

Where:

Tfnstall = the maximum engine torque at 
fnstall.
fnidle = for engines with an adjustable warm idle speed, 
use the maximum warm idle speed, fnidlemax. For engines 
without an adjustable warm idle speed, use warm idle speed, 
fnidle.
fnstall = the stall speed of the torque converter; use 
fntest or 2250 r/min, whichever is lower.
Pacc = accessory power for the vehicle class; use 1500 W 
for Vocational Light HDV, 2500 W for Vocational Medium HDV, and 3500 
W for Tractors and Vocational Heavy HDV. If your engine is going to 
be installed in multiple vehicle classes, perform the test with the 
accessory power for the largest vehicle class the engine will be 
installed in.

Example:

Tfnstall = 1870 N [middot] m
fntest = 1740.8 r/min = 182.30 rad/s
fnstall = 1740.8 r/min = 182.30 rad/s
fnidle = 700 r/min = 73.30 rad/s
Pacc = 1500 W
[GRAPHIC] [TIFF OMITTED] TP28MR22.056

    (iii) Select one or more equally spaced intermediate torque 
setpoints, as needed, such that the increment between torque setpoints 
is no greater than one-ninth of Tmax,mapped. Remove the 
points from the default map that are below 115% of the maximum speed 
and 115% of the maximum torque of the boundaries of the points measured 
in paragraph (d)(1) of this section.
    (e) Correction for net energy content. Correct the measured or 
calculated mean fuel mass flow rate, mifuel, for each test 
interval to a mass-specific net energy content of a reference fuel 
using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.057

Where:

Emfuelmeas = the mass-specific net energy content of the 
test fuel as determined in Sec.  1036.530(b)(1).
EmfuelCref = the reference value of carbon-mass-specific 
net energy content for the appropriate fuel. Use the values shown in 
Table 1 in Sec.  1036.530 for the designated fuel types, or values 
we approve for other fuel types.
wCref = the reference value of carbon mass fraction for 
the test fuel as shown in Table 1 of Sec.  1036.530 for the 
designated fuels. For any fuel not identified in the table, use the 
reference carbon mass fraction of diesel fuel for engines subject to 
compression-ignition standards, and use the reference carbon mass 
fraction of gasoline for engines subject to spark-ignition 
standards.

Example:

mifuel = 0.933 g/s
Emfuelmeas = 42.7984 MJ/kgC
EmfuelCref = 49.3112 MJ/kgC
wCref = 0.874
[GRAPHIC] [TIFF OMITTED] TP28MR22.058

    (f) Measuring NOX emissions. Measure NOX emissions for 
each sampling period in g/s. You may perform these measurements using a 
NOX emission-measurement system that meets the requirements 
of 40 CFR part 1065, subpart J. If a system malfunction prevents you 
from measuring NOX emissions during a test under this 
section but the test otherwise gives valid results, you may consider 
this a valid test and omit the NOX emission measurements; 
however, we may require you to repeat the test if we determine that you 
inappropriately voided the test with respect to NOX emission 
measurement.
    (g) Measured vs. declared fuel-consumption. Determine declared fuel 
consumption as follows:
    (1) Select fuel-consumption rates in g/s to characterize the 
engine's fuel maps. You must select a declared value for each test 
point that is at or above the corresponding value determined in 
paragraphs (b) through (e) of this section, including those from 
redundant measurements.
    (2) Declared fuel-consumption serves as emission standards under 
Sec.  1036.108. These are the values that vehicle manufacturers will 
use for certification under 40 CFR part 1037. Note that production 
engines are subject to GEM cycle-weighted limits as described in Sec.  
1036.301.
    (3) If you perform the carbon balance error verification, select 
declared values that are at or above the following emission 
measurements:
    (i) If you pass the [epsi]rC verification, you may use 
the average of the values from direct and indirect fuel measurements.
    (ii) If you fail [epsi]rC verification, but pass either 
the [epsi]aC or [epsi]aCrate verification, use 
the value from indirect fuel measurement.
    (iii) If you fail all three verifications, you must either void the 
test interval or use the highest value from direct and indirect fuel 
measurements. Note that we will consider our test results to be invalid 
if we fail all three verifications.


Sec.  1036.540  Determining cycle-average engine fuel maps.

    (a) Overview. This section describes how to determine an engine's 
cycle-average fuel maps for model year 2021 and later vehicles. Vehicle 
manufacturers may need cycle-average

[[Page 17709]]

fuel maps for transient duty cycles, highway cruise cycles, or both to 
demonstrate compliance with emission standards under 40 CFR part 1037. 
Generate cycle-average engine fuel maps as follows:
    (1) Determine the engine's torque maps as described in Sec.  
1036.503(c).
    (2) Determine the engine's steady-state fuel map and fuel 
consumption at idle as described in Sec.  1036.535. If you are applying 
cycle-average fuel mapping for highway cruise cycles, you may instead 
use GEM's default fuel map instead of generating the steady-state fuel 
map in Sec.  1036.535(b).
    (3) Simulate several different vehicle configurations using GEM 
(see 40 CFR 1037.520) to create new engine duty cycles as described in 
paragraph (c) of this section. The transient vehicle duty cycles for 
this simulation are in 40 CFR part 1037, appendix A; the highway cruise 
cycles with grade are in 40 CFR part 1037, appendix D. Note that GEM 
simulation relies on vehicle service classes as described in 40 CFR 
1037.140.
    (4) Test the engines using the new duty cycles to determine fuel 
consumption, cycle work, and average vehicle speed as described in 
paragraph (d) of this section and establish GEM inputs for those 
parameters for further vehicle simulations as described in paragraph 
(e) of this section.
    (b) General test provisions. The following provisions apply for 
testing under this section:
    (1) To perform fuel mapping under this section for hybrid engines, 
make sure the engine and its hybrid features are appropriately 
configured to represent the hybrid features in your testing.
    (2) Measure NOX emissions for each specified sampling 
period in grams. You may perform these measurements using a 
NOX emission-measurement system that meets the requirements 
of 40 CFR part 1065, subpart J. Include these measured NOX 
values any time you report to us your fuel consumption values from 
testing under this section. If a system malfunction prevents you from 
measuring NOX emissions during a test under this section but 
the test otherwise gives valid results, you may consider this a valid 
test and omit the NOX emission measurements; however, we may 
require you to repeat the test if we determine that you inappropriately 
voided the test with respect to NOX emission measurement.
    (3) The provisions related to carbon balance error verification in 
Sec.  1036.543 apply for all testing in this section. These procedures 
are optional, but we will perform carbon balance error verification for 
all testing under this section.
    (4) Correct fuel mass flow rate to a mass-specific net energy 
content of a reference fuel as described in paragraph (d)(13) of this 
section.
    (5) This section uses engine parameters and variables that are 
consistent with 40 CFR part 1065.
    (c) Create engine duty cycles. Use GEM to simulate your engine 
operation with several different vehicle configurations to create 
transient and highway cruise engine duty cycles corresponding to each 
vehicle configuration as follows:
    (1) Set up GEM to simulate your engine's operation based on your 
engine's torque maps, steady-state fuel maps, warm-idle speed as 
defined in 40 CFR 1037.520(h)(1), and fuel consumption at idle as 
described in paragraphs (a)(1) and (2) of this section.
    (2) Set up GEM with transmission parameters for different vehicle 
service classes and vehicle duty cycles. Specify the transmission's 
torque limit for each gear as the engine's maximum torque as determined 
in 40 CFR 1065.510. Specify the transmission type as Automatic 
Transmission for all engines and for all engine and vehicle duty 
cycles, except that the transmission type is Automated Manual 
Transmission for Heavy HDE operating over the highway cruise cycles or 
the SET duty cycle. For automatic transmissions set neutral idle to 
``Y'' in the vehicle file. Select gear ratios for each gear as shown in 
the following table:

                    Table 1 to Paragraph (c)(2) of Sec.   1036.540--GEM Input for Gear Ratio
----------------------------------------------------------------------------------------------------------------
                                                                  Spark-ignition
                                                                    HDE, light
                                                                     HDE, and       Heavy HDE--     Heavy HDE--
                            Gear No.                               medium HDE--    transient and  cruise and SET
                                                                  all engine and     FTP duty       duty cycles
                                                                   vehicle duty       cycles
                                                                      cycles
----------------------------------------------------------------------------------------------------------------
1...............................................................            3.10            3.51            12.8
2...............................................................            1.81            1.91            9.25
3...............................................................            1.41            1.43            6.76
4...............................................................            1.00            1.00            4.90
5...............................................................            0.71            0.74            3.58
6...............................................................            0.61            0.64            2.61
7...............................................................  ..............  ..............            1.89
8...............................................................  ..............  ..............            1.38
9...............................................................  ..............  ..............            1.00
10..............................................................  ..............  ..............            0.73
Lockup Gear.....................................................               3               3  ..............
----------------------------------------------------------------------------------------------------------------

    (3) Run GEM for each simulated vehicle configuration and use the 
GEM outputs of instantaneous engine speed and engine flywheel torque 
for each vehicle configuration to generate a 10 Hz transient duty cycle 
corresponding to each vehicle configuration operating over each vehicle 
duty cycle. Run GEM for the specified number of vehicle configurations. 
You may run additional vehicle configurations to represent a wider 
range of in-use vehicles. Run GEM as follows:

[[Page 17710]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.059

[GRAPHIC] [TIFF OMITTED] TP28MR22.060

Where:

fn[speed] = engine's angular speed as determined in 
paragraph (c)(3)(ii) or (iii) of this section.
ktopgear = transmission gear ratio in the highest 
available gear from Table 1 of this section.
vref = reference speed. Use 65 mi/hr for the transient 
cycle and the 65 mi/hr highway cruise cycle and use 55 mi/hr for the 
55 mi/hr highway cruise cycle.
[GRAPHIC] [TIFF OMITTED] TP28MR22.061

    (ii) Vehicle configurations for Spark-ignition HDE, Light HDE, and 
Medium HDE. Test at least eight different vehicle configurations for 
engines that will be installed in vocational Light HDV or vocational 
Medium HDV using vehicles in the following table:

[[Page 17711]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.062

    (iii) Vehicle configurations for Heavy HDE. Test at least nine 
different vehicle configurations for engines that will be installed in 
vocational Heavy HDV and for tractors that are not heavy-haul tractors. 
Test six different vehicle configurations for engines that will be 
installed in heavy-haul tractors. Use the settings specific to each 
vehicle configuration as shown in Table 3 or Table 4 in this section, 
as appropriate. Engines subject to testing under both Table 3 and Table 
4 in this section need not repeat overlapping vehicle configurations, 
so complete fuel mapping requires testing 12 (not 15) vehicle 
configurations for those engines. However, the preceding sentence does 
not apply if you choose to create two separate maps from the vehicle 
configurations defined in Table 3 and Table 4 in this section. Tables 3 
and 4 follow:
[GRAPHIC] [TIFF OMITTED] TP28MR22.063


[[Page 17712]]


    (iv) Vehicle configurations for mixed-use engines. If the engine 
will be installed in a combination of vehicles defined in paragraphs 
(c)(3)(ii) and (iii) of this section, use good engineering judgment to 
select at least nine vehicle configurations from Table 2 and Table 3 in 
this section that best represent the range of vehicles your engine will 
be sold in. This may require you to define additional representative 
vehicle configurations. For example, if your engines will be installed 
in vocational Medium HDV and vocational Heavy HDV, you might select 
Tests 2, 4, 6 and 8 of Table 2 of this section to represent vocational 
Medium HDV and Tests 3, 6, and 9 of Table 3 in this section to 
represent vocational Heavy HDV and add two more vehicle configurations 
that you define.
    (v) Programming GEM. Use the defined values in Tables 1 through 4 
in this section to set up GEM with the correct regulatory subcategory 
and vehicle weight reduction.
    (d) Test the engine with GEM cycles. Test the engine over each of 
the transient engine duty cycles generated in paragraph (c) of this 
section as follows:
    (1) Operate the engine over a sequence of required and optional 
engine duty cycles as follows:
    (i) Sort the list of engine duty cycles into three separate groups 
by vehicle duty cycle: Transient vehicle cycle, 55 mi/hr highway cruise 
cycle, and 65 mi/hr highway cruise cycle.
    (ii) Within each group of engine duty cycles derived from the same 
vehicle duty cycle, first run the engine duty cycle with the highest 
reference cycle work, followed by the cycle with the lowest cycle work; 
followed by the cycle with second-highest cycle work, followed by the 
cycle with the second-lowest cycle work; continuing through all the 
cycles for that vehicle duty cycle. The series of engine duty cycles to 
represent a single vehicle duty cycle is a single fuel-mapping 
sequence. Each engine duty cycle represents a different interval. 
Repeat the fuel-mapping sequence for the engine duty cycles derived 
from the other vehicle duty cycles until testing is complete.
    (iii) Operate the engine over two full engine duty cycles to 
precondition before each interval in the fuel-mapping sequence. 
Precondition the engine before the first and second engine duty cycle 
in each fuel-mapping sequence by repeating operation with the engine 
duty cycle with the highest reference cycle work over the relevant 
vehicle duty cycle. The preconditioning for the remaining cycles in the 
fuel-mapping sequence consists of operation over the preceding two 
engine duty cycles in the fuel-mapping sequence (with or without 
measurement). For transient vehicle duty cycles, start each engine duty 
cycle within 10 seconds after finishing the preceding engine duty cycle 
(with or without measurement). For highway cruise cycles, start each 
engine duty cycle and interval after linearly ramping to the speed and 
torque setpoints over 5 seconds and stabilizing for 15 seconds.
    (2) If the engine has an adjustable warm idle speed setpoint, set 
it to the value defined in 40 CFR 1037.520(h)(1).
    (3) Control speed and torque to meet the cycle validation criteria 
in 40 CFR 1065.514 for each interval, except that the standard error of 
the estimate in Table 2 of 40 CFR 1065.514 is the only speed criterion 
that applies if the range of reference speeds is less than 10 percent 
of the mean reference speed. For spark-ignition gaseous-fueled engines 
with fuel delivery at a single point in the intake manifold, you may 
apply the statistical criteria in Table 5 in this section for transient 
testing. Note that 40 CFR part 1065 does not allow reducing cycle 
precision to a lower frequency than the 10 Hz reference cycle generated 
by GEM.

   Table 5 to Paragraph (c)(3) of Sec.   1036.540--Statistical Criteria for Validating Duty Cycles for Spark-
                                         Ignition Gaseous-Fueled Engines
----------------------------------------------------------------------------------------------------------------
            Parameter                             Speed                        Torque               Power
----------------------------------------------------------------------------------------------------------------
Slope, a1........................  See 40 CFR 1065.514................  See 40 CFR 1065.514  See 40 CFR
                                                                                              1065.514.
Absolute value of intercept,       See 40 CFR 1065.514................  <=3% of maximum      See 40 CFR
 [verbar]a0[verbar].                                                     mapped torque.       1065.514.
Standard error of the estimate,    See 40 CFR 1065.514................  <=15% of maximum     <=15% of maximum
 SEE.                                                                    mapped torque.       mapped power.
Coefficient of determination,      See 40 CFR 1065.514................  >=0.700............  >=0.750.
 r\2\.
----------------------------------------------------------------------------------------------------------------

    (4) Record measurements using direct and/or indirect measurement of 
fuel flow as follows:
    (i) Direct fuel-flow measurement. Record speed and torque and 
measure fuel consumption with a fuel flow meter for the interval 
defined by the engine duty cycle. Determine the corresponding mean 
values for the interval. Use of redundant direct fuel-flow measurements 
require prior EPA approval.
    (ii) Indirect fuel-flow measurement. Record speed and torque and 
measure emissions and other inputs needed to run the chemical balance 
in 40 CFR 1065.655(c) for the interval defined by the engine duty 
cycle. Determine the corresponding mean values for the interval. Use of 
redundant indirect fuel-flow measurements require prior EPA approval. 
Measure background concentration as described in 40 CFR 1065.140, 
except that you may use one of the following methods to apply a single 
background reading to multiple intervals:
    (A) If you use batch sampling to measure background emissions, you 
may sample periodically into the bag over the course of multiple 
intervals. If you use this provision, you must apply the same 
background readings to correct emissions from each of the applicable 
intervals.
    (B) You may determine background emissions by sampling from the 
dilution air over multiple engine duty cycles. If you use this 
provision, you must allow sufficient time for stabilization of the 
background measurement; followed by an averaging period of at least 30 
seconds. Use the average of the two background readings to correct the 
measurement from each engine duty cycle. The first background reading 
must be taken no greater than 30 minutes before the start of the first 
applicable engine duty cycle and the second background reading must be 
taken no later than 30 minutes after the end of the last applicable 
engine duty cycle. Background readings may not span more than a full 
fuel-mapping sequence for a vehicle duty cycle.
    (5) Warm up the engine as described in 40 CFR 1065.510(b)(2). 
Within 60 seconds after concluding the warm-up, start the linear ramp 
of speed and torque over 20 seconds to the first speed and torque 
setpoint of the preconditioning cycle.
    (6) Precondition the engine before the start of testing as 
described in paragraph (d)(1)(iii) of this section.
    (7) Operate the engine over the first engine duty cycle. Record 
measurements during the interval. Measure and report NOX 
emissions over

[[Page 17713]]

each interval as described in paragraph (b)(2) of this section.
    (8) Continue testing engine duty cycles that are derived from the 
other vehicle duty cycles until testing is complete.
    (9) You may interrupt the fuel-mapping sequence after completing 
any interval. You may calibrate analyzers, read and evacuate background 
bag samples, or sample dilution air for measuring background 
concentration before restarting. Shut down the engine during any 
interruption. If you restart the sequence within 30 minutes or less, 
restart the sequence at paragraph (d)(6) of this section and then 
restart testing at the next interval in the fuel-mapping sequence. If 
you restart the sequence after more than 30 minutes, restart the 
sequence at paragraph (d)(5) of this section and then restart testing 
at the next interval in the fuel-mapping sequence.
    (10) The following provisions apply for infrequent regeneration 
events, other interruptions during intervals, and otherwise voided 
intervals:
    (i) Stop testing if an infrequent regeneration event occurs during 
a interval or a interval is interrupted for any other reason. Void the 
interrupted interval and any additional intervals for which you are not 
able to meet requirements for measuring background concentration. If 
the infrequent regeneration event occurs between intervals, void 
completed intervals only if you are not able to meet requirements for 
measuring background concentration for those intervals.
    (ii) If an infrequent regeneration event occurs, allow the 
regeneration event to finish with the engine operating at a speed and 
load that allows effective regeneration.
    (iii) If you interrupt testing during an interval, if you restart 
the sequence within 30 minutes or less, restart the sequence at 
paragraph (d)(6) of this section and then restart testing at the next 
interval in the fuel-mapping sequence. If you restart the sequence 
after more than 30 minutes, restart the sequence at paragraph (d)(5) of 
this section and then restart testing at the next interval in the fuel-
mapping sequence.
    (iv) If you void one or more intervals, you must perform additional 
testing to get results for all intervals. You may rerun a complete 
fuel-mapping sequence or any contiguous part of the fuel-mapping 
sequence. If you get a second valid measurement for any interval, use 
only the result from the last valid interval. If you restart the 
sequence within 30 minutes or less, restart the sequence at paragraph 
(d)(6) of this section and then restart testing at the first selected 
interval in the fuel-mapping sequence. If you restart the sequence 
after more than 30 minutes, restart the sequence at paragraph (d)(5) of 
this section and then restart testing at the first selected interval in 
the fuel-mapping sequence. Continue testing until you have valid 
results for all intervals. The following examples illustrate possible 
scenarios for a partial run through a fuel-mapping sequence:
    (A) If you voided only the interval associated with the fourth 
engine duty cycle in the sequence, you may restart the sequence using 
the second and third engine duty cycles as the preconditioning cycles 
and stop after completing the interval associated with the fourth 
engine duty cycle.
    (B) If you voided the intervals associated with the fourth and 
sixth engine duty cycles, you may restart the sequence using the second 
and third engine duty cycles for preconditioning and stop after 
completing the interval associated with the sixth engine duty cycle.
    (11) You may send signals to the engine controller during the test, 
such as current transmission gear and vehicle speed, if that allows 
engine operation during the to better represent in-use operation.
    (12) Calculate the fuel mass flow rate, mfuel, for each 
duty cycle using one of the following equations:
    (i) Determine fuel-consumption rates using emission measurements 
from the raw or diluted exhaust, calculate the mass of fuel for each 
duty cycle, mfuel[cycle], as follows:
    (A) For calculations that use continuous measurement of emissions 
and continuous CO2 from urea, calculate 
mfuel[cycle] using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.064

Where:

MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of 
fuels) as determined in 40 CFR 1065.655(d), except that you may not 
use the default properties in Table 2 of 40 CFR 1065.655 to 
determine a, b, and wC. You may not account for the 
contribution to a, b, g, and d of diesel exhaust fluid or other non-
fuel fluids injected into the exhaust.
i = an indexing variable that represents one recorded emission 
value.
N = total number of measurements over the duty cycle.
nexh = exhaust molar flow rate from which you measured 
emissions.
xCcombdry = amount of carbon from fuel and any injected 
fluids in the exhaust per mole of dry exhaust as determined in 40 
CFR 1065.655(c).
xH2Oexhdry = amount of H2O in exhaust per mole 
of exhaust as determined in 40 CFR 1065.655(c).
[Delta]t = 1/frecord
MCO2 = molar mass of carbon dioxide.
mC02DEFi = mass emission rate of CO2 resulting 
from diesel exhaust fluid decomposition over the duty cycle as 
determined from Sec.  1036.535(b)(9). If your engine does not 
utilize diesel exhaust fluid for emission control, or if you choose 
not to perform this correction, set mC02DEFi equal to 0.

Example:

MC = 12.0107 g/mol
wCmeas = 0.867
N = 6680
nexh1= 2.876 mol/s
nexh2 = 2.224 mol/s
xCcombdry1 = 2.61[middot]10-3 mol/mol
xCcombdry2 = 1.91[middot]10-3 mol/mol
xH2Oexh1= 3.53[middot]10-2 mol/mol
xH2Oexh2= 3.13[middot]10-2 mol/mol
frecord = 10 Hz
[Delta]t = 1/10 = 0.1 s
MCO2 = 44.0095 g/mol
mCO2DEF1 = 0.0726 g/s
mCO2DEF2 = 0.0751 g/s
mfueltransientTest1 =

[[Page 17714]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.065


[[Page 17715]]


Where:

i = an indexing variable that represents one recorded value.
N = total number of measurements over the duty cycle. For batch fuel 
mass measurements, set N = 1.
mfueli = the fuel mass flow rate, for each point, i, 
starting from i = 1.
[Delta]t = 1/frecord
frecord = the data recording frequency.

Example:

N = 6680
mfuel1 = 1.856 g/s
mfuel2 = 1.962 g/s
frecord = 10 Hz
Dt = 1/10 = 0.1 s
mfueltransient = (1.856 + 1.962 + . . . + 
mfuel6680) [middot] 0.1
mfueltransient = 111.95 g

    (13) Correct the measured or calculated fuel mass flow rate, 
mfuel, for each result to a mass-specific net energy content 
of a reference fuel as described in Sec.  1036.535(e), replacing 
mifuel with mfuel in Eq. 1036.535-4.
    (e) Determine GEM inputs. Use the results of engine testing in 
paragraph (d) of this section to determine the GEM inputs for the 
transient duty cycle and optionally for each of the highway cruise 
cycles corresponding to each simulated vehicle configuration as 
follows:
    (1) Your declared fuel mass consumption, mfuel[cycle]. 
Using the calculated fuel mass consumption values described in 
paragraph (d) of this section, declare values using the methods 
described in Sec.  1036.535(g)(2) and (3).
    (2) We will determine mfuel[cycle] values using the 
method described in Sec.  1036.535(g)(3).
[GRAPHIC] [TIFF OMITTED] TP28MR22.066

    (4) Positive work determined according to 40 CFR part 1065, 
W[cycle], by using the engine speed and engine torque 
measured during the engine test while the vehicle is moving. Note that 
the engine cycle created by GEM has a flag to indicate when the vehicle 
is moving.
    (5) The engine idle speed and torque, by taking the average engine 
speed and torque measured during the engine test while the vehicle is 
not moving. Note that the engine cycle created by GEM has a flag to 
indicate when the vehicle is moving.
    (6) The following table illustrates the GEM data inputs 
corresponding to the different vehicle configurations for a given duty 
cycle:
[GRAPHIC] [TIFF OMITTED] TP28MR22.067

Sec.  1036.543  Carbon balance error verification.

    The optional carbon balance error verification in 40 CFR 1065.543 
compares independent assessments of the flow of carbon through the 
system (engine plus aftertreatment). This procedure applies for each 
individual interval in Sec.  1036.535(b), (c), and (d), Sec.  1036.540, 
and 40 CFR 1037.550.

Subpart G--Special Compliance Provisions


Sec.  1036.601  Overview of compliance provisions.

    (a) Engine and vehicle manufacturers, as well as owners, operators, 
and rebuilders of engines subject to the requirements of this part, and 
all other persons, must observe the provisions of this part, the 
provisions of 40 CFR part 1068, and the provisions of the Clean Air 
Act. The provisions of 40 CFR part 1068 apply for heavy-duty highway 
engines as specified in that part, subject to the following provisions:
    (1) The exemption provisions of 40 CFR 1068.201 through 1068.230, 
1068.240, and 1068.260 through 265 apply for heavy-duty motor vehicle 
engines. The other exemption provisions, which are specific to

[[Page 17716]]

nonroad engines, do not apply for heavy-duty vehicles or heavy-duty 
engines.
    (2) Engine signals to indicate a need for maintenance under Sec.  
1036.125(a)(1)(ii) are considered an element of design of the emission 
control system. Disabling, resetting, or otherwise rendering such 
signals inoperative without also performing the indicated maintenance 
procedure is therefore prohibited under 40 CFR 1068.101(b)(1).
    (3) The warranty-related prohibitions in section 203(a)(4) of the 
Act (42 U.S.C. 7522(a)(4)) apply to manufacturers of new heavy-duty 
highway engines in addition to the prohibitions described in 40 CFR 
1068.101(b)(6). We may assess a civil penalty up to $44,539 for each 
engine or vehicle in violation.
    (b) The following provisions from 40 CFR parts 85 and 86 continue 
to apply after model year 2026 for engines subject to the requirements 
of this part:
    (1) The tampering prohibition in 40 CFR 1068.101(b)(1) applies for 
alternative fuel conversions as specified in 40 CFR part 85, subpart F.
    (2) Engine manufacturers must meet service information requirements 
as specified in 40 CFR 86.010-38(j).
    (3) Provisions related to nonconformance penalties apply as 
described in 40 CFR part 86, subpart L.
    (4) The manufacturer-run in-use testing program applies as 
described in 40 CFR part 86, subpart T.
    (c) The emergency vehicle field modification provisions of 40 CFR 
85.1716 apply with respect to the standards of this part.
    (d) Subpart C of this part describes how to test and certify dual-
fuel and flexible-fuel engines. Some multi-fuel engines may not fit 
either of those defined terms. For such engines, we will determine 
whether it is most appropriate to treat them as single-fuel engines, 
dual-fuel engines, or flexible-fuel engines based on the range of 
possible and expected fuel mixtures. For example, an engine might burn 
natural gas but initiate combustion with a pilot injection of diesel 
fuel. If the engine is designed to operate with a single fueling 
algorithm (i.e., fueling rates are fixed at a given engine speed and 
load condition), we would generally treat it as a single-fuel engine. 
In this context, the combination of diesel fuel and natural gas would 
be its own fuel type. If the engine is designed to also operate on 
diesel fuel alone, we would generally treat it as a dual-fuel engine. 
If the engine is designed to operate on varying mixtures of the two 
fuels, we would generally treat it as a flexible-fuel engine. To the 
extent that requirements vary for the different fuels or fuel mixtures, 
we may apply the more stringent requirements.


Sec.  1036.605  Alternate emission standards for engines used in 
specialty vehicles.

    Starting in model year 2027, compression-ignition engines at or 
above 56 kW and spark-ignition engines of any size that will be 
installed in specialty vehicles as allowed by 40 CFR 1037.605 are 
exempt from the standards of subpart B this part. Qualifying engines 
must certify under this part by meeting alternate emission standards as 
follows:
    (a) Spark-ignition engines must be of a configuration that is 
identical to one that is certified under 40 CFR part 1048 to Blue Sky 
standards under 40 CFR 1048.140.
    (b) Compression-ignition engines must be of a configuration that is 
identical to one that is certified under 40 CFR part 1039, and meet the 
following additional standards using the same duty cycles that apply 
under 40 CFR part 1039:
    (1) The engines must be certified with a Family Emission Limit for 
PM of 0.020 g/kW-hr.
    (2) Diesel-fueled engines using selective catalytic reduction must 
meet an emission standard of 0.1 g/kW-hr for N2O.
    (c) Except as specified in this section, engines certified under 
this section must meet all the requirements that apply under 40 CFR 
part 1039 or 1048 instead of the comparable provisions in this part. 
Before shipping engines under this section, you must have written 
assurance from vehicle manufacturers that they need a certain number of 
exempted engines under this section. In your annual production report 
under 40 CFR 1039.250 or 1048.250, count these engines separately and 
identify the vehicle manufacturers that will be installing them. Treat 
these engines as part of the corresponding engine family under 40 CFR 
part 1039 or part 1048 for compliance purposes such as testing 
production engines, in-use testing, defect reporting, and recall.
    (d) The engines must be labeled as described in Sec.  1036.135, 
with the following statement instead of the one specified in Sec.  
1036.135(c)(8): ``This engine conforms to alternate standards for 
specialty vehicles under 40 CFR 1036.605.'' Engines certified under 
this section may not have the label specified for nonroad engines in 40 
CFR part 1039 or part 1048 or any other label identifying them as 
nonroad engines.
    (e) In a separate application for a certificate of conformity, 
identify the corresponding nonroad engine family, describe the label 
required under section, state that you meet applicable diagnostic 
requirements under 40 CFR part 1039 or part 1048, and identify your 
projected U.S.-directed production volume.
    (f) No additional certification fee applies for engines certified 
under this section.
    (g) Engines certified under this section may not generate or use 
emission credits under this part or under 40 CFR part 1039. The 
vehicles in which these engines are installed may generate or use 
emission credits as described in 40 CFR part 1037.


Sec.  1036.610  Off-cycle technology credits and adjustments for 
reducing greenhouse gas emissions.

    (a) You may ask us to apply the provisions of this section for 
CO2 emission reductions resulting from powertrain 
technologies that were not in common use with heavy-duty vehicles 
before model year 2010 that are not reflected in the specified 
procedure. While you are not required to prove that such technologies 
were not in common use with heavy-duty vehicles before model year 2010, 
we will not approve your request if we determine that they do not 
qualify. We will apply these provisions only for technologies that will 
result in a measurable, demonstrable, and verifiable real-world 
CO2 reduction. Note that prior to model year 2016, these 
technologies were referred to as ``innovative technologies''.
    (b) The provisions of this section may be applied as either an 
improvement factor (used to adjust emission results) or as a separate 
credit, consistent with good engineering judgment. Note that the term 
``credit'' in this section describes an additive adjustment to emission 
rates and is not equivalent to an emission credit in the ABT program of 
subpart H of this part. We recommend that you base your credit/
adjustment on A to B testing of pairs of engines/vehicles differing 
only with respect to the technology in question.
    (1) Calculate improvement factors as the ratio of in-use emissions 
with the technology divided by the in-use emissions without the 
technology. Adjust the emission results by multiplying by the 
improvement factor. Use the improvement-factor approach where good 
engineering judgment indicates that the actual benefit will be 
proportional to emissions measured over the procedures specified in 
this part. For example, the benefits from technologies that reduce 
engine operation would generally be proportional to the engine's 
emission rate.

[[Page 17717]]

    (2) Calculate separate credits based on the difference between the 
in-use emission rate (g/ton-mile) with the technology and the in-use 
emission rate without the technology. Subtract this value from your 
measured emission result and use this adjusted value to determine your 
FEL. We may also allow you to calculate the credits based on g/
hp[middot]hr emission rates. Use the separate-credit approach where 
good engineering judgment indicates that the actual benefit will not be 
proportional to emissions measured over the procedures specified in 
this part.
    (3) We may require you to discount or otherwise adjust your 
improvement factor or credit to account for uncertainty or other 
relevant factors.
    (c) Send your request to the Designated Compliance Officer. We 
recommend that you do not begin collecting data (for submission to EPA) 
before contacting us. For technologies for which the vehicle 
manufacturer could also claim credits (such as transmissions in certain 
circumstances), we may require you to include a letter from the vehicle 
manufacturer stating that it will not seek credits for the same 
technology. Your request must contain the following items:
    (1) A detailed description of the off-cycle technology and how it 
functions to reduce CO2 emissions under conditions not 
represented on the duty cycles required for certification.
    (2) A list of the engine configurations that will be equipped with 
the technology.
    (3) A detailed description and justification of the selected 
engines.
    (4) All testing and simulation data required under this section, 
plus any other data you have considered in your analysis. You may ask 
for our preliminary approval of your plan under Sec.  1036.210.
    (5) A complete description of the methodology used to estimate the 
off-cycle benefit of the technology and all supporting data, including 
engine testing and in-use activity data. Also include a statement 
regarding your recommendation for applying the provisions of this 
section for the given technology as an improvement factor or a credit.
    (6) An estimate of the off-cycle benefit by engine model, and the 
fleetwide benefit based on projected sales of engine models equipped 
with the technology.
    (7) A demonstration of the in-use durability of the off-cycle 
technology, based on any available engineering analysis or durability 
testing data (either by testing components or whole engines).
    (d) We may seek public comment on your request, consistent with the 
provisions of 40 CFR 86.1869-12(d). However, we will generally not seek 
public comment on credits/adjustments based on A to B engine 
dynamometer testing, chassis testing, or in-use testing.
    (e) We may approve an improvement factor or credit for any 
configuration that is properly represented by your testing.
    (1) For model years before 2021, you may continue to use an 
approved improvement factor or credit for any appropriate engine 
families in future model years through 2020.
    (2) For model years 2021 and later, you may not rely on an approval 
for model years before 2021. You must separately request our approval 
before applying an improvement factor or credit under this section for 
2021 and later engines, even if we approved an improvement factor or 
credit for similar engine models before model year 2021. Note that 
approvals for model year 2021 and later may carry over for multiple 
years.


Sec.  1036.615  Engines with Rankine cycle waste heat recovery and 
hybrid powertrains.

    This section specifies how to generate advanced-technology emission 
credits for hybrid powertrains that include energy storage systems and 
regenerative braking (including regenerative engine braking) and for 
engines that include Rankine-cycle (or other bottoming cycle) exhaust 
energy recovery systems. This section applies only for model year 2020 
and earlier engines.
    (a) Pre-transmission hybrid powertrains. Test pre-transmission 
hybrid powertrains with the hybrid engine procedures of 40 CFR part 
1065 or with the post-transmission procedures in 40 CFR 1037.550. Pre-
transmission hybrid powertrains are those engine systems that include 
features to recover and store energy during engine motoring operation 
but not from the vehicle's wheels. Engines certified with pre-
transmission hybrid powertrains must be certified to meet the 
diagnostic requirements as specified in Sec.  1036.110 with respect to 
powertrain components and systems; if different manufacturers produce 
the engine and the hybrid powertrain, the hybrid powertrain 
manufacturer may separately certify its powertrain relative to 
diagnostic requirements.
    (b) Rankine engines. Test engines that include Rankine-cycle 
exhaust energy recovery systems according to the procedures specified 
in subpart F of this part unless we approve alternate procedures.
    (c) Calculating credits. Calculate credits as specified in subpart 
H of this part. Credits generated from engines and powertrains 
certified under this section may be used in other averaging sets as 
described in Sec.  1036.740(c).
    (d) Off-cycle technologies. You may certify using both the 
provisions of this section and the off-cycle technology provisions of 
Sec.  1036.610, provided you do not double-count emission benefits.


Sec.  1036.620  Alternate CO2 standards based on model year 2011 
compression-ignition engines.

    For model years 2014 through 2016, you may certify your 
compression-ignition engines to the CO2 standards of this 
section instead of the CO2 standards in Sec.  1036.108. 
However, you may not certify engines to these alternate standards if 
they are part of an averaging set in which you carry a balance of 
banked credits. You may submit applications for certifications before 
using up banked credits in the averaging set, but such certificates 
will not become effective until you have used up (or retired) your 
banked credits in the averaging set. For purposes of this section, you 
are deemed to carry credits in an averaging set if you carry credits 
from advanced technology that are allowed to be used in that averaging 
set.
    (a) The standards of this section are determined from the measured 
emission rate of the engine of the applicable baseline 2011 engine 
family or families as described in paragraphs (b) and (c) of this 
section. Calculate the CO2 emission rate of the baseline 
engine using the same equations used for showing compliance with the 
otherwise applicable standard. The alternate CO2 standard 
for light and medium heavy-duty vocational-certified engines (certified 
for CO2 using the transient cycle) is equal to the baseline 
emission rate multiplied by 0.975. The alternate CO2 
standard for tractor-certified engines (certified for CO2 
using the SET duty cycle) and all other Heavy HDE is equal to the 
baseline emission rate multiplied by 0.970. The in-use FEL for these 
engines is equal to the alternate standard multiplied by 1.03.
    (b) This paragraph (b) applies if you do not certify all your 
engine families in the averaging set to the alternate standards of this 
section. Identify separate baseline engine families for each engine 
family that you are certifying to the alternate standards of this 
section. For an engine family to be considered the baseline engine 
family, it must meet the following criteria:
    (1) It must have been certified to all applicable emission 
standards in model year 2011. If the baseline engine was

[[Page 17718]]

certified to a NOX FEL above the standard and incorporated 
the same emission control technologies as the new engine family, you 
may adjust the baseline CO2 emission rate to be equivalent 
to an engine meeting the 0.20 g/hp[middot]hr NOX standard 
(or your higher FEL as specified in this paragraph (b)(1)), using 
certification results from model years 2009 through 2011, consistent 
with good engineering judgment.
    (i) Use the following equation to relate model year 2009-2011 
NOX and CO2 emission rates (g/hp[middot]hr): 
CO2 = a x log(NOX)+b.
    (ii) For model year 2014-2016 engines certified to NOX 
FELs above 0.20 g/hp[middot]hr, correct the baseline CO2 
emissions to the actual NOX FELs of the 2014-2016 engines.
    (iii) Calculate separate adjustments for emissions over the SET 
duty cycle and the transient cycle.
    (2) The baseline configuration tested for certification must have 
the same engine displacement as the engines in the engine family being 
certified to the alternate standards, and its rated power must be 
within five percent of the highest rated power in the engine family 
being certified to the alternate standards.
    (3) The model year 2011 U.S.-directed production volume of the 
configuration tested must be at least one percent of the total 2011 
U.S.-directed production volume for the engine family.
    (4) The tested configuration must have cycle-weighted BSFC 
equivalent to or better than all other configurations in the engine 
family.
    (c) This paragraph (c) applies if you certify all your engine 
families in the primary intended service class to the alternate 
standards of this section. For purposes of this section, you may 
combine Light HDE and Medium HDE into a single averaging set. Determine 
your baseline CO2 emission rate as the production-weighted 
emission rate of the certified engine families you produced in the 2011 
model year. If you produce engines for both tractors and vocational 
vehicles, treat them as separate averaging sets. Adjust the 
CO2 emission rates to be equivalent to an engine meeting the 
average NOX FEL of new engines (assuming engines certified 
to the 0.20 g/hp[middot]hr NOX standard have a 
NOX FEL equal to 0.20 g/hp[middot]hr), as described in 
paragraph (b)(1) of this section.
    (d) Include the following statement on the emission control 
information label: ``THIS ENGINE WAS CERTIFIED TO AN ALTERNATE 
CO2 STANDARD UNDER Sec.  1036.620.''
    (e) You may not bank CO2 emission credits for any engine 
family in the same averaging set and model year in which you certify 
engines to the standards of this section. You may not bank any 
advanced-technology credits in any averaging set for the model year you 
certify under this section (since such credits would be available for 
use in this averaging set). Note that the provisions of Sec.  1036.745 
apply for deficits generated with respect to the standards of this 
section.
    (f) You need our approval before you may certify engines under this 
section, especially with respect to the numerical value of the 
alternate standards. We will not approve your request if we determine 
that you manipulated your engine families or engine configurations to 
certify to less stringent standards, or that you otherwise have not 
acted in good faith. You must keep and provide to us any information we 
need to determine that your engine families meet the requirements of 
this section. Keep these records for at least five years after you stop 
producing engines certified under this section.


Sec.  1036.625  In-use compliance with CO2 family emission limits 
(FELs).

    Section 1036.225 describes how to change the FEL for an engine 
family during the model year. This section, which describes how you may 
ask us to increase an engine family's CO2 FEL after the end 
of the model year, is intended to address circumstances in which it is 
in the public interest to apply a higher in-use CO2 FEL 
based on forfeiting an appropriate number of emission credits. For 
example, this may be appropriate where we determine that recalling 
vehicles would not significantly reduce in-use emissions. We will 
generally not allow this option where we determine the credits being 
forfeited would likely have expired.
    (a) You may ask us to increase an engine family's FEL after the end 
of the model year if you believe some of your in-use engines exceed the 
CO2 FEL that applied during the model year (or the 
CO2 emission standard if the family did not generate or use 
emission credits). We may consider any available information in making 
our decision to approve or deny your request.
    (b) If we approve your request under this section, you must apply 
emission credits to cover the increased FEL for all affected engines. 
Apply the emission credits as part of your credit demonstration for the 
current production year. Include the appropriate calculations in your 
final report under Sec.  1036.730.
    (c) Submit your request to the Designated Compliance Officer. 
Include the following in your request:
    (1) Identify the names of each engine family that is the subject of 
your request. Include separate family names for different model years
    (2) Describe why your request does not apply for similar engine 
models or additional model years, as applicable.
    (3) Identify the FEL(s) that applied during the model year and 
recommend a replacement FEL for in-use engines; include a supporting 
rationale to describe how you determined the recommended replacement 
FEL.
    (4) Describe whether the needed emission credits will come from 
averaging, banking, or trading.
    (d) If we approve your request, we will identify the replacement 
FEL. The value we select will reflect our best judgment to accurately 
reflect the actual in-use performance of your engines, consistent with 
the testing provisions specified in this part. We may apply the higher 
FELs to other engine families from the same or different model years to 
the extent they used equivalent emission controls. We may include any 
appropriate conditions with our approval.
    (e) If we order a recall for an engine family under 40 CFR 
1068.505, we will no longer approve a replacement FEL under this 
section for any of your engines from that engine family, or from any 
other engine family that relies on equivalent emission controls.


Sec.  1036.630  Certification of engine greenhouse gas emissions for 
powertrain testing.

    For engines included in powertrain families under 40 CFR part 1037, 
you may choose to include the corresponding engine emissions in your 
engine families under this part instead of (or in addition to) the 
otherwise applicable engine fuel maps.
    (a) If you choose to certify powertrain fuel maps in an engine 
family, the declared powertrain emission levels become standards that 
apply for selective enforcement audits and in-use testing. We may 
require that you provide to us the engine cycle (not normalized) 
corresponding to a given powertrain for each of the specified duty 
cycles.
    (b) If you choose to certify only fuel map emissions for an engine 
family and to not certify emissions over powertrain cycles under 40 CFR 
1037.550, we will not presume you are responsible for emissions over 
the powertrain cycles. However, where we determine that you are 
responsible in whole or in part for the emission exceedance in such 
cases,

[[Page 17719]]

we may require that you participate in any recall of the affected 
vehicles. Note that this provision to limit your responsibility does 
not apply if you also hold the certificate of conformity for the 
vehicle.
    (c) If you split an engine family into subfamilies based on 
different fuel-mapping procedures as described in Sec.  1036.230(f)(2), 
the fuel-mapping procedures you identify for certifying each subfamily 
also apply for selective enforcement audits and in-use testing.


Sec.  1036.635  [Reserved]


Sec.  1036.655  Special provisions for diesel-fueled engines sold in 
American Samoa or the Commonwealth of the Northern Mariana Islands.

    (a) The prohibitions in 40 CFR 1068.101(a)(1) do not apply to 
diesel-fueled engines, subject to the following conditions:
    (1) The engine is intended for use and will be used in American 
Samoa or the Commonwealth of the Northern Mariana Islands.
    (2) The engine meets the emission standards that applied to model 
year 2006 engines as specified in appendix A of this part.
    (3) You meet all the requirements of 40 CFR 1068.265.
    (b) If you introduce an engine into U.S. commerce under this 
section, you must meet the labeling requirements in Sec.  1036.135, but 
add the following statement instead of the compliance statement in 
Sec.  1036.135(c)(8):
    THIS ENGINE (or VEHICLE, as applicable) CONFORMS TO US EPA EMISSION 
STANDARDS APPLICABLE TO MODEL YEAR 2006. THIS ENGINE (or VEHICLE, as 
applicable) DOES NOT CONFORM TO US EPA EMISSION REQUIREMENTS IN EFFECT 
AT TIME OF PRODUCTION AND MAY NOT BE IMPORTED INTO THE UNITED STATES OR 
ANY TERRITORY OF THE UNITED STATES EXCEPT AMERICAN SAMOA OR THE 
COMMONWEALTH OF THE NORTHERN MARIANA ISLANDS.
    (c) Introducing into U.S. commerce an engine exempted under this 
section in any state or territory of the United States other than 
American Samoa or the Commonwealth of the Northern Mariana Islands, 
throughout its lifetime, violates the prohibitions in 40 CFR 
1068.101(a)(1), unless it is exempt under a different provision.
    (d) The exemption provisions in this section also applied for model 
year 2007 and later engines introduced into commerce in Guam before 
[the effective date of the final rule].

Subpart H--Averaging, Banking, and Trading for Certification


Sec.  1036.701  General provisions.

    (a) You may average, bank, and trade (ABT) emission credits for 
purposes of certification as described in this subpart and in subpart B 
of this part to show compliance with the standards of Sec. Sec.  
1036.104 and 1036.108. Participation in this program is voluntary. Note 
that certification to NOX standards in Sec.  1036.104 is 
based on a Family Emission Limit (FEL) and certification to 
CO2 standards in Sec.  1036.108 is based on a Family 
Certification Level (FCL). This subpart refers to ``FEL/FCL'' to 
simultaneously refer to FELs for NOX and FCLs for 
CO2. Note also that subpart B of this part requires you to 
assign an FCL to all engine families, whether or not they participate 
in the ABT provisions of this subpart.
    (b) The definitions of subpart I of this part apply to this subpart 
in addition to the following definitions:
    (1) Actual emission credits means emission credits you have 
generated that we have verified by reviewing your final report.
    (2) Averaging set means a set of engines in which emission credits 
may be exchanged. See Sec.  1036.740.
    (3) Broker means any entity that facilitates a trade of emission 
credits between a buyer and seller.
    (4) Buyer means the entity that receives emission credits as a 
result of a trade.
    (5) Reserved emission credits means emission credits you have 
generated that we have not yet verified by reviewing your final report.
    (6) Seller means the entity that provides emission credits during a 
trade.
    (7) Standard means the emission standard that applies under subpart 
B of this part for engines not participating in the ABT program of this 
subpart.
    (8) Trade means to exchange emission credits, either as a buyer or 
seller.
    (c) Emission credits may be exchanged only within an averaging set, 
except as specified in Sec.  1036.740.
    (d) You may not use emission credits generated under this subpart 
to offset any emissions that exceed an FEL/FCL or standard. This 
paragraph (d) applies for all testing, including certification testing, 
in-use testing, selective enforcement audits, and other production-line 
testing. However, if emissions from an engine exceed an FEL/FCL or 
standard (for example, during a selective enforcement audit), you may 
use emission credits to recertify the engine family with a higher FEL/
FCL that applies only to future production.
    (e) You may use either of the following approaches to retire or 
forego emission credits:
    (1) You may retire emission credits generated from any number of 
your engines. This may be considered donating emission credits to the 
environment. Identify any such credits in the reports described in 
Sec.  1036.730. Engines must comply with the applicable FELs even if 
you donate or sell the corresponding emission credits. Donated credits 
may no longer be used by anyone to demonstrate compliance with any EPA 
emission standards.
    (2) You may certify an engine family using an FEL/FCL below the 
emission standard as described in this part and choose not to generate 
emission credits for that family. If you do this, you do not need to 
calculate emission credits for those engine families, and you do not 
need to submit or keep the associated records described in this subpart 
for that family.
    (f) Emission credits may be used in the model year they are 
generated. Surplus emission credits may be banked for future model 
years. Surplus emission credits may sometimes be used for past model 
years, as described in Sec.  1036.745.
    (g) You may increase or decrease an FEL/FCL during the model year 
by amending your application for certification under Sec.  1036.225. 
The new FEL/FCL may apply only to engines you have not already 
introduced into commerce.
    (h) See Sec.  1036.740 for special credit provisions that apply for 
greenhouse gas credits generated under 40 CFR 86.1819-14(k)(7) or Sec.  
1036.615 or 40 CFR 1037.615.
    (i) Unless the regulations in this part explicitly allow it, you 
may not calculate Phase 1 credits more than once for any emission 
reduction. For example, if you generate Phase 1 CO2 emission 
credits for a hybrid engine under this part for a given vehicle, no one 
may generate CO2 emission credits for that same hybrid 
engine and the associated vehicle under 40 CFR part 1037. However, 
Phase 1 credits could be generated for identical vehicles using engines 
that did not generate credits under this part.
    (j) Credits you generate with compression-ignition engines in 2020 
and earlier model years may be used in model year 2021 and later as 
follows:
    (1) For credit-generating engines certified to the tractor engine 
standards in Sec.  1036.108, you may use credits calculated relative to 
the tractor engine standards.

[[Page 17720]]

    (2) For credit-generating engines certified to the vocational 
engine standards in Sec.  1036.108, you may optionally carry over 
adjusted vocational credits from an averaging set, and you may use 
credits calculated relative to the emission levels in the following 
table:

   Table 1 to Paragraph (j)(2) of Sec.   1036.701--Emission Levels for
                           Credit Calculation
------------------------------------------------------------------------
         Medium heavy-duty engines            Heavy heavy-duty engines
------------------------------------------------------------------------
558 g/hp[middot]hr........................  525 g/hp[middot]hr.
------------------------------------------------------------------------

    (k) Engine families you certify with a nonconformance penalty under 
40 CFR part 86, subpart L, may not generate emission credits.


Sec.  1036.705  Generating and calculating emission credits.

    (a) The provisions of this section apply separately for calculating 
emission credits for each pollutant.
    (b) For each participating family, calculate positive or negative 
emission credits relative to the otherwise applicable emission 
standard. Calculate positive emission credits for a family that has an 
FEL/FCL below the standard. Calculate negative emission credits for a 
family that has an FEL/FCL above the standard. Sum your positive and 
negative credits for the model year before rounding.
    (1) Calculate emission credits to the nearest megagram (Mg) for 
each family or subfamily using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.068

Where:

Std = the emission standard, in (mg NOX)/hp[middot]hr or 
(g CO2)/hp[middot]hr, that applies under subpart B of 
this part for engines not participating in the ABT program of this 
subpart (the ``otherwise applicable standard'').
FL = the engine family's FEL for NOX, in mg/hp[middot]hr, 
and FCL for CO2, in g/hp[middot]hr, rounded to the same 
number of decimal places as the emission standard.
CF = a transient cycle conversion factor (hp[middot]hr/mile), 
calculated by dividing the total (integrated) horsepower-hour over 
the applicable duty cycle by 6.3 miles for engines subject to spark-
ignition standards and 6.5 miles for engines subject to compression-
ignition standards. This represents the average work performed over 
the duty cycle. See paragraph (b)(3) of this section for provisions 
that apply for CO2.
Volume = the number of engines eligible to participate in the 
averaging, banking, and trading program within the given engine 
family or subfamily during the model year, as described in paragraph 
(c) of this section.
UL = the useful life for the standard that applies for a given 
primary intended service class, in miles.
c = use 10-6 for CO2 and 10-9 for 
NOX.

Example for model year 2025 Heavy HDE generating CO2 credits for a 
model year 2028 Heavy HDE:

Std = 432 g/hp[middot]hr
FL = 401 g/hp[middot]hr
CF = 9.78 hp[middot]hr/mile
Volume = 15,342
UL = 435,000 miles
c = 10-6
Emission credits = (432-401) [middot] 9.78 [middot] 15,342 [middot] 
435,000 [middot] 10-6 = 28,131,142 Mg

    (2) [Reserved]
    (3) The following additional provisions apply for calculating 
CO2 credits:
    (i) For engine families certified to both the vocational and 
tractor engine standards, calculate credits separately for the 
vocational engines and the tractor engines. We may allow you to use 
statistical methods to estimate the total production volumes where a 
small fraction of the engines cannot be tracked precisely.
    (ii) Calculate the transient cycle conversion factor for vocational 
engines based on the average of vocational engine configurations 
weighted by their production volumes. Similarly, calculate the 
transient cycle conversion factor for tractor engines based on the 
average of tractor engine configurations weighted by their production 
volumes. Note that calculating the transient cycle conversion factor 
for tractors requires you to use the conversion factor even for engines 
certified to standards based on the SET duty cycle.
    (iii) The FCL for CO2 is based on measurement over the 
FTP duty cycle for vocational engines and over the SET duty cycle for 
tractor engines.
    (4) You may not generate emission credits for tractor engines 
(i.e., engines not certified to the transient cycle for CO2) 
installed in vocational vehicles (including vocational tractors 
certified under 40 CFR 1037.630 or exempted under 40 CFR 1037.631). We 
will waive this provision where you demonstrate that less than five 
percent of the engines in your tractor family were installed in 
vocational vehicles. For example, if you know that 96 percent of your 
tractor engines were installed in non-vocational tractors but cannot 
determine the vehicle type for the remaining four percent, you may 
generate credits for all the engines in the family.
    (5) You may generate CO2 emission credits from a model 
year 2021 or later medium heavy-duty engine family subject to spark-
ignition standards for exchanging with other engine families only if 
the engines in the family are gasoline-fueled. You may generate 
CO2 credits from non-gasoline engine families only for the 
purpose of offsetting CH4 and/or N2O emissions 
within the same engine family as described in paragraph (d) of this 
section.
    (c) As described in Sec.  1036.730, compliance with the 
requirements of this subpart is determined at the end of the model year 
based on actual U.S.-directed production volumes. Keep appropriate 
records to document these production volumes. Do not include any of the 
following engines to calculate emission credits:
    (1) Engines that you do not certify to the CO2 standards 
of this part because they are permanently exempted under subpart G of 
this part or under 40 CFR part 1068.
    (2) Exported engines.
    (3) Engines not subject to the requirements of this part, such as 
those excluded under Sec.  1036.5. For example, do not include engines 
used in vehicles certified to the greenhouse gas standards of 40 CFR 
86.1819.
    (4) Any other engines if we indicate elsewhere in this part that 
they are not to be included in the calculations of this subpart.
    (d) You may use CO2 emission credits to show compliance 
with CH4 and/or N2O FELs instead of the otherwise 
applicable emission standards. To do

[[Page 17721]]

this, calculate the CH4 and/or N2O emission 
credits needed (negative credits) using the equation in paragraph (b) 
of this section, using the FEL(s) you specify for your engines during 
certification instead of the FCL. You must use 34 Mg of positive 
CO2 credits to offset 1 Mg of negative CH4 
credits for model year 2021 and later engines, and you must use 25 Mg 
of positive CO2 credits to offset 1 Mg of negative 
CH4 credits for earlier engines. You must use 298 Mg of 
positive CO2 credits to offset 1 Mg of negative 
N2O credits.


Sec.  1036.710  Averaging.

    (a) Averaging is the exchange of emission credits among your engine 
families. You may average emission credits only within the same 
averaging set, except as specified in Sec.  1036.740.
    (b) You may certify one or more engine families to an FEL/FCL above 
the applicable standard, subject to any applicable FEL caps and other 
the provisions in subpart B of this part, if you show in your 
application for certification that your projected balance of all 
emission-credit transactions in that model year is greater than or 
equal to zero, or that a negative balance is allowed under Sec.  
1036.745.
    (c) If you certify an engine family to an FEL/FCL that exceeds the 
otherwise applicable standard, you must obtain enough emission credits 
to offset the engine family's deficit by the due date for the final 
report required in Sec.  1036.730. The emission credits used to address 
the deficit may come from your other engine families that generate 
emission credits in the same model year (or from later model years as 
specified in Sec.  1036.745), from emission credits you have banked, or 
from emission credits you obtain through trading.


Sec.  1036.715  Banking.

    (a) Banking is the retention of surplus emission credits by the 
manufacturer generating the emission credits for use in future model 
years for averaging or trading.
    (b) You may designate any emission credits you plan to bank in the 
reports you submit under Sec.  1036.730 as reserved credits. During the 
model year and before the due date for the final report, you may 
designate your reserved emission credits for averaging or trading.
    (c) Reserved credits become actual emission credits when you submit 
your final report. However, we may revoke these emission credits if we 
are unable to verify them after reviewing your reports or auditing your 
records.
    (d) Banked credits retain the designation of the averaging set in 
which they were generated.


Sec.  1036.720  Trading.

    (a) Trading is the exchange of emission credits between 
manufacturers. You may use traded emission credits for averaging, 
banking, or further trading transactions. Traded emission credits 
remain subject to the averaging-set restrictions based on the averaging 
set in which they were generated.
    (b) You may trade actual emission credits as described in this 
subpart. You may also trade reserved emission credits, but we may 
revoke these emission credits based on our review of your records or 
reports or those of the company with which you traded emission credits. 
You may trade banked credits within an averaging set to any certifying 
manufacturer.
    (c) If a negative emission credit balance results from a 
transaction, both the buyer and seller are liable, except in cases we 
deem to involve fraud. See Sec.  1036.255(e) for cases involving fraud. 
We may void the certificates of all engine families participating in a 
trade that results in a manufacturer having a negative balance of 
emission credits. See Sec.  1036.745.


Sec.  1036.725  Required information for certification.

    (a) You must declare in your application for certification your 
intent to use the provisions of this subpart for each engine family 
that will be certified using the ABT program. You must also declare the 
FEL/FCL you select for the engine family for each pollutant for which 
you are using the ABT program. Your FELs must comply with the 
specifications of subpart B of this part, including the FEL caps.
    (b) Include the following in your application for certification:
    (1) A statement that, to the best of your belief, you will not have 
a negative balance of emission credits for any averaging set when all 
emission credits are calculated at the end of the year; or a statement 
that you will have a negative balance of emission credits for one or 
more averaging sets, but that it is allowed under Sec.  1036.745.
    (2) Detailed calculations of projected emission credits (positive 
or negative) based on projected U.S.-directed production volumes. We 
may require you to include similar calculations from your other engine 
families to project your net credit balances for the model year. If you 
project negative emission credits for a family, state the source of 
positive emission credits you expect to use to offset the negative 
emission credits.


Sec.  1036.730  ABT reports.

    (a) If you certify any of your engine families using the ABT 
provisions of this subpart, you must send us a final report by 
September 30 following the end of the model year.
    (b) Your report must include the following information for each 
engine family participating in the ABT program:
    (1) Engine-family designation and averaging set.
    (2) The emission standards that would otherwise apply to the engine 
family.
    (3) The FEL/FCL for each pollutant. If you change the FEL/FCL after 
the start of production, identify the date that you started using the 
new FEL/FCL and/or give the engine identification number for the first 
engine covered by the new FEL/FCL. In this case, identify each 
applicable FEL/FCL and calculate the positive or negative emission 
credits as specified in Sec.  1036.225(f).
    (4) The projected and actual U.S.-directed production volumes for 
the model year. If you changed an FEL/FCL during the model year, 
identify the actual U.S.-directed production volume associated with 
each FEL/FCL.
    (5) The transient cycle conversion factor for each engine 
configuration as described in Sec.  1036.705.
    (6) Useful life.
    (7) Calculated positive or negative emission credits for the whole 
engine family. Identify any emission credits that you traded, as 
described in paragraph (d)(1) of this section.
    (c) Your report must include the following additional information:
    (1) Show that your net balance of emission credits from all your 
participating engine families in each averaging set in the applicable 
model year is not negative, except as allowed under Sec.  1036.745. 
Your credit tracking must account for the limitation on credit life 
under Sec.  1036.740(d).
    (2) State whether you will reserve any emission credits for 
banking.
    (3) State that the report's contents are accurate.
    (d) If you trade emission credits, you must send us a report within 
90 days after the transaction, as follows:
    (1) As the seller, you must include the following information in 
your report:
    (i) The corporate names of the buyer and any brokers.
    (ii) A copy of any contracts related to the trade.
    (iii) The averaging set corresponding to the engine families that 
generated emission credits for the trade, including the number of 
emission credits from each averaging set.

[[Page 17722]]

    (2) As the buyer, you must include the following information in 
your report:
    (i) The corporate names of the seller and any brokers.
    (ii) A copy of any contracts related to the trade.
    (iii) How you intend to use the emission credits, including the 
number of emission credits you intend to apply for each averaging set.
    (e) Send your reports electronically to the Designated Compliance 
Officer using an approved information format. If you want to use a 
different format, send us a written request with justification for a 
waiver.
    (f) Correct errors in your report as follows:
    (1) If you or we determine by September 30 after the end of the 
model year that errors mistakenly decreased your balance of emission 
credits, you may correct the errors and recalculate the balance of 
emission credits. You may not make these corrections for errors that 
are determined later than September 30 after the end of the model year. 
If you report a negative balance of emission credits, we may disallow 
corrections under this paragraph (f)(1).
    (2) If you or we determine any time that errors mistakenly 
increased your balance of emission credits, you must correct the errors 
and recalculate the balance of emission credits.


Sec.  1036.735  Recordkeeping.

    (a) You must organize and maintain your records as described in 
this section. We may review your records at any time.
    (b) Keep the records required by this section for at least eight 
years after the due date for the end-of-year report. You may not use 
emission credits for any engines if you do not keep all the records 
required under this section. You must therefore keep these records to 
continue to bank valid credits. Store these records in any format and 
on any media, as long as you can promptly send us organized, written 
records in English if we ask for them. You must keep these records 
readily available. We may review them at any time.
    (c) Keep a copy of the reports we require in Sec. Sec.  1036.725 
and 1036.730.
    (d) Keep records of the engine identification number (usually the 
serial number) for each engine you produce that generates or uses 
emission credits under the ABT program. You may identify these numbers 
as a range. If you change the FEL after the start of production, 
identify the date you started using each FEL/FCL and the range of 
engine identification numbers associated with each FEL/FCL. You must 
also identify the purchaser and destination for each engine you produce 
to the extent this information is available.
    (e) We may require you to keep additional records or to send us 
relevant information not required by this section in accordance with 
the Clean Air Act.


Sec.  1036.740  Restrictions for using emission credits.

    The following restrictions apply for using emission credits:
    (a) Averaging sets. Except as specified in paragraph (c) of this 
section, emission credits may be exchanged only within the following 
averaging sets based on primary intended service class:
    (1) Spark-ignition HDE.
    (2) Light HDE.
    (3) Medium HDE.
    (4) Heavy HDE.
    (b) Applying credits to prior year deficits. Where your 
CO2 credit balance for the previous year is negative, you 
may apply credits to that deficit only after meeting your credit 
obligations for the current year.
    (c) CO2 credits from hybrid engines and other advanced 
technologies. CO2 credits you generate under Sec.  1036.615 
may be used for any of the averaging sets identified in paragraph (a) 
of this section; you may also use those credits to demonstrate 
compliance with the CO2 emission standards in 40 CFR 86.1819 
and 40 CFR part 1037. Similarly, you may use Phase 1 advanced-
technology credits generated under 40 CFR 86.1819-14(k)(7) or 40 CFR 
1037.615 to demonstrate compliance with the CO2 standards in 
this part. In the case of Spark-ignition HDE and Light HDE you may not 
use more than 60,000 Mg of credits from other averaging sets in any 
model year.
    (1) The maximum CO2 credits you may bring into the 
following service class groups is 60,000 Mg per model year:
    (i) Spark-ignition HDE, Light HDE, and Light HDV. This group 
comprises the averaging sets listed in paragraphs (a)(1) and (2) of 
this section and the averaging set listed in 40 CFR 1037.740(a)(1).
    (ii) Medium HDE and Medium HDV. This group comprises the averaging 
sets listed in paragraph (a)(3) of this section and 40 CFR 
1037.740(a)(2).
    (iii) Heavy HDE and Heavy HDV. This group comprises the averaging 
sets listed in paragraph (a)(4) of this section and 40 CFR 
1037.740(a)(3).
    (2) Paragraph (c)(1) of this section does not limit the advanced-
technology credits that can be used within a service class group if 
they were generated in that same service class group.
    (d) NOX and CO2 credit life. NOX and CO2 
credits may be used only for five model years after the year in which 
they are generated. For example, credits you generate in model year 
2027 may be used to demonstrate compliance with emission standards only 
through model year 2032.
    (e) Other restrictions. Other sections of this part specify 
additional restrictions for using emission credits under certain 
special provisions.


Sec.  1036.741  Using emission credits from electric vehicles and 
hydrogen fuel-cell vehicles.

    NOX credits you generate under 40 CFR 1037.616 from 
electric vehicles may be used to demonstrate compliance with the 
NOX emission standards in this part as follows:
    (a) Credits may be averaged, banked, or traded as described in this 
subpart H.
    (b) Averaging sets apply as specified in Sec.  1036.740 and 40 CFR 
1037.102(b)(1).
    (c) Banked credits may be used only for five model years as 
described in Sec.  1036.740(d).


Sec.  1036.745  End-of-year CO2 credit deficits.

    Except as allowed by this section, we may void the certificate of 
any engine family certified to an FCL above the applicable standard for 
which you do not have sufficient credits by the deadline for submitting 
the final report.
    (a) Your certificate for an engine family for which you do not have 
sufficient CO2 credits will not be void if you remedy the 
deficit with surplus credits within three model years. For example, if 
you have a credit deficit of 500 Mg for an engine family at the end of 
model year 2015, you must generate (or otherwise obtain) a surplus of 
at least 500 Mg in that same averaging set by the end of model year 
2018.
    (b) You may not bank or trade away CO2 credits in the 
averaging set in any model year in which you have a deficit.
    (c) You may apply only surplus credits to your deficit. You may not 
apply credits to a deficit from an earlier model year if they were 
generated in a model year for which any of your engine families for 
that averaging set had an end-of-year credit deficit.
    (d) You must notify us in writing how you plan to eliminate the 
credit deficit within the specified time frame. If we determine that 
your plan is unreasonable or unrealistic, we may deny an application 
for certification for a vehicle family if its FEL would increase your 
credit deficit. We may determine that your plan is unreasonable or 
unrealistic based on a consideration of past and projected use of 
specific technologies, the historical sales mix of your vehicle models, 
your

[[Page 17723]]

commitment to limit production of higher-emission vehicles, and 
expected access to traded credits. We may also consider your plan 
unreasonable if your credit deficit increases from one model year to 
the next. We may require that you send us interim reports describing 
your progress toward resolving your credit deficit over the course of a 
model year.
    (e) If you do not remedy the deficit with surplus credits within 
three model years, we may void your certificate for that engine family. 
We may void the certificate based on your end-of-year report. Note that 
voiding a certificate applies ab initio. Where the net deficit is less 
than the total amount of negative credits originally generated by the 
family, we will void the certificate only with respect to the number of 
engines needed to reach the amount of the net deficit. For example, if 
the original engine family generated 500 Mg of negative credits, and 
the manufacturer's net deficit after three years was 250 Mg, we would 
void the certificate with respect to half of the engines in the family.
    (f) For purposes of calculating the statute of limitations, the 
following actions are all considered to occur at the expiration of the 
deadline for offsetting a deficit as specified in paragraph (a) of this 
section:
    (1) Failing to meet the requirements of paragraph (a) of this 
section.
    (2) Failing to satisfy the conditions upon which a certificate was 
issued relative to offsetting a deficit.
    (3) Selling, offering for sale, introducing or delivering into U.S. 
commerce, or importing vehicles that are found not to be covered by a 
certificate as a result of failing to offset a deficit.


Sec.  1036.750  Consequences for noncompliance.

    (a) For each engine family participating in the ABT program, the 
certificate of conformity is conditioned upon full compliance with the 
provisions of this subpart during and after the model year. You are 
responsible to establish to our satisfaction that you fully comply with 
applicable requirements. We may void the certificate of conformity for 
an engine family if you fail to comply with any provisions of this 
subpart.
    (b) You may certify your engine family to an FEL/FCL above an 
applicable standard based on a projection that you will have enough 
emission credits to offset the deficit for the engine family. See Sec.  
1036.745 for provisions specifying what happens if you cannot show in 
your final report that you have enough actual emission credits to 
offset a deficit for any pollutant in an engine family.
    (c) We may void the certificate of conformity for an engine family 
if you fail to keep records, send reports, or give us information we 
request. Note that failing to keep records, send reports, or give us 
information we request is also a violation of 42 U.S.C. 7522(a)(2).
    (d) You may ask for a hearing if we void your certificate under 
this section (see Sec.  1036.820).


Sec.  1036.755  Information provided to the Department of 
Transportation.

    After receipt of each manufacturer's final report as specified in 
Sec.  1036.730 and completion of any verification testing required to 
validate the manufacturer's submitted final data, we will issue a 
report to the Department of Transportation with CO2 emission 
information and will verify the accuracy of each manufacturer's 
equivalent fuel consumption data that required by NHTSA under 49 CFR 
535.8. We will send a report to DOT for each engine manufacturer based 
on each regulatory category and subcategory, including sufficient 
information for NHTSA to determine fuel consumption and associated 
credit values. See 49 CFR 535.8 to determine if NHTSA deems submission 
of this information to EPA to also be a submission to NHTSA.

Subpart I--Definitions and Other Reference Information


Sec.  1036.801  Definitions.

    The following definitions apply to this part. The definitions apply 
to all subparts unless we note otherwise. All undefined terms have the 
meaning the Act gives to them. The definitions follow:
    Act means the Clean Air Act, as amended, 42 U.S.C. 7401-7671q.
    Adjustable parameter has the meaning given in 40 CFR 1068.50.
    Advanced technology means technology certified under 40 CFR 
86.1819-14(k)(7), Sec.  1036.615, or 40 CFR 1037.615.
    Aftertreatment means relating to a catalytic converter, particulate 
filter, or any other system, component, or technology mounted 
downstream of the exhaust valve (or exhaust port) whose design function 
is to decrease emissions in the engine exhaust before it is exhausted 
to the environment. Exhaust gas recirculation (EGR) and turbochargers 
are not aftertreatment.
    Aircraft means any vehicle capable of sustained air travel more 
than 100 feet above the ground.
    Alcohol-fueled engine mean an engine that is designed to run using 
an alcohol fuel. For purposes of this definition, alcohol fuels do not 
include fuels with a nominal alcohol content below 25 percent by 
volume.
    Auxiliary emission control device means any element of design that 
senses temperature, motive speed, engine speed (r/min), transmission 
gear, or any other parameter for the purpose of activating, modulating, 
delaying, or deactivating the operation of any part of the emission 
control system.
    Averaging set has the meaning given in Sec.  1036.740.
    Calibration means the set of specifications and tolerances specific 
to a particular design, version, or application of a component or 
assembly capable of functionally describing its operation over its 
working range.
    Carryover means relating to certification based on emission data 
generated from an earlier model year as described in Sec.  1036.235(d).
    Certification means relating to the process of obtaining a 
certificate of conformity for an engine family that complies with the 
emission standards and requirements in this part.
    Certified emission level means the highest deteriorated emission 
level in an engine family for a given pollutant from the applicable 
transient and/or steady-state testing, rounded to the same number of 
decimal places as the applicable standard. Note that you may have two 
certified emission levels for CO2 if you certify a family 
for both vocational and tractor use.
    Charge-depleting has the meaning given in 40 CFR 1066.1001.
    Charge-sustaining has the meaning given in 40 CFR 1066.1001.
    Complete vehicle means a vehicle meeting the definition of complete 
vehicle in 40 CFR 1037.801 when it is first sold as a vehicle. For 
example, where a vehicle manufacturer sells an incomplete vehicle to a 
secondary vehicle manufacturer, the vehicle is not a complete vehicle 
under this part, even after its final assembly.
    Compression-ignition means relating to a type of reciprocating, 
internal-combustion engine that is not a spark-ignition engine. Note 
that Sec.  1036.1 also deems gas turbine engines and other engines to 
be compression-ignition engines.
    Crankcase emissions means airborne substances emitted to the 
atmosphere from any part of the engine crankcase's ventilation or 
lubrication systems. The crankcase is the housing for the crankshaft 
and other related internal parts.
    Criteria pollutants means emissions of NOX, HC, PM, and 
CO.

[[Page 17724]]

    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
    Defeat device has the meaning given in Sec.  1036.115(h).
    Designated Compliance Officer means one of the following:
    (1) For engines subject to compression-ignition standards, 
Designated Compliance Officer means Director, Diesel Engine Compliance 
Center, U.S. Environmental Protection Agency, 2000 Traverwood Drive, 
Ann Arbor, MI 48105; [email protected]; www.epa.gov/ve-certification.
    (2) For engines subject to spark-ignition standards, Designated 
Compliance Officer means Director, Gasoline Engine Compliance Center, 
U.S. Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor, 
MI 48105; [email protected]; www.epa.gov/ve-certification.
    Deteriorated emission level means the emission level that results 
from applying the appropriate deterioration factor to the official 
emission result of the emission-data engine. Note that where no 
deterioration factor applies, references in this part to the 
deteriorated emission level mean the official emission result.
    Deterioration factor means the relationship between emissions at 
the end of useful life (or point of highest emissions if it occurs 
before the end of useful life) and emissions at the low-hour/low-
mileage point, expressed in one of the following ways:
    (1) For multiplicative deterioration factors, the ratio of 
emissions at the end of useful life (or point of highest emissions) to 
emissions at the low-hour point.
    (2) For additive deterioration factors, the difference between 
emissions at the end of useful life (or point of highest emissions) and 
emissions at the low-hour point.
    Diesel exhaust fluid (DEF) means a liquid reducing agent (other 
than the engine fuel) used in conjunction with selective catalytic 
reduction to reduce NOX emissions. Diesel exhaust fluid is 
generally understood to be an aqueous solution of urea conforming to 
the specifications of ISO 22241.
    Dual-fuel means relating to an engine designed for operation on two 
different types of fuel but not on a continuous mixture of those fuels 
(see Sec.  1036.601(d)). For purposes of this part, such an engine 
remains a dual-fuel engine even if it is designed for operation on 
three or more different fuels.
    Electronic control module (ECM) means an engine's electronic device 
that uses data from engine sensors to control engine parameters.
    Emission control system means any device, system, or element of 
design that controls or reduces the emissions of regulated pollutants 
from an engine.
    Emission-data engine means an engine that is tested for 
certification. This includes engines tested to establish deterioration 
factors.
    Emission-related component has the meaning given in 40 CFR part 
1068, appendix A.
    Emission-related maintenance means maintenance that substantially 
affects emissions or is likely to substantially affect emission 
deterioration.
    Engine configuration means a unique combination of engine hardware 
and calibration (related to the emission standards) within an engine 
family, which would include hybrid components for engines certified as 
hybrid engines and hybrid powertrains. Engines within a single engine 
configuration differ only with respect to normal production variability 
or factors unrelated to compliance with emission standards.
    Engine family has the meaning given in Sec.  1036.230.
    Excluded means relating to engines that are not subject to some or 
all of the requirements of this part as follows:
    (1) An engine that has been determined not to be a heavy-duty 
engine is excluded from this part.
    (2) Certain heavy-duty engines are excluded from the requirements 
of this part under Sec.  1036.5.
    (3) Specific regulatory provisions of this part may exclude a 
heavy-duty engine generally subject to this part from one or more 
specific standards or requirements of this part.
    Exempted has the meaning given in 40 CFR 1068.30.
    Exhaust gas recirculation means a technology that reduces emissions 
by routing exhaust gases that had been exhausted from the combustion 
chamber(s) back into the engine to be mixed with incoming air before or 
during combustion. The use of valve timing to increase the amount of 
residual exhaust gas in the combustion chamber(s) that is mixed with 
incoming air before or during combustion is not considered exhaust gas 
recirculation for the purposes of this part.
    Family certification level (FCL) means a CO2 emission 
level declared by the manufacturer that is at or above emission results 
for all emission-data engines. The FCL serves as the emission standard 
for the engine family with respect to certification testing if it is 
different than the otherwise applicable standard.
    Family emission limit (FEL) means one of the following:
    (1) For NOX emissions, family emission limit (FEL) means 
a NOX emission level declared by the manufacturer to serve 
in place of an otherwise applicable emission standard under the ABT 
program in subpart H of this part. The FEL serves as the emission 
standard for the engine family with respect to all required testing.
    (2) For greenhouse gas standards, family emission limit (FEL) is 
the standard that applies for testing individual engines. The 
CO2 FEL is equal to the CO2 FCL multiplied by 
1.03 and rounded to the same number of decimal places as the standard.
    Federal Test Procedure (FTP) means the applicable transient duty 
cycle described in Sec.  1036.510 designed to measure exhaust emissions 
during urban driving.
    Flexible-fuel means relating to an engine designed for operation on 
any mixture of two or more different types of fuels (see Sec.  
1036.601(d)).
    Fuel type means a general category of fuels such as diesel fuel, 
gasoline, or natural gas. There can be multiple grades within a single 
fuel type, such as premium gasoline, regular gasoline, or gasoline with 
10 percent ethanol.
    Good engineering judgment has the meaning given in 40 CFR 1068.30. 
See 40 CFR 1068.5 for the administrative process we use to evaluate 
good engineering judgment.
    Greenhouse gas means one or more compounds regulated under this 
part based primarily on their impact on the climate. This generally 
includes CO2, CH4, and N2O.
    Greenhouse gas Emissions Model (GEM) means the GEM simulation tool 
described in 40 CFR 1037.520. Note that an updated version of GEM 
applies starting in model year 2021.
    Gross vehicle weight rating (GVWR) means the value specified by the 
vehicle manufacturer as the maximum design loaded weight of a single 
vehicle, consistent with good engineering judgment.
    Heavy-duty engine means any engine which the engine manufacturer 
could reasonably expect to be used for motive power in a heavy-duty 
vehicle. For purposes of this definition in this part, the term 
``engine'' includes internal combustion engines and other devices that 
convert chemical fuel into motive power. For example, a fuel cell or a 
gas turbine used in a heavy-duty vehicle is a heavy-duty engine.
    Heavy-duty vehicle means any motor vehicle above 8,500 pounds GVWR. 
An incomplete vehicle is also a heavy-duty vehicle if it has a curb 
weight above

[[Page 17725]]

6,000 pounds or a basic vehicle frontal area greater than 45 square 
feet. Curb weight and basic vehicle frontal area have the meaning given 
in 40 CFR 86.1803-01.
    Hybrid means an engine or powertrain that includes energy storage 
features other than a conventional battery system or conventional 
flywheel. Supplemental electrical batteries and hydraulic accumulators 
are examples of hybrid energy storage systems. Note that certain 
provisions in this part treat hybrid engines and hybrid powertrains 
intended for vehicles that include regenerative braking different than 
those intended for vehicles that do not include regenerative braking.
    Hybrid engine means a hybrid system with features for storing and 
recovering energy that are integral to the engine or are otherwise 
upstream of the vehicle's transmission other than a conventional 
battery system or conventional flywheel. Supplemental electrical 
batteries and hydraulic accumulators are examples of hybrid energy 
storage systems. Examples of hybrids that could be considered hybrid 
engines are P0, P1, and P2 hybrids where hybrid features are connected 
to the front end of the engine, at the crankshaft, or connected between 
the clutch and the transmission where the clutch upstream of the hybrid 
feature is in addition to the transmission clutch(s), respectively. 
Note other examples of systems that qualify as hybrid engines are 
systems that recover kinetic energy and use it to power an electric 
heater in the aftertreatment.
    Hybrid powertrain means a powertrain that includes energy storage 
features other than a conventional battery system or conventional 
flywheel. Supplemental electrical batteries and hydraulic accumulators 
are examples of hybrid energy storage systems. Note other examples of 
systems that qualify as hybrid powertrains are systems that recover 
kinetic energy and use it to power an electric heater in the 
aftertreatment.
    Hydrocarbon (HC) has the meaning given in 40 CFR 1065.1001.
    Identification number means a unique specification (for example, a 
model number/serial number combination) that allows someone to 
distinguish a particular engine from other similar engines.
    Incomplete vehicle means a vehicle meeting the definition of 
incomplete vehicle in 40 CFR 1037.801 when it is first sold (or 
otherwise delivered to another entity) as a vehicle.
    Innovative technology means technology certified under Sec.  
1036.610 (also described as ``off-cycle technology'').
    Liquefied petroleum gas (LPG) means a liquid hydrocarbon fuel that 
is stored under pressure and is composed primarily of nonmethane 
compounds that are gases at atmospheric conditions. Note that, although 
this commercial term includes the word ``petroleum'', LPG is not 
considered to be a petroleum fuel under the definitions of this 
section.
    Low-hour means relating to an engine that has stabilized emissions 
and represents the undeteriorated emission level. This would generally 
involve less than 300 hours of operation for engines with 
NOX aftertreatment and 125 hours of operation for other 
engines.
    Manufacture means the physical and engineering process of 
designing, constructing, and/or assembling a heavy-duty engine or a 
heavy-duty vehicle.
    Manufacturer has the meaning given in 40 CFR 1068.30.
    Medium-duty passenger vehicle has the meaning given in 40 CFR 
86.1803.
    Mild hybrid means a hybrid engine or powertrain with regenerative 
braking capability where the system recovers less than 20 percent of 
the total braking energy over the transient cycle defined in appendix A 
of 40 CFR part 1037.
    Model year means the manufacturer's annual new model production 
period, except as restricted under this definition. It must include 
January 1 of the calendar year for which the model year is named, may 
not begin before January 2 of the previous calendar year, and it must 
end by December 31 of the named calendar year. Manufacturers may not 
adjust model years to circumvent or delay compliance with emission 
standards or to avoid the obligation to certify annually.
    Motor vehicle has the meaning given in 40 CFR 85.1703.
    Natural gas means a fuel whose primary constituent is methane.
    New motor vehicle engine has the meaning given in the Act. This 
generally means a motor vehicle engine meeting any of the following:
    (1) A motor vehicle engine for which the ultimate purchaser has 
never received the equitable or legal title is a new motor vehicle 
engine. This kind of engine might commonly be thought of as ``brand 
new'' although a new motor vehicle engine may include previously used 
parts. Under this definition, the engine is new from the time it is 
produced until the ultimate purchaser receives the title or places it 
into service, whichever comes first.
    (2) An imported motor vehicle engine is a new motor vehicle engine 
if it was originally built on or after January 1, 1970.
    (3) Any motor vehicle engine installed in a new motor vehicle.
    Noncompliant engine means an engine that was originally covered by 
a certificate of conformity, but is not in the certified configuration 
or otherwise does not comply with the conditions of the certificate.
    Nonconforming engine means an engine not covered by a certificate 
of conformity that would otherwise be subject to emission standards.
    Nonmethane hydrocarbon (NMHC) means the sum of all hydrocarbon 
species except methane, as measured according to 40 CFR part 1065.
    Nonmethane hydrocarbon equivalent (NMHCE) has the meaning given in 
40 CFR 1065.1001.
    Nonmethane nonethane hydrocarbon equivalent (NMNEHC) has the 
meaning given in 40 CFR 1065.1001.
    Off-cycle technology means technology certified under Sec.  
1036.610 (also described as ``innovative technology'').
    Official emission result means the measured emission rate for an 
emission-data engine on a given duty cycle before the application of 
any deterioration factor, but after the applicability of any required 
regeneration or other adjustment factors.
    Owners manual means a document or collection of documents prepared 
by the engine or vehicle manufacturer for the owner or operator to 
describe appropriate engine maintenance, applicable warranties, and any 
other information related to operating or keeping the engine. The 
owners manual is typically provided to the ultimate purchaser at the 
time of sale. The owners manual may be in paper or electronic format.
    Oxides of nitrogen has the meaning given in 40 CFR 1065.1001.
    Percent has the meaning given in 40 CFR 1065.1001. Note that this 
means percentages identified in this part are assumed to be infinitely 
precise without regard to the number of significant figures. For 
example, one percent of 1,493 is 14.93.
    Placed into service means put into initial use for its intended 
purpose, excluding incidental use by the manufacturer or a dealer.
    Preliminary approval means approval granted by an authorized EPA 
representative prior to submission of an application for certification, 
consistent with the provisions of Sec.  1036.210.
    Primary intended service class has the meaning given in Sec.  
1036.140.
    QR Code means Quick Response Code, which is a registered trademark 
of Denso Wave, Incorporated.

[[Page 17726]]

    Rechargeable Energy Storage System (RESS) has the meaning given in 
40 CFR 1065.1001.
    Relating to as used in this section means relating to something in 
a specific, direct manner. This expression is used in this section only 
to define terms as adjectives and not to broaden the meaning of the 
terms.
    Revoke has the meaning given in 40 CFR 1068.30.
    Round has the meaning given in 40 CFR 1065.1001.
    Sample means the collection of engines selected from the population 
of an engine family for emission testing. This may include testing for 
certification, production-line testing, or in-use testing.
    Scheduled maintenance means adjusting, removing, disassembling, 
cleaning, or replacing components or systems periodically to keep a 
part or system from failing, malfunctioning, or wearing prematurely.
    Small manufacturer means a manufacturer meeting the criteria 
specified in 13 CFR 121.201. The employee and revenue limits apply to 
the total number of employees and total revenue together for affiliated 
companies. Note that manufacturers with low production volumes may or 
may not be ``small manufacturers''.
    Spark-ignition means relating to a gasoline-fueled engine or any 
other type of engine with a spark plug (or other sparking device) and 
with operating characteristics significantly similar to the theoretical 
Otto combustion cycle. Spark-ignition engines usually use a throttle to 
regulate intake air flow to control power during normal operation.
    Steady-state has the meaning given in 40 CFR 1065.1001. This 
includes fuel mapping and idle testing where engine speed and load are 
held at a finite set of nominally constant values.
    Suspend has the meaning given in 40 CFR 1068.30.
    Test engine means an engine in a sample.
    Tractor means a vehicle meeting the definition of ``tractor'' in 40 
CFR 1037.801, but not classified as a ``vocational tractor'' under 40 
CFR 1037.630, or relating to such a vehicle.
    Tractor engine means an engine certified for use in tractors. Where 
an engine family is certified for use in both tractors and vocational 
vehicles, ``tractor engine'' means an engine that the engine 
manufacturer reasonably believes will be (or has been) installed in a 
tractor. Note that the provisions of this part may require a 
manufacturer to document how it determines that an engine is a tractor 
engine.
    Ultimate purchaser means, with respect to any new engine or 
vehicle, the first person who in good faith purchases such new engine 
or vehicle for purposes other than resale.
    United States has the meaning given in 40 CFR 1068.30.
    Upcoming model year means for an engine family the model year after 
the one currently in production.
    U.S.-directed production volume means the number of engines, 
subject to the requirements of this part, produced by a manufacturer 
for which the manufacturer has a reasonable assurance that sale was or 
will be made to ultimate purchasers in the United States. This does not 
include engines certified to state emission standards that are 
different than the emission standards in this part.
    Vehicle has the meaning given in 40 CFR 1037.801.
    Vocational engine means an engine certified for use in vocational 
vehicles. Where an engine family is certified for use in both tractors 
and vocational vehicles, ``vocational engine'' means an engine that the 
engine manufacturer reasonably believes will be (or has been) installed 
in a vocational vehicle. Note that the provisions of this part may 
require a manufacturer to document how it determines that an engine is 
a vocational engine.
    Vocational vehicle means a vehicle meeting the definition of 
``vocational'' vehicle in 40 CFR 1037.801.
    Void has the meaning given in 40 CFR 1068.30.
    We (us, our) means the Administrator of the Environmental 
Protection Agency and any authorized representatives.


Sec.  1036.805  Symbols, abbreviations, and acronyms.

    The procedures in this part generally follow either the 
International System of Units (SI) or the United States customary 
units, as detailed in NIST Special Publication 811 (incorporated by 
reference in Sec.  1036.810). See 40 CFR 1065.20 for specific 
provisions related to these conventions. This section summarizes the 
way we use symbols, units of measure, and other abbreviations.
    (a) Symbols for chemical species. This part uses the following 
symbols for chemical species and exhaust constituents:

    Table 1 to Paragraph (a) of Sec.   1036.805--Symbols for Chemical
                    Species and Exhaust Constituents
------------------------------------------------------------------------
                  Symbol                               Species
------------------------------------------------------------------------
C.........................................  carbon.
CH4.......................................  methane.
CH4N2O....................................  urea.
CO........................................  carbon monoxide.
CO2.......................................  carbon dioxide.
H2O.......................................  water.
HC........................................  hydrocarbon.
NMHC......................................  nonmethane hydrocarbon.
NMHCE.....................................  nonmethane hydrocarbon
                                             equivalent.
NMNEHC....................................  nonmethane nonethane
                                             hydrocarbon.
NO........................................  nitric oxide.
NO2.......................................  nitrogen dioxide.
NOX.......................................  oxides of nitrogen.
N2O.......................................  nitrous oxide.
PM........................................  particulate matter.
------------------------------------------------------------------------

    (b) Symbols for quantities. This part uses the following symbols 
and units of measure for various quantities:

                       Table 2 to Paragraph (b) of Sec.   1036.805--Symbols for Quantities
----------------------------------------------------------------------------------------------------------------
                                                                                               Unit in terms of
             Symbol                    Quantity              Unit             Unit symbol        SI base units
----------------------------------------------------------------------------------------------------------------
a...............................  atomic hydrogen-to- mole per mole.....  mol/mol...........  1
                                   carbon ratio.
A...............................  Area..............  square meter......  m\2\..............  m\2\
b...............................  atomic oxygen-to-   mole per mole.....  mol/mol...........  1
                                   carbon ratio.
CdA.............................  drag area.........  meter squared.....  m\2\..............  m\2\
Crr.............................  coefficient of      newton per          N/kN..............  10-3
                                   rolling             kilonewton.
                                   resistance.
D...............................  distance..........  miles or meters...  mi or m...........  m
e...............................  efficiency
E...............................  Difference or
                                   error quantity
e...............................  mass weighted       grams/ton-mile....  g/ton-mi..........  g/kg-km
                                   emission result.
Eff.............................  efficiency
Em..............................  mass-specific net   megajoules/         MJ/kg.............  m\2\[middot]s-2
                                   energy content.     kilogram.
fn..............................  angular speed       revolutions per     r/min.............  [pi][middot]30[mid
                                   (shaft).            minute.                                 dot]s-1

[[Page 17727]]

 
g...............................  gravitational       meters per second   m/s\2\............  m[middot]s-\2\
                                   acceleration.       squared.
i...............................  indexing variable
ka..............................  drive axle ratio..  ..................  ..................  1
ktopgear........................  highest available
                                   transmission gear
m...............................  Mass..............  pound mass or       lbm or kg.........  kg
                                                       kilogram.
M...............................  molar mass........  gram per mole.....  g/mol.............  10-
                                                                                               \3\[middot]kg[mid
                                                                                               dot]mol-\1\
M...............................  total number in a
                                   series
M...............................  vehicle mass......  kilogram..........  kg................  kg
Mrotating.......................  inertial mass of    kilogram..........  kg................  kg
                                   rotating
                                   components.
N...............................  total number in a
                                   series
Q...............................  total number in a
                                   series
P...............................  Power.............  kilowatt..........  kW................  103[middot]m\2\[mi
                                                                                               ddot]kg[middot]s-
                                                                                               3
r...............................  mass density......  kilogram per cubic  kg/m3.............  m-\3\[middot]kg
                                                       meter.
r...............................  tire radius.......  meter.............  m.................  m
SEE.............................  standard error of
                                   the estimate
s...............................  standard deviation
T...............................  torque (moment of   newton meter......  N[middot]m........  m\2\[middot]kg[mid
                                   force).                                                     dot]s-2
t...............................  Time..............  second............  s.................  s
Dt..............................  time interval,      second............  s.................  s
                                   period, 1/
                                   frequency.
UF..............................  utility factor
v...............................  Speed.............  miles per hour or   mi/hr or m/s......  m[middot]s-1
                                                       meters per second.
W...............................  Work..............  kilowatt-hour.....  kW[middot]hr......  3.6[middot]m\2\[mi
                                                                                               ddot]kg[middot]s-
                                                                                               1
wC..............................  carbon mass         gram/gram.........  g/g...............  1
                                   fraction.
wCH4N2O.........................  urea mass fraction  gram/gram.........  g/g...............  1
x...............................  amount of           mole per mole.....  mol/mol...........  1
                                   substance mole
                                   fraction.
xb..............................  brake energy
                                   fraction
xbl.............................  brake energy limit
----------------------------------------------------------------------------------------------------------------

    (c) Superscripts. This part uses the following superscripts for 
modifying quantity symbols:

        Table 3 to Paragraph (c) of Sec.   1036.805--Superscripts
------------------------------------------------------------------------
                Superscript                            Meaning
------------------------------------------------------------------------
overbar (such as y).......................  arithmetic mean.
overdot (such as y).......................  quantity per unit time.
------------------------------------------------------------------------

    (d) Subscripts. This part uses the following subscripts for 
modifying quantity symbols:

                             Table 4 to Paragraph (d) of Sec.   1036.805--Subscripts
----------------------------------------------------------------------------------------------------------------
            Subscript                                                 Meaning
----------------------------------------------------------------------------------------------------------------
65...............................  65 miles per hour.
A................................  A speed.
a................................  absolute (e.g., absolute difference or error).
acc..............................  accessory.
app..............................  approved.
axle.............................  axle.
B................................  B speed.
C................................  C speed.
C................................  carbon mass.
Ccombdry.........................  carbon from fuel per mole of dry exhaust.
CD...............................  charge-depleting.
CO2DEF...........................  CO2 resulting from diesel exhaust fluid decomposition.
comb.............................  combustion.
comp.............................  composite.
cor..............................  corrected.
CS...............................  charge-sustaining.
cycle............................  cycle.
D................................  distance.
D................................  D speed.
DEF..............................  diesel exhaust fluid.
engine...........................  engine.
exh..............................  raw exhaust.
front............................  frontal.
fuel.............................  fuel.
H2Oexhaustdry....................  H2O in exhaust per mole of exhaust.

[[Page 17728]]

 
hi...............................  high.
i................................  an individual of a series.
idle.............................  idle.
int..............................  test interval.
j................................  an individual of a series.
k................................  an individual of a series.
m................................  mass.
max..............................  maximum.
mapped...........................  mapped.
meas.............................  measured quantity.
MY...............................  model year.
neg..............................  negative.
pos..............................  positive.
R................................  range.
r................................  relative (e.g., relative difference or error).
rate.............................  rate (divided by time).
rated............................  rated.
record...........................  record.
ref..............................  reference quantity.
speed............................  speed.
stall............................  stall.
test.............................  test.
tire.............................  tire.
transient........................  transient.
[mu].............................  vector.
UF...............................  utility factor.
vehicle..........................  vehicle.
----------------------------------------------------------------------------------------------------------------

    (e) Other acronyms and abbreviations. This part uses the following 
additional abbreviations and acronyms:

                  Table 5 to Paragraph (e) of Sec.   1036.805--Other Acronyms and Abbreviations
----------------------------------------------------------------------------------------------------------------
             Acronym                                                  Meaning
----------------------------------------------------------------------------------------------------------------
ABT..............................  averaging, banking, and trading.
AECD.............................  auxiliary emission control device.
ASTM.............................  American Society for Testing and Materials.
BTU..............................  British thermal units.
CD...............................  charge-depleting.
CFR..............................  Code of Federal Regulations.
CI...............................  compression-ignition.
COV..............................  coefficient of variation.
CS...............................  charge-sustaining.
DEF..............................  diesel exhaust fluid.
DF...............................  deterioration factor.
DOT..............................  Department of Transportation.
E85..............................  gasoline blend including nominally 85 percent denatured ethanol.
ECM..............................  Electronic Control Module.
EGR..............................  exhaust gas recirculation.
EPA..............................  Environmental Protection Agency.
FCL..............................  Family Certification Level.
FEL..............................  Family Emission Limit.
FTP..............................  Federal Test Procedure.
GEM..............................  Greenhouse gas Emissions Model.
g/hp[middot]hr...................  grams per brake horsepower-hour.
GPS..............................  global positioning system.
GVWR.............................  gross vehicle weight rating.
Heavy HDE........................  heavy heavy-duty engine (see Sec.   1036.140).
Heavy HDV........................  heavy heavy-duty vehicle (see 40 CFR 1037.140).
Light HDE........................  light heavy-duty engine (see Sec.   1036.140).
Light HDV........................  light heavy-duty vehicle (see 40 CFR 1037.140).
LLC..............................  Low Load Cycle.
LPG..............................  liquefied petroleum gas.
Medium HDE.......................  medium heavy-duty engine (see Sec.   1036.140).
Medium HDV.......................  medium heavy-duty vehicle (see 40 CFR 1037.140).
NARA.............................  National Archives and Records Administration.
NHTSA............................  National Highway Traffic Safety Administration.

[[Page 17729]]

 
NTE..............................  not-to-exceed.
PEMS.............................  portable emission measurement system.
RESS.............................  rechargeable energy storage system.
SCR..............................  selective catalytic reduction.
SEE..............................  standard error of the estimate.
SET..............................  Supplemental Emission Test.
Spark-ignition HDE...............  spark-ignition heavy-duty engine (see Sec.   1036.140).
SI...............................  spark-ignition.
UL...............................  useful life.
U.S..............................  United States.
U.S.C............................  United States Code.
----------------------------------------------------------------------------------------------------------------

    (f) Constants. This part uses the following constants:

         Table 6 to Paragraph (f) of Sec.   1036.805--Constants
------------------------------------------------------------------------
           Symbol                   Quantity                Value
------------------------------------------------------------------------
g...........................  gravitational         9.80665 m[middot]s-
                               constant.             \2\.
------------------------------------------------------------------------

    (g) Prefixes. This part uses the following prefixes to define a 
quantity:

          Table 7 to Paragraph (g) of Sec.   1036.805--Prefixes
------------------------------------------------------------------------
             Symbol                      Quantity              Value
------------------------------------------------------------------------
[mu]...........................  micro..................            10-6
m..............................  milli..................            10-3
c..............................  centi..................            10-2
k..............................  kilo...................           10\3\
M..............................  mega...................             106
------------------------------------------------------------------------

Sec.  1036.810  Incorporation by reference.

    Certain material is incorporated by reference into this part with 
the approval of the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than 
that specified in this section, the Environmental Protection Agency 
(EPA) must publish a document in the Federal Register and the material 
must be available to the public. All approved material is available for 
inspection at the EPA and at the National Archives and Records 
Administration (NARA). Contact EPA at: U.S. EPA, Air and Radiation 
Docket and Information Center, 1301 Constitution Ave. NW, Room B102, 
EPA West Building, Washington, DC 20460, www.epa.gov/dockets, (202) 
202-1744. For information on the availability of this material at NARA, 
email: [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html. The material may be obtained from the 
following sources:
    (a) ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West 
Conshohocken, PA 19428-2959, (877) 909-2786, or www.astm.org.
    (1) ASTM D975-21, Standard Specification for Diesel Fuel, approved 
August 1, 2021 (``ASTM D975''); IBR approved for Sec.  1036.415(c).
    (2) ASTM D3588-98 (Reapproved 2017)e1, Standard Practice for 
Calculating Heat Value, Compressibility Factor, and Relative Density of 
Gaseous Fuels, approved April 1, 2017 (``ASTM D3588''); IBR approved 
for Sec.  1036.530(b).
    (3) ASTM D4809-13, Standard Method for Heat of Combustion of Liquid 
Hydrocarbon Fuels by Bomb Calorimeter (Precision Method), approved May 
1, 2013 (``ASTM D4809''); IBR approved for Sec.  1036.530(b).
    (4) ASTM D4814-21c, Standard Specification for Automotive Spark-
Ignition Engine Fuel, approved December 15, 2021 (``ASTM D4814''); IBR 
approved for Sec.  1036.415(c).
    (5) ASTM D7467-20a, Standard Specification for Diesel Fuel Oil, 
Biodiesel Blend (B6 to B20), approved June 1, 2020 (``ASTM D7467''); 
IBR approved for Sec.  1036.415(c).
    (b) National Institute of Standards and Technology, 100 Bureau 
Drive, Stop 1070, Gaithersburg, MD 20899-1070, (301) 975-6478, or 
www.nist.gov.
    (1) NIST Special Publication 811, Guide for the Use of the 
International System of Units (SI), 2008 Edition, March 2008; IBR 
approved for Sec.  1036.805.
    (2) [Reserved]
    (c) International Organization for Standardization, Case Postale 
56, CH-1211 Geneva 20, Switzerland, (41) 22749 0111, www.iso.org, or 
[email protected].
    (1) ISO/IEC 18004:2015(E), Information technology--Automatic 
identification and data capture techniques--QR Code bar code symbology 
specification, Third Edition, February 2015; IBR approved for Sec.  
1036.135(c).
    (2) [Reserved]
    (d) California Air Resources Board, 1001 I Street, Sacramento, CA 
95812, (916) 322-2884, or www.arb.ca.gov:

[[Page 17730]]

    (1) California's 2019 heavy-duty OBD requirements adopted under 13 
CCR 1968.2, 1968.5, and 1971.5; IBR approved for Sec.  1036.110(b).
    (2) California's 2019 heavy-duty OBD requirements adopted under 13 
CCR 1971.1; IBR approved for Sec. Sec.  1036.110(b) and (c); 
1036.111(a) and (c).
    (e) SAE International, 400 Commonwealth Dr., Warrendale, PA 15096-
0001, (877) 606-7323 (U.S. and Canada) or (724) 776-4970 (outside the 
U.S. and Canada), or www.sae.org:
    (1) SAE J1979-2, E/E Diagnostic Test Modes: OBDonUDS, April 22, 
2021; IBR approved for Sec.  1036.150(u).
    (2) [Reserved]


Sec.  1036.815  Confidential information.

    (a) The provisions of 40 CFR 1068.10 and 1068.11 apply for 
submitted information you submit under this part.
    (b) Emission data or information that is publicly available cannot 
be treated as confidential business information as described in 40 CFR 
1068.11. Data that vehicle manufacturers need for demonstrating 
compliance with greenhouse gas emission standards, including fuel-
consumption data as described in Sec.  1036.535 and 40 CFR 1037.550, 
also qualify as emission data for purposes of confidentiality 
determinations.


Sec.  1036.820  Requesting a hearing.

    (a) You may request a hearing under certain circumstances, as 
described elsewhere in this part. To do this, you must file a written 
request, including a description of your objection and any supporting 
data, within 30 days after we make a decision.
    (b) For a hearing you request under the provisions of this part, we 
will approve your request if we find that your request raises a 
substantial factual issue.
    (c) If we agree to hold a hearing, we will use the procedures 
specified in 40 CFR part 1068, subpart G.


Sec.  1036.825  Reporting and recordkeeping requirements.

    (a) This part includes various requirements to submit and record 
data or other information. Unless we specify otherwise, store required 
records in any format and on any media and keep them readily available 
for eight years after you send an associated application for 
certification, or eight years after you generate the data if they do 
not support an application for certification. We may review these 
records at any time. You must promptly give us organized, written 
records in English if we ask for them. We may require you to submit 
written records in an electronic format.
    (b) The regulations in Sec.  1036.255 and 40 CFR 1068.25 and 
1068.101 describe your obligation to report truthful and complete 
information. This includes information not related to certification. 
Failing to properly report information and keep the records we specify 
violates 40 CFR 1068.101(a)(2), which may involve civil or criminal 
penalties.
    (c) Send all reports and requests for approval to the Designated 
Compliance Officer (see Sec.  1036.801).
    (d) Any written information we require you to send to or receive 
from another company is deemed to be a required record under this 
section. Such records are also deemed to be submissions to EPA. Keep 
these records for eight years unless the regulations specify a 
different period. We may require you to send us these records whether 
or not you are a certificate holder.
    (e) Under the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the 
Office of Management and Budget approves the reporting and 
recordkeeping specified in the applicable regulations. The following 
items illustrate the kind of reporting and recordkeeping we require for 
engines and vehicles regulated under this part:
    (1) We specify the following requirements related to engine 
certification in this part:
    (i) In Sec.  1036.135 we require engine manufacturers to keep 
certain records related to duplicate labels sent to vehicle 
manufacturers.
    (ii) In Sec.  1036.150 we include various reporting and 
recordkeeping requirements related to interim provisions.
    (iii) In subpart C of this part we identify a wide range of 
information required to certify engines.
    (iv) In Sec. Sec.  1036.430 and 1036.435 we identify reporting and 
recordkeeping requirements related to field testing in-use engines.
    (v) In subpart G of this part we identify several reporting and 
recordkeeping items for making demonstrations and getting approval 
related to various special compliance provisions.
    (vi) In Sec. Sec.  1036.725, 1036.730, and 1036.735 we specify 
certain records related to averaging, banking, and trading.
    (2) We specify the following requirements related to testing in 40 
CFR part 1065:
    (i) In 40 CFR 1065.2 we give an overview of principles for 
reporting information.
    (ii) In 40 CFR 1065.10 and 1065.12 we specify information needs for 
establishing various changes to published procedures.
    (iii) In 40 CFR 1065.25 we establish basic guidelines for storing 
information.
    (iv) In 40 CFR 1065.695 we identify the specific information and 
data items to record when measuring emissions.
    (3) We specify the following requirements related to the general 
compliance provisions in 40 CFR part 1068:
    (i) In 40 CFR 1068.5 we establish a process for evaluating good 
engineering judgment related to testing and certification.
    (ii) In 40 CFR 1068.25 we describe general provisions related to 
sending and keeping information
    (iii) In 40 CFR 1068.27 we require manufacturers to make engines 
available for our testing or inspection if we make such a request.
    (iv) In 40 CFR 1068.105 we require vehicle manufacturers to keep 
certain records related to duplicate labels from engine manufacturers.
    (v) In 40 CFR 1068.120 we specify recordkeeping related to 
rebuilding engines.
    (vi) In 40 CFR part 1068, subpart C, we identify several reporting 
and recordkeeping items for making demonstrations and getting approval 
related to various exemptions.
    (vii) In 40 CFR part 1068, subpart D, we identify several reporting 
and recordkeeping items for making demonstrations and getting approval 
related to importing engines.
    (viii) In 40 CFR 1068.450 and 1068.455 we specify certain records 
related to testing production-line engines in a selective enforcement 
audit.
    (ix) In 40 CFR 1068.501 we specify certain records related to 
investigating and reporting emission-related defects.
    (x) In 40 CFR 1068.525 and 1068.530 we specify certain records 
related to recalling nonconforming engines.
    (xi) In 40 CFR part 1068, subpart G, we specify certain records for 
requesting a hearing.

Appendix A of Part 1036--Summary of Previous Emission Standards

    The following standards, which EPA originally adopted under 40 
CFR part 85 or part 86, apply to compression-ignition engines 
produced before model year 2007 and to spark-ignition engines 
produced before model year 2008:
    (a) Smoke. Smoke standards applied for compression-ignition 
engines based on opacity measurement using the test procedures in 40 
CFR part 86, subpart I, as follows:
    (1) Engines were subject to the following smoke standards for 
model years 1970 through 1973:

[[Page 17731]]

    (i) 40 percent during the engine acceleration mode.
    (ii) 20 percent during the engine lugging mode.
    (2) The smoke standards in 40 CFR 86.007-11 started to apply in 
model year 1974.
    (b) Idle CO. A standard of 0.5 percent of exhaust gas flow at 
curb idle applied through model year 2016 to the following engines:
    (1) Spark-ignition engines with aftertreatment starting in model 
year 1987. This standard applied only for gasoline-fueled engines 
through model year 1997. Starting in model year 1998, the same 
standard applied for engines fueled by methanol, LPG, and natural 
gas. The idle CO standard no longer applied for engines certified to 
meet onboard diagnostic requirements starting in model year 2005.
    (2) Methanol-fueled compression-ignition engines starting in 
model year 1990. This standard also applied for natural gas and LPG 
engines starting in model year 1997. The idle CO standard no longer 
applied for engines certified to meet onboard diagnostic 
requirements starting in model year 2007.
    (c) Crankcase emissions. The requirement to design engines to 
prevent crankcase emissions applied starting with the following 
engines:
    (1) Spark-ignition engines starting in model year 1968. This 
standard applied only for gasoline-fueled engines through model year 
1989, and applied for spark-ignition engines using other fuels 
starting in model year 1990.
    (2) Naturally aspirated diesel-fueled engines starting in model 
year 1985.
    (3) Methanol-fueled compression-ignition engines starting in 
model year 1990.
    (4) Naturally aspirated gaseous-fueled engines starting in model 
year 1997, and all other gaseous-fueled engines starting in 1998.
    (d) Early steady-state standards. The following criteria 
standards applied to heavy-duty engines based on steady-state 
measurement procedures:

               Table 1 of Appendix A--Early Steady-State Emission Standards for Heavy-Duty Engines
----------------------------------------------------------------------------------------------------------------
                                                                               Pollutant
           Model year                    Fuel        -----------------------------------------------------------
                                                              HC               NOX + HC               CO
----------------------------------------------------------------------------------------------------------------
1970-1973.......................  gasoline..........  275 ppm...........  ..................  1.5 volume
                                                                                               percent.
1974-1978.......................  gasoline and        ..................  16 g/hp[middot]hr.  40 g/hp[middot]hr.
                                   diesel.
1979-1984 \a\...................  gasoline and        ..................  5 g/hp[middot]hr    25 g/hp[middot]hr.
                                   diesel.                                 for diesel.
                                                                          5.0 g/hp[middot]hr
                                                                           for gasoline.
----------------------------------------------------------------------------------------------------------------
\a\ An optional NOX + HC standard of 10 g/hp[middot]hr applied in 1979 through 1984 in conjunction with a
  separate HC standard of 1.5 g/hp[middot]hr.

    (e) Transient emission standards for spark-ignition engines. The 
following criteria standards applied for spark-ignition engines 
based on transient measurement using the test procedures in 40 CFR 
part 86, subpart N. Starting in model year 1991, manufacturers could 
generate or use emission credits for NOX and 
NOX + NMHC standards. Table 2 to this appendix follows:

             Table 2 of Appendix A--Transient Emission Standards for Spark-Ignition Engines \a\ \b\
----------------------------------------------------------------------------------------------------------------
                                                                    Pollutant (g/hp[middot]hr)
                   Model year                    ---------------------------------------------------------------
                                                        HC              CO              NOX         NOX + NMHC
----------------------------------------------------------------------------------------------------------------
1985-1987.......................................             1.1            14.4            10.6  ..............
1988-1990.......................................             1.1            14.4             6.0  ..............
1991-1997.......................................             1.1            14.4             5.0  ..............
1998-2004 \c\...................................             1.1            14.4             4.0  ..............
2005-2007.......................................  ..............            14.4  ..............         \d\ 1.0
----------------------------------------------------------------------------------------------------------------
\a\ Standards applied only for gasoline-fueled engines through model year 1989. Standards started to apply for
  methanol in model year 1990, and for LPG and natural gas in model year 1998.
\b\ Engines intended for installation only in heavy-duty vehicles above 14,000 pounds GVWR were subject to an HC
  standard of 1.9 g/hp[middot]hr for model years 1987 through 2004, and a CO standard of 37.1 g/hp[middot]hr for
  model years 1987 through 2007. In addition, for model years 1987 through 2007, up to 5 percent of a
  manufacturer's sales of engines intended for installation in heavy-duty vehicles at or below 14,000 pounds
  GVWR could be certified to the alternative HC and CO standards.
\c\ For natural gas engines in model years 1998 through 2004, the NOX standard was 5.0 g/hp[middot]hr; the HC
  standards were 1.7 g/hp[middot]hr for engines intended for installation only in vehicles above 14,000 pounds
  GVWR, and 0.9 g/hp[middot]hr for other engines.
\d\ Manufacturers could delay the 1.0 g/hp[middot]hr NOX + NMHC standard until model year 2008 by meeting an
  alternate NOX + NMHC standard of 1.5 g/hp[middot]hr applied for model years 2004 through 2007.

    (f) Transient emission standards for compression-ignition 
engines. The following criteria standards applied for compression-
ignition engines based on transient measurement using the test 
procedures in 40 CFR part 86, subpart N. Starting in model year 
1991, manufacturers could generate or use emission credits for 
NOX, NOX + NMHC, and PM standards. Table 3 to 
this appendix follows:

            Table 3 of Appendix A--Transient Emission Standards for Compression-Ignition Engines \a\
----------------------------------------------------------------------------------------------------------------
                                                           Pollutant (g/hp[middot]hr)
          Model year           ---------------------------------------------------------------------------------
                                      HC              CO              NOX         NOX + NMHC           PM
----------------------------------------------------------------------------------------------------------------
1985-1987.....................             1.3            15.5            10.7  ..............  ................
1988-1989.....................             1.3            15.5            10.7  ..............  0.60.
1990..........................             1.3            15.5             6.0  ..............  0.60.
1991-1992.....................             1.3            15.5             5.0  ..............  0.25.
1993..........................             1.3            15.5             5.0  ..............  0.25 truck, 0.10
                                                                                                 bus.
1994-1995.....................             1.3            15.5             5.0  ..............  0.10 truck, 0.07
                                                                                                 urban bus.

[[Page 17732]]

 
1996-1997.....................             1.3            15.5             5.0  ..............  0.10 truck, 0.05
                                                                                                 urban bus.\b\
1998-2003.....................             1.3            15.5             4.0  ..............  0.10 truck, 0.05
                                                                                                 urban bus.\b\
2004-2006.....................  ..............            15.5  ..............         \c\ 2.4  0.10 truck, 0.05
                                                                                                 urban bus.\b\
----------------------------------------------------------------------------------------------------------------
\a\ Standards applied only for diesel-fueled engines through model year 1989. Standards started to apply for
  methanol in model year 1990, and for LPG and natural gas in model year 1997. An alternate HC standard of 1.2 g/
  hp[middot]hr applied for natural gas engines for model years 1997 through 2003.
\b\ The in-use PM standard for urban bus engines in model years 1996 through 2006 was 0.07 g/hp[middot]hr.
\c\ An optional NOX + NMHC standard of 2.5 g/hp[middot]hr applied in 2004 through 2006 in conjunction with a
  separate NMHC standard of 0.5 g/hp[middot]hr.

Appendix B of Part 1036--Transient Duty Cycles

    (a) This appendix specifies transient duty cycles for the engine 
and powertrain testing described in Sec. Sec.  1036.510 and 
1036.512, as follows:
    (1) The transient duty cycle for testing engines involves a 
schedule of normalized engine speed and torque values.
    (2) The transient duty cycles for powertrain testing involves a 
schedule of vehicle speeds and road grade. Determine road grade at 
each point based on the peak rated power of the powertrain system, 
Prated, determined in Sec.  1036.527 and road grade coefficients 
using the following equation: Road grade = a [middot] 
P\2\rated + b [middot] Prated + c
    (b) The following transient duty cycle applies for spark-
ignition engines and powertrains:
BILLING CODE 6560-50-P

[[Page 17733]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.134


[[Page 17734]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.135


[[Page 17735]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.136


[[Page 17736]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.137


[[Page 17737]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.138


[[Page 17738]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.139


[[Page 17739]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.140


[[Page 17740]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.141


[[Page 17741]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.142


[[Page 17742]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.143


[[Page 17743]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.144


[[Page 17744]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.145


[[Page 17745]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.146


[[Page 17746]]


    (c) The following transient duty cycle applies for compression-
ignition engines and powertrains:
[GRAPHIC] [TIFF OMITTED] TP28MR22.147


[[Page 17747]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.148


[[Page 17748]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.149


[[Page 17749]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.150


[[Page 17750]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.151


[[Page 17751]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.152


[[Page 17752]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.153


[[Page 17753]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.154


[[Page 17754]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.155


[[Page 17755]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.156


[[Page 17756]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.157


[[Page 17757]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.158


[[Page 17758]]


    (d) The following transient Low Load Cycle applies for 
compression-ignition engines and powertrains:
[GRAPHIC] [TIFF OMITTED] TP28MR22.159


[[Page 17759]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.160


[[Page 17760]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.161


[[Page 17761]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.162


[[Page 17762]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.163


[[Page 17763]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.164


[[Page 17764]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.165


[[Page 17765]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.166


[[Page 17766]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.167


[[Page 17767]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.168


[[Page 17768]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.169


[[Page 17769]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.170


[[Page 17770]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.171


[[Page 17771]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.172


[[Page 17772]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.173


[[Page 17773]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.174


[[Page 17774]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.175


[[Page 17775]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.176


[[Page 17776]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.177


[[Page 17777]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.178


[[Page 17778]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.179


[[Page 17779]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.180


[[Page 17780]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.181


[[Page 17781]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.182


[[Page 17782]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.183


[[Page 17783]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.184


[[Page 17784]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.185


[[Page 17785]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.186


[[Page 17786]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.187


[[Page 17787]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.188


[[Page 17788]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.189


[[Page 17789]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.190


[[Page 17790]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.191


[[Page 17791]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.192


[[Page 17792]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.193


[[Page 17793]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.194


[[Page 17794]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.195


[[Page 17795]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.196


[[Page 17796]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.197


[[Page 17797]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.198


[[Page 17798]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.199


[[Page 17799]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.200


[[Page 17800]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.201


[[Page 17801]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.202


[[Page 17802]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.203


[[Page 17803]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.204


[[Page 17804]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.205


[[Page 17805]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.206

Appendix C of Part 1036--Default Engine Fuel Maps for Sec.  1036.540

    GEM contains the default steady-state fuel maps in this appendix 
for performing cycle-average engine fuel mapping as described in 
Sec.  1036.503(b)(2). Note that manufacturers have the option to 
replace these default values in GEM if they generate a steady-state 
fuel map as described in Sec.  1036.535(b).
    (a) Use the following default fuel map for compression-ignition 
engines that will be installed in Tractors and Vocational Heavy HDV:

[[Page 17806]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.207


[[Page 17807]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.208


[[Page 17808]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.209

    (b) Use the following default fuel map for compression-ignition 
engines that will be installed in Vocational Light HDV and 
Vocational Medium HDV:
[GRAPHIC] [TIFF OMITTED] TP28MR22.210


[[Page 17809]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.211


[[Page 17810]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.212

    (c) Use the following default fuel map for all spark-ignition 
engines:

[[Page 17811]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.213


[[Page 17812]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.214


[[Page 17813]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.215

BILLING CODE 6560-50-C

PART 1037--CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES

0
87. The authority citation for part 1037 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
88. Amend Sec.  1037.1 by revising paragraph (a) to read as follows:


Sec.  1037.1  Applicability.

    (a) The regulations in this part 1037 apply for all new heavy-duty 
vehicles, except as provided in Sec. Sec.  1037.5 and 1037.104. This 
includes electric vehicles, fuel cell vehicles, and vehicles fueled by 
conventional and alternative fuels. This also includes certain trailers 
as described in Sec. Sec.  1037.5, 1037.150, and 1037.801.
* * * * *
0
89. Amend Sec.  1037.5 by revising paragraph (e) to read as follows:


Sec.  1037.5  Excluded vehicles.

* * * * *
    (e) Vehicles subject to the heavy-duty emission standards of 40 CFR 
part 86. See 40 CFR 86.1816 and 86.1819 for emission standards that 
apply for these vehicles. This exclusion generally applies for complete 
heavy-duty vehicles at or below 14,000 pounds GVWR and all vehicles at 
or below 14,000 pounds GVWR that have no installed propulsion engine, 
such as electric vehicles.
* * * * *
0
90. Amend Sec.  1037.10 by revising paragraph (c) to read as follows:


Sec.  1037.10  How is this part organized?

* * * * *
    (c) Subpart C of this part describes how to apply for a certificate 
of conformity.
* * * * *
0
91. Revise Sec.  1037.101 to read as follows:


Sec.  1037.101  Overview of emission standards.

    This part specifies emission standards for certain vehicles and for 
certain pollutants. This part contains standards and other regulations 
applicable to the emission of the air pollutant defined as the 
aggregate group of six greenhouse gases: carbon dioxide, nitrous oxide, 
methane, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.
    (a) You must show that vehicles meet the following emission 
standards:
    (1) Exhaust emissions of criteria pollutants. Criteria pollutant 
standards for NOX, HC, PM, and CO apply as described in 
Sec.  1037.102. These pollutants are sometimes described collectively 
as ``criteria pollutants'' because they are either criteria pollutants 
under the Clean Air Act or precursors to the criteria pollutants ozone 
and PM.
    (2) Exhaust emissions of greenhouse gases. These pollutants are 
described collectively in this part as ``greenhouse gas pollutants'' 
because they are regulated primarily based on their impact on the 
climate. Emission standards apply as follows for greenhouse gas (GHG) 
emissions:
    (i) CO2, CH4, and N2O emission 
standards apply as described in Sec. Sec.  1037.105 through 1037.107.
    (ii) Hydrofluorocarbon standards apply as described in Sec.  
1037.115(e). These pollutants are also ``greenhouse

[[Page 17814]]

gas pollutants'' but are treated separately from exhaust greenhouse gas 
pollutants listed in paragraph (b)(2)(i) of this section.
    (3) Fuel evaporative emissions. Requirements related to fuel 
evaporative emissions are described in Sec.  1037.103.
    (b) The regulated heavy-duty vehicles are addressed in different 
groups as follows:
    (1) For criteria pollutants, vocational vehicles and tractors are 
regulated based on gross vehicle weight rating (GVWR), whether they are 
considered ``spark-ignition'' or ``compression-ignition,'' and whether 
they are first sold as complete or incomplete vehicles.
    (2) For greenhouse gas pollutants, vehicles are regulated in the 
following groups:
    (i) Tractors above 26,000 pounds GVWR.
    (ii) Trailers.
    (iii) Vocational vehicles.
    (3) The greenhouse gas emission standards apply differently 
depending on the vehicle service class as described in Sec.  1037.140. 
In addition, standards apply differently for vehicles with spark-
ignition and compression-ignition engines. References in this part 1037 
to ``spark-ignition'' or ``compression-ignition'' generally relate to 
the application of standards under 40 CFR 1036.140. For example, a 
vehicle with an engine certified to spark-ignition standards under 40 
CFR part 1036 is generally subject to requirements under this part 1037 
that apply for spark-ignition vehicles. However, note that emission 
standards for Heavy HDE are considered to be compression-ignition 
standards for purposes of applying vehicle emission standards under 
this part. Also, for spark-ignition engines voluntarily certified as 
compression-ignition engines under 40 CFR part 1036, you must choose at 
certification whether your vehicles are subject to spark-ignition 
standards or compression-ignition standards. Heavy-duty vehicles with 
no installed propulsion engine, such as electric vehicles, are subject 
to compression-ignition emission standards for the purpose of 
calculating emission credits.
    (4) For evaporative and refueling emissions, vehicles are regulated 
based on the type of fuel they use. Vehicles fueled with volatile 
liquid fuels or gaseous fuels are subject to evaporative emission 
standards.
0
92. Revise Sec.  1037.102 to read as follows:


Sec.  1037.102  Exhaust emission standards for NOX, HC, PM, and CO.

    (a) Engines installed in heavy-duty vehicles are subject to 
criteria pollutant standards for NOX, HC, PM, and CO under 
40 CFR part 86 through model year 2026 and 40 CFR part 1036 for model 
years 2027 and later.
    (b) Heavy-duty vehicles with no installed propulsion engine, such 
as electric vehicles, are subject to criteria pollutant standards under 
this part. The emission standards that apply are the same as the 
standards that apply for compression-ignition engines under 40 CFR 
86.007-11 and 1036.104 for a given model year. Additional requirements 
apply to vehicles with no installed propulsion engine as specified in 
this part.
    (1) Where this part references standards or other requirements in 
40 CFR part 86 or 1036 that apply differently based on primary intended 
service class, apply the Light HDE provisions to Light HDV, apply the 
Medium HDE provisions to Medium HDV, and apply the Heavy HDE provisions 
to Heavy HDV.
    (2) Criteria pollutant emission standards and related requirements 
apply for the useful life specified in 40 CFR 86.001-2 through model 
year 2026 and as specified in 40 CFR 1036.104 for model year 2027 and 
later. You may alternatively select the useful life values identified 
in Sec.  1037.105(e) if you do not generate NOX credits 
under Sec.  1037.616.
    (3) The following requirements apply for vehicles generating 
NOX credits under Sec.  1037.616:
    (i) Electric vehicles. Measure initial useable battery energy for 
electric vehicles using the test procedure in Sec.  1037.552. Useable 
battery energy must remain at or above 70 percent throughout the useful 
life.
    (ii) Fuel cell vehicles. Measure initial fuel cell voltage for fuel 
cell vehicles using the test procedure in Sec.  1037.554. Fuel cell 
voltage must remain at or above 80 percent throughout the useful life.
0
93. Amend Sec.  1037.103 by:
0
a. Revising paragraph (b)(1).
0
b. Removing paragraph (b)(6).
0
c. Revising paragraphs (f) and (g)(1) and (2).
    The revisions read as follows:


Sec.  1037.103  Evaporative and refueling emission standards.

* * * * *
    (b) * * *
    (1) The refueling standards in 40 CFR 86.1813-17(b) apply to 
complete vehicles starting in model year 2022; they apply for 
incomplete vehicles starting in model year 2027.
* * * * *
    (f) Useful life. The evaporative and refueling emission standards 
of this section apply for the full useful life, expressed in service 
miles or calendar years, whichever comes first. The useful life values 
for the standards of this section are the same as the values described 
for evaporative emission standards in 40 CFR 86.1805.
    (g) * * *
    (1) Auxiliary engines and associated fuel-system components must be 
installed when testing fully assembled vehicles. If the auxiliary 
engine draws fuel from a separate fuel tank, you must fill the extra 
fuel tank before the start of diurnal testing as described for the 
vehicle's main fuel tank. Use good engineering judgment to ensure that 
any nonmetal portions of the fuel system related to the auxiliary 
engine have reached stabilized levels of permeation emissions. The 
auxiliary engine must not operate during the running loss test or any 
other portion of testing under this section.
    (2) For testing with partially assembled vehicles, you may omit 
installation of auxiliary engines and associated fuel-system components 
as long as those components installed in the final configuration are 
certified to meet the applicable emission standards for Small SI 
equipment described in 40 CFR 1054.112 or for Large SI engines in 40 
CFR 1048.105. For any fuel-system components that you do not install, 
your installation instructions must describe this certification 
requirement.
0
94. Amend Sec.  1037.105 by revising paragraphs (b)(1), (g)(2), and 
(h)(1) and (5) through (7) to read as follows:


Sec.  1037.105  CO2 emission standards for vocational vehicles.

* * * * *
    (b) * * *
    (1) Model year 2027 and later vehicles are subject to 
CO2 standards corresponding to the selected subcategories as 
shown in the following table:

[[Page 17815]]



       Table 1 of Sec.   1037.105--Phase 2 CO2 Standards for Model Year 2027 and Later Vocational Vehicles
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
             Engine cycle                     Vehicle size         Multi-purpose     Regional          Urban
----------------------------------------------------------------------------------------------------------------
Compression-ignition..................  Light HDV...............             325             286             361
Compression-ignition..................  Medium HDV..............             231             215             254
Compression-ignition..................  Heavy HDV...............             226             186             265
Spark-ignition........................  Light HDV...............             372             319             413
Spark-ignition........................  Medium HDV..............             268             247             297
----------------------------------------------------------------------------------------------------------------

* * * * *
    (g) * * *
    (2) Class 8 hybrid vehicles with Light HDE or Medium HDE may be 
certified to compression-ignition standards for the Heavy HDV service 
class. You may generate and use credits as allowed for the Heavy HDV 
service class.
* * * * *
    (h) * * *
    (1) The following alternative emission standards apply by vehicle 
type and model year as follows:

                          Table 5 of Sec.   1037.105--Phase 2 Custom Chassis Standards
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
               Vehicle type \a\                 Assigned vehicle service class     MY 2021-2026      MY 2027+
----------------------------------------------------------------------------------------------------------------
School bus...................................  Medium HDV......................              291             267
Motor home...................................  Medium HDV......................              228             226
Coach bus....................................  Heavy HDV.......................              210             205
Other bus....................................  Heavy HDV.......................              300             282
Refuse hauler................................  Heavy HDV.......................              313             298
Concrete mixer...............................  Heavy HDV.......................              319             316
Mixed-use vehicle............................  Heavy HDV.......................              319             316
Emergency vehicle............................  Heavy HDV.......................              324             319
----------------------------------------------------------------------------------------------------------------
\a\ Vehicle types are generally defined in Sec.   1037.801. ``Other bus'' includes any bus that is not a school
  bus or a coach bus. A ``mixed-use vehicle'' is one that meets at least one of the criteria specified in Sec.
  1037.631(a)(1) or (2).

* * * * *
    (5) Emergency vehicles are deemed to comply with the standards of 
this paragraph (h) if they use tires with TRRL at or below 8.4 N/kN 
(8.7 N/kN for model years 2021 through 2026).
    (6) Concrete mixers and mixed-use vehicles are deemed to comply 
with the standards of this paragraph (h) if they use tires with TRRL at 
or below 7.1 N/kN (7.6 N/kN for model years 2021 through 2026).
    (7) Motor homes are deemed to comply with the standards of this 
paragraph (h) if they have tires with TRRL at or below 6.0 N/kN (6.7 N/
kN for model years 2021 through 2026) and automatic tire inflation 
systems or tire pressure monitoring systems with wheels on all axles.
* * * * *
0
95. Amend Sec.  1037.106 by revising paragraphs (b) and (f)(1) to read 
as follows:


Sec.  1037.106  Exhaust emission standards for tractors above 26,000 
pounds GVWR.

* * * * *
    (b) The CO2 standards for tractors above 26,000 pounds 
GVWR in Table 1 of this section apply based on modeling and testing as 
described in subpart F of this part. The provisions of Sec.  1037.241 
specify how to comply with these standards in this paragraph (b).

            Table 1 of Sec.   1037.106--CO2 Standards for Class 7 and Class 8 Tractors by Model Year
                                                  [g/ton-mile]
----------------------------------------------------------------------------------------------------------------
                                    Phase 1         Phase 1         Phase 2         Phase 2          Phase 2
                                 standards for   standards for   standards for   standards for    standards for
        Subcategory \a\           model years     model years     model years     model years    model year 2027
                                   2014-2016       2017-2020       2021-2023       2024-2026        and later
----------------------------------------------------------------------------------------------------------------
Class 7 Low-Roof (all cab                  107             104           105.5            99.8              94.8
 styles)......................
Class 7 Mid-Roof (all cab                  119             115           113.2           107.1             101.8
 styles)......................
Class 7 High-Roof (all cab                 124             120           113.5           106.6              98.5
 styles)......................
Class 8 Low-Roof Day Cab......              81              80            80.5            76.2              72.3
Class 8 Low-Roof Sleeper Cab..              68              66            72.3            68.0              64.1
Class 8 Mid-Roof Day Cab......              88              86            85.4            80.9              76.8
Class 8 Mid-Roof Sleeper Cab..              76              73            78.0            73.5              69.6
Class 8 High-Roof Day Cab.....              92              89            85.6            80.4              74.6
Class 8 High-Roof Sleeper Cab.              75              72            75.7            70.7              64.3
Heavy-Haul Tractors...........  ..............  ..............            52.4            50.2              48.3
----------------------------------------------------------------------------------------------------------------
\a\ Sub-category terms are defined in Sec.   1037.801.

* * * * *
    (f) * * *
    (1) You may optionally certify 4x2 tractors with Heavy HDE to the 
standards and useful life for Class 8 tractors, with no restriction on

[[Page 17816]]

generating or using emission credits within the Class 8 averaging set.
* * * * *
0
96. Amend Sec.  1037.115 by revising paragraphs (a) and (e)(3) to read 
as follows:


Sec.  1037.115  Other requirements.

* * * * *
    (a) Adjustable parameters. Vehicles that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. We may require that you set adjustable 
parameters to any specification within the adjustable range during any 
testing. See 40 CFR 1068.50 for general provisions related to 
adjustable parameters. You must ensure safe vehicle operation 
throughout the physically adjustable range of each adjustable 
parameter, including consideration of production tolerances. Note that 
adjustable roof fairings and trailer rear fairings are deemed not to be 
adjustable parameters.
* * * * *
    (e) * * *
    (3) If air conditioning systems are designed such that a compliance 
demonstration under 40 CFR 86.1867-12(a) is impossible or impractical, 
you may ask to use alternative means to demonstrate that your air 
conditioning system achieves an equivalent level of control.
0
97. Amend Sec.  1037.120 by revising paragraphs (b) and (c) to read as 
follows:


Sec.  1037.120  Emission-related warranty requirements.

* * * * *
    (b) Warranty period. (1) Except as specified in paragraph (b)(2) of 
this section, your emission-related warranty must be valid for at 
least:
    (i) 5 years or 50,000 miles for Light HDV (except tires).
    (ii) 5 years or 100,000 miles for Medium HDV and Heavy HDV (except 
tires).
    (iii) 5 years for trailers (except tires).
    (iv) 1 year for tires installed on trailers, and 2 years or 24,000 
miles for all other tires.
    (2) Your emission-related warranty with respect to the standards 
under Sec.  1037.102(b) must be valid for at least the periods 
specified for engines in 40 CFR 1036.120(b) if you generate 
NOX credits under Sec.  1037.616.
    (3) You may offer an emission-related warranty more generous than 
we require. The emission-related warranty for the vehicle may not be 
shorter than any basic mechanical warranty you provide to that owner 
without charge for the vehicle. Similarly, the emission-related 
warranty for any component may not be shorter than any warranty you 
provide to that owner without charge for that component. This means 
that your warranty for a given vehicle may not treat emission-related 
and nonemission-related defects differently for any component. The 
warranty period begins when the vehicle is placed into service.
    (c) Components covered. The emission-related warranty covers tires, 
automatic tire inflation systems, tire pressure monitoring systems, 
vehicle speed limiters, idle-reduction systems, hybrid system 
components, and devices added to the vehicle to improve aerodynamic 
performance (not including standard components such as hoods or mirrors 
even if they have been optimized for aerodynamics), to the extent such 
emission-related components are included in your application for 
certification. The emission-related warranty also covers other added 
emission-related components to the extent they are included in your 
application for certification. The emission-related warranty covers 
components designed to meet requirements under Sec.  1037.102(b)(3). 
The emission-related warranty covers all components whose failure would 
increase a vehicle's emissions of air conditioning refrigerants (for 
vehicles subject to air conditioning leakage standards), and it covers 
all components whose failure would increase a vehicle's evaporative and 
refueling emissions (for vehicles subject to evaporative and refueling 
emission standards). The emission-related warranty covers these 
components even if another company produces the component. Your 
emission-related warranty does not need to cover components whose 
failure would not increase a vehicle's emissions of any regulated 
pollutant.
* * * * *
0
98. Amend Sec.  1037.125 by revising paragraph (d) to read as follows:


Sec.  1037.125  Maintenance instructions and allowable maintenance.

* * * * *
    (d) Noncritical emission-related maintenance. Subject to the 
provisions of this paragraph (d), you may schedule any amount of 
emission-related inspection or maintenance that is not covered by 
paragraph (a) of this section (that is, maintenance that is neither 
explicitly identified as critical emission-related maintenance, nor 
that we approve as critical emission-related maintenance). Noncritical 
emission-related maintenance generally includes maintenance on the 
components we specify in 40 CFR part 1068, appendix A, that is not 
covered in paragraph (a) of this section. You must state in the owners 
manual that these steps are not necessary to keep the emission-related 
warranty valid. If operators fail to do this maintenance, this does not 
allow you to disqualify those vehicles from in-use testing or deny a 
warranty claim. Do not take these inspection or maintenance steps 
during service accumulation on your emission-data vehicles.
* * * * *
0
99. Amend Sec.  1037.130 by revising paragraph (b)(3) to read as 
follows:


Sec.  1037.130  Assembly instructions for secondary vehicle 
manufacturers.

* * * * *
    (b) * * *
    (3) Describe the necessary steps for installing emission-related 
diagnostic systems.
* * * * *
0
100. Amend Sec.  1037.135 by revising paragraph (c)(6) to read as 
follows:


Sec.  1037.135  Labeling.

* * * * *
    (c) * * *
    (6) Identify the emission control system. Use terms and 
abbreviations as described in appendix C to this part or other 
applicable conventions. Phase 2 tractors and Phase 2 vocational 
vehicles may omit this information.
* * * * *
0
101. Amend Sec.  1037.140 by revising paragraph (g) to read as follows:


Sec.  1037.140  Classifying vehicles and determining vehicle 
parameters.

* * * * *
    (g) The standards and other provisions of this part apply to 
specific vehicle service classes for tractors and vocational vehicles 
as follows:
    (1) Phase 1 and Phase 2 tractors are divided based on GVWR into 
Class 7 tractors and Class 8 tractors. Where provisions of this part 
apply to both tractors and vocational vehicles, Class 7 tractors are 
considered ``Medium HDV'' and Class 8 tractors are considered ``Heavy 
HDV''. This paragraph (g)(1) applies for hybrid and non-hybrid 
vehicles.
    (2) Phase 1 vocational vehicles are divided based on GVWR. ``Light 
HDV'' includes Class 2b through Class 5 vehicles; ``Medium HDV'' 
includes Class 6 and Class 7 vehicles; and ``Heavy HDV'' includes Class 
8 vehicles.
    (3) Phase 2 vocational vehicles propelled by engines subject to the 
spark-ignition standards of 40 CFR part 1036 are divided as follows:
    (i) Class 2b through Class 5 vehicles are considered ``Light HDV''.

[[Page 17817]]

    (ii) Class 6 through Class 8 vehicles are considered ``Medium 
HDV''.
    (4) Phase 2 vocational vehicles propelled by engines subject to the 
compression-ignition standards in 40 CFR part 1036 are divided as 
follows:
    (i) Class 2b through Class 5 vehicles are considered ``Light HDV''.
    (ii) Class 6 through 8 vehicles are considered ``Heavy HDV'' if the 
installed engine's primary intended service class is Heavy HDE (see 40 
CFR 1036.140), except that Class 8 hybrid vehicles are considered 
``Heavy HDV'' regardless of the engine's primary intended service 
class.
    (iii) All other Class 6 through Class 8 vehicles are considered 
``Medium HDV''.
    (5) Heavy-duty vehicles with no installed propulsion engine, such 
as electric vehicles, are divided as follows:
    (i) Class 2b through Class 5 vehicles are considered ``Light HDV''.
    (ii) Class 6 and 7 vehicles are considered ``Medium HDV''.
    (iii) Class 8 vehicles are considered ``Heavy HDV''.
    (6) In certain circumstances, you may certify vehicles to standards 
that apply for a different vehicle service class. For example, see 
Sec. Sec.  1037.105(g) and 1037.106(f). If you optionally certify 
vehicles to different standards, those vehicles are subject to all the 
regulatory requirements as if the standards were mandatory.
* * * * *
0
102. Amend Sec.  1037.150 by revising paragraphs (f) and (y)(1) to read 
as follows:


Sec.  1037.150  Interim provisions.

* * * * *
    (f) Electric and hydrogen fuel cell vehicles. Tailpipe emissions of 
regulated GHG pollutants from electric vehicles and hydrogen fuel cell 
vehicles are deemed to be zero. No CO2-related emission 
testing is required for electric vehicles. Use good engineering 
judgment to apply other requirements of this part to electric vehicles.
* * * * *
    (y) * * *
    (1) For vocational Light HDV and vocational Medium HDV, emission 
credits you generate in model years 2018 through 2021 may be used 
through model year 2027, instead of being limited to a five-year credit 
life as specified in Sec.  1037.740(c). For Class 8 vocational vehicles 
with Medium HDE, we will approve your request to generate these credits 
in and use these credits for the Medium HDV averaging set if you show 
that these vehicles would qualify as Medium HDV under the Phase 2 
program as described in Sec.  1037.140(g)(4).
* * * * *
0
103. Amend Sec.  1037.205 by revising paragraphs (p) and (q) to read as 
follows:


Sec.  1037.205  What must I include in my application?

* * * * *
    (p) Where applicable, describe all adjustable operating parameters 
(see Sec.  1037.115), including production tolerances. For any 
operating parameters that do not qualify as adjustable parameters, 
include a description supporting your conclusion (see 40 CFR 
1068.50(c)). Include the following in your description of each 
adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
    (q) Include the following information for electric vehicles and 
fuel cell vehicles to show that they meet the standards of this part:
    (1) You may attest that vehicles comply with the standards of Sec.  
1037.102 instead of submitting test data.
    (2) For vehicles generating credits under Sec.  1037.616, you may 
attest that the vehicle meets the durability requirements described in 
Sec.  1037.102(b)(3) based on an engineering analysis of measured 
values and other information, consistent with good engineering 
judgment, instead of testing at the end of the useful life. Send us 
your test results for work produced over the FTP and initial useable 
battery energy or initial fuel cell voltage. Also send us your 
engineering analysis describing how you meet the durability 
requirements if we ask for it.
* * * * *
0
104. Amend Sec.  1037.225 by revising the introductory text and 
paragraph (g) to read as follows:


Sec.  1037.225  Amending applications for certification.

    Before we issue you a certificate of conformity, you may amend your 
application to include new or modified vehicle configurations, subject 
to the provisions of this section. After we have issued your 
certificate of conformity, you may send us an amended application any 
time before the end of the model year requesting that we include new or 
modified vehicle configurations within the scope of the certificate, 
subject to the provisions of this section. You must amend your 
application if any changes occur with respect to any information that 
is included or should be included in your application.
* * * * *
    (g) You may produce vehicles or modify in-use vehicles as described 
in your amended application for certification and consider those 
vehicles to be in a certified configuration. Modifying a new or in-use 
vehicle to be in a certified configuration does not violate the 
tampering prohibition of 40 CFR 1068.101(b)(1), as long as this does 
not involve changing to a certified configuration with a higher family 
emission limit. See Sec.  1037.621(g) for special provisions that apply 
for changing to a different certified configuration in certain 
circumstances.
0
105. Amend Sec.  1037.230 by revising paragraph (c) to read as follows:


Sec.  1037.230  Vehicle families, sub-families, and configurations.

* * * * *
    (c) Group vehicles into configurations consistent with the 
definition of ``vehicle configuration'' in Sec.  1037.801. Note that 
vehicles with hardware or software differences that are related to 
measured or modeled emissions are considered to be different vehicle 
configurations even if they have the same modeling inputs and FEL. Note 
also, that you are not required to separately identify all 
configurations for certification. Note that you are not required to 
identify all possible configurations for certification; also, you are 
required to include in your final ABT report only those configurations 
you produced.
* * * * *
0
106. Amend Sec.  1037.231 by revising paragraph (b)(1) to read as 
follows:


Sec.  1037.231  Powertrain families.

* * * * *
    (b) * * *
    (1) Engine family as specified in 40 CFR 1036.230.
* * * * *
0
107. Amend Sec.  1037.250 by revising paragraph (a) to read as follows:


Sec.  1037.250  Reporting and recordkeeping.

    (a) By September 30 following the end of the model year, send the 
Designated Compliance Officer a report including

[[Page 17818]]

the total U.S.-directed production volume of vehicles you produced in 
each vehicle family during the model year (based on information 
available at the time of the report). Report by vehicle identification 
number and vehicle configuration and identify the subfamily identifier. 
Report uncertified vehicles sold to secondary vehicle manufacturers. We 
may waive the reporting requirements of this paragraph (a) for small 
manufacturers.
* * * * *
0
108. Amend Sec.  1037.320 by removing Table 1 to Sec.  1037.320 and 
revising paragraph (b) to read as follows:


Sec.  1037.320  Audit procedures for axles and transmissions.

* * * * *
    (b) Run GEM for each applicable vehicle configuration and GEM 
regulatory subcategory identified in 40 CFR 1036.540 and for each 
vehicle class as defined in Sec.  1037.140(g) using the applicable 
default engine map in appendix C of 40 CFR part 1036, the cycle-average 
fuel map in Table 1 of this section, the torque curve in Table 2 of 
this section for both the engine full-load torque curve and parent 
engine full-load torque curve, the motoring torque curve in Table 3 of 
this section, the idle fuel map in Table 4 of this section. For axle 
testing, this may require omitting several vehicle configurations based 
on selecting axle ratios that correspond to the tested axle. For 
transmission testing, use the test transmission's gear ratios in place 
of the gear ratios defined in 40 CFR 1036.540. The GEM ``Default FEL 
CO2 Emissions'' result for each vehicle configuration counts 
as a separate test for determining whether the family passes the audit. 
For vocational vehicles, use the GEM ``Default FEL CO2 
Emissions'' result for the Regional subcategory. Table 1 through Table 
4 follow:
BILLING CODE 6560-01-P

[[Page 17819]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.216

BILLING CODE 6560-01-C

[[Page 17820]]



                                  Table 2 to Paragraph (b) of Sec.   1037.320--Full-Load Torque Curves by Vehicle Class
--------------------------------------------------------------------------------------------------------------------------------------------------------
      Light HDV and medium HDV--spark-ignition         Light HDV and medium HDV--compression-ignition                       Heavy HDV
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Engine torque                                      Engine torque                                     Engine torque
   Engine speed (r/min)          (N[middot]m)          Engine speed (r/min)         (N[middot]m)          Engine speed (r/min)         (N[middot]m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                  600                       433                       750                      470                       600                     1200
                  700                       436                       907                      579                       750                     1320
                  800                       445                      1055                      721                       850                     1490
                  900                       473                      1208                      850                       950                     1700
                 1000                       492                      1358                      876                      1050                     1950
                 1100                       515                      1507                      866                      1100                     2090
                 1200                       526                      1660                      870                      1200                     2100
                 1300                       541                      1809                      868                      1250                     2100
                 1400                       542                      1954                      869                      1300                     2093
                 1500                       542                      2105                      878                      1400                     2092
                 1600                       542                      2258                      850                      1500                     2085
                 1700                       547                      2405                      800                      1520                     2075
                 1800                       550                      2556                      734                      1600                     2010
                 1900                       551                      2600                        0                      1700                     1910
                 2000                       554      .......................  ........................                  1800                     1801
                 2100                       553      .......................  ........................                  1900                     1640
                 2200                       558      .......................  ........................                  2000                     1350
                 2300                       558      .......................  ........................                  2100                      910
                 2400                       566      .......................  ........................                  2250                        0
                 2500                       571
                 2600                       572
                 2700                       581
                 2800                       586
                 2900                       587
                 3000                       590
                 3100                       591
                 3200                       589
                 3300                       585
                 3400                       584
                 3500                       582
                 3600                       573
                 3700                       562
                 3800                       555
                 3900                       544
                 4000                       534
                 4100                       517
                 4200                       473
                 4291                       442
                 4500                       150
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                  Table 3 to Paragraph (b) of Sec.   1037.320--Motoring Torque Curves by Vehicle Class
--------------------------------------------------------------------------------------------------------------------------------------------------------
      Light HDV and medium HDV--spark-ignition         Light HDV and medium HDV--compression-ignition                      Heavy HDV
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Engine torque                                      Engine torque                                     Engine torque
   Engine speed (r/min)          (N[middot]m)          Engine speed (r/min)         (N[middot]m)          Engine speed (r/min)         (N[middot]m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                  700                       -41                       750                     -129                       600                      -98
                  800                       -42                       907                     -129                       750                     -121
                  900                       -43                      1055                     -130                       850                     -138
                 1000                       -45                      1208                     -132                       950                     -155
                 1100                       -48                      1358                     -135                      1050                     -174
                 1200                       -49                      1507                     -138                      1100                     -184
                 1300                       -50                      1660                     -143                      1200                     -204
                 1411                       -51                      1809                     -148                      1250                     -214
                 1511                       -52                      1954                     -155                      1300                     -225
                 1611                       -53                      2105                     -162                      1400                     -247
                 1711                       -56                      2258                     -170                      1500                     -270
                 1811                       -56                      2405                     -179                      1520                     -275
                 1911                       -57                      2556                     -189                      1600                     -294
                 2011                       -57      .......................  ........................                  1700                     -319
                 2111                       -58      .......................  ........................                  1800                     -345
                 2211                       -60      .......................  ........................                  1900                     -372
                 2311                       -65      .......................  ........................                  2000                     -400
                 2411                       -81      .......................  ........................                  2100                     -429
                 2511                       -85
                 2611                       -87

[[Page 17821]]

 
                 2711                       -88
                 2811                       -89
                 2911                       -91
                 3011                       -91
                 3111                       -96
                 3211                       -96
                 3311                       -97
                 3411                       -98
                 3511                       -99
                 3611                      -104
                 3711                      -105
                 3811                      -108
                 3911                      -108
                 4011                      -111
                 4111                      -111
                 4211                      -115
                 4291                      -112
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                   Table 4 to Paragraph (b) of Sec.   1037.320--Engine Idle Fuel Maps by Vehicle Class
--------------------------------------------------------------------------------------------------------------------------------------------------------
       Light HDV and medium HDV--spark-ignition          Light HDV and medium HDV--compression-ignition                      Heavy HDV
--------------------------------------------------------------------------------------------------------------------------------------------------------
 Engine speed (r/   Engine torque   Fuel mass rate (g/ Engine speed (r/  Engine torque   Fuel mass rate    Engine speed    Engine torque  Fuel mass rate
       min)          (N[middot]m)           s)               min)        (N[middot]m)         (g/s)           (r/min)      (N[middot]m)        (g/s)
--------------------------------------------------------------------------------------------------------------------------------------------------------
            600                 0            0.4010               750               0           0.2595              600               0          0.3501
            700                 0            0.4725               850               0           0.2626              700               0          0.4745
            600               100            0.6637               750             100           0.6931              600             100          0.6547
            700               100            0.7524               850             100           0.7306              700             100          0.8304
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * *
0
109. Amend Sec.  1037.510 by revising paragraphs (a)(1)(i), (2), and 
(3) and (d) to read as follows:


Sec.  1037.510  Duty-cycle exhaust testing.

* * * * *
    (a) * * *
    (1) * * *
    (i) Transient cycle. The transient cycle is specified in appendix A 
of this part. Warm up the vehicle. Start the duty cycle within 30 
seconds after concluding the preconditioning procedure. Start sampling 
emissions at the start of the duty cycle.
* * * * *
    (2) Perform cycle-average engine fuel mapping as described in 40 
CFR 1036.540. For powertrain testing under Sec.  1037.550 or Sec.  
1037.555, perform testing as described in this paragraph (a)(2) to 
generate GEM inputs for each simulated vehicle configuration, and test 
runs representing different idle conditions. Perform testing as 
follows:
    (i) Transient cycle. The transient cycle is specified in appendix A 
of this part.
    (ii) Highway cruise cycles. The grade portion of the route 
corresponding to the 55 mi/hr and 65 mi/hr highway cruise cycles is 
specified in appendix D of this part. Maintain vehicle speed between -
1.0 mi/hr and 3.0 mi/hr of the speed setpoint; this speed tolerance 
applies instead of the approach specified in 40 CFR 1066.425(b)(1) and 
(2).
    (iii) Drive idle. Perform testing at a loaded idle condition for 
Phase 2 vocational vehicles. For engines with an adjustable warm idle 
speed setpoint, test at the minimum warm idle speed and the maximum 
warm idle speed; otherwise simply test at the engine's warm idle speed. 
Warm up the powertrain as described in 40 CFR 1036.527(c)(1). Within 60 
seconds after concluding the warm-up, linearly ramp the powertrain down 
to zero vehicle speed over 20 seconds. Apply the brake and keep the 
transmission in drive (or clutch depressed for manual transmission). 
Stabilize the powertrain for (60  1) seconds and then 
sample emissions for (30  1) seconds.
    (iv) Parked idle. Perform testing at an no-load idle condition for 
Phase 2 vocational vehicles. For engines with an adjustable warm idle 
speed setpoint, test at the minimum warm idle speed and the maximum 
warm idle speed; otherwise simply test at the engine's warm idle speed. 
Warm up the powertrain as described in 40 CFR 1036.527(c)(1). Within 60 
seconds after concluding the warm-up, linearly ramp the powertrain down 
to zero vehicle speed in 20 seconds. Put the transmission in park (or 
neutral for manual transmissions and apply the parking brake if 
applicable). Stabilize the powertrain for (180  1) seconds 
and then sample emissions for (600  1) seconds.
    (3) Where applicable, perform testing on a chassis dynamometer as 
follows:
    (i) Transient cycle. The transient cycle is specified in appendix A 
of this part. Warm up the vehicle by operating over one transient 
cycle. Within 60 seconds after concluding the warm up cycle, start 
emission sampling and operate the vehicle over the duty cycle.
    (ii) Highway cruise cycle. The grade portion of the route 
corresponding to the 55 mi/hr and 65 mi/hr highway cruise cycles is 
specified in appendix D of this part. Warm up the vehicle by operating 
it at the appropriate speed setpoint over the duty cycle. Within 60 
seconds after concluding the preconditioning cycle, start emission 
sampling and operate the vehicle over the duty cycle, maintaining 
vehicle speed within 1.0 mi/hr of the speed setpoint; this 
speed tolerance applies

[[Page 17822]]

instead of the approach specified in 40 CFR 1066.425(b)(1) and (2).
* * * * *
    (d) For highway cruise and transient testing, compare actual 
second-by-second vehicle speed with the speed specified in the test 
cycle and ensure any differences are consistent with the criteria as 
specified in Sec.  1037.550(g)(1). If the speeds do not conform to 
these criteria, the test is not valid and must be repeated.
* * * * *
0
110. Amend Sec.  1037.520 by revising paragraphs (c)(2) and (3), (f), 
and (h)(1) to read as follows:


Sec.  1037.520  Modeling CO2 emissions to show compliance for 
vocational vehicles and tractors.

* * * * *
    (c) * * *
    (2) Measure tire rolling resistance in kg per metric ton as 
specified in ISO 28580 (incorporated by reference in Sec.  1037.810), 
except as specified in this paragraph (c). Use good engineering 
judgment to ensure that your test results are not biased low. You may 
ask us to identify a reference test laboratory to which you may 
correlate your test results. Prior to beginning the test procedure in 
Section 7 of ISO 28580 for a new bias-ply tire, perform a break-in 
procedure by running the tire at the specified test speed, load, and 
pressure for (60  2) minutes.
    (3) For each tire design tested, measure rolling resistance of at 
least three different tires of that specific design and size. Perform 
the test at least once for each tire. Calculate the arithmetic mean of 
these results to the nearest 0.1 N/kN and use this value or any higher 
value as your GEM input for TRRL. You must test at least one tire size 
for each tire model, and may use engineering analysis to determine the 
rolling resistance of other tire sizes of that model. Note that for 
tire sizes that you do not test, we will treat your analytically 
derived rolling resistances the same as test results, and we may 
perform our own testing to verify your values. We may require you to 
test a small sub-sample of untested tire sizes that we select.
* * * * *
    (f) Engine characteristics. Enter information from the engine 
manufacturer to describe the installed engine and its operating 
parameters as described in 40 CFR 1036.503. Note that you do not need 
fuel consumption at idle for tractors.
* * * * *
    (h) * * *
    (1) For engines with no adjustable warm idle speed, input vehicle 
idle speed as the manufacturer's declared warm idle speed. For engines 
with adjustable warm idle speed, input your vehicle idle speed as 
follows:

------------------------------------------------------------------------
                                                          Your default
                                  And your engine is      vehicle idle
  If your vehicle is a . . .       subject to . . .       speed is . .
                                                              .\a\
------------------------------------------------------------------------
(i) Heavy HDV.................  compression-ignition    600 r/min.
                                 or spark-ignition
                                 standards.
(ii) Medium HDV tractor.......  compression-ignition    700 r/min.
                                 standards.
(iii) Light HDV or Medium HDV   compression-ignition    750 r/min.
 vocational vehicle.             standards.
(iv) Light HDV or Medium HDV..  spark-ignition          600 r/min.
                                 standards.
------------------------------------------------------------------------
\a\ If the default idle speed is above or below the engine
  manufacturer's whole range of declared warm idle speeds, use the
  manufacturer's maximum or minimum declared warm idle speed,
  respectively, instead of the default value.

* * * * *
0
111. Amend Sec.  1037.534 by revising paragraph (d)(2) to read as 
follows:


Sec.  1037.534  Constant-speed procedure for calculating drag area 
(CdA).

* * * * *
    (d) * * *
    (2) Perform testing as described in paragraph (d)(3) of this 
section over a sequence of test segments at constant vehicle speed as 
follows:
    (i) (300  30) seconds in each direction at 10 mi/hr.
    (ii) (450  30) seconds in each direction at 70 mi/hr.
    (iii) (450  30) seconds in each direction at 50 mi/hr.
    (iv) (450  30) seconds in each direction at 70 mi/hr.
    (v) (450  30) seconds in each direction at 50 mi/hr.
    (vi) (300  30) seconds in each direction at 10 mi/hr.
* * * * *
0
112. Amend Sec.  1037.540 by revising the introductory text and 
paragraphs (b)(3), (7), and (8), and (f)(3) to read as follows:


Sec.  1037.540  Special procedures for testing vehicles with hybrid 
power take-off.

    This section describes optional procedures for quantifying the 
reduction in greenhouse gas emissions for vehicles as a result of 
running power take-off (PTO) devices with a hybrid energy delivery 
system. See Sec.  1037.550 for powertrain testing requirements that 
apply for drivetrain hybrid systems. The procedures are written to test 
the PTO by ensuring that the engine produces all of the energy with no 
net change in stored energy (charge-sustaining), and for plug-in hybrid 
vehicles, also allowing for drawing down the stored energy (charge-
depleting). The full charge-sustaining test for the hybrid vehicle is 
from a fully charged rechargeable energy storage system (RESS) to a 
depleted RESS and then back to a fully charged RESS. You must include 
all hardware for the PTO system. You may ask us to modify the 
provisions of this section to allow testing hybrid vehicles other than 
battery electric hybrids, consistent with good engineering judgment. 
For plug-in hybrids, use a utility factor to properly weight charge-
sustaining and charge-depleting operation as described in paragraph 
(f)(3) of this section.
* * * * *
    (b) * * *
    (3) Denormalize the PTO duty cycle in appendix B of this part using 
the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.069

Where:

prefi = the reference pressure at each point i in the PTO 
cycle.
pi = the normalized pressure at each point i in the PTO cycle 
(relative to pmax).
pmax = the mean maximum pressure measured in paragraph 
(b)(2) of this section.
pmin = the mean minimum pressure measured in paragraph 
(b)(2) of this section.
* * * * *
    (7) Depending on the number of circuits the PTO system has, operate 
the vehicle over one or concurrently over both of the denormalized PTO 
duty cycles in appendix B of this part. Measure emissions during 
operation over each duty cycle using the provisions of 40 CFR part 
1066.
    (8) Measured pressures must meet the cycle-validation 
specifications in the following table for each test run over the duty 
cycle:

[[Page 17823]]



Table 1 to Paragraph (b)(8) of Sec.   1037.540--Statistical Criteria for
              Validating Each Test Run Over the Duty Cycle
------------------------------------------------------------------------
               Parameter \a\                          Pressure
------------------------------------------------------------------------
Slope, a1.................................  0.950 <= a1 <= 1.030
Absolute value of intercept,                <=2.0% of maximum mapped
 [verbar]a0[verbar].                         pressure
Standard error of the estimate, SEE.......  <=10% of maximum mapped
                                             pressure
Coefficient of determination, r\2\........  >=0.970
------------------------------------------------------------------------
\a\ Determine values for specified parameters as described in 40 CFR
  1065.514(e) by comparing measured values to denormalized pressure
  values from the duty cycle in appendix B of this part.

* * * * *
    (f) * * *
    (3) For plug-in hybrid electric vehicles calculate the utility 
factor weighted fuel consumption in g/ton-mile, as follows:
    (i) Determine the utility factor fraction for the PTO system from 
the table in appendix E of this part using interpolation based on the 
total time of the charge-depleting portion of the test as determined in 
paragraphs (c)(6) and (d)(3) of this section.
    (ii) Weight the emissions from the charge-sustaining and charge-
depleting portions of the test to determine the utility factor-weighted 
fuel mass, mfuelUF[cycle]plug-in, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.070

Where:

i = an indexing variable that represents one test interval.
N = total number of charge-depleting test intervals.
mfuelPTOCD = total mass of fuel per ton-mile in the 
charge-depleting portion of the test for each test interval, i, 
starting from i = 1.
UFDCDi = utility factor fraction at time tCDi 
as determined in paragraph (f)(3)(i) of this section for each test 
interval, i, starting from i = 1.
j = an indexing variable that represents one test interval.
M = total number of charge-sustaining test intervals.
mfuelPTOCS = total mass of fuel per ton-mile in the 
charge-sustaining portion of the test for each test interval, j, 
starting from j = 1.
UFRCD = utility factor fraction at the full charge-
depleting time, tCD, as determined by interpolating the 
approved utility factor curve. tCD is the sum of the time 
over N charge-depleting test intervals.
* * * * *
0
113. Revise Sec.  1037.550 to read as follows:


Sec.  1037.550  Powertrain testing.

    This section describes the procedure to measure fuel consumption 
and create engine fuel maps by testing a powertrain that includes an 
engine coupled with a transmission, drive axle, and hybrid components 
or any assembly with one or more of those hardware elements. Engine 
fuel maps are part of demonstrating compliance with Phase 2 vehicle 
standards under this part; the powertrain test procedure in this 
section is one option for generating this fuel-mapping information as 
described in 40 CFR 1036.503. Additionally, this powertrain test 
procedure is one option for certifying hybrids to the engine standards 
in 40 CFR 1036.108.
    (a) General test provisions. The following provisions apply broadly 
for testing under this section:
    (1) Measure NOX emissions as described in paragraph (k) 
of this section. Include these measured NOX values any time 
you report to us your greenhouse gas emissions or fuel consumption 
values from testing under this section.
    (2) The procedures of 40 CFR part 1065 apply for testing in this 
section except as specified. This section uses engine parameters and 
variables that are consistent with 40 CFR part 1065.
    (3) Powertrain testing depends on models to calculate certain 
parameters. You can use the detailed equations in this section to 
create your own models, or use the GEM HIL model (incorporated by 
reference in Sec.  1037.810) to simulate vehicle hardware elements as 
follows:
    (i) Create driveline and vehicle models that calculate the angular 
speed setpoint for the test cell dynamometer, 
[fnof]nref,dyno, based on the torque measurement location. 
Use the detailed equations in paragraph (f) of this section, the GEM 
HIL model's driveline and vehicle submodels, or a combination of the 
equations and the submodels. You may use the GEM HIL model's 
transmission submodel in paragraph (f) of this section to simulate a 
transmission only if testing hybrid engines.
    (ii) Create a driver model or use the GEM HIL model's driver 
submodel to simulate a human driver modulating the throttle and brake 
pedals to follow the test cycle as closely as possible.
    (iii) Create a cycle-interpolation model or use the GEM HIL model's 
cycle submodel to interpolate the duty-cycles and feed the driver model 
the duty-cycle reference vehicle speed for each point in the duty-
cycle.
    (4) The powertrain test procedure in this section is designed to 
simulate operation of different vehicle configurations over specific 
duty cycles. See paragraphs (h) and (j) of this section.
    (5) For each test run, record engine speed and torque as defined in 
40 CFR 1065.915(d)(5) with a minimum sampling frequency of 1 Hz. These 
engine speed and torque values represent a duty cycle that can be used 
for separate testing with an engine mounted on an engine dynamometer 
under Sec.  1037.551, such as for a selective enforcement audit as 
described in Sec.  1037.301.
    (6) For hybrid powertrains with no plug-in capability, correct for 
the net energy change of the energy storage device as described in 40 
CFR 1066.501. For plug-in hybrid electric powertrains, follow 40 CFR 
1066.501 to determine End-of-Test for charge-depleting operation. You 
must get our approval in advance for your utility factor curve; we will 
approve it if you can show that you created it, using good engineering 
judgment, from sufficient in-use data of vehicles in the same 
application as the vehicles in which the plug-in hybrid electric 
powertrain will be installed. You may use methodologies described in 
SAE J2841 (incorporated by reference in Sec.  1037.810) to develop the 
utility factor curve.
    (7) The provisions related to carbon balance error verification in 
40 CFR

[[Page 17824]]

1036.543 apply for all testing in this section. These procedures are 
optional if you are only performing direct or indirect fuel-flow 
measurement, but we will perform carbon balance error verification for 
all testing under this section.
    (8) If you test a powertrain over the duty cycle specified in 40 
CFR 1036.512, control and apply the electrical accessory loads using 
one of the following systems:
    (i) An alternator with dynamic electrical load control.
    (ii) A load bank connected directly to the powertrain's electrical 
system.
    (b) Test configuration. Select a powertrain for testing as 
described in Sec.  1037.235 or 40 CFR 1036.235 as applicable. Set up 
the engine according to 40 CFR 1065.110 and 40 CFR 1065.405(b). Set the 
engine's idle speed to the minimum warm-idle speed. If warm idle speed 
is not adjustable, simply let the engine operate at its warm idle 
speed.
    (1) The default test configuration consists of a powertrain with 
all components upstream of the axle. This involves connecting the 
powertrain's output shaft directly to the dynamometer or to a gear box 
with a fixed gear ratio and measuring torque at the axle input shaft. 
You may instead set up the dynamometer to connect at the wheel hubs and 
measure torque at that location. The preceeding sentence may apply if 
your powertrain configuration requires it, such as for hybrid 
powertrains or if you want to represent the axle performance with 
powertrain test results.
    (2) For testing hybrid engines, connect the engine's crankshaft 
directly to the dynamometer and measure torque at that location.
    (c) Powertrain temperatures during testing. Cool the powertrain 
during testing so temperatures for oil, coolant, block, head, 
transmission, battery, and power electronics are within the 
manufacturer's expected ranges for normal operation. You may use 
electronic control module outputs to comply with this paragraph (c). 
You may use auxiliary coolers and fans.
    (d) Engine break in. Break in the engine according to 40 CFR 
1065.405, the axle assembly according to Sec.  1037.560, and the 
transmission according to Sec.  1037.565. You may instead break in the 
powertrain as a complete system using the engine break in procedure in 
40 CFR 1065.405.
    (e) Dynamometer setup. Set the dynamometer to operate in speed-
control mode (or torque-control mode for hybrid engine testing at idle, 
including idle portions of transient duty cycles). Record data as 
described in 40 CFR 1065.202. Command and control the dynamometer speed 
at a minimum of 5 Hz, or 10 Hz for testing engine hybrids. Run the 
vehicle model to calculate the dynamometer setpoints at a rate of at 
least 100 Hz. If the dynamometer's command frequency is less than the 
vehicle model dynamometer setpoint frequency, subsample the calculated 
setpoints for commanding the dynamometer setpoints.
    (f) Driveline and vehicle model. Use the GEM HIL model's driveline 
and vehicle submodels or the equations in this paragraph (f) to 
calculate the dynamometer speed setpoint, [fnof]nref,dyno, 
based on the torque measurement location. Note that the GEM HIL model 
is configured to set the accessory load to zero and it comes configured 
with the tire slip model disabled. Note that the GEM HIL model is 
configured to set the accessory load to zero and it comes configured 
with the tire slip model disabled.
    (1) Driveline model with a transmission in hardware. For testing 
with torque measurement at the axle input shaft or wheel hubs, 
calculate, fnref,dyno, using the GEM HIL model's driveline 
submodel or the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.071

Where:

ka[speed] = drive axle ratio as determined in paragraph 
(h) of this section. Set ka[speed] equal to 1.0 if torque 
is measured at the wheel hubs.
vrefi = simulated vehicle reference speed as calculated 
in paragraph (f)(3) of this section.
r[speed] = tire radius as determined in paragraph (h) of 
this section.

    (2) Driveline model with a simulated transmission. For testing with 
the torque measurement at the engine's crankshaft, 
fnref,dyno is the dynamometer target speed from the GEM HIL 
model's transmission submodel. You may request our approval to change 
the transmission submodel, as long as the changes do not affect the 
gear selection logic. Before testing, initialize the transmission model 
with the engine's measured torque curve and the applicable steady-state 
fuel map from the GEM HIL model. You may request our approval to input 
your own steady-state fuel map. For example, this request for approval 
could include using a fuel map that represents the combined performance 
of the engine and hybrid components. Configure the torque converter to 
simulate neutral idle when using this procedure to generate engine fuel 
maps in 40 CFR 1036.503 or to perform the Supplemental Emission Test 
(SET) testing under 40 CFR 1036.505. You may change engine commanded 
torque at idle to better represent CITT for transient testing under 40 
CFR 1036.510. You may change the simulated engine inertia to match the 
inertia of the engine under test. We will evaluate your requests under 
this paragraph (f)(2) based on your demonstration that that the 
adjusted testing better represents in-use operation.
    (i) The transmission submodel needs the following model inputs:
    (A) Torque measured at the engine's crankshaft.
    (B) Engine estimated torque determined from the electronic control 
module or by converting the instantaneous operator demand to an 
instantaneous torque in N[middot]m.
    (C) Dynamometer mode when idling (speed-control or torque-control).
    (D) Measured engine speed when idling.
    (E) Transmission output angular speed, fni,transmission, 
calculated as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.072

Where:

ka[speed] = drive axle ratio as determined in paragraph 
(h) of this section.
vrefi = simulated vehicle reference speed as calculated 
in paragraph (f)(3) of this section.
r[speed] = tire radius as determined in paragraph (h) of 
this section.

    (ii) The transmission submodel generates the following model 
outputs:
    (A) Dynamometer target speed.
    (B) Dynamometer idle load.
    (C) Transmission engine load limit.
    (D) Engine speed target.
    (3) Vehicle model. Calculate the simulated vehicle reference speed, 
vrefi, using the GEM HIL model's vehicle submodel or the 
equations in this paragraph (f)(3):

[[Page 17825]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.073

Where:

i= a time-based counter corresponding to each measurement during the 
sampling period. Let vref1 = 0; start calculations at i = 
2. A 10-minute sampling period will generally involve 60,000 
measurements.
T = instantaneous measured torque at the axle input, measured at the 
wheel hubs, or simulated by the GEM HIL model's transmission 
submodel.
Effaxle = axle efficiency. Use Effaxle = 0.955 
for T >= 0, and use Effaxle = 1/0.955 for T < 0. Use 
Effaxle = 1.0 if torque is measured at the wheel hubs.
M = vehicle mass for a vehicle class as determined in paragraph (h) 
of this section.
g = gravitational constant = 9.80665 m/s\2\.
Crr = coefficient of rolling resistance for a vehicle 
class as determined in paragraph (h) of this section.
Gi-1 = the percent grade interpolated at distance, 
Di-1, from the duty cycle in appendix D to this part 
corresponding to measurement (i-1).
[GRAPHIC] [TIFF OMITTED] TP28MR22.074

r = air density at reference conditions. Use r = 1.1845 kg/m\3\.
CdA = drag area for a vehicle class as determined in 
paragraph (h) of this section.
Fbrake,i-1 = instantaneous braking force 
applied by the driver model.
[GRAPHIC] [TIFF OMITTED] TP28MR22.133

Dt = the time interval between measurements. For example, at 100 Hz, 
Dt = 0.0100 seconds.
Mrotating = inertial mass of rotating components. Let 
Mrotating = 340 kg for vocational Light HDV or vocational 
Medium HDV. See paragraph (h) of this section for tractors and for 
vocational Heavy HDV.

    (4) Example. The following example illustrates a calculation of 
fnref,dyno using paragraph (f)(1) of this section where 
torque is measured at the axle input shaft. This example is for a 
vocational Light HDV or vocational Medium HDV with 6 speed automatic 
transmission at B speed (Test 4 in Table 1 to paragraph (h)(2)(ii) of 
this section).

kaB = 4.0
rB = 0.399 m
T999 = 500.0 N[middot]m
Crr = 7.7 N/kN = 7.7[middot]10-3 N/N
M = 11408 kg
CdA = 5.4 m2
G999 = 0.39% = 0.0039
[GRAPHIC] [TIFF OMITTED] TP28MR22.075

Fbrake,999 = 0 N
vref,999 = 20.0 m/s
Fgrade,999 = 11408 [middot] 981 [middot] 
sin(atan(0.0039)) = 436.5 N
    [Delta]t = 0.0100 s
Mrotating = 340 kg
[GRAPHIC] [TIFF OMITTED] TP28MR22.076

[GRAPHIC] [TIFF OMITTED] TP28MR22.077

    (g) Driver model. Use the GEM HIL model's driver submodel or design 
a driver model to simulate a human driver modulating the throttle and 
brake pedals. In either case, tune the model to follow the test cycle 
as closely as possible meeting the following specifications:
    (1) The driver model must meet the following speed requirements:
    (i) For operation over the highway cruise cycles, the speed 
requirements described in 40 CFR 1066.425(b) and (c).
    (ii) For operation over the transient cycle specified in appendix A 
of this part, the SET as defined 40 CFR 1036.505, the Federal Test 
Procedure (FTP) as defined in 40 CFR 1036.510, and the Low Load Cycle 
(LLC) as defined in 40 CFR 1036.512, the speed requirements described 
in 40 CFR 1066.425(b) and (c).
    (iii) The exceptions in 40 CFR 1066.425(b)(4) apply to the highway 
cruise cycles, the transient cycle specified in appendix A of this 
part, SET, FTP, and LLC.

[[Page 17826]]

    (iv) If the speeds do not conform to these criteria, the test is 
not valid and must be repeated.
    (2) Send a brake signal when operator demand is zero and vehicle 
speed is greater than the reference vehicle speed from the test cycle. 
Include a delay before changing the brake signal to prevent dithering, 
consistent with good engineering judgment.
    (3) Allow braking only if operator demand is zero.
    (4) Compensate for the distance driven over the duty cycle over the 
course of the test. Use the following equation to perform the 
compensation in real time to determine your time in the cycle:
[GRAPHIC] [TIFF OMITTED] TP28MR22.078

Where:

vvehicle = measured vehicle speed.
vcycle = reference speed from the test cycle. If 
vcycle,i-1 < 1.0 m/s, set vcycle,i-1 = 
vvehicle,i-1.

    (h) Vehicle configurations to evaluate for generating fuel maps as 
defined in 40 CFR 1036.503. Configure the driveline and vehicle models 
from paragraph (f) of this section in the test cell to test the 
powertrain. Simulate multiple vehicle configurations that represent the 
range of intended vehicle applications using one of the following 
options:
    (1) Use at least three equally spaced axle ratios or tire sizes and 
three different road loads (nine configurations), or at least four 
equally spaced axle ratios or tire sizes and two different road loads 
(eight configurations). Select axle ratios to represent the full range 
of expected vehicle installations. Instead of selecting axle ratios and 
tire sizes based on the range of intended vehicle applications as 
described in paragraph (h)(2) of this section, you may select axle 
ratios and tire sizes such that the ratio of engine speed to vehicle 
speed covers the range of ratios of minimum and maximum engine speed to 
vehicle speed when the transmission is in top gear for the vehicles in 
which the powertrain will be installed. Note that you do not have to 
use the same axle ratios and tire sizes for each GEM regulatory 
subcategory. You may determine your own Crr, CdA, 
and M to cover the range of intended vehicle applications or you may 
use the road loads in paragraph (h)(2) of this section.
    (2) Determine the vehicle model inputs for a set of vehicle 
configurations as described in 40 CFR 1036.540(c)(3) with the following 
exceptions:
    (i) In the equations of 40 CFR 1036.540(c)(3)(i), 
ktopgear is the actual top gear ratio of the powertrain 
instead of the transmission gear ratio in the highest available gear 
given in Table 1 in 40 CFR 1036.540.
    (ii) Test at least eight different vehicle configurations for 
powertrains that will be installed in Spark-ignition HDE, vocational 
Light HDV, and vocational Medium HDV using the following table instead 
of Table 2 in 40 CFR 1036.540:
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TP28MR22.079

    (iii) Select and test vehicle configurations as described in 40 CFR 
1036.540(c)(3)(iii) for powertrains that will be installed in 
vocational Heavy HDV and tractors using the following tables instead of 
Table 3 and Table 4 in 40 CFR 1036.540:

[[Page 17827]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.080

BILLING CODE 6560-50-C
    (3) For hybrid powertrain systems where the transmission will be 
simulated, use the transmission parameters defined in 40 CFR 
1036.540(c)(2) to determine transmission type and gear ratio. Use a 
fixed transmission efficiency of 0.95. The GEM HIL transmission model 
uses a transmission parameter file for each test that includes the 
transmission type, gear ratios, lockup gear, torque limit per gear from 
40 CFR 1036.540(c)(2), and the values from 40 CFR 1036.503(b)(4) and 
(c).
    (i) [Reserved]
    (j) Duty cycles to evaluate. Operate the powertrain over each of 
the duty cycles specified in Sec.  1037.510(a)(2), and for each 
applicable vehicle configuration from paragraph (h) of this section. 
Determine cycle-average powertrain fuel maps by testing the powertrain 
using

[[Page 17828]]

the procedures in 40 CFR 1036.540(d) with the following exceptions:
    (1) Understand ``engine'' to mean ``powertrain''.
    (2) Warm up the powertrain as described in 40 CFR 1036.527(c)(1).
    (3) Within 90 seconds after concluding the warm-up, start the 
transition to the preconditioning cycle as described in paragraph 
(j)(5) of this section.
    (4) For plug-in hybrid engines, precondition the battery and then 
complete all back-to-back tests for each vehicle configuration 
according to 40 CFR 1066.501 before moving to the next vehicle 
configuration.
    (5) If the preceding duty cycle does not end at 0 mi/hr, transition 
between duty cycles by decelerating at a rate of 2 mi/hr/s at 0% grade 
until the vehicle reaches zero speed. Shut off the powertrain. Prepare 
the powertrain and test cell for the next duty-cycle.
    (6) Start the next duty-cycle within 60 to 180 seconds after 
shutting off the powertrain.
    (i) To start the next duty-cycle, for hybrid powertrains, key on 
the vehicle and then start the duty-cycle. For conventional powertrains 
key on the vehicle, start the engine, wait for the engine to stabilize 
at idle speed, and then start the duty-cycle.
    (ii) If the duty-cycle does not start at 0 mi/hr, transition to the 
next duty cycle by accelerating at a target rate of 1 mi/hr/s at 0% 
grade. Stabilize for 10 seconds at the initial duty cycle conditions 
and start the duty-cycle.
    (7) Calculate cycle work using GEM or the speed and torque from the 
driveline and vehicle models from paragraph (f) of this section to 
determine the sequence of duty cycles.
    (8) Calculate the mass of fuel consumed for idle duty cycles as 
described in paragraph (n) of this section.
    (k) Measuring NOX emissions. Measure NOX emissions for 
each sampling period in grams. You may perform these measurements using 
a NOX emission-measurement system that meets the 
requirements of 40 CFR part 1065, subpart J. If a system malfunction 
prevents you from measuring NOX emissions during a test 
under this section but the test otherwise gives valid results, you may 
consider this a valid test and omit the NOX emission 
measurements; however, we may require you to repeat the test if we 
determine that you inappropriately voided the test with respect to 
NOX emission measurement.
    (l) [Reserved]
    (m) Measured output speed validation. For each test point, validate 
the measured output speed with the corresponding reference values. If 
the range of reference speed is less than 10 percent of the mean 
reference speed, you need to meet only the standard error of the 
estimate in Table 1 of this section. You may delete points when the 
vehicle is stopped. If your speed measurement is not at the location of 
fnref, correct your measured speed using the constant speed 
ratio between the two locations. Apply cycle-validation criteria for 
each separate transient or highway cruise cycle based on the following 
parameters:

  Table 4 to Paragraph (m) of Sec.   1037.550--Statistical Criteria for
                         Validating Duty Cycles
------------------------------------------------------------------------
               Parameter \a\                        Speed control
------------------------------------------------------------------------
Slope, [alpha]1...........................  0.990 <= [alpha]1 <= 1.010.
Absolute value of intercept,                <=2.0% of maximum fnref
 [bond][alpha]0[bond].                       speed.
Standard error of the estimate, SEE.......  <=2.0% of maximum fnref
                                             speed.
Coefficient of determination, r2..........  >=0.990.
------------------------------------------------------------------------
\a\ Determine values for specified parameters as described in 40 CFR
  1065.514(e) by comparing measured and reference values for fnref,dyno.

    (n) Fuel consumption at idle. Determine the mass of fuel consumed 
at idle for the applicable duty cycles described in Sec.  
1037.510(a)(2) as follows:
    (1) Measure fuel consumption with a fuel flow meter and report the 
mean idle fuel mass flow rate for each duty cycle as applicable, 
mifuelidle.
    (2) If you do not measure fuel mass flow rate, calculate the idle 
fuel mass flow rate for each duty cycle, mifuelidle, for 
each set of vehicle settings, as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.081

Where:

MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of test 
fuels) as determined in 40 CFR 1065.655(d), except that you may not 
use the default properties in Table 2 of 40 CFR 1065.655 to 
determine a, b, and wC for liquid fuels.
niexh = the mean raw exhaust molar flow rate from which 
you measured emissions according to 40 CFR 1065.655.
xCcombdry = the mean concentration of carbon from fuel 
and any injected fluids in the exhaust per mole of dry exhaust.
xH2Oexhdry = the mean concentration of H2O in 
exhaust per mole of dry exhaust.
miCO2DEF = the mean CO2 mass emission rate 
resulting from diesel exhaust fluid decomposition over the duty 
cycle as determined in 40 CFR 1036.535(b)(7). If your engine does 
not use diesel exhaust fluid, or if you choose not to perform this 
correction, set miCO2DEF equal to 0.
MCO2 = molar mass of carbon dioxide.

Example:

MC = 12.0107 g/mol
wCmeas = 0.867
niexh = 25.534 mol/s
xCcombdry = 2.805 [middot] 10-3 mol/mol
xH2Oexhdry = 3.53 [middot] 10-2 mol/mol
miCO2DEF = 0.0726 g/s
MCO2 = 44.0095
[GRAPHIC] [TIFF OMITTED] TP28MR22.082

mifuelidle = 0.405 g/s = 1458.6 g/hr

    (o) Create GEM inputs. Use the results of powertrain testing to 
determine GEM inputs for the different simulated vehicle configurations 
as follows:
    (1) Correct the measured or calculated fuel masses, 
mfuel[cycle], and mean idle fuel mass flow rates, 
mifuelidle, if applicable, for each test result to a mass-
specific net energy content of a reference fuel as described in 40 CFR 
1036.535(f), replacing mifuel with mmfuel[cycle] 
where applicable in Eq. 1036.535-4.

[[Page 17829]]

    (2) Declare fuel masses, mfuel[cycle] and 
mifuelidle. Determine mmfuel[cycle] using the 
calculated fuel mass consumption values described in 40 CFR 
1036.540(d). In addition, declare mean fuel mass flow rate for each 
applicable idle duty cycle, mifuelidle. These declared 
values may not be lower than any corresponding measured values 
determined in this section. If you use both direct and indirect 
measurement of fuel flow, determine the corresponding declared values 
as described in 40 CFR 1036.535(g)(2) and (3). These declared values, 
which serve as emission standards, collectively represent the 
powertrain fuel map for certification.
    (3) For engines designed for plug-in hybrid electric vehicles, the 
mass of fuel for each cycle, mfuel[cycle], is the utility 
factor-weighted fuel mass, mfuelUF[cycle]. This is 
determined by calculating mfuel for the full charge-
depleting and charge-sustaining portions of the test and weighting the 
results, using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.083

Where:

i = an indexing variable that represents one test interval.
N = total number of charge-depleting test intervals.
mfuel[cycle]CDi = total mass of fuel in the charge-
depleting portion of the test for each test interval, i, starting 
from i = 1, including the test interval(s) from the transition 
phase.
UFDCDi = utility factor fraction at distance 
DCDi from Eq. 1037.505-9 as determined by interpolating 
the approved utility factor curve for each test interval, i, 
starting from i = 1. Let UFDCD0 = 0
j = an indexing variable that represents one test interval.
M = total number of charge-sustaining test intervals.
mfuel[cycle]CSj = total mass of fuel over the charge-
sustaining portion of the test for each test interval, j, starting 
from j = 1.
UFRCD = utility factor fraction at the full charge-
depleting distance, RCD, as determined by interpolating 
the approved utility factor curve. RCD is the cumulative 
distance driven over N charge-depleting test intervals.
[GRAPHIC] [TIFF OMITTED] TP28MR22.084

Where:

k = an indexing variable that represents one recorded velocity 
value.
Q = total number of measurements over the test interval.
v = vehicle velocity at each time step, k, starting from k = 1. For 
tests completed under this section, v is the vehicle velocity as 
determined by Eq. 1037.550-1. Note that this should include charge-
depleting test intervals that start when the engine is not yet 
operating.
[Delta]t = 1/frecord
frecord = the record rate

Example for the 55 mi/hr cruise cycle:

Q = 8790
v1 = 55.0 mi/hr
v2 = 55.0 mi/hr
v3 = 55.1 mi/hr
frecord = 10 Hz
[Delta]t = 1/10 Hz = 0.1 s
[GRAPHIC] [TIFF OMITTED] TP28MR22.085

DCD2 = 13.4 mi
DCD3 = 13.4 mi
N = 3
UFDCD1 = 0.05
UFDCD2 = 0.11
UFDCD3 = 0.21
mfuel55cruiseCD1 = 0 g
mfuel55cruiseCD2 = 0 g
mfuel55cruiseCD3 = 1675.4 g
M = 1
mfuel55cruiseCS = 4884.1 g
UFRCD = 0.21

[[Page 17830]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.086

    (ii) For testing with torque measurement at the wheel hubs, use Eq. 
1037.550-8 setting ka equal to 1.
    (iii) For testing with torque measurement at the engine's 
crankshaft:
[GRAPHIC] [TIFF OMITTED] TP28MR22.087

Where:

fengine = average engine speed when vehicle speed is at 
or above 0.100 m/s.
vref = average simulated vehicle speed at or above 0.100 
m/s.

Example:

fengine = 1870 r/min = 31.17 r/s
vref = 19.06 m/s
[GRAPHIC] [TIFF OMITTED] TP28MR22.088

    (5) Calculate positive work, W[cycle], as the work over 
the duty cycle at the axle input shaft, wheel hubs, or the engine's 
crankshaft, as applicable, when vehicle speed is at or above 0.100 m/s. 
For plug-in hybrids engines and powertrains, calculate, 
W[cycle], by calculating the positive work over each of the 
charge-sustaining and charge-depleting test intervals and then 
averaging them together.
    (6) Calculate engine idle speed, by taking the average engine speed 
measured during the transient cycle test while the vehicle speed is 
below 0.100 m/s.
    (7) The following table illustrates the GEM data inputs 
corresponding to the different vehicle configurations for a given duty 
cycle:

[[Page 17831]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.089

0
114. Amend Sec.  1037.551 by revising the introductory text and 
paragraphs (b) and (c) to read as follows:


Sec.  1037.551  Engine-based simulation of powertrain testing.

    Section 1037.550 describes how to measure fuel consumption over 
specific duty cycles with an engine coupled to a transmission; Sec.  
1037.550(a)(5) describes how to create equivalent duty cycles for 
repeating those same measurements with just the engine. This Sec.  
1037.551 describes how to perform this engine testing to simulate the 
powertrain test. These engine-based measurements may be used for 
confirmatory testing as described in Sec.  1037.235, or for selective 
enforcement audits as described in Sec.  1037.301, as long as the test 
engine's operation represents the engine operation observed in the 
powertrain test. If we use this approach for confirmatory testing, when 
making compliance determinations, we will consider the uncertainty 
associated with this approach relative to full powertrain testing. Use 
of this approach for engine SEAs is optional for engine manufacturers.
* * * * *
    (b) Operate the engine over the applicable engine duty cycles 
corresponding to the vehicle cycles specified in Sec.  1037.510(a)(2) 
for powertrain testing over the applicable vehicle simulations 
described in Sec.  1037.550(j). Warm up the engine to prepare for the 
transient test or one of the highway cruise cycles by operating it one 
time over one of the simulations of the corresponding duty cycle. Warm 
up the engine to prepare for the idle test by operating it over a 
simulation of the 65-mi/hr highway cruise cycle for 600 seconds. Within 
60 seconds after concluding the warm up cycle, start emission sampling 
while the engine operates over the duty cycle. You may perform any 
number of test runs directly in succession once the engine is warmed 
up. Perform cycle validation as described in 40 CFR 1065.514 for engine 
speed, torque, and power.
    (c) Calculate the mass of fuel consumed as described in Sec.  
1037.550(n) and (o). Correct each measured value for the test fuel's 
mass-specific net energy content as described in 40 CFR 1036.530. Use 
these corrected values to determine whether the engine's emission 
levels conform to the declared fuel-consumption rates from the 
powertrain test.
0
115. Add Sec.  1037.552 to subpart F read as follows:


Sec.  1037.552  Multicycle powertrain test for battery electric 
vehicles.

    This section describes a procedure to measure work produced over 
the Heavy-Duty Transient Cycle (HDTC), useable battery energy (UBE) of 
a powertrain that propels a battery electric vehicle, and a transient 
cycle conversion factor, CFBEV, for use in Sec.  1037.616. 
Work produced over the HDTC and UBE are part of demonstrating 
compliance with criteria pollutant standards under Sec.  1037.102 if 
you choose to generate NOX emission credits under this part. 
This test procedure is one option for generating work produced over the 
HDTC and UBE. You may ask to use alternative test methods to 
demonstrate compliance with the standards.
    (a) General test provisions. The following provisions apply broadly 
for testing under this section:
    (1) The procedures of 40 CFR part 1065 apply for testing in this 
section except as specified. This section uses engine parameters and 
variables that are consistent with 40 CFR part 1065.
    (2) For powertrains that propel a battery electric vehicle, follow 
the procedures of 40 CFR 1036.505, 1036.510, and 1036.512 for testing 
the respective duty-cycles in this section except as specified. For the 
purposes of testing under this section, testing over the HDTC is 
carried out using the transient duty cycle described in 40 CFR 
1036.510(a)(2) with a cold start testing only being required for the 
first HDTC of the test sequence.
    (3) The following instruments are required for determination of the 
required voltages and currents during testing and must be installed on 
the powertrain to measure these values during testing:
    (i) Measure the voltage and current of the battery pack directly 
with a DC wideband voltage, Ampere, and Watt-hour meter (power 
analyzer). Install this meter in such a way as to measure all current 
leaving and entering the battery pack (no other connections upstream of 
the measurement point). The maximum integration period for ampere-hour 
meters using an integration technique is 0.05 seconds to accommodate 
abrupt current changes without introducing significant integration 
errors. Use a power analyzer that has an accuracy for current and 
voltage measurements of 1% of point or 0.3% of max, whichever is 
greater. Use an instrument that is not susceptible to offset errors 
while measuring current as very small current offsets can be integrated 
throughout the cycle and provide erroneous energy or ampere-hour 
results.
    (ii) If voltage sensing is not available, then optionally measure 
amp hours without directly measuring voltage

[[Page 17832]]

using a DC wideband ampere-hour meter. In this case, the voltage is 
determined from the powertrain ECM.
    (iii) Install an AC Watt-hour meter to measure AC recharge energy 
in such a way as to measure all AC electrical energy entering the 
powertrain charger. Use an AC Watt-hour meter that has an accuracy for 
current and voltage measurements of 1% of point or 0.3% of max, 
whichever is greater.
    (4) You must include in the test the powertrain's cooling system 
(e.g., battery, power electronics, and electric motor(s)) such that the 
energy used from these accessories is accounted for during the test, 
including the pre- and post- test soak and charging periods.
    (5) Stabilize powertrains tested under this section by following 
manufacturer recommendations.
    (i) For determining the initial UBE, test a powertrain that has 
accumulated a minimum of 1,000 miles, but no more than 6,200 miles 
using a manufacturer defined durability driving schedule. Age the 
battery as follows:
    (A) Include it in the powertrain that was operated over the 
durability driving schedule.
    (B) Condition it using test procedure #2, Constant Current 
Discharge Test Series, in the United States Advanced Battery 
Consortium's Electric Vehicle Battery Test Procedures Manual 
(incorporated by reference in Sec.  1037.810). Note that the number of 
charge/discharge cycles for bench aging a lead acid battery must be 
equivalent to at least 1000 vehicle miles. You may use other battery 
aging periods for non-lead-acid battery technologies, if supported by 
the manufacturer as being equivalent.
    (ii) For determining aged UBE, test a powertrain that has 
accumulated targeted aged miles.
    (6) Cycle all batteries in accordance with the powertrain 
manufacturers' recommendations before starting testing.
    (b) Precondition the powertrain by repeatedly operating it over the 
HDTC, without soaks and leaving the key in the on position between 
cycles, until the powertrain's battery is fully depleted. This method 
is recommended to ensure that the subsequent recharge event produces a 
repeatable battery energy capacity prior to the test; however, a 
preconditioning sequence that does not fully deplete the battery but 
consists of at least one HDTC is also acceptable if it results in 
equivalent pre-test UBE.
    (c) Following the preconditioning, soak the powertrain, including 
the battery and thermal management system, if any, at (20 to 30) [deg]C 
for 12 to 36 hours. Charge the powertrain for the duration of the soak 
period measuring the DC recharge energy, EDCRC, and do not 
end the soak period prior to reaching full charge. Upon completion of 
the soak, install the powertrain, if not already installed, in the test 
cell and attach it to the dynamometer. The powertrain will be tested in 
a cold start condition for this test. Start the powertrain test no more 
than one hour after the powertrain is taken off charge.
    (d) Measure DC discharge energy, EDCD, in Watt-hours and 
DC discharge current per hour, CD, for the entire Multicycle 
Test (MCT). The measurement points for the battery(ies) must capture 
all the current flowing into and out of the battery(ies) during 
powertrain operation, including current associated with regenerative 
braking. The equation for calculating powertrain EDCD is 
given in Eq. 1037.552-1, however, it is expected that this calculation 
will typically be performed internally by the power analyzer specified 
in paragraph (a)(3)(i) of this section. Battery voltage measurements 
made by the powertrain's own on-board sensors (such as those available 
via a diagnostic port) may be used for calculating EDCD if 
these measurements are equivalent to those produced by applicable 
external measurement equipment, such as a power analyzer.
[GRAPHIC] [TIFF OMITTED] TP28MR22.090

Where:

f = frequency of the current measurement in Hz.
i = an indexing variable that represents one individual measurement.
N = total number of measurements.
V = battery DC bus voltage in volts.
I = battery current in amps.

    (e) The MCT range test consists of four HDTCs, two LLCs, two SETs, 
and two constant speed cycles: CSCM at the mid-test point 
and CSCE at the end of test.
    (1) The test sequence follows: HDTC-HDTC-LLC-SET-CSCM-
HDTC-HDTC-LLC-SET-CSCE.
    (2) The CSC is used to rapidly deplete battery energy, and consists 
of a steady-state speed schedule of 55 mi/hr or 90% of maximum 
sustainable speed if a powertrain cannot reach 55 mi/hr. When 
transitioning from the SET to CSC, smoothly accelerate to 55 mi/hr 
within 1 minute of the key switch being placed in the ``on'' position. 
Maintain powertrain speed to within 1.0 mi/hr of the speed 
setpoint.
    (3) Use one of the following methods to determine the duration of 
CSCM, tCSCM, prior to carrying out the test 
sequence:
    (i) DC recharge energy method. This method requires data from the 
recharge event preceding the test as described in paragraph (b) of this 
section or known UBE, cycle DC discharge energy, 
EDCD[dutycycle], and DC energy consumption rates, EC, 
measured either before or during the MCT.
    (A) If a reasonable estimate of the powertrain's UBE is not 
available, determine UBEest as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.091

Where:

Beff = estimated battery efficiency = 0.95. You may 
develop your own estimated battery efficiency.
EDCRC = DC recharge energy measured during the pre-test 
recharging event. If DC recharge energy is not available, use the AC 
recharge energy, EACRC, from the pre-test recharging 
event which includes the total AC energy supplied to the powertrain 
from the electrical grid, including all energy used to power 
charging equipment (e.g., charger, electrical vehicle supply 
equipment, 12V battery charger, etc.), and define a suitable (lower) 
battery plus charger efficiency factor to calculate 
UBEest.

Example:

EDCRC = 600000 W [middot] hrs
Beff = 0.95
UBEest = 0.95 [middot] 600000 = 570000 W [middot] hrs

    (B) Determine length of CSCM, DCSCM, using 
the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.092


[[Page 17833]]


Where:

CSCMfactor = multiplier intended to leave 10% of the 
total energy for CSCE = 0.9. You may choose a smaller 
factor, but target no more than 20% of the total energy for 
CSCE.
EDCDHDTC = discharge energy from HDTC #2 of the MCT.
EDCDLLC = discharge energy from LLC #1 of the MCT.
EDCDSET = discharge energy from SET #1 of the MCT.
ECCSC = DC energy consumption from the preconditioning 
run in paragraph (b) of this section.

Example:

EDCDHDTC = 25604 W [middot] hr
EDCDLLC = 37312 W [middot] hr
EDCDSET = 129009 W [middot] hr
ECCSC = 1380 W [middot] hr/mi
CSCMfactor = 0.9
[GRAPHIC] [TIFF OMITTED] TP28MR22.093

    (C) Determine tCSCM using the following equation:
    [GRAPHIC] [TIFF OMITTED] TP28MR22.094
    
Where:

vCSC = powertrain speed over the CSC = 55 mi/hr.

Example:
[GRAPHIC] [TIFF OMITTED] TP28MR22.095

    (ii) Projected range method. Use this method if the DC cycle 
discharge energy and DC recharge energy are unknown. Determine 
CSCM using the powertrain's projected range on the HDTC, 
LLC, SET, and CSC.
    (A) Using the powertrain's projected range and distance on the duty 
cycle(s), determine DCSCM as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.096

Where:

RCSCest = estimated range from the charge depleting test 
run in paragraph (e)(2) of this section.
RHDTCest = estimated range on repeat HDTC cycles 
determine in paragraph (k) of this section.
RLLCest = estimated range on repeat LLC cycles determine 
in paragraph (k) of this section.
RSETest = estimated range on repeat SET cycles determine 
in paragraph (k) of this section.
DHDTC = scheduled driving distance of one HDTC = 6.75 
miles.
DLLC = scheduled driving distance of one LLC = 15.70 
miles.
DSET = scheduled driving distance of one SET = 35.47 
miles.
CSCEfactor = multiplier intended to leave 20% of the 
total energy for CSCE = 0.2. You may choose a smaller 
factor if your range estimates allow for accurate determination of 
the factor.

Example:

RCSCest = 413.0 miles
RHDTCest = 180.3 miles
RLLCest = 299.8 miles
RSETest = 156.7 miles
DHDTC = 6.75 miles
DLLC = 15.70 miles
DSET = 35.47 miles
CSCEfactor = 0.2
[GRAPHIC] [TIFF OMITTED] TP28MR22.097

    (B) Determine tCSCM using Eq. 1037.552-4.

Example:
[GRAPHIC] [TIFF OMITTED] TP28MR22.098

    (4) Operate the powertrain over the test sequence described in 
Figure 1 of this section. Measure and report the total work, 
W[cycle], EDCD, and CD from each of 
the test intervals. During soaks, use test cell ventilation to maintain 
a powertrain soak temperature of (20 to 30) [deg]C with the key or 
power switch in the ``off'' position and the brake pedal not depressed.

[[Page 17834]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.099

    (f) The test is complete when the following end-of-test criteria 
during CSCE have been met.
    (1) The test termination criterion for the full-depletion range and 
energy consumption test for powertrains capable of meeting the 
prescribed speed vs. time relationship of the applicable drive cycle 
follows:
    (i) The test is complete when the powertrain, due to power 
limitations, is incapable of maintaining 1.0 mi/hr of the 
speed setpoint or the manufacturer determines that the test should be 
terminated for safety reasons (e.g., excessively high battery 
temperature, abnormally low battery voltage, etc.).
    (ii) Immediately apply the brake and decelerate the powertrain to a 
stop within 15 seconds once the test termination criteria have been 
met.
    (2) The test termination criterion for the full-depletion range and 
energy consumption test for powertrains that are not capable of meeting 
the prescribed speed vs. time relationship of the applicable drive 
cycle for the initial phase of that cycle (i.e., the phase that begins 
with the powertrain fully charged) and operated at maximum available 
power follows:
    (i) The test is complete when the powertrain, while operated at 
maximum available power or ``full throttle'', is unable to reproduce 
the best-effort speed vs. time relationship established by the 
powertrain in the first phase of the test.
    (ii) The best-effort trace drive tolerance are the speed 
requirements described in 40 CFR 1066.425(b)(1) and (2).
    (g) Place the powertrain on-charge within 3 hours of completing the 
MCT and charge the battery to full capacity to measure the total AC 
recharge energy, EACRC, and DC recharge current per hour, 
CRC.
    (1) Carryout recharging at the same nominal ambient temperature as 
the pre-test soak/charging period.
    (2) Established that the system is fully charged using the 
manufacturer's recommended charging procedure and appropriate 
equipment. Use the powertrain charger if it came equipped with one. 
Otherwise, charge the powertrain using an external charger recommended 
by the powertrain manufacturer. If multiple charging power levels are 
available, recharge the powertrain at the power level recommended by 
the manufacturer. If the manufacturer does not specify a power level, 
recharging the system at the power level expected to be most widely 
used by end users. Use this power level for all pre- and post-test 
recharging events.
    (3) Measure all AC energy supplied to the powertrain from the 
electrical grid, including all energy used to power charging equipment 
(e.g., charger, electrical vehicle supply equipment, 12V battery 
charger, etc.).
    (4) Determine EAC in Watt-hours and CC in amp 
hours, using the instruments specified in paragraph (a)(3) of this 
section, for powertrains that require less than 12 hours to reach full 
charge by measuring the EAC and CC for a 12 hour 
period following the connection of the powertrain to the electrical 
vehicle supply equipment.
    (5) Collect data for powertrains requiring more than 12 hours to 
reach full charge, until full charge is achieved.

[[Page 17835]]

Note that the 12 hour minimum data collection period is intended to 
better replicate expected in-use charging practices (i.e., overnight 
charging) and to provide a standard time period that can be used 
quantify any ancillary recharging loads, such as those resulting from 
battery thermal conditioning.
    (6) Charge recovery is used to evaluate the equivalence of the pre- 
and post-test charge. Since the net amp-hours required to return the 
battery to a full charge during the post MCT recharging event in 
paragraph (g)(1) of this section must be greater than or equal to net 
amp hours discharged by the battery during the MCT, the charge recovery 
ratio should be >=1 for most battery types. Since the determination of 
full charge verification must also take into account error in the 
associated measurement devices, the pre- and post-test charge events 
can be considered equivalent if the charge recovery is greater than 
0.97. Verify the charge recovery, CR, of the post-test battery charge 
as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.100

Where:

CDCRC = total post-MCT DC recharge current per hour.
CDCD = total DC discharge current per hour during the 
MCT.

Example:

CDCRC = 1425.0 amp [middot] hrs
CDCD = 1452.1 amp [middot] hrs
[GRAPHIC] [TIFF OMITTED] TP28MR22.101

    (h) The UBE is defined as the total DC discharge energy, 
EDCDtotal, measured in DC Watt hours, over the MCT as 
determined as described in paragraph (d) of this section. The UBE 
represents the total deliverable energy the battery is capable of 
providing while a powertrain is following a duty cycle on a 
dynamometer. Determine a declared UBE that is at or below the 
corresponding value determined in paragraph (d) of this section, 
including those from redundant measurements. This declared UBE serves 
as the initial UBE that must be submitted under Sec.  1037.205(q)(2).
    (i) [Reserved]
    (j) Determine the transient cycle conversion factor, 
CFBEV, in hp [middot] hr/mile. This represents the average 
work performed over the test interval for use in the credit calculation 
for battery electric vehicles in Sec.  1037.616.
[GRAPHIC] [TIFF OMITTED] TP28MR22.102

Where:

WHDTC2 = total (integrated) work generated over the 
second HDTC test interval in the MTC.
d = duty-cycle distance for engines subject to compression-ignition 
standards from the CF determination for the emission credit 
calculation in 40 CFR 1036.705 = 6.5 miles.

Example:

WHDTC2 = 32.62 hp [middot] hr
d = 6.5 miles
[GRAPHIC] [TIFF OMITTED] TP28MR22.103

    (k) If you use the projected range option for determining the 
duration of CSCM, tCSCM, in paragraph (e)(3)(ii) 
of this section, determine the total range and energy consumption for a 
BEV over the HDTC, LLC, and SET when operated on a dynamometer over 
repeats of a respective duty-cycle. This is a single cycle test (SCT) 
where the powertrain is driven until the useable energy content of the 
powertrain's battery is fully depleted. The intent of this section is 
to provide a standard powertrain procedure for testing BEVs so that 
their performances can be compared when operated over the certification 
duty cycles. Measure CD as described in paragraph (d) of 
this section during the entire dynamometer test procedure (duty cycles 
and soaks) in order to validate the equivalence of the pre- and post-
test charge.
    (1) Precondition and soak the powertrain prior to testing as 
described in paragraphs (b) and (c) of this section.
    (2) Operate the powertrain over one of the following drive cycles:
    (i) HDTC.
    (ii) LLC.
    (iii) SET.
    (3) Operate the powertrain over one of the duty-cycles described in 
paragraph (k)(2) of this section using the following soak times between 
each duty-cycle; soak the powertrain as described in paragraph (e)(4) 
of this section:
    (i) HDTC. 10 to 30 minutes between each duty-cycle.
    (ii) LLC. A 15 second key on pause.
    (iii) SET. A 15 second key on pause.
    (4) Repeat testing over the duty cycle until the end-of-test 
criteria in paragraph (f) of this section have been met. You may 
specify other earlier test termination criterion, for example, to 
prevent battery damage. In this case, you may specify a battery 
characteristic such as terminal voltage under load to be the test 
termination criterion.
    (5) Place the powertrain on-charge within 3 hours of completing the 
SCT and charge the battery to full capacity as described in paragraph 
(g) of this section.
    (6) The range for an SCT, R[cycle], is defined as the 
total test distance driven in miles from the beginning of the test 
until the point where the powertrain reaches zero speed after 
satisfying the end-of-test criteria.
0
116. Add Sec.  1037.554 to subpart F read as follows:


Sec.  1037.554  Multicycle powertrain test for fuel cell vehicles.

    This section describes a procedure to measure work produced over 
the heavy-duty transient cycle (HDTC) and fuel cell voltage (FCV) of a 
powertrain that propels a fuel cell vehicle. Work produced over the 
HDTC and FCV are part of demonstrating compliance with criteria 
pollutant standards under Sec.  1037.102 if you choose to generate 
NOX emission credits under this part. This test procedure is 
one option for generating work produced over the HDTC and FCV. You may 
ask to use alternative test methods to demonstrate compliance with the 
standards.
    (a) The following provisions apply broadly for testing under this 
section:
    (1) The procedures of 40 CFR part 1065 apply for testing in this 
section except as specified. This section uses engine parameters and 
variables that are consistent with 40 CFR part 1065.
    (2) For powertrains that propel a fuel cell vehicle, follow the 
procedures of 40 CFR 1036.505, 1036.510, and 1036.512 for testing the 
respective duty-cycles in this section except as specified.
    (3) Use the instruments in Sec.  1037.552(a)(3)(i) and (ii) for 
determination of the required voltages and currents during testing and 
install these on the powertrain to measure these values during testing.
    (4) Stabilize powertrains tested under this section by following 
manufacturer recommendations.

[[Page 17836]]

    (i) For determining the initial mean fuel cell voltage, FCV, test a 
powertrain that has accumulated a minimum of 1000 miles, but no more 
than 6200 miles using a manufacturer defined durability driving 
schedule.
    (ii) For determining aged FCV, test a powertrain that has 
accumulated targeted aged miles.
    (b) Operate the powertrain over the SET, FTP, and LLC as defined in 
40 CFR 1036.505, 1036.510(a)(2), and 1036.512, while measuring FCV and 
fuel cell current (FCC) upstream of any RESS, if present.
    (c) Determine FCV, by taking the mean of the FCV when the FCC is 
between 55% and 65% of rated stack current, using the data collected in 
paragraph (b) of this section. Determine a declared that is at or below 
the corresponding value determined in this paragraph (c). This declared 
serves as the FCV that must be submitted under Sec.  1037.205(q)(2).
    (d) Determine the transient cycle conversion factor, 
CFFCEV, in hp [middot] hr/mile. This represents the average 
work performed over the test interval for use in the credit calculation 
for fuel cell vehicles in Sec.  1037.616.
[GRAPHIC] [TIFF OMITTED] TP28MR22.104

Where:

WHDTC = total (integrated) work generated over the hot-
start HDTC test interval from the FTP test.
D = duty-cycle distance for engine subject to compression-ignition 
standards from the CF determination for the emission credit 
calculation in 40 CFR 1036.705 = 6.5 miles.

Example:

WHDTC = 31.71 hp [middot] hr
D = 6.5 miles
[GRAPHIC] [TIFF OMITTED] TP28MR22.105

0
117. Amend Sec.  1037.555 by revising paragraph (g) to read as follows:


Sec.  1037.555  Special procedures for testing Phase 1 hybrid systems.

* * * * *
    (g) The driver model should be designed to follow the cycle as 
closely as possible and must meet the requirements of Sec.  1037.510 
for steady-state testing and 40 CFR 1066.425 for transient testing. The 
driver model should be designed so that the brake and throttle are not 
applied at the same time.
* * * * *
0
118. Amend Sec.  1037.601 by revising paragraph (a)(1) to read as 
follows:


Sec.  1037.601  General compliance provisions.

    (a) * * *
    (1) Except as specifically allowed by this part or 40 CFR part 
1068, it is a violation of 40 CFR 1068.101(a)(1) to introduce into U.S. 
commerce a tractor or vocational vehicle that is not certified to the 
applicable requirements of this part. Similarly, it is a violation of 
40 CFR 1068.101(a)(1) to introduce into U.S. commerce a tractor or 
vocational vehicle containing an engine that is not certified to the 
applicable requirements of 40 CFR part 86 or 1036. Further, it is a 
violation to introduce into U.S. commerce a Phase 1 tractor containing 
an engine not certified for use in tractors; or to introduce into U.S. 
commerce a vocational vehicle containing a Light HDE or Medium HDE not 
certified for use in vocational vehicles. These prohibitions apply 
especially to the vehicle manufacturer. Note that this paragraph (a)(1) 
allows the use of Heavy heavy-duty tractor engines in vocational 
vehicles.
* * * * *
0
119. Amend Sec.  1037.605 by revising paragraphs (a) introductory text 
and (a)(4) to read as follows:


Sec.  1037.605  Installing engines certified to alternate standards for 
specialty vehicles.

    (a) General provisions. This section allows vehicle manufacturers 
to introduce into U.S. commerce certain new motor vehicles using 
engines certified to alternate emission standards specified in 40 CFR 
1036.605 for motor vehicle engines used in specialty vehicles. You may 
not install an engine certified to these alternate standards if there 
is an engine certified to the full set of requirements of 40 CFR part 
1036 that has the appropriate physical and performance characteristics 
to power the vehicle. Note that, although these alternate emission 
standards are mostly equivalent to standards that apply for nonroad 
engines under 40 CFR part 1039 or 1048, they are specific to motor 
vehicle engines. The provisions of this section apply for the following 
types of specialty vehicles:
* * * * *
    (4) Through model year 2027, vehicles with a hybrid powertrain in 
which the engine provides energy only for the Rechargeable Energy 
Storage System.
* * * * *
0
120. Amend Sec.  1037.615 by revising paragraph (f) to read as follows:


Sec.  1037.615  Advanced technologies.

* * * * *
    (f) For electric vehicles and for fuel cells powered by hydrogen, 
calculate CO2 credits using an FEL of 0 g/ton-mile. Note 
that these vehicles are subject to compression-ignition standards for 
CO2.
* * * * *
0
121. Add Sec.  1037.616 to subpart G to read as follows:


Sec.  1037.616  NOX credits for electric vehicles and fuel cell 
vehicles.

    Starting in model year 2024, electric vehicles and fuel cell 
vehicles may generate NOX credits for certifying heavy-duty 
engines under 40 CFR part 1036 as follows:
    (a) Calculate NOX credits as described in 40 CFR 
1036.705 based on the following values:
    (1) Select a useful life value as specified in Sec.  1037.102(b).
    (2) Select the family emission limit that represents the 
NOX emission standards that the vehicle will meet throughout 
the vehicle's useful life.
    (3) Use the NOX emission standard that applies as 
specified in Sec.  1037.102(b) for engines tested over the FTP duty 
cycle corresponding to the vehicle's model year.
    (4) For ``volume'', use the number of vehicles generating emission 
credits within each averaging set specified in Sec.  1037.740 during 
the model year.
    (5) Determine conversion factors, CF, in hp [middot] hr/mile using 
the procedures specified in Sec. Sec.  1037.552 and 1037.554.
    (b) You may use NOX credits generated under this section 
as specified in 40 CFR 1036.741.
0
122. Amend Sec.  1037.635 by revising paragraph (b)(2) to read as 
follows:


Sec.  1037.635  Glider kits and glider vehicles.

* * * * *
    (b) * * *
    (2) The engine must meet the criteria pollutant standards of 40 CFR 
part 86 or 40 CFR part 1036 that apply for the engine model year 
corresponding to the vehicle's date of manufacture.
* * * * *

[[Page 17837]]

0
123. Amend Sec.  1037.705 by revising paragraph (b) to read as follows:


Sec.  1037.705  Generating and calculating emission credits.

* * * * *
    (b) For each participating family or subfamily, calculate positive 
or negative emission credits relative to the otherwise applicable 
emission standard. Calculate positive emission credits for a family or 
subfamily that has an FEL below the standard. Calculate negative 
emission credits for a family or subfamily that has an FEL above the 
standard. Sum your positive and negative credits for the model year 
before rounding. Round the sum of emission credits to the nearest 
megagram (Mg), using consistent units with the following equation:

Emission credits (Mg) = (Std-FEL) [middot] PL [middot] Volume [middot] 
UL [middot] 10-6

Where:

Std = the emission standard associated with the specific regulatory 
subcategory (g/ton-mile).
FEL = the family emission limit for the vehicle subfamily (g/ton-
mile).
PL = standard payload, in tons.
Volume = U.S.-directed production volume of the vehicle subfamily. 
For example, if you produce three configurations with the same FEL, 
the subfamily production volume would be the sum of the production 
volumes for these three configurations.
UL = useful life of the vehicle, in miles, as described in 
Sec. Sec.  1037.105 and 1037.106. Use 250,000 miles for trailers.
* * * * *
0
124. Amend Sec.  1037.725 by revising the section heading to read as 
follows:


Sec.  1037.725  Required information for certification.

* * * * *
0
125. Amend Sec.  1037.730 by revising paragraphs (a), (b) introductory 
text, (c), and (f) to read as follows:


Sec.  1037.730  ABT reports.

    (a) If you certify any vehicle families using the ABT provisions of 
this subpart, send us a final report by September 30 following the end 
of the model year.
    (b) Your report must include the following information for each 
vehicle family participating in the ABT program:
* * * * *
    (c) Your report must include the following additional information:
    (1) Show that your net balance of emission credits from all your 
participating vehicle families in each averaging set in the applicable 
model year is not negative, except as allowed under Sec.  1037.745. 
Your credit tracking must account for the limitation on credit life 
under Sec.  1037.740(c).
    (2) State whether you will retain any emission credits for banking. 
If you choose to retire emission credits that would otherwise be 
eligible for banking, identify the families that generated the emission 
credits, including the number of emission credits from each family.
    (3) State that the report's contents are accurate.
    (4) Identify the technologies that make up the certified 
configuration associated with each vehicle identification number. You 
may identify this as a range of identification numbers for vehicles 
involving a single, identical certified configuration.
* * * * *
    (f) Correct errors in your report as follows:
    (1) If you or we determine by September 30 after the end of the 
model year that errors mistakenly decreased your balance of emission 
credits, you may correct the errors and recalculate the balance of 
emission credits. You may not make these corrections for errors that 
are determined later than September 30 after the end of the model year. 
If you report a negative balance of emission credits, we may disallow 
corrections under this paragraph (f)(1).
    (2) If you or we determine any time that errors mistakenly 
increased your balance of emission credits, you must correct the errors 
and recalculate the balance of emission credits.
0
126. Amend Sec.  1037.735 by revising paragraph (b) to read as follows:


Sec.  1037.735  Recordkeeping.

* * * * *
    (b) Keep the records required by this section for at least eight 
years after the due date for the final report. You may not use emission 
credits for any vehicles if you do not keep all the records required 
under this section. You must therefore keep these records to continue 
to bank valid credits.
* * * * *
0
127. Amend Sec.  1037.740 by revising paragraph (b) to read as follows:


Sec.  1037.740  Restrictions for using emission credits.

* * * * *
    (b) Credits from hybrid vehicles and other advanced technologies. 
The following provisions apply for credits you generate under Sec.  
1037.615.
    (1) Credits generated from Phase 1 vehicles may be used for any of 
the averaging sets identified in paragraph (a) of this section; you may 
also use those credits to demonstrate compliance with the CO2 emission 
standards in 40 CFR 86.1819 and 40 CFR part 1036. Similarly, you may 
use Phase 1 advanced-technology credits generated under 40 CFR 86.1819-
14(k)(7) or 40 CFR 1036.615 to demonstrate compliance with the CO2 
standards in this part. The maximum amount of advanced-technology 
credits generated from Phase 1 vehicles that you may bring into each of 
the following service class groups is 60,000 Mg per model year:
    (i) Spark-ignition HDE, Light HDE, and Light HDV. This group 
comprises the averaging set listed in paragraph (a)(1) of this section 
and the averaging set listed in 40 CFR 1036.740(a)(1) and (2).
    (ii) Medium HDE and Medium HDV. This group comprises the averaging 
sets listed in paragraph (a)(2) of this section and 40 CFR 
1036.740(a)(3).
    (iii) Heavy HDE and Heavy HDV. This group comprises the averaging 
sets listed in paragraph (a)(3) of this section and 40 CFR 
1036.740(a)(4).
    (iv) This paragraph (b)(1) does not limit the advanced-technology 
credits that can be used within a service class group if they were 
generated in that same service class group.
    (2) Credits generated from Phase 2 vehicles are subject to all the 
averaging-set restrictions that apply to other emission credits.
* * * * *
0
128. Amend Sec.  1037.801 by:
0
a. Adding definitions for ``Charge-depleting'', and ``Charge-
sustaining'' in alphabetical order.
0
b. Revising the definitions of ``Designated Compliance Officer''.
0
c. Adding a definition for ``Emission-related component'' in 
alphabetical order.
0
d. Revising the definitions for ``Low rolling resistance tire'', 
``Neutral coasting'', ``Rechargeable Energy Storage System (RESS)'', 
and ``Tire rolling resistance level (TRRL)''.
    The additions and revisions read as follows:


Sec.  1037.801  Definitions.

* * * * *
    Charge-depleting has the meaning given in 40 CFR 1066.1001.
    Charge-sustaining has the meaning given in 40 CFR 1066.1001.
* * * * *
    Designated Compliance Officer means one of the following:
    (1) For compression-ignition engines, Designated Compliance Officer 
means Director, Diesel Engine Compliance Center, U.S. Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
[email protected]; www.epa.gov/ve-certification.

[[Page 17838]]

    (2) For spark-ignition engines, Designated Compliance Officer means 
Director, Gasoline Engine Compliance Center, U.S. Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
[email protected]; www.epa.gov/ve-certification.
* * * * *
    Emission-related component has the meaning given in 40 CFR part 
1068, appendix A.
* * * * *
    Low rolling resistance tire means a tire on a vocational vehicle 
with a TRRL at or below of 7.7 N/kN, a steer tire on a tractor with a 
TRRL at or below 7.7 N/kN, a drive tire on a tractor with a TRRL at or 
below 8.1 N/kN, a tire on a non-box trailer with a TRRL at or below of 
6.5 N/kN, or a tire on a box van with a TRRL at or below of 6.0 N/kN.
* * * * *
    Neutral coasting means a vehicle technology that automatically puts 
the transmission in neutral when the vehicle has minimal power demand 
while in motion, such as driving downhill.
* * * * *
    Rechargeable Energy Storage System (RESS) has the meaning given in 
40 CFR 1065.1001.
* * * * *
    Tire rolling resistance level (TRRL) means a value with units of N/
kN that represents the rolling resistance of a tire configuration. 
TRRLs are used as modeling inputs under Sec. Sec.  1037.515 and 
1037.520. Note that a manufacturer may use the measured value for a 
tire configuration's coefficient of rolling resistance, or assign some 
higher value.
* * * * *
0
129. Amend Sec.  1037.805 by revising paragraphs (a), (b), (d), (e), 
and (g) to read as follows:


Sec.  1037.805  Symbols, abbreviations, and acronyms.

* * * * *
    (a) Symbols for chemical species. This part uses the following 
symbols for chemical species and exhaust constituents:

    Table 1 to Paragraph (a) of Sec.   1037.805--Symbols for Chemical
                    Species and Exhaust Constituents
------------------------------------------------------------------------
                  Symbol                               Species
------------------------------------------------------------------------
C.........................................  carbon.
CH4.......................................  methane.
CO........................................  carbon monoxide.
CO2.......................................  carbon dioxide.
H2O.......................................  water.
HC........................................  hydrocarbon.
NMHC......................................  nonmethane hydrocarbon.
NMHCE.....................................  nonmethane hydrocarbon
                                             equivalent.
NO........................................  nitric oxide.
NO2.......................................  nitrogen dioxide.
NOX.......................................  oxides of nitrogen.
N2O.......................................  nitrous oxide.
PM........................................  particulate matter.
THC.......................................  total hydrocarbon.
THCE......................................  total hydrocarbon
                                             equivalent.
------------------------------------------------------------------------

    (b) Symbols for quantities. This part 1037 uses the following 
symbols and units of measure for various quantities:

                       Table 2 to Paragraph (b) of Sec.   1037.805--Symbols for Quantities
----------------------------------------------------------------------------------------------------------------
                                                                                        Unit in terms of SI base
      Symbol             Quantity             Unit                 Unit symbol                    units
----------------------------------------------------------------------------------------------------------------
A.................  vehicle            pound force or     lbf or N....................  kg[middot]m[middot]s-2.
                     frictional load.   newton.
a.................  axle position
                     regression
                     coefficient.
[alpha]...........  atomic hydrogen-   mole per mole....  mol/mol.....................  1.
                     to-carbon ratio.
[alpha]...........  axle position
                     regression
                     coefficient.
[alpha]0..........  intercept of air
                     speed correction.
[alpha]1..........  slope of air
                     speed correction.
ag................  acceleration of    meters per second  m/s2........................  m[middot]s-2.
                     Earth's gravity.   squared.
a0................  intercept of
                     least squares
                     regression.
a1................  slope of least
                     squares
                     regression.
B.................  vehicle load from  pound force per    lbf/(mi/hr) or N[middot]s/m.  kg[middot]s-1.
                     drag and rolling   mile per hour or
                     resistance.        newton second
                                        per meter.
b.................  axle position
                     regression
                     coefficient.
[beta]............  atomic oxygen-to-  mole per mole....  mol/mol.....................  1.
                     carbon ratio.
[beta]............  axle position
                     regression
                     coefficient.
[beta]0...........  intercept of air
                     direction
                     correction.
[beta]1...........  slope of air
                     direction
                     correction.
Beff..............  estimated battery
                     efficiency.
C.................  vehicle-specific   pound force per    lbf/mph2 or N[middot]s2/m2..  kg[middot]m-1.
                     aerodynamic        mile per hour
                     effects.           squared or
                                        newton-second
                                        squared per
                                        meter squared.
C.................  current of one     ampere per hour..  kA[middot]hr................  3.6 kA[middot]s.
                     ampere flowing
                     for one hour.
c.................  axle position
                     regression
                     coefficient.
ci................  axle test
                     regression
                     coefficients.
Ci................  constant.........
[Delta]CdA........  differential drag  meter squared....  m2..........................  m2.
                     area.
CdA...............  drag area........  meter squared....  m2..........................  m2.
Cd................  drag coefficient.
CF................  correction factor
CF................  conversion factor
CR................  charge recovery..
Crr...............  coefficient of     newton per         N/kN........................  10-3.
                     rolling            kilonewton.
                     resistance.
D.................  distance.........  miles or meters..  mi or m.....................  m.
E.................  energy...........  kilowatt-hour....  kW[middot]hr................  3.6[middot]m2[middot]kg[
                                                                                         middot]s-1.
e.................  mass-weighted      grams per ton-     g/ton-mi....................  g/kg-km.
                     emission result.   mile.
EC................  energy             kilowatt-hour per  kW[middot]hr/mi.............  3.6[middot]m2[middot]kg[
                     consumption.       mile.                                            middot]s-1[middot]mi-1.
Eff...............  efficiency.......
F.................  adjustment factor

[[Page 17839]]

 
F.................  force............  pound force or     lbf or N....................  kg[middot]m[middot]s-2.
                                        newton.
fn................  angular speed      revolutions per    r/min.......................  [pi][middot]30[middot]s-
                     (shaft).           minute.                                          1.
G.................  road grade.......  percent..........  %...........................  10-2.
g.................  gravitational      meters per second  m/s2........................  m[middot]s-2.
                     acceleration.      squared.
h.................  elevation or       meters...........  m...........................  m.
                     height.
I.................  current..........  amphere..........  A...........................  A.
i.................  indexing variable
ka................  drive axle ratio.  .................  ............................  1.
kd................  transmission gear
                     ratio.
ktopgear..........  highest available
                     transmission
                     gear.
L.................  load over axle...  pound force or     lbf or N....................  kg[middot]m[middot]s-2.
                                        newton.
m.................  mass.............  pound mass or      lbm or kg...................  kg.
                                        kilogram.
M.................  molar mass.......  gram per mole....  g/mol.......................  10-3[middot]kg[middot]mo
                                                                                         l-1.
M.................  total number in
                     series.
M.................  vehicle mass.....  kilogram.........  kg..........................  kg.
Me................  vehicle effective  kilogram.........  kg..........................  kg.
                     mass.
Mrotating.........  inertial mass of   kilogram.........  kg..........................  kg.
                     rotating
                     components.
N.................  total number in
                     series.
n.................  number of tires..
n.................  amount of          mole per second..  mol/s.......................  mol[middot]s-1.
                     substance rate.
Q.................  total number in
                     series.
P.................  power............  kilowatt.........  kW..........................  103[middot]m2[middot]kg[
                                                                                         middot]s-3.
p.................  pressure.........  pascal...........  Pa..........................  kg[middot]m-1[middot]s-
                                                                                         2.
[rho].............  mass density.....  kilogram per       kg/m3.......................  kg[middot]m-3.
                                        cubic meter.
PL................  payload..........  tons.............  ton.........................  kg.
[phis]............  direction........  degrees..........  [deg].......................  [deg].
[Psi].............  direction........  degrees..........  [deg].......................  [deg].
R.................  range............  miles or meters..  mi or m.....................  m.
r.................  tire radius......  meter............  m...........................  m.
r2................  coefficient of
                     determination.
Re...............  Reynolds number..
SEE...............  standard error of
                     the estimate.
[sigma]...........  standard
                     deviation.
TRPM..............  tire revolutions   revolutions per    r/mi........................
                     per mile.          mile.
TRRL..............  tire rolling       newton per         N/kN........................  10-3.
                     resistance level.  kilonewton.
T.................  absolute           kelvin...........  K...........................  K.
                     temperature.
T.................  Celsius            degree Celsius...  [deg]C......................  K-273.15.
                     temperature.
T.................  torque (moment of  newton meter.....  N[middot]m..................  m2[middot]kg[middot]s-2.
                     force).
t.................  time.............  hour or second...  hr or s.....................  s.
[Delta]t..........  time interval,     second...........  s...........................  s.
                     period, 1/
                     frequency.
UBE...............  useable battery    watt-hour........  W[middot]hr.................  3600[middot]m2[middot]kg
                     energy.                                                             [middot]s-1.
UF................  utility factor...
V.................  voltage..........  volts............  V...........................  kg[middot]m2[middot]s-
                                                                                         3[middot]A-1.
v.................  speed............  miles per hour or  mi/hr or m/s................  m[middot]s-1.
                                        meters per
                                        second.
w.................  weighting factor.
w.................  wind speed.......  miles per hour...  mi/hr.......................  m[middot]s-1.
W.................  work.............  kilowatt-hour....  kW[middot]hr................  3.6[middot]m2[middot]kg[
                                                                                         middot]s-1.
wC................  carbon mass        Gram per gram....  g/g.........................  1.
                     fraction.
WR................  weight reduction.  pound mass.......  lbm.........................  kg.
x.................  amount of          mole per mole....  mol/mol.....................  1.
                     substance mole
                     fraction.
----------------------------------------------------------------------------------------------------------------

* * * * *
    (d) Subscripts. This part uses the following subscripts for 
modifying quantity symbols:

                             Table 4 to Paragraph (d) of Sec.   1037.805--Subscripts
----------------------------------------------------------------------------------------------------------------
            Subscript                                                 Meaning
----------------------------------------------------------------------------------------------------------------
6....................  6[deg] yaw angle sweep.
A................................  A speed.
AC...............................  alternating current.
ACRC.............................  alternating current recharge.
air..............................  air.
aero.............................  aerodynamic.
alt..............................  alternative.
act..............................  actual or measured condition.
air..............................  air.

[[Page 17840]]

 
axle.............................  axle.
B................................  B speed.
BEV..............................  battery electric vehicle.
brake............................  brake.
C................................  C speed.
Ccombdry.........................  carbon from fuel per mole of dry exhaust.
CD...............................  charge-depleting.
circuit..........................  circuit.
CO2DEF...........................  CO2 resulting from diesel exhaust fluid decomposition.
CO2PTO...........................  CO2 emissions for PTO cycle.
coastdown........................  coastdown.
comp.............................  composite.
CS...............................  charge-sustaining.
CSC..............................  constant-speed cycle.
CSCM.............................  constant-speed cycle midpoint.
cycle............................  test cycle.
D................................  distance.
DC...............................  direct current.
DCD..............................  direct current discharge.
DCRC.............................  direct current recharge.
drive............................  drive axle.
drive-idle.......................  idle with the transmission in drive.
driver...........................  driver.
dyno.............................  dynamometer.
E................................  end-of-test.
effective........................  effective.
end..............................  end.
eng..............................  engine.
factor...........................  factor.
FCEV.............................  fuel cell electric vehicle.
est..............................  estimate.
event............................  event.
FTP..............................  Federal Test Procedure.
fuel.............................  fuel.
full.............................  full.
grade............................  grade.
H2Oexhaustdry....................  H2O in exhaust per mole of exhaust.
HDTC.............................  Heavy-Duty Transient Cycle.
hi...............................  high.
i................................  an individual of a series.
idle.............................  idle.
in...............................  inlet.
inc..............................  increment.
j................................  an individual of a series.
k................................  an individual of a series.
LLC..............................  Low Load Cycle.
lo...............................  low.
loss.............................  loss.
M................................  midpoint.
max..............................  maximum.
meas.............................  measured quantity.
med..............................  median.
min..............................  minimum.
moving...........................  moving.
out..............................  outlet.
P................................  power.
pair.............................  pair of speed segments.
parked-idle......................  idle with the transmission in park.
partial..........................  partial.
ploss............................  power loss.
plug-in..........................  plug-in hybrid electric vehicle.
powertrain.......................  powertrain.
PTO..............................  power take-off.
R................................  range.
rated............................  rated speed.
RC...............................  recharge.
record...........................  record.
ref..............................  reference quantity.
RL...............................  road load.
rotating.........................  rotating.
seg..............................  segment.
SET..............................  Supplemental Emission Test.

[[Page 17841]]

 
speed............................  speed.
spin.............................  axle spin loss.
start............................  start.
steer............................  steer axle.
t................................  tire.
test.............................  test.
th...............................  theoretical.
total............................  total.
trac.............................  traction.
trac10...........................  traction force at 10 mi/hr.
trailer..........................  trailer axle.
transient........................  transient.
TRR..............................  tire rolling resistance.
UF...............................  utility factor.
urea.............................  urea.
veh..............................  vehicle.
w................................  wind.
wa...............................  wind average.
yaw..............................  yaw angle.
ys...............................  yaw sweep.
zero.............................  zero quantity.
----------------------------------------------------------------------------------------------------------------

    (e) Other acronyms and abbreviations. This part uses the following 
additional abbreviations and acronyms:

                  Table 5 to Paragraph (e) of Sec.   1037.805--Other Acronyms and Abbreviations
----------------------------------------------------------------------------------------------------------------
             Acronym                                                  Meaning
----------------------------------------------------------------------------------------------------------------
ABT..............................  averaging, banking, and trading.
AC...............................  alternating current.
AECD.............................  auxiliary emission control device.
AES..............................  automatic engine shutdown.
APU..............................  auxiliary power unit.
CD...............................  charge-depleting.
CFD..............................  computational fluid dynamics.
CFR..............................  Code of Federal Regulations.
CITT.............................  curb idle transmission torque.
CS...............................  charge-sustaining.
CSC..............................  constant-speed cycle.
DC...............................  direct current.
DOT..............................  Department of Transportation.
ECM..............................  electronic control module.
EPA..............................  Environmental Protection Agency.
FCC..............................  fuel cell current.
FCV..............................  fuel cell voltage.
FE...............................  fuel economy.
FEL..............................  Family Emission Limit.
FTP..............................  Federal Test Procedure.
GAWR.............................  gross axle weight rating.
GCWR.............................  gross combination weight rating.
GEM..............................  greenhouse gas emission model.
GVWR.............................  gross vehicle weight rating.
HDTC.............................  Heavy-Duty Transient Cycle.
Heavy HDE........................  heavy heavy-duty engine (see 40 CFR 1036.140).
Heavy HDV........................  heavy heavy-duty vehicle (see Sec.   1037.140).
HVAC.............................  heating, ventilating, and air conditioning.
ISO..............................  International Organization for Standardization.
Light HDE........................  light heavy-duty engine (see 40 CFR 1036.140).
Light HDV........................  light heavy-duty vehicle (see Sec.   1037.140).
LLC..............................  Low Load Cycle.
MCT..............................  Multicycle Test.
Medium HDE.......................  medium heavy-duty engine (see 40 CFR 1036.140).
Medium HDV.......................  medium heavy-duty vehicle (see Sec.   1037.140).
NARA.............................  National Archives and Records Administration.
NHTSA............................  National Highway Transportation Safety Administration.
PHEV.............................  plug-in hybrid electric vehicle.
PTO..............................  power take-off.
RESS.............................  rechargeable energy storage system.

[[Page 17842]]

 
SAE..............................  SAE International.
SCT..............................  single cycle test.
SEE..............................  standard error of the estimate.
SET..............................  Supplemental Emission Test.
SKU..............................  stock-keeping unit.
Spark-ignition HDE...............  spark-ignition heavy-duty engine (see 40 CFR 1036.140).
TRPM.............................  tire revolutions per mile.
TRRL.............................  tire rolling resistance level.
UBE..............................  useable battery energy.
U.S.C............................  United States Code.
VSL..............................  vehicle speed limiter.
----------------------------------------------------------------------------------------------------------------

* * * * *
    (g) Prefixes. This part uses the following prefixes to define a 
quantity:

          Table 7 to Paragraph (g) of Sec.   1037.805--Prefixes
------------------------------------------------------------------------
             Symbol                    Quantity              Value
------------------------------------------------------------------------
[micro].........................  micro.............  10-6
m...............................  milli.............  10-3
c...............................  centi.............  10-2
k...............................  kilo..............  103
M...............................  mega..............  106
------------------------------------------------------------------------

0
130. Amend Sec.  1037.810 by revising paragraphs (a) and (e) and adding 
paragraph (f) to read as follows:


Sec.  1037.810  Incorporation by reference.

    (a) Certain material is incorporated by reference into this part 
with the approval of the Director of the Federal Register in accordance 
with 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other 
than that specified in this section, the Environmental Protection 
Agency (EPA) must publish a document in the Federal Register and the 
material must be available to the public. All approved material is 
available for inspection at the EPA and at the National Archives and 
Records Administration (NARA). Contact EPA at: U.S. EPA, Air and 
Radiation Docket and Information Center, 1301 Constitution Ave. NW, 
Room B102, EPA West Building, Washington, DC 20460, www.epa.gov/dockets, (202) 202-1744. For information on the availability of this 
material at NARA, email: [email protected], or go to: 
www.archives.gov/federal-register/cfr/ibr-locations.html. The material 
may be obtained from the sources in the following paragraphs of this 
section.
* * * * *
    (e) SAE International, 400 Commonwealth Dr., Warrendale, PA 15096-
0001, (877) 606-7323 (U.S. and Canada) or (724) 776-4970 (outside the 
U.S. and Canada), www.sae.org.
    (1) SAE J1025, Test Procedures for Measuring Truck Tire Revolutions 
Per Kilometer/Mile, Stabilized August 2012, (``SAE J1025''); IBR 
approved for Sec.  1037.520(c).
    (2) SAE J1252, SAE Wind Tunnel Test Procedure for Trucks and Buses, 
Revised July 2012, (``SAE J1252''); IBR approved for Sec. Sec.  
1037.525(b); 1037.530(a).
    (3) SAE J1263, Road Load Measurement and Dynamometer Simulation 
Using Coastdown Techniques, revised March 2010, (``SAE J1263''); IBR 
approved for Sec. Sec.  1037.528 introductory text, (a), (b), (c), (e), 
and (h); 1037.665(a).
    (4) SAE J1594, Vehicle Aerodynamics Terminology, Revised July 2010, 
(``SAE J1594''); IBR approved for Sec.  1037.530(d).
    (5) SAE J2071, Aerodynamic Testing of Road Vehicles--Open Throat 
Wind Tunnel Adjustment, Revised June 1994, (``SAE J2071''); IBR 
approved for Sec.  1037.530(b).
    (6) SAE J2263, Road Load Measurement Using Onboard Anemometry and 
Coastdown Techniques, Revised May 2020, (``SAE J2263''); IBR approved 
for Sec. Sec.  1037.528 introductory text, (a), (b), (d), and (f); 
1037.665(a).
    (7) SAE J2343, Recommended Practice for LNG Medium and Heavy-Duty 
Powered Vehicles, Revised July 2008, (``SAE J2343''); IBR approved for 
Sec.  1037.103(e).
    (8) SAE J2452, Stepwise Coastdown Methodology for Measuring Tire 
Rolling Resistance, Revised June 1999, (``SAE J2452''); IBR approved 
for Sec.  1037.528(h).
    (9) SAE J2841, Utility Factor Definitions for Plug-In Hybrid 
Electric Vehicles Using 2001 U.S. DOT National Household Travel Survey 
Data, Issued March 2009, (``SAE J2841''); IBR approved for Sec.  
1037.550(a).
    (10) SAE J2966, Guidelines for Aerodynamic Assessment of Medium and 
Heavy Commercial Ground Vehicles Using Computational Fluid Dynamics, 
Issued September 2013, (``SAE J2966''); IBR approved for Sec.  
1037.532(a).
    (f) Idaho National Laboratory, 2525 Fremont Ave., Idaho Falls, ID 
83415-3805, (866) 495-7440, or www.inl.gov.
    (1) U.S. Advanced Battery Consortium, Electric Vehicle Battery Test 
Procedures Manual, Revision 2, January 1996; IBR approved for Sec.  
1037.552(a).
    (2) [Reserved]
0
131. Revise Sec.  1037.815 to read as follows:


Sec.  1037.815  Confidential information.

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.

Appendix I to Part 1037--[Redesignated as Appendix A to Part 1037]

Appendix II to Part 1037--[Redesignated as Appendix B to Part 1037]

Appendix III to Part 1037--[Redesignated as Appendix C to Part 1037]

Appendix IV to Part 1037--[Redesignated as Appendix D to Part 1037]

Appendix V to Part 1037--[Redesignated as Appendix E to Part 1037]

0
132. Redesignate appendices to part 1037 as follows:

------------------------------------------------------------------------
            Old appendix                         New appendix
------------------------------------------------------------------------
appendix I to part 1037              appendix A to part 1037
appendix II to part 1037             appendix B to part 1037
appendix III to part 1037            appendix C to part 1037
appendix IV to part 1037             appendix D to part 1037
appendix V to part 1037              appendix E to part 1037
------------------------------------------------------------------------

PART 1039--CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD 
COMPRESSION-IGNITION ENGINES

0
133. The authority citation for part 1039 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.


[[Page 17843]]


0
134. Amend Sec.  1039.105 by revising the section heading and 
paragraphs (a) introductory text and (b) introductory text to read as 
follows:


Sec.  1039.105  What smoke opacity standards must my engines meet?

    (a) The smoke opacity standards in this section apply to all 
engines subject to emission standards under this part, except for the 
following engines:
* * * * *
    (b) Measure smoke opacity as specified in Sec.  1039.501(c). Smoke 
opacity from your engines may not exceed the following standards:
* * * * *
0
135. Amend Sec.  1039.115 by revising paragraphs (e) and (f) to read as 
follows:


Sec.  1039.115  What other requirements apply?

* * * * *
    (e) Adjustable parameters. Engines that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. We may require that you set adjustable 
parameters to any specification within the adjustable range during any 
testing, including certification testing, selective enforcement 
auditing, or in-use testing. General provisions for adjustable 
parameters apply as specified in 40 CFR 1068.50.
    (f) Prohibited controls. (1) General provisions. You may not design 
your engines with emission control devices, systems, or elements of 
design that cause or contribute to an unreasonable risk to public 
health, welfare, or safety while operating. For example, an engine may 
not emit a noxious or toxic substance it would otherwise not emit that 
contributes to such an unreasonable risk.
    (2) Vanadium sublimation in SCR catalysts. For engines equipped 
with vanadium-based SCR catalysts, you must design the engine and its 
emission controls to prevent vanadium sublimation and protect the 
catalyst from high temperatures. We will evaluate your engine design 
based on the following information that you must include in your 
application for certification:
    (i) Identify the threshold temperature for vanadium sublimation for 
your specified SCR catalyst formulation as described in 40 CFR 
1065.1113 through 1065.1121.
    (ii) Describe how you designed your engine to prevent catalyst 
inlet temperatures from exceeding the temperature you identify in 
paragraph (f)(2)(i) of this section, including consideration of engine 
wear through the useful life. Also describe your design for catalyst 
protection in case catalyst temperatures exceed the specified 
temperature. In your description, include how you considered elevated 
catalyst temperature resulting from sustained high-load engine 
operation, catalyst exotherms, DPF regeneration, and component failure 
resulting in unburned fuel in the exhaust stream.
* * * * *
0
136. Amend Sec.  1039.205 by revising paragraph (s) to read as follows:


Sec.  1039.205  What must I include in my application?

* * * * *
    (s) Describe all adjustable operating parameters (see Sec.  
1039.115(e)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to limit adjustable ranges, and production 
tolerances of the limits or stops used to establish each physically 
adjustable range. Also include information showing why the limits, 
stops, or other means of inhibiting adjustment are effective in 
preventing adjustment of parameters on in-use engines to settings 
outside your intended physically adjustable ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
137. Amend Sec.  1039.245 by adding paragraph (e) to read as follows:


Sec.  1039.245  How do I determine deterioration factors from exhaust 
durability testing?

* * * * *
    (e) You may alternatively determine and verify deterioration 
factors based on bench-aged aftertreatment as described in 40 CFR 
1036.245 and 1036.246, with the following exceptions:
    (1) Apply the percentage of useful life from Table 1 of 40 CFR 
1036.246 based on hours of operation rather than vehicle mileage.
    (2) Use good engineering judgment to perform verification testing 
using the procedures of Sec.  1039.515 rather than 40 CFR 1036.520. 
Measure emissions as the equipment goes through its normal operation 
over the course of the day (or shift-day).
    (3) Apply infrequent regeneration adjustment factors as specified 
in Sec.  1039.525 rather than 40 CFR 1036.522.
0
138. Amend Sec.  1039.501 by revising paragraph (c) to read as follows:


Sec.  1039.501  How do I run a valid emission test?

* * * * *
    (c) Measure smoke opacity using the procedures in 40 CFR part 1065, 
subpart L, for evaluating whether engines meet the smoke opacity 
standards in Sec.  1039.105, except that you may test two-cylinder 
engines with an exhaust muffler like those installed on in-use engines.
* * * * *
0
139. Revise Sec.  1039.655 to read as follows:


Sec.  1039.655  What special provisions apply to engines sold in 
American Samoa or the Commonwealth of the Northern Mariana Islands?

    (a) The prohibitions in 40 CFR 1068.101(a)(1) do not apply to 
engines at or above 56 kW if the following conditions are met:
    (1) The engine is intended for use and will be used in American 
Samoa or the Commonwealth of the Northern Mariana Islands.
    (2) The engine meets the latest applicable emission standards in 
appendix I of this part.
    (3) You meet all the requirements of 40 CFR 1068.265.
    (b) If you introduce an engine into commerce in the United States 
under this section, you must meet the labeling requirements in Sec.  
1039.135, but add the following statement instead of the compliance 
statement in Sec.  1039.135(c)(12):

    THIS ENGINE DOES NOT COMPLY WITH U.S. EPA TIER 4 EMISSION 
REQUIREMENTS. IMPORTING THIS ENGINE INTO THE UNITED STATES OR ANY 
TERRITORY OF THE UNITED STATES EXCEPT AMERICAN SAMOA OR THE 
COMMONWEALTH OF THE NORTHERN MARIANA ISLANDS MAY BE A VIOLATION OF 
FEDERAL LAW SUBJECT TO CIVIL PENALTY.

    (c) Introducing into commerce an engine exempted under this section 
in any state or territory of the United States other than American 
Samoa or the Commonwealth of the Northern Mariana Islands, throughout 
its lifetime, violates the prohibitions in 40 CFR 1068.101(a)(1), 
unless it is exempt under a different provision.
    (d) The exemption provisions in this section also applied for 
engines that were introduced into commerce in

[[Page 17844]]

Guam before [the effective date of the final rule] if they would 
otherwise have been subject to Tier 4 standards.
0
140. Amend Sec.  1039.801 by revising the definitions of ``Critical 
emission-related component'' and ``Designated Compliance Officer'' to 
read as follows:


Sec.  1039.801  What definitions apply to this part?

* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
    Designated Compliance Officer means the Director, Diesel Engine 
Compliance Center, U.S. Environmental Protection Agency, 2000 
Traverwood Drive, Ann Arbor, MI 48105; [email protected]; 
www.epa.gov/ve-certification.
* * * * *

PART 1042--CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE 
COMPRESSION-IGNITION ENGINES AND VESSELS

0
141. The authority citation for part 1042 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
142. Amend Sec.  1042.110 by revising paragraph (a)(1) to read as 
follows:


Sec.  1042.110  Recording reductant use and other diagnostic functions.

    (a) * * *
    (1) The diagnostic system must monitor reductant supply and alert 
operators to the need to restore the reductant supply, or to replace 
the reductant if it does not meet your concentration specifications. 
Unless we approve other alerts, use a warning lamp and an audible 
alarm. You do not need to separately monitor reductant quality if your 
system uses input from an exhaust NOX sensor (or other 
sensor) to alert operators when reductant quality is inadequate. 
However, tank level or DEF flow must be monitored in all cases.
* * * * *
0
143. Amend Sec.  1042.115 by revising paragraphs (d) introductory text 
and (e) to read as follows:


Sec.  1042.115  Other requirements.

* * * * *
    (d) Adjustable parameters. General provisions for adjustable 
parameters apply as specified in 40 CFR 1068.50. The following 
additional category-specific provisions apply:
* * * * *
    (e) Prohibited controls. (1) General provisions. You may not design 
your engines with emission control devices, systems, or elements of 
design that cause or contribute to an unreasonable risk to public 
health, welfare, or safety while operating. For example, an engine may 
not emit a noxious or toxic substance it would otherwise not emit that 
contributes to such an unreasonable risk.
    (2) Vanadium sublimation in SCR catalysts. For engines equipped 
with vanadium-based SCR catalysts, you must design the engine and its 
emission controls to prevent vanadium sublimation and protect the 
catalyst from high temperatures. We will evaluate your engine design 
based on the following information that you must include in your 
application for certification:
    (i) Identify the threshold temperature for vanadium sublimation for 
your specified SCR catalyst formulation as described in 40 CFR 
1065.1113 through 1065.1121.
    (ii) Describe how you designed your engine to prevent catalyst 
inlet temperatures from exceeding the temperature you identify in 
paragraph (e)(2)(i) of this section, including consideration of engine 
wear through the useful life. Also describe your design for catalyst 
protection in case catalyst temperatures exceed the specified 
temperature. In your description, include how you considered elevated 
catalyst temperature resulting from sustained high-load engine 
operation, catalyst exotherms, DPF regeneration, and component failure 
resulting in unburned fuel in the exhaust stream.
* * * * *
0
144. Amend Sec.  1042.145 by adding paragraph (h) to read as follows:


Sec.  1042.145  Interim provisions.

* * * * *
    (h) Expanded production-line testing. Production-line testing 
requirements for Category 1 engine families with a projected U.S.-
directed production volume below 100 engines and for all families 
certified by small-volume engine manufacturers start to apply in model 
year 2024. All manufacturers must test no more than four engine 
families in a single model year, and small-volume engine manufacturers 
must test no more than two engine families in a single model year.
* * * * *
0
145. Amend Sec.  1042.205 by revising paragraphs (c) and (s) to read as 
follows:


Sec.  1042.205  Application requirements.

* * * * *
    (c) If your engines are equipped with an engine diagnostic system 
as required under Sec.  1042.110, explain how it works, describing 
especially the engine conditions (with the corresponding diagnostic 
trouble codes) that cause the warning lamp to go on. Also identify the 
communication protocol (SAE J1939, SAE J1979, etc.).
* * * * *
    (s) Describe all adjustable operating parameters (see Sec.  
1042.115(d)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges.
    (i) For Category 1 engines, include information showing why the 
limits, stops, or other means of inhibiting mechanical adjustment are 
effective in preventing adjustment of parameters on in-use engines to 
settings outside your intended physically adjustable ranges.
    (ii) For Category 2 and Category 3 engines, propose a range of 
mechanical adjustment for each adjustable parameter, as described in 
Sec.  1042.115(d). Include information showing why the limits, stops, 
or other means of inhibiting mechanical adjustment are effective in 
preventing adjustment of parameters on in-use engines to settings 
outside your proposed adjustable ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
146. Amend Sec.  1042.245 by adding paragraph (e) to read as follows:


Sec.  1042.245  Deterioration factors.

* * * * *
    (e) You may alternatively determine and verify deterioration 
factors based on bench-aged aftertreatment as described in 40 CFR 
1036.245 and 1036.246, with the following exceptions:
    (1) Apply the percentage of useful life from Table 1 of 40 CFR 
1036.246 based on hours of operation rather than vehicle mileage.
    (2) Use good engineering judgment to perform verification testing 
using the procedures of Sec.  1042.515 rather than 40 CFR 1036.520. 
Measure emissions as the vessel goes through its normal operation over 
the course of the day (or shift-day).
    (3) Apply infrequent regeneration adjustment factors as specified 
in Sec.  1042.525 rather than 40 CFR 1036.522.

[[Page 17845]]

0
147. Revise Sec.  1042.301 to read as follows:


Sec.  1042.301  General provisions.

    (a) If you produce freshly manufactured marine engines that are 
subject to the requirements of this part, you must test them as 
described in this subpart.
    (b) We may suspend or revoke your certificate of conformity for 
certain engine families if your production-line engines do not meet the 
requirements of this part or you do not fulfill your obligations under 
this subpart (see Sec. Sec.  1042.325 and 1042.340). Similarly, we may 
deny applications for certification for the upcoming model year if you 
do not fulfill your obligations under this subpart (see Sec.  
1042.255(c)(1)).
    (c) Other regulatory provisions authorize us to suspend, revoke, or 
void your certificate of conformity, or order recalls for engine 
families, without regard to whether they have passed production-line 
testing requirements. The requirements of this subpart do not affect 
our ability to do selective enforcement audits, as described in 40 CFR 
part 1068. Individual engines in families that pass production-line 
testing requirements must also conform to all applicable regulations of 
this part and 40 CFR part 1068.
    (d) You may ask to use another alternate program or measurement 
method for testing production-line engines. In your request, you must 
show us that the alternate program gives equal assurance that your 
engines meet the requirements of this part. We may waive some or all of 
this subpart's requirements if we approve your alternate program.
    (e) If you certify a Category 1 or Category 2 engine family with 
carryover emission data, as described in Sec.  1042.235(d), you may 
omit production-line testing if you fulfilled your testing requirements 
with a related engine family in an earlier year, except as follows:
    (1) We may require that you perform additional production-line 
testing under this subpart in any model year for cause, such as if you 
file a defect report related to the engine family or if you amend your 
application for certification in any of the following ways:
    (i) You designate a different supplier or change technical 
specifications for any critical emission-related components.
    (ii) You add a new or modified engine configuration such that the 
test data from the original emission-data engine do not clearly 
continue to serve as worst-case testing for certification.
    (iii) You change your family emission limit without submitting new 
emission data.
    (2) If you certify an engine family with carryover emission data 
with no production-line testing for more than five model years, we may 
require that you perform production-line testing again for one of those 
later model years unless you demonstrate that none of the circumstances 
identified in paragraph (e)(1) of this section apply for the engine 
family.
    (f) We may ask you to make a reasonable number of production-line 
engines available for a reasonable time so we can test or inspect them 
for compliance with the requirements of this part. For Category 3 
engines, you are not required to deliver engines to us, but we may 
inspect and test your engines at any facility at which they are 
assembled or installed in vessels.
0
148. Amend Sec.  1042.302 by revising the introductory text to read as 
follows:


Sec.  1042.302  Applicability of this subpart for Category 3 engines.

    If you produce Tier 3 or later Category 3 engines that are subject 
to the requirements of this part, you must test them as described in 
this subpart, except as specified in this section.
* * * * *
0
149. Amend Sec.  1042.305 by revising paragraph (a) to read as follows:


Sec.  1042.305  Preparing and testing production-line engines.

* * * * *
    (a) Test procedures. Test your production-line engines using the 
applicable testing procedures in subpart F of this part to show you 
meet the duty-cycle emission standards in subpart B of this part. For 
Category 1 and Category 2 engines, the not-to-exceed standards apply 
for this testing of Category 1 and Category 2 engines, but you need not 
do additional testing to show that production-line engines meet the 
not-to-exceed standards. The mode cap standards apply for testing 
Category 3 engines subject to Tier 3 standards (or for engines subject 
to the Annex VI Tier III NOX standards under Sec.  
1042.650(d)).
* * * * *
0
150. Revise Sec.  1042.310 to read as follows:


Sec.  1042.310  Engine selection for Category 1 and Category 2 engines.

    (a) For Category 1 and Category 2 engine families, the minimum 
sample size is one engine. You may ask us to approve treating 
commercial and recreational engines as being from the same engine 
family for purposes of production-line testing if you certify them 
using the same emission-data engine.
    (b) Select engines for testing as follows:
    (1) For Category 1 engines, randomly select one engine within the 
first 60 days of the start of production for each engine family.
    (2) For Category 2 engines, randomly select one engine within 60 
days after you produce the fifth engine from an engine family (or from 
successive families that are related based on your use of carryover 
data under Sec.  1042.230(d)).
    (3) If you do not produce an engine from the engine family in the 
specified time frame, test the next engine you produce.
    (4) You may preferentially test engines earlier than we specify.
    (5) You meet the requirement to randomly select engines under this 
section if you assemble the engine in a way that fully represents your 
normal production and quality procedures.
    (c) For each engine that fails to meet emission standards, test two 
engines from the same engine family from the next fifteen engines 
produced or within seven days, whichever is later. If you do not 
produce fifteen additional engines within 90 days, test two additional 
engines within 90 days or as soon as practicable. If an engine fails to 
meet emission standards for any pollutant, count it as a failing engine 
under this paragraph (c).
    (d) Continue testing until one of the following things happens:
    (1) You test the number of engines required under paragraphs (b) 
and (c) of this section. For example, if the initial engine fails and 
then two engines pass, testing is complete for that engine family.
    (2) The engine family does not comply according to Sec.  1042.315 
or you choose to declare that the engine family does not comply with 
the requirements of this subpart.
    (e) You may elect to test more randomly chosen engines than we 
require under this section.
0
151. Amend Sec.  1042.315 by revising paragraphs (a)(1) and (b) to read 
as follows:


Sec.  1042.315  Determining compliance.

* * * * *
    (a) * * *
    (1) Initial and final test results. Calculate and round the test 
results for each engine. If you do multiple tests on an engine in a 
given configuration (without modifying the engine), calculate the 
initial results for each test, then add all the test results together 
and divide by the number of tests. Round

[[Page 17846]]

this final calculated value for the final test results on that engine. 
Include the Green Engine Factor to determine low-hour emission results, 
if applicable.
* * * * *
    (b) For Category 1 and Category 2 engines, if a production-line 
engine fails to meet emission standards and you test additional engines 
as described in Sec.  1042.310, calculate the average emission level 
for each pollutant for all the engines. If the calculated average 
emission level for any pollutant exceeds the applicable emission 
standard, the engine family fails the production-line testing 
requirements of this subpart. Tell us within ten working days if an 
engine fails. You may request to amend the application for 
certification to raise the FEL of the engine family as described in 
Sec.  1042.225(f).
0
152. Amend Sec.  1042.320 by revising paragraph (c) to read as follows:


Sec.  1042.320  What happens if one of my production-line engines fails 
to meet emission standards?

* * * * *
    (c) Use test data from a failing engine for the compliance 
demonstration under Sec.  1042.315 as follows:
    (1) Use the original, failing test results as described in Sec.  
1042.315, whether or not you modify the engine or destroy it. However, 
for catalyst-equipped engines, you may ask us to allow you to exclude 
an initial failed test if all the following are true:
    (i) The catalyst was in a green condition when tested initially.
    (ii) The engine met all emission standards when retested after 
degreening the catalyst.
    (iii) No additional emission-related maintenance or repair was 
performed between the initial failed test and the subsequent passing 
test.
    (2) Do not use test results from a modified engine as final test 
results under Sec.  1042.315, unless you change your production process 
for all engines to match the adjustments you made to the failing 
engine. If you change production processes and use the test results 
from a modified engine, count the modified engine as the next engine in 
the sequence, rather than averaging the results with the testing that 
occurred before modifying the engine.
0
153. Amend Sec.  1042.325 by revising paragraph (b) to read as follows:


Sec.  1042.325  What happens if an engine family fails the production-
line testing requirements?

* * * * *
    (b) We will tell you in writing if we suspend your certificate in 
whole or in part. We will not suspend a certificate until at least 15 
days after the engine family fails as described in Sec.  1042.315(b). 
The suspension is effective when you receive our notice.
* * * * *
0
154. Revise Sec.  1042.345 to read as follows:


Sec.  1042.345  Reporting.

    (a) Send us a test report within 45 days after you complete 
production-line testing for a Category 1 or Category 2 engine family, 
and within 45 days after you finish testing each Category 3 engine. We 
may approve a later submission for Category 3 engines if it allows you 
to combine test reports for multiple engines.
    (b) Include the following information in the report:
    (1) Describe any facility used to test production-line engines and 
state its location.
    (2) For Category 1 and Category 2 engines, describe how you 
randomly selected engines.
    (3) Describe each test engine, including the engine family's 
identification and the engine's model year, build date, model number, 
identification number, and number of hours of operation before testing. 
Also describe how you developed and applied the Green Engine Factor, if 
applicable.
    (4) Identify how you accumulated hours of operation on the engines 
and describe the procedure and schedule you used.
    (5) Provide the test number; the date, time and duration of 
testing; test procedure; all initial test results; final test results; 
and final deteriorated test results for all tests. Provide the emission 
results for all measured pollutants. Include information for both valid 
and invalid tests and the reason for any invalidation.
    (6) Describe completely and justify any nonroutine adjustment, 
modification, repair, preparation, maintenance, or test for the test 
engine if you did not report it separately under this subpart. Include 
the results of any emission measurements, regardless of the procedure 
or type of engine.
    (c) We may ask you to add information to your written report so we 
can determine whether your new engines conform with the requirements of 
this subpart. We may also ask you to send less information.
    (d) An authorized representative of your company must sign the 
following statement:
    We submit this report under sections 208 and 213 of the Clean Air 
Act. Our production-line testing conformed completely with the 
requirements of 40 CFR part 1042. We have not changed production 
processes or quality-control procedures for test engines in a way that 
might affect emission controls. All the information in this report is 
true and accurate to the best of my knowledge. I know of the penalties 
for violating the Clean Air Act and the regulations. (Authorized 
Company Representative)
    (e) Send electronic reports of production-line testing to the 
Designated Compliance Officer using an approved information format. If 
you want to use a different format, send us a written request with 
justification for a waiver. You may combine reports from multiple 
engines and engine families into a single report.
    (f) We will send copies of your reports to anyone from the public 
who asks for them. See Sec.  1042.915 for information on how we treat 
information you consider confidential.
0
155. Amend Sec.  1042.515 by revising paragraph (d) to read as follows:


Sec.  1042.515  Test procedures related to not-to-exceed standards.

* * * * *
    (d) Engine testing may occur at any conditions expected during 
normal operation but that are outside the conditions described in 
paragraph (c) of this section, as long as measured values are corrected 
to be equivalent to the nearest end of the specified range, using good 
engineering judgment. Correct NOX emissions for humidity as 
specified in 40 CFR part 1065, subpart G.
* * * * *
0
156. Amend Sec.  1042.615 by revising paragraph (g) introductory text 
to read as follows:


Sec.  1042.615  Replacement engine exemption.

* * * * *
    (g) In unusual circumstances, you may ask us to allow you to apply 
the replacement engine exemption of this section for repowering a 
steamship or a vessel that becomes a ``new vessel'' under Sec.  
1042.901 as a result of modifications, as follows:
* * * * *
0
157. Amend Sec.  1042.660 by revising paragraph (b) to read as follows:


Sec.  1042.660  Requirements for vessel manufacturers, owners, and 
operators.

* * * * *
    (b) For vessels equipped with SCR systems requiring the use of urea 
or other reductants, owners and operators must report to the Designated 
Compliance Officer within 30 days any operation of such vessels without 
the appropriate reductant. For each

[[Page 17847]]

reportable incident, include the cause of the noncompliant operation, 
the remedy, and an estimate of the extent of operation without 
reductant. You must remedy the problem as soon as practicable to avoid 
violating the tampering prohibition in 40 CFR 1068.101(b)(1). If the 
remedy is not complete within 30 days of the incident, notify the 
Designated Compliance Officer when the issue is resolved, along with 
any relevant additional information related to the repair. This 
reporting requirement applies for all engines on covered vessels even 
if the engines are certified to Annex VI standards instead of or in 
addition to EPA standards under this part. Failure to comply with the 
reporting requirements of this paragraph (b) is a violation of 40 CFR 
1068.101(a)(2). Note that operating such engines without reductant is a 
violation of 40 CFR 1068.101(b)(1).
* * * * *
0
158. Amend Sec.  1042.901 by revising the definitions of ``Category 
1'', ``Category 2'', ``Critical emission-related component'', and 
``Designated Compliance Officer'' and removing the definition of 
``Designated Enforcement Officer'' to read as follows:


Sec.  1042.901  Definitions.

* * * * *
    Category 1 means relating to a marine engine with specific engine 
displacement below 7.0 liters per cylinder. See Sec.  1042.670 to 
determine equivalent per-cylinder displacement for nonreciprocating 
marine engines (such as gas turbine engines). Note that the maximum 
specific engine displacement for Category 1 engines subject to Tier 1 
and Tier 2 standards was 5.0 liters per cylinder.
    Category 2 means relating to a marine engine with a specific engine 
displacement at or above 7.0 liters per cylinder but less than 30.0 
liters per cylinder. See Sec.  1042.670 to determine equivalent per-
cylinder displacement for nonreciprocating marine engines (such as gas 
turbine engines). Note that the minimum specific engine displacement 
for Category 2 engines subject to Tier 1 and Tier 2 standards was 5.0 
liters per cylinder.
* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
    Designated Compliance Officer means the Director, Diesel Engine 
Compliance Center, U.S. Environmental Protection Agency, 2000 
Traverwood Drive, Ann Arbor, MI 48105; [email protected]; 
www.epa.gov/ve-certification.
* * * * *
0
159. Amend appendix I to part 1042 by revising paragraph (a) to read as 
follows:

Appendix I to Part 1042--Summary of Previous Emission Standards

* * * * *
    (a) Engines below 37 kW. Tier 1 and Tier 2 standards for engines 
below 37 kW originally adopted under 40 CFR part 89 apply as 
follows:

                        Table 1 to Appendix I--Emission Standards for Engines Below 37 kW
                                                    [g/kW-hr]
----------------------------------------------------------------------------------------------------------------
       Rated power (kW)               Tier          Model year      NMHC + NOX          CO              PM
----------------------------------------------------------------------------------------------------------------
kW < 8........................  Tier 1..........            2000            10.5             8.0             1.0
                                Tier 2..........            2005             7.5             8.0            0.80
8 <= kW <= 19.................  Tier 1..........            2000             9.5             6.6            0.80
                                Tier 2..........            2005             7.5             6.6            0.80
19 >= kW >= 37................  Tier 1..........            1999             9.5             5.5            0.80
                                Tier 2..........            2004             7.5             5.5            0.60
----------------------------------------------------------------------------------------------------------------

* * * * *

PART 1043--CONTROL OF NOX, SOX, AND PM EMISSIONS FROM MARINE 
ENGINES AND VESSELS SUBJECT TO THE MARPOL PROTOCOL

0
160. The authority citation for part 1043 continues to read as follows:

    Authority:  33 U.S.C. 1901-1912.

0
161. Amend Sec.  1043.20 by removing the definition of ``Public 
vessels'' and adding a definition of ``Public vessel'' in alphabetical 
order to read as follows:


Sec.  1043.20  Definitions.

* * * * *
    Public vessel means a warship, naval auxiliary vessel, or other 
vessel owned or operated by a sovereign country when engaged in 
noncommercial service. Vessels with a national security exemption under 
40 CFR 1042.635 are deemed to be public vessels with respect to 
compliance with NOX-related requirements of this part when 
engaged in noncommercial service. Similarly, vessels with one or more 
installed engines that have a national security exemption under 40 CFR 
1090.605 are deemed to be public vessels with respect to compliance 
with fuel content requirements when engaged in noncommercial service.
* * * * *
0
162. Amend Sec.  1043.55 by revising paragraphs (a) and (b) to read as 
follows:


Sec.  1043.55  Applying equivalent controls instead of complying with 
fuel requirements.

* * * * *
    (a) The U.S. Coast Guard is the approving authority under APPS for 
such equivalent methods for U.S.-flagged vessels.
    (b) The provisions of this paragraph (b) apply for vessels equipped 
with controls certified by the U.S. Coast Guard or the Administration 
of a foreign-flag vessel to achieve emission levels equivalent to those 
achieved by the use of fuels meeting the applicable fuel sulfur limits 
of Regulation 14 of Annex VI. Fuels not meeting the applicable fuel 
sulfur limits of Regulation 14 of Annex VI may be used on such vessels 
consistent with the provisions of the IAPP certificate, APPS and Annex 
VI.
* * * * *
0
163. Amend Sec.  1043.95 by revising paragraph (b) to read as follows:


Sec.  1043.95  Great Lakes provisions.

* * * * *
    (b) The following exemption provisions apply for ships qualifying 
under paragraph (a) of this section:
    (1) The fuel-use requirements of this part do not apply through 
December 31, 2025, if we approved an exemption under this section 
before [effective date of the final rule] based on the use of 
replacement engines certified to applicable standards under 40 CFR part 
1042 corresponding to the date the vessel entered dry dock for service. 
All other requirements under this part 1043 continue to apply to 
exempted vessels,

[[Page 17848]]

including requirements related to bunker delivery notes.
    (2) A marine diesel engine installed to repower a steamship may be 
a replacement engine under Regulation 13.2.2 of Annex VI. Such an 
engine may qualify for an exemption from the Tier III NOX 
standard under Regulation 13.2.2 of Annex VI.
* * * * *

PART 1045--CONTROL OF EMISSIONS FROM SPARK-IGNITION PROPULSION 
MARINE ENGINES AND VESSELS

0
164. The authority citation for part 1045 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
165. Amend Sec.  1045.115 by revising paragraphs (e) and (f) to read as 
follows:


Sec.  1045.115  What other requirements apply?

* * * * *
    (e) Adjustable parameters. Engines that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. We may require that you set adjustable 
parameters to any specification within the adjustable range during any 
testing, including certification testing, production-line testing, or 
in-use testing. General provisions for adjustable parameters apply as 
specified in 40 CFR 1068.50.
    (f) Prohibited controls. You may not design your engines with 
emission control devices, systems, or elements of design that cause or 
contribute to an unreasonable risk to public health, welfare, or safety 
while operating. For example, an engine may not emit a noxious or toxic 
substance it would otherwise not emit that contributes to such an 
unreasonable risk.
* * * * *
0
166. Amend Sec.  1045.205 by revising paragraph (r) to read as follows:


Sec.  1045.205  What must I include in my application?

* * * * *
    (r) Describe all adjustable operating parameters (see Sec.  
1045.115(e)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
167. Amend Sec.  1045.801 by revising the definition of ``Critical 
emission-related component'' to read as follows:


Sec.  1045.801  What definitions apply to this part?

* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
0
168. Revise Sec.  1045.815 to read as follows:


Sec.  1045.815  What provisions apply to confidential information?

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.

PART 1048--CONTROL OF EMISSIONS FROM NEW, LARGE NONROAD SPARK-
IGNITION ENGINES

0
169. The authority citation for part 1048 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
170. Amend Sec.  1048.115 by revising paragraphs (e) and (f) to read as 
follows:


Sec.  1048.115  What other requirements apply?

* * * * *
    (e) Adjustable parameters. Engines that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. We may require that you set adjustable 
parameters to any specification within the adjustable range during any 
testing, including certification testing, production-line testing, or 
in-use testing. General provisions for adjustable parameters apply as 
specified in 40 CFR 1068.50.
    (f) Prohibited controls. You may not design your engines with 
emission control devices, systems, or elements of design that cause or 
contribute to an unreasonable risk to public health, welfare, or safety 
while operating. For example, an engine may not emit a noxious or toxic 
substance it would otherwise not emit that contributes to such an 
unreasonable risk.
* * * * *
0
171. Amend Sec.  1048.205 by revising paragraph (t) to read as follows:


Sec.  1048.205  What must I include in my application?

* * * * *
    (t) Describe all adjustable operating parameters (see Sec.  
1048.115(e)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
172. Amend Sec.  1048.240 by adding paragraph (f) to read as follows:


Sec.  1048.240  How do I demonstrate that my engine family complies 
with exhaust emission standards?

* * * * *
    (f) You may alternatively determine and verify deterioration 
factors based on bench-aged aftertreatment as described in 40 CFR 
1036.245 and 1036.246, with the following exceptions:
    (1) Apply the percentage of useful life from Table 1 of 40 CFR 
1036.246 based on hours of operation rather than vehicle mileage.
    (2) Use good engineering judgment to perform verification testing 
using the procedures of Sec.  1048.515 rather than 40 CFR 1036.520. 
Measure emissions as the equipment goes through its normal operation 
over the course of the day (or shift-day).
0
173. Amend Sec.  1048.501 by revising paragraph (e)(2) to read as 
follows:


Sec.  1048.501  How do I run a valid emission test?

* * * * *
    (e) * * *
    (2) For engines equipped with carbon canisters that store fuel 
vapors that will be purged for combustion in the engine, precondition 
the canister as specified in 40 CFR 86.132-96(h) and then operate the 
engine for 60 minutes over repeat runs of the duty cycle specified in 
appendix II of this part.
* * * * *

[[Page 17849]]

0
174. Amend Sec.  1048.620 by revising paragraphs (a)(3), (d), and (e) 
to read as follows:


Sec.  1048.620  What are the provisions for exempting large engines 
fueled by natural gas or liquefied petroleum gas?

    (a) * * *
    (3) The engine must be in an engine family that has a valid 
certificate of conformity showing that it meets emission standards for 
engines of that power rating under 40 CFR part 1039.
* * * * *
    (d) Engines exempted under this section are subject to all the 
requirements affecting engines under 40 CFR part 1039. The requirements 
and restrictions of 40 CFR part 1039 apply to anyone manufacturing 
engines exempted under this section, anyone manufacturing equipment 
that uses these engines, and all other persons in the same manner as if 
these were nonroad diesel engines.
    (e) You may request an exemption under this section by submitting 
an application for certification for the engines under 40 CFR part 
1039.
0
175. Amend Sec.  1048.801 by revising the definition of ``Critical 
emission-related component'' to read as follows:


Sec.  1048.801  What definitions apply to this part?

* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
0
176. Revise Sec.  1048.815 to read as follows:


Sec.  1048.815  What provisions apply to confidential information?

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.

PART 1051--CONTROL OF EMISSIONS FROM RECREATIONAL ENGINES AND 
VEHICLES

0
177. The authority citation for part 1051 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
178. Amend Sec.  1051.115 by revising paragraphs (c), (d) introductory 
text, (d)(1), (d)(2) introductory text, and (e) to read as follows:


Sec.  1051.115  What other requirements apply?

* * * * *
    (c) Adjustable parameters. Vehicles that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. Note that parameters that control the air-
fuel ratio may be treated separately under paragraph (d) of this 
section. We may require that you set adjustable parameters to any 
specification within the adjustable range during any testing, including 
certification testing, production-line testing, or in-use testing. 
General provisions for adjustable parameters apply as specified in 40 
CFR 1068.50.
    (d) Other adjustments. The following provisions apply for engines 
with carburetor jets or needles, and for engines with any other 
technology involving service to adjust air-fuel ratio that falls within 
the time and cost specifications of 40 CFR 1068.50(d)(1):
    (1) In your application for certification, specify the physically 
adjustable range of air-fuel ratios you expect to occur in use. You may 
specify it in terms of engine parts (such as the carburetor jet size 
and needle configuration as a function of atmospheric conditions).
    (2) The physically adjustable range specified in paragraph (d)(1) 
of this section must include all air-fuel ratios between the lean limit 
and the rich limit, unless you can show that some air-fuel ratios will 
not occur in use.
* * * * *
    (e) Prohibited controls. You may not design your engines with 
emission control devices, systems, or elements of design that cause or 
contribute to an unreasonable risk to public health, welfare, or safety 
while operating. For example, an engine may not emit a noxious or toxic 
substance it would otherwise not emit that contributes to such an 
unreasonable risk.
* * * * *
0
179. Amend Sec.  1051.205 by revising paragraph (q) to read as follows:


Sec.  1051.205  What must I include in my application?

* * * * *
    (q) Describe all adjustable operating parameters (see Sec.  
1051.115(e)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
vehicles or engines are designed to prevent unauthorized adjustments.
* * * * *
0
180. Amend Sec.  1051.501 by revising paragraphs (c)(2), (d)(2)(i) and 
(d)(3) to read as follows:


Sec.  1051.501  What procedures must I use to test my vehicles or 
engines?

* * * * *
    (c) * * *
    (2) Prior to permeation testing of fuel line, precondition the fuel 
line by filling it with the fuel specified in paragraph (d)(3) of this 
section, sealing the openings, and soaking it for 4 weeks at (23  5) [deg]C. To measure fuel-line permeation emissions, use the 
equipment and procedures specified in SAE J30 as described in 40 CFR 
1060.810. Use the fuel specified in paragraph (d)(3) of this section. 
Perform daily measurements for 14 days, except that you may omit up to 
two daily measurements in any seven-day period. Maintain an ambient 
temperature of (23  2) [deg]C throughout the sampling 
period, except for intervals up to 30 minutes for weight measurements.
    (d) * * *
    (2) * * *
    (i) For the preconditioning soak described in Sec.  1051.515(a)(1) 
and fuel slosh durability test described in Sec.  1051.515(d)(3), use 
the fuel specified in 40 CFR 1065.710(b), or the fuel specified in 40 
CFR 1065.710(c) blended with 10 percent ethanol by volume. As an 
alternative, you may use Fuel CE10, which is Fuel C as specified in 
ASTM D471 (see 40 CFR 1060.810) blended with 10 percent ethanol by 
volume.
* * * * *
    (3) Fuel hose permeation. Use the fuel specified in 40 CFR 
1065.710(b), or the fuel specified in 40 CFR 1065.710(c) blended with 
10 percent ethanol by volume for permeation testing of fuel lines. As 
an alternative, you may use Fuel CE10, which is Fuel C as specified in 
ASTM D471 (see 40 CFR 1060.810) blended with 10 percent ethanol by 
volume.
* * * * *
0
181. Amend Sec.  1051.515 by revising paragraph (a)(1) to read as 
follows:


Sec.  1051.515  How do I test my fuel tank for permeation emissions?

* * * * *
    (a) * * *
    (1) Fill the tank with the fuel specified in Sec.  
1051.501(d)(2)(i), seal it,

[[Page 17850]]

and allow it to soak at 28  5 [deg]C for 20 weeks or at (43 
 5) [deg]C for 10 weeks.
* * * * *
0
182. Amend Sec.  1051.740 by revising paragraph (b)(5) to read as 
follows:


Sec.  1051.740  Are there special averaging provisions for snowmobiles?

* * * * *
    (b) * * *
    (5) Credits can also be calculated for Phase 3 using both sets of 
standards. Without regard to the trigger level values, if your net 
emission reduction for the redesignated averaging set exceeds the 
requirements of Phase 3 in Sec.  1051.103 (using both HC and CO in the 
Phase 3 equation in Sec.  1051.103), then your credits are the 
difference between the Phase 3 reduction requirement of that section 
and your calculated value.
0
183. Amend Sec.  1051.801 by revising the definition of ``Critical 
emission-related component'' to read as follows:


Sec.  1051.801  What definitions apply to this part?

* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
0
184. Revise Sec.  1051.815 to read as follows:


Sec.  1051.815  What provisions apply to confidential information?

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.

PART 1054--CONTROL OF EMISSIONS FROM NEW, SMALL NONROAD SPARK-
IGNITION ENGINES AND EQUIPMENT

0
185. The authority citation for part 1054 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
186. Amend Sec.  1054.115 by revising paragraphs (b) and (d) to read as 
follows:


Sec.  1054.115  What other requirements apply?

* * * * *
    (b) Adjustable parameters. Engines that have adjustable parameters 
must meet all the requirements of this part for any adjustment in the 
physically adjustable range. We may require that you set adjustable 
parameters to any specification within the adjustable range during any 
testing, including certification testing, production-line testing, or 
in-use testing. You may ask us to limit idle-speed or carburetor 
adjustments to a smaller range than the physically adjustable range if 
you show us that the engine will not be adjusted outside of this 
smaller range during in-use operation without significantly degrading 
engine performance. General provisions for adjustable parameters apply 
as specified in 40 CFR 1068.50.
* * * * *
    (d) Prohibited controls. You may not design your engines with 
emission control devices, systems, or elements of design that cause or 
contribute to an unreasonable risk to public health, welfare, or safety 
while operating. For example, an engine may not emit a noxious or toxic 
substance it would otherwise not emit that contributes to such an 
unreasonable risk.
* * * * *
0
187. Amend Sec.  1054.205 by revising paragraph (q) to read as follows:


Sec.  1054.205  What must I include in my application?

* * * * *
    (q) Describe all adjustable operating parameters (see Sec.  
1054.115(b)), including production tolerances. For any operating 
parameters that do not qualify as adjustable parameters, include a 
description supporting your conclusion (see 40 CFR 1068.50(c)). Include 
the following in your description of each adjustable parameter:
    (1) For mechanically controlled parameters, include the nominal or 
recommended setting, the intended physically adjustable range, and the 
limits or stops used to establish adjustable ranges. Also include 
information showing why the limits, stops, or other means of inhibiting 
adjustment are effective in preventing adjustment of parameters on in-
use engines to settings outside your intended physically adjustable 
ranges.
    (2) For electronically controlled parameters, describe how your 
engines are designed to prevent unauthorized adjustments.
* * * * *
0
188. Amend Sec.  1054.230 by revising paragraphs (b)(8) and (9) to read 
as follows:


Sec.  1054.230  How do I select emission families?

* * * * *
    (b) * * *
    (8) Method of control for engine operation, other than governing. 
For example, multi-cylinder engines with port fuel injection may not be 
grouped into an emission family with engines that have a single 
throttle-body injector or carburetor.
    (9) The numerical level of the applicable emission standards. For 
example, an emission family may not include engines certified to 
different family emission limits, though you may change family emission 
limits without recertifying as specified in Sec.  1054.225.
* * * * *
0
189. Amend Sec.  1054.505 by revising paragraphs (a), (b) introductory 
text, (b)(2), and (d) to read as follows:


Sec.  1054.505  How do I test engines?

    (a) This section describes how to test engines under steady-state 
conditions. We may also perform other testing as allowed by the Clean 
Air Act. Sample emissions separately for each mode, then calculate an 
average emission level for the whole cycle using the weighting factors 
specified for each mode. Control engine speed as specified in this 
section. Use one of the following methods for confirming torque values 
for nonhandheld engines:
    (1) Calculate torque-related cycle statistics and compare with the 
established criteria as specified in 40 CFR 1065.514 to confirm that 
the test is valid.
    (2) Evaluate each mode separately to validate the duty cycle. All 
torque feedback values recorded during non-idle sampling periods must 
be within 2 percent of the reference value or within 0.27 N[middot]m of the reference value, whichever is greater. 
Also, the mean torque value during non-idle sampling periods must be 
within 1 percent of the reference value or 0.12 
N[middot]m of the reference value, whichever is greater. Control torque 
during idle as specified in paragraph (c) of this section.
    (b) Measure emissions by testing engines on a dynamometer with the 
test procedures for constant-speed engines in 40 CFR part 1065 while 
using the steady-state duty cycles identified in this paragraph (b) to 
determine whether it meets the exhaust emission standards specified in 
Sec.  1054.101(a). This paragraph (b) applies for all engines, 
including those not meeting the definition of ``constant-speed engine'' 
in 40 CFR 1065.1001.
* * * * *
    (2) For nonhandheld engines designed to idle, use the six-mode duty 
cycle described in paragraph (b)(1) of appendix II of this part; use 
the five-mode duty cycle described in paragraph (b)(2) of appendix II 
of this part for engines that are not designed to idle. Control engine 
speed during the full-load operating mode as specified in paragraph (d) 
of this section. For all other modes, control engine speed to within 5 
percent of the nominal speed specified in paragraph (d) of this section 
or let the installed governor (in the

[[Page 17851]]

production configuration) control engine speed. For all modes except 
idle, control torque as needed to meet the cycle-validation criteria in 
paragraph (a) of this section. The governor may be adjusted before 
emission sampling to target the nominal speed identified in paragraph 
(d) of this section, but the installed governor must control engine 
speed throughout the emission-sampling period whether the governor is 
adjusted or not.
* * * * *
    (d) During full-load operation for nonhandheld engines, operate the 
engine with the following parameters:
    (1) Select an engine speed for testing as follows:
    (i) For engines with a governed speed at full load between 2700 and 
4000 rpm, select appropriate test speeds for the emission family. If 
all the engines in the emission family are used in intermediate-speed 
equipment, select a test speed of 3060 rpm. The test associated with 
intermediate-speed operation is referred to as the A Cycle. If all the 
engines in the emission family are used in rated-speed equipment, 
select a test speed of 3600 rpm. The test associated with rated-speed 
operation is referred to as the B Cycle. If an emission family includes 
engines used in both intermediate-speed equipment and rated-speed 
equipment, measure emissions at test speeds of both 3060 and 3600 rpm. 
In unusual circumstances, you may ask to use a test speed different 
than that specified in this paragraph (d)(1)(i) if it better represents 
in-use operation.
    (ii) For engines with a governed speed below 2700 or above 4000 
rpm, ask us to approve one or more test speeds to represent those 
engines using the provisions for special procedures in 40 CFR 
1065.10(c)(2).
* * * * *
0
190. Amend Sec.  1054.801 by:
0
a. Revising the definition for ``Critical emission-related component''.
0
b. Removing the definition for ``Discrete mode''.
0
c. Revising the definition for ``Intermediate-speed equipment''.
0
d. Removing the definition for ``Ramped-modal''.
0
e. Revising the definitions for ``Rated-speed equipment'' and ``Steady-
state''.
    The revisions read as follows:


Sec.  1054.801  What definitions apply to this part?

* * * * *
    Critical emission-related component has the meaning given in 40 CFR 
1068.30.
* * * * *
    Intermediate-speed equipment includes all nonhandheld equipment in 
which the installed engine's governed speed at full load is below 3330 
rpm. It may also include nonhandheld equipment in which the installed 
engine's governed speed at full load is as high as 3400 rpm.
* * * * *
    Rated-speed equipment includes all nonhandheld equipment in which 
the installed engine's governed speed at full load is at or above 3400 
rpm. It may also include nonhandheld equipment in which the installed 
engine's governed speed at full load is as low as 3330 rpm.
* * * * *
    Steady-state means relating to emission tests in which engine speed 
and load are held at a finite set of essentially constant values.
* * * * *
0
191. Revise Sec.  1054.815 to read as follows:


Sec.  1054.815  What provisions apply to confidential information?

    The provisions of 40 CFR 1068.10 and 1068.11 apply for information 
you submit under this part.
0
192. Redesignate appendix I to part 1054 as appendix A to part 1054 and 
amend newly redesignated appendix A by revising paragraph (b)(3) 
introductory text to read as follows:

Appendix A to Part 1054--Summary of Previous Emission Standards

* * * * *
    (b) * * *
    (3) Note that engines subject to Phase 1 standards were not 
subject to useful life, deterioration factor, production-line 
testing, or in-use testing provisions. In addition, engines subject 
to Phase 1 standards and engines subject to Phase 2 standards were 
both not subject to the following provisions:
* * * * *
0
193. Redesignate appendix II to part 1054 as appendix B to part 1054 
and revise newly redesignated appendix B to read as follows:

Appendix B to Part 1054--Duty Cycles for Laboratory Testing

    (a) Test handheld engines with the following steady-state duty 
cycle:

         Table 1 to Appendix B--Duty Cycle for Handheld Engines
------------------------------------------------------------------------
                                              Torque         Weighting
      G3 mode No.       Engine speed \a\   (percent) \b\      factors
------------------------------------------------------------------------
1.....................  Rated speed.....             100            0.85
2.....................  Warm idle.......               0            0.15
------------------------------------------------------------------------
\a\ Test engines at the specified speeds as described in Sec.
  1054.505.
\b\ Test engines at 100 percent torque by setting operator demand to
  maximum. Control torque during idle at its warm idle speed as
  described in 40 CFR 1065.510.

    (b) Test nonhandheld engines with one of the following steady-
state duty cycles:
    (1) The following duty cycle applies for engines designed to 
idle:

   Table 2 to Appendix B--Duty Cycle for Nonhandheld Engines With Idle
------------------------------------------------------------------------
                                              Torque         Weighting
             G2 mode No. \a\               (percent) \b\      factors
------------------------------------------------------------------------
1.......................................             100            0.09
2.......................................              75            0.20
3.......................................              50            0.29
4.......................................              25            0.30
5.......................................              10            0.07
6.......................................               0            0.05
------------------------------------------------------------------------
\a\ Control engine speed as described in Sec.   1054.505. Control engine
  speed for Mode 6 as described in Sec.   1054.505(c) for idle
  operation.
\b\ The percent torque is relative to the value established for full-
  load torque, as described in Sec.   1054.505.

    (2) The following duty cycle applies for engines that are not 
designed to idle:

 Table 3 to Appendix B--Duty Cycle for Nonhandheld Engines Without Idle
------------------------------------------------------------------------
                                              Torque         Weighting
              Mode No. \a\                 (percent) \b\      factors
------------------------------------------------------------------------
1.......................................             100            0.09

[[Page 17852]]

 
2.......................................              75            0.21
3.......................................              50            0.31
4.......................................              25            0.32
5.......................................              10            0.07
------------------------------------------------------------------------
\a\ Control engine speed as described in Sec.   1054.505.
\b\ The percent torque is relative to the value established for full-
  load torque, as described in Sec.   1054.505.

PART 1060--CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE 
NONROAD AND STATIONARY EQUIPMENT

0
194. The authority citation for part 1060 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
195. Amend Sec.  1060.515 by revising paragraphs (c) and (d) to read as 
follows:


Sec.  1060.515  How do I test EPA Nonroad Fuel Lines and EPA Cold-
Weather Fuel Lines for permeation emissions?

* * * * *
    (c) Except as specified in paragraph (d) of this section, measure 
fuel line permeation emissions using the equipment and procedures for 
weight-loss testing specified in SAE J30 or SAE J1527 (incorporated by 
reference in Sec.  1060.810). Start the measurement procedure within 8 
hours after draining and refilling the fuel line. Perform the emission 
test over a sampling period of 14 days. You may omit up to two daily 
measurements in any seven-day period. Determine your final emission 
result based on the average of measured values over the 14-day period. 
Maintain an ambient temperature of (232) [deg]C throughout 
the sampling period, except for intervals up to 30 minutes for daily 
weight measurements.
    (d) For fuel lines with a nominal inner diameter below 5.0 mm, you 
may alternatively measure fuel line permeation emissions using the 
equipment and procedures for weight-loss testing specified in SAE J2996 
(incorporated by reference in Sec.  1060.810). Determine your final 
emission result based on the average of measured values over the 14-day 
sampling period. Maintain an ambient temperature of (232) 
[deg]C throughout the sampling period, except for intervals up to 30 
minutes for daily weight measurements.
* * * * *
0
196. Amend Sec.  1060.520 by revising paragraph (b)(1) to read as 
follows:


Sec.  1060.520  How do I test fuel tanks for permeation emissions?

* * * * *
    (b) * * *
    (1) Fill the fuel tank to its nominal capacity with the fuel 
specified in paragraph (e) of this section, seal it, and allow it to 
soak at (285) [deg]C for at least 20 weeks. Alternatively, 
the fuel tank may be soaked for at least 10 weeks at (435) 
[deg]C. You may count the time of the preconditioning steps in 
paragraph (a) of this section as part of the preconditioning fuel soak 
as long as the ambient temperature remains within the specified 
temperature range and the fuel tank continues to be at least 40 percent 
full throughout the test; you may add or replace fuel as needed to 
conduct the specified durability procedures. Void the test if you 
determine that the fuel tank has any kind of leak.
* * * * *

PART 1065--ENGINE-TESTING PROCEDURES

0
197. The authority citation for part 1065 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
198. Amend Sec.  1065.1 by revising paragraphs (a)(1) through (5) and 
(8) to read as follows:


Sec.  1065.1  Applicability.

    (a) * * *
    (1) Locomotives we regulate under 40 CFR part 1033.
    (2) Heavy-duty highway engines we regulate under 40 CFR parts 86 
and 1036.
    (3) Nonroad compression-ignition engines we regulate under 40 CFR 
part 1039 and stationary diesel engines that are certified to the 
standards in 40 CFR part 1039 as specified in 40 CFR part 60, subpart 
IIII.
    (4) Marine compression-ignition engines we regulate under 40 CFR 
part 1042.
    (5) Marine spark-ignition engines we regulate under 40 CFR part 
1045.
* * * * *
    (8) Small nonroad spark-ignition engines we regulate under 40 CFR 
part 1054 and stationary engines that are certified to the standards in 
40 CFR part 1054 as specified in 40 CFR part 60, subpart JJJJ.
* * * * *
0
199. Amend Sec.  1065.5 by revising paragraphs (a) introductory text 
and (c) to read as follows:


Sec.  1065.5  Overview of this part 1065 and its relationship to the 
standard-setting part.

    (a) This part specifies procedures that apply generally to 
measuring brake-specific emissions from various categories of engines. 
See subpart L of this part for measurement procedures for testing 
related to standards other than brake-specific emission standards. See 
the standard-setting part for directions in applying specific 
provisions in this part for a particular type of engine. Before using 
this part's procedures, read the standard-setting part to answer at 
least the following questions:
* * * * *
    (c) The following table shows how this part divides testing 
specifications into subparts:

       Table 1 of Sec.   1065.5--Description of Part 1065 Subparts
------------------------------------------------------------------------
                                   Describes these specifications or
         This subpart                          procedures
------------------------------------------------------------------------
Subpart A....................  Applicability and general provisions.
Subpart B....................  Equipment for testing.
Subpart C....................  Measurement instruments for testing.
Subpart D....................  Calibration and performance verifications
                                for measurement systems.
Subpart E....................  How to prepare engines for testing,
                                including service accumulation.
Subpart F....................  How to run an emission test over a
                                predetermined duty cycle.
Subpart G....................  Test procedure calculations.
Subpart H....................  Fuels, engine fluids, analytical gases,
                                and other calibration standards.
Subpart I....................  Special procedures related to oxygenated
                                fuels.
Subpart J....................  How to test with portable emission
                                measurement systems (PEMS).
Subpart L....................  How to test for unregulated and special
                                pollutants.
------------------------------------------------------------------------


[[Page 17853]]

0
200. Amend Sec.  1065.10 by revising paragraph (c)(7)(ii) to read as 
follows:


Sec.  1065.10  Other procedures.

* * * * *
    (c) * * *
    (7) * * *
    (ii) Submission. Submit requests in writing to the EPA Program 
Officer.
* * * * *
0
201. Amend Sec.  1065.12 by revising paragraph (a) to read as follows:


Sec.  1065.12  Approval of alternate procedures.

    (a) To get approval for an alternate procedure under Sec.  
1065.10(c), send the EPA Program Officer an initial written request 
describing the alternate procedure and why you believe it is equivalent 
to the specified procedure. Anyone may request alternate procedure 
approval. This means that an individual engine manufacturer may request 
to use an alternate procedure. This also means that an instrument 
manufacturer may request to have an instrument, equipment, or procedure 
approved as an alternate procedure to those specified in this part. We 
may approve your request based on this information alone, whether or 
not it includes all the information specified in this section. Where we 
determine that your original submission does not include enough 
information for us to determine that the alternate procedure is 
equivalent to the specified procedure, we may ask you to submit 
supplemental information showing that your alternate procedure is 
consistently and reliably at least as accurate and repeatable as the 
specified procedure.
* * * * *
0
202. Amend Sec.  1065.140 by revising paragraph (b)(2) introductory 
text, (c)(2) and (6), and (e)(4) to read as follows:


Sec.  1065.140  Dilution for gaseous and PM constituents.

* * * * *
    (b) * * *
    (2) Measure these background concentrations the same way you 
measure diluted exhaust constituents, or measure them in a way that 
does not affect your ability to demonstrate compliance with the 
applicable standards in this chapter. For example, you may use the 
following simplifications for background sampling:
* * * * *
    (c) * * *
    (2) Pressure control. Maintain static pressure at the location 
where raw exhaust is introduced into the tunnel within 1.2 
kPa of atmospheric pressure. You may use a booster blower to control 
this pressure. If you test using more careful pressure control and you 
show by engineering analysis or by test data that you require this 
level of control to demonstrate compliance at the applicable standards 
in this chapter, we will maintain the same level of static pressure 
control when we test.
* * * * *
    (6) Aqueous condensation. You must address aqueous condensation in 
the CVS as described in this paragraph (c)(6). You may meet these 
requirements by preventing or limiting aqueous condensation in the CVS 
from the exhaust inlet to the last emission sample probe. See paragraph 
(c)(6)(2)(B) of this section for provisions related to the CVS between 
the last emission sample probe and the CVS flow meter. You may heat 
and/or insulate the dilution tunnel walls, as well as the bulk stream 
tubing downstream of the tunnel to prevent or limit aqueous 
condensation. Where we allow aqueous condensation to occur, use good 
engineering judgment to ensure that the condensation does not affect 
your ability to demonstrate that your engines comply with the 
applicable standards in this chapter (see Sec.  1065.10(a)).
* * * * *
    (e) * * *
    (4) Control sample temperature to a (475) [deg]C 
tolerance, as measured anywhere within 20 cm upstream or downstream of 
the PM storage media (such as a filter). You may instead measure sample 
temperature up to 30 cm upstream of the filter or other PM storage 
media if it is housed within a chamber with temperature controlled to 
stay within the specified temperature range. Measure sample temperature 
with a bare-wire junction thermocouple with wires that are (0.500 
0.025) mm diameter, or with another suitable instrument 
that has equivalent performance.
0
203. Amend Sec.  1065.170 by revising paragraphs (a)(1) and (c)(1)(ii) 
and (iii) to read as follows:


Sec.  1065.170  Batch sampling for gaseous and PM constituents.

* * * * *
    (a) * * *
    (1) Verify proportional sampling after an emission test as 
described in Sec.  1065.545. You must exclude from the proportional 
sampling verification any portion of the test where you are not 
sampling emissions because the engine is turned off and the batch 
samplers are not sampling, accounting for exhaust transport delay in 
the sampling system. Use good engineering judgment to select storage 
media that will not significantly change measured emission levels 
(either up or down). For example, do not use sample bags for storing 
emissions if the bags are permeable with respect to emissions or if 
they off gas emissions to the extent that it affects your ability to 
demonstrate compliance with the applicable gaseous emission standards 
in this chapter. As another example, do not use PM filters that 
irreversibly absorb or adsorb gases to the extent that it affects your 
ability to demonstrate compliance with the applicable PM emission 
standards in this chapter.
* * * * *
    (c) * * *
    (1) * * *
    (ii) The filter must be circular, with an overall diameter of 
(46.500.6) mm and an exposed diameter of at least 38 mm. 
See the cassette specifications in paragraph (c)(1)(vii) of this 
section.
    (iii) We highly recommend that you use a pure PTFE filter material 
that does not have any flow-through support bonded to the back and has 
an overall thickness of (4020) [mu]m. An inert polymer ring 
may be bonded to the periphery of the filter material for support and 
for sealing between the filter cassette parts. We consider 
Polymethylpentene (PMP) and PTFE inert materials for a support ring, 
but other inert materials may be used. See the cassette specifications 
in paragraph (c)(1)(vii) of this section. We allow the use of PTFE-
coated glass fiber filter material, as long as this filter media 
selection does not affect your ability to demonstrate compliance with 
the applicable standards in this chapter, which we base on a pure PTFE 
filter material. Note that we will use pure PTFE filter material for 
compliance testing, and we may require you to use pure PTFE filter 
material for any compliance testing we require, such as for selective 
enforcement audits.
* * * * *


Sec.  1065.190  [Amended]

0
204. Amend Sec.  1065.190 by removing paragraphs (g)(5) and (6).
0
205. Amend Sec.  1065.210 by revising paragraph (a) to read as follows:


Sec.  1065.210  Work input and output sensors.

    (a) Application. Use instruments as specified in this section to 
measure work inputs and outputs during engine operation. We recommend 
that you use sensors, transducers, and meters that meet the 
specifications in Table 1 of Sec.  1065.205. Note that your overall 
systems for measuring work inputs and outputs must meet the linearity 
verifications in Sec.  1065.307. We recommend that you measure work 
inputs and outputs where they cross the system boundary as shown in 
Figure 1

[[Page 17854]]

of Sec.  1065.210. The system boundary is different for air-cooled 
engines than for liquid-cooled engines. If you choose to measure work 
before or after a work conversion, relative to the system boundary, use 
good engineering judgment to estimate any work-conversion losses in a 
way that avoids overestimation of total work. For example, if it is 
impractical to instrument the shaft of an exhaust turbine generating 
electrical work, you may decide to measure its converted electrical 
work. As another example, you may decide to measure the tractive (i.e., 
electrical output) power of a locomotive, rather than the brake power 
of the locomotive engine. In these cases, divide the electrical work by 
accurate values of electrical generator efficiency ([eta]<1), or assume 
an efficiency of 1 ([eta]=1), which would over-estimate brake-specific 
emissions. For the example of using locomotive tractive power with a 
generator efficiency of 1 ([eta]=1), this means using the tractive 
power as the brake power in emission calculations. Do not underestimate 
any work conversion efficiencies for any components outside the system 
boundary that do not return work into the system boundary. And do not 
overestimate any work conversion efficiencies for components outside 
the system boundary that do return work into the system boundary. In 
all cases, ensure that you are able to accurately demonstrate 
compliance with the applicable standards in this chapter.
BILLING CODE 6560-50-P

[[Page 17855]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.106

BILLING CODE 6560-50-C
* * * * *
0
206. Add Sec.  1065.274 to subpart C to read as follows:


Sec.  1065.274  Zirconium dioxide (ZrO2) NOX analyzer.

    (a) Application. You may use a zirconia oxide (ZrO2) 
analyzer to measure NOX in raw exhaust for field-testing 
engines.
    (b) Component requirements. We recommend that you use a 
ZrO2 analyzer that meets the specifications in

[[Page 17856]]

Table 1 of Sec.  1065.205. Note that your ZrO2-based system 
must meet the linearity verification in Sec.  1065.307.
    (c) Species measured. The ZrO2-based system must be able 
to measure and report NO and NO2 together as NOX. If the 
ZrO2-based system cannot measure all of the NO2, you may 
develop and apply correction factors based on good engineering judgment 
to account for this deficiency.
    (d) Interference. You must account for NH3 interference 
with the NOX measurement.
0
207. Amend Sec.  1065.284 by revising the section heading to read as 
follows:


Sec.  1065.284  Zirconium dioxide (ZrO2) air-fuel ratio and O2 
analyzer.

* * * * *
0
208. Add Sec.  1065.298 to subpart C to read as follows:


Sec.  1065.298  Correcting real-time PM measurement based on 
gravimetric PM filter measurement for field-testing analysis.

    (a) Application. You may quantify net PM on a sample medium for 
field testing with a continuous PM measurement with correction based on 
gravimetric PM filter measurement.
    (b) Measurement principles. Photoacoustic or electrical aerosol 
instruments used in field-testing typically under-report PM emissions. 
Apply the verifications and corrections described in this section to 
meet accuracy requirements.
    (c) Component requirements. (1) Gravimetric PM measurement must 
meet the laboratory measurement requirements of this part 1065, noting 
that there are specific exceptions to some laboratory requirements and 
specification for field testing given in Sec.  1065.905(d)(2). In 
addition to those exceptions, field testing does not require you to 
verify proportional flow control as specified in Sec.  1065.545. Note 
also that the linearity requirements of Sec.  1065.307 apply only as 
specified in this section.
    (2) Check the calibration and linearity of the photoacoustic and 
electrical aerosol instruments according to the instrument 
manufacturer's instructions and the following recommendations:
    (i) For photoacoustic instruments we recommend one of the 
following:
    (A) Use a reference elemental carbon-based PM source to calibrate 
the instrument Verify the photoacoustic instrument by comparing results 
either to a gravimetric PM measurement collected on the filter or to an 
elemental carbon analysis of collected PM.
    (B) Use a light absorber that has a known amount of laser light 
absorption to periodically verify the instrument's calibration factor. 
Place the light absorber in the path of the laser beam. This 
verification checks the integrity of the microphone sensitivity, the 
power of the laser diode, and the performance of the analog-to-digital 
converter.
    (C) Verify that you meet the linearity requirements in Table 1 of 
Sec.  1065.307 by generating a maximum reference PM mass concentration 
(verified gravimetrically) and then using partial-flow sampling to 
dilute to various evenly distributed concentrations.
    (ii) For electrical aerosol instruments we recommend one of the 
following:
    (A) Use reference monodisperse or polydisperse PM-like particles 
with a mobility diameter or count median diameter greater than 45 nm. 
Use an electrometer or condensation particle counter that has a d50 at 
or below 10 nm to verify the reference values.
    (B) Verify that you meet the linearity requirements in Table 1 of 
Sec.  1065.307 using a maximum reference particle concentration, a 
zero-reference concentration, and at least two other evenly distributed 
points. Use partial-flow dilution to create the additional reference PM 
concentrations. The difference between measured values from the 
electrical aerosol and reference instruments at each point must be no 
greater than 15% of the mean value from the two measurements at that 
point.
    (d) Loss correction. You may use PM loss corrections to account for 
PM loss in the sample handling system.
    (e) Correction. Develop a multiplicative correction factor to 
ensure that total PM measured by photoacoustic or electrical aerosol 
instruments equate to the gravimetric filter-based total PM 
measurement. Calculate the correction factor by dividing the mass of PM 
captured on the gravimetric filter by the quantity represented by the 
total concentration of PM measured by the instrument multiplied by the 
time over the test interval multiplied by the gravimetric filter sample 
flow rate.
0
209. Amend Sec.  1065.301 by revising paragraph (d) to read as follows:


Sec.  1065.301  Overview and general provisions.

* * * * *
    (d) Use NIST-traceable standards to the tolerances we specify for 
calibrations and verifications. Where we specify the need to use NIST-
traceable standards, you may alternatively use international standards 
recognized by the CIPM Mutual Recognition Arrangement that are not 
NIST-traceable.
0
210. Amend Sec.  1065.305 by revising paragraph (d)(10)(ii) to read as 
follows:


Sec.  1065.305  Verifications for accuracy, repeatability, and noise.

* * * * *
    (d) * * *
    (10) * * *
    (ii) The measurement deficiency does not adversely affect your 
ability to demonstrate compliance with the applicable standards in this 
chapter.
0
211. Amend Sec.  1065.307 by revising paragraphs (b), (d) introductory 
text, and (f) to read as follows:


Sec.  1065.307  Linearity verification.

* * * * *
    (b) Performance requirements. If a measurement system does not meet 
the applicable linearity criteria referenced in Table 1 of this 
section, correct the deficiency by re-calibrating, servicing, or 
replacing components as needed. Repeat the linearity verification after 
correcting the deficiency to ensure that the measurement system meets 
the linearity criteria. Before you may use a measurement system that 
does not meet linearity criteria, you must demonstrate to us that the 
deficiency does not adversely affect your ability to demonstrate 
compliance with the applicable standards in this chapter.
* * * * *
    (d) Reference signals. This paragraph (d) describes recommended 
methods for generating reference values for the linearity-verification 
protocol in paragraph (c) of this section. Use reference values that 
simulate actual values, or introduce an actual value and measure it 
with a reference-measurement system. In the latter case, the reference 
value is the value reported by the reference-measurement system. 
Reference values and reference-measurement systems must be NIST-
traceable. We recommend using calibration reference quantities that are 
NIST-traceable within 0.5% uncertainty, if not specified 
elsewhere in this part 1065. Use the following recommended methods to 
generate reference values or use good engineering judgment to select a 
different reference:
* * * * *
    (f) Performance criteria for measurement systems. Table 1 follows:
BILLING CODE 6560-50-P

[[Page 17857]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.217

* * * * *
BILLING CODE 6560-50-C
0
212. Amend Sec.  1065.308 by revising paragraph (e)(3) to read as 
follows:


Sec.  1065.308  Continuous gas analyzer system-response and updating-
recording verification--for gas analyzers not continuously compensated 
for other gas species.

* * * * *
    (e) * * *
    (3) If a measurement system fails the criteria in paragraphs (e)(1) 
and (2) of this section, you may use the measurement system only if the 
deficiency does not adversely affect your ability to show compliance 
with the applicable standards in this chapter.
* * * * *
0
213. Amend Sec.  1065.309 by revising paragraph (e)(3) to read as 
follows:


Sec.  1065.309  Continuous gas analyzer system-response and updating-
recording verification--for gas analyzers continuously compensated for 
other gas species.

* * * * *
    (e) * * *
    (3) If a measurement system fails the criteria in paragraphs (e)(1) 
and (2) of this section, you may use the measurement system only if the 
deficiency does not adversely affect your ability to show compliance 
with the applicable standards in this chapter.
* * * * *
0
214. Amend Sec.  1065.315 by revising paragraphs (a)(1) through (3) and 
(b) to read as follows:


Sec.  1065.315  Pressure, temperature, and dewpoint calibration.

    (a) * * *
    (1) Pressure. We recommend temperature-compensated, digital-
pneumatic, or deadweight pressure calibrators, with data-logging

[[Page 17858]]

capabilities to minimize transcription errors. We recommend using 
calibration reference quantities that are NIST-traceable within 0.5% uncertainty.
    (2) Temperature. We recommend digital dry-block or stirred-liquid 
temperature calibrators, with data logging capabilities to minimize 
transcription errors. We recommend using calibration reference 
quantities that are NIST-traceable within 0.5% uncertainty. 
You may perform linearity verification for temperature measurement 
systems with thermocouples, RTDs, and thermistors by removing the 
sensor from the system and using a simulator in its place. Use a NIST-
traceable simulator that is independently calibrated and, as 
appropriate, cold-junction compensated. The simulator uncertainty 
scaled to absolute temperature must be less than 0.5% of 
Tmax. If you use this option, you must use sensors that the 
supplier states are accurate to better than 0.5% of Tmax 
compared with their standard calibration curve.
    (3) Dewpoint. We recommend a minimum of three different 
temperature-equilibrated and temperature-monitored calibration salt 
solutions in containers that seal completely around the dewpoint 
sensor. We recommend using calibration reference quantities that are 
NIST-traceable within 0.5% uncertainty.
    (b) You may remove system components for off-site calibration. We 
recommend specifying calibration reference quantities that are NIST-
traceable within 0.5% uncertainty.
0
215. Amend Sec.  1065.320 by revising paragraph (c) to read as follows:


Sec.  1065.320  Fuel-flow calibration.

* * * * *
    (c) You may remove system components for off-site calibration. When 
installing a flow meter with an off-site calibration, we recommend that 
you consider the effects of the tubing configuration upstream and 
downstream of the flow meter. We recommend specifying calibration 
reference quantities that are NIST-traceable within 0.5% 
uncertainty.
0
216. Amend Sec.  1065.325 by revising paragraphs (a) and (b) to read as 
follows:


Sec.  1065.325  Intake-flow calibration.

    (a) Calibrate intake-air flow meters upon initial installation. 
Follow the instrument manufacturer's instructions and use good 
engineering judgment to repeat the calibration. We recommend using a 
calibration subsonic venturi, ultrasonic flow meter or laminar flow 
element. We recommend using calibration reference quantities that are 
NIST-traceable within 0.5% uncertainty.
    (b) You may remove system components for off-site calibration. When 
installing a flow meter with an off-site calibration, we recommend that 
you consider the effects of the tubing configuration upstream and 
downstream of the flow meter. We recommend specifying calibration 
reference quantities that are NIST-traceable within 0.5% 
uncertainty.
* * * * *
0
217. Amend Sec.  1065.330 by revising paragraphs (a) and (b) to read as 
follows:


Sec.  1065.330  Exhaust-flow calibration.

    (a) Calibrate exhaust-flow meters upon initial installation. Follow 
the instrument manufacturer's instructions and use good engineering 
judgment to repeat the calibration. We recommend that you use a 
calibration subsonic venturi or ultrasonic flow meter and simulate 
exhaust temperatures by incorporating a heat exchanger between the 
calibration meter and the exhaust-flow meter. If you can demonstrate 
that the flow meter to be calibrated is insensitive to exhaust 
temperatures, you may use other reference meters such as laminar flow 
elements, which are not commonly designed to withstand typical raw 
exhaust temperatures. We recommend using calibration reference 
quantities that are NIST-traceable within 0.5% uncertainty.
    (b) You may remove system components for off-site calibration. When 
installing a flow meter with an off-site calibration, we recommend that 
you consider the effects of the tubing configuration upstream and 
downstream of the flow meter. We recommend specifying calibration 
reference quantities that are NIST-traceable within 0.5% 
uncertainty.
* * * * *
0
218. Amend Sec.  1065.345 by revising paragraph (d) to read as follows:


Sec.  1065.345  Vacuum-side leak verification.

* * * * *
    (d) Dilution-of-span-gas leak test. You may use any gas analyzer 
for this test. If you use a FID for this test, correct for any HC 
contamination in the sampling system according to Sec.  1065.660. If 
you use an O2 analyzer described in Sec.  1065.280 for this 
test, you may use purified N2 to detect a leak. To avoid 
misleading results from this test, we recommend using only analyzers 
that have a repeatability of 0.5% or better at the reference gas 
concentration used for this test. Perform a vacuum-side leak test as 
follows:
    (1) Prepare a gas analyzer as you would for emission testing.
    (2) Supply reference gas to the analyzer span port and record the 
measured value.
    (3) Route overflow reference gas to the inlet of the sample probe 
or at a tee fitting in the transfer line near the exit of the probe. 
You may use a valve upstream of the overflow fitting to prevent 
overflow of reference gas out of the inlet of the probe, but you must 
then provide an overflow vent in the overflow supply line.
    (4) Verify that the measured overflow reference gas concentration 
is within 0.5% of the concentration measured in paragraph 
(d)(2) of this section. A measured value lower than expected indicates 
a leak, but a value higher than expected may indicate a problem with 
the reference gas or the analyzer itself. A measured value higher than 
expected does not indicate a leak.
* * * * *
0
219. Amend Sec.  1065.350 by revising paragraph (e)(1) to read as 
follows:


Sec.  1065.350  H2O interference verification for CO2 NDIR analyzers.

* * * * *
    (e) * * *
    (1) You may omit this verification if you can show by engineering 
analysis that for your CO2 sampling system and your 
emission-calculation procedures, the H2O interference for 
your CO2 NDIR analyzer always affects your brake-specific 
emission results within 0.5% of each of the applicable 
standards in this chapter. This specification also applies for vehicle 
testing, except that it relates to emission results in g/mile or g/
kilometer.
* * * * *
0
220. Amend Sec.  1065.405 by revising paragraph (a) to read as follows:


Sec.  1065.405  Test engine preparation and maintenance.

* * * * *
    (a) If you are testing an emission-data engine for certification, 
make sure it is built to represent production engines, consistent with 
paragraph (f) of this section.
    (1) This includes governors that you normally install on production 
engines. Production engines should also be tested with their installed 
governors. If your engine is equipped with multiple user-selectable 
governor types and if the governor does not manipulate the emission 
control system (i.e., the governor only modulates an ``operator 
demand'' signal such as commanded fuel rate, torque, or power), choose 
the governor type that allows the test cell to most accurately follow 
the duty cycle. If the governor manipulates the emission control 
system, treat it as an adjustable

[[Page 17859]]

parameter. If you do not install governors on production engines, 
simulate a governor that is representative of a governor that others 
will install on your production engines.
    (2) In certain circumstances, you may incorporate test cell 
components to simulate an in-use configuration, consistent with good 
engineering judgment. For example, Sec. Sec.  1065.122 and 1065.125 
allow the use of test cell components to represent engine cooling and 
intake air systems.
    (3) The provisions in Sec.  1065.110(e) also apply to emission-data 
engines for certification.
    (4) For engines using SCR, use any size DEF tank and fuel tank. We 
may require you to give us a production-type DEF tank, including any 
associated sensors, for our testing.
* * * * *
0
221. Amend Sec.  1065.410 by revising paragraph (c) to read as follows:


Sec.  1065.410  Maintenance limits for stabilized test engines.

* * * * *
    (c) If you inspect an engine, keep a record of the inspection and 
update your application for certification to document any changes that 
result. You may use any kind of equipment, instrument, or tool that is 
available at dealerships and other service outlets to identify 
malfunctioning components or perform maintenance. You may inspect using 
electronic tools to monitor engine performance, but only if the 
information is readable without specialized equipment.
* * * * *
0
222. Amend Sec.  1065.501 by revising paragraph (a) introductory text 
to read as follows:


Sec.  1065.501  Overview.

    (a) Use the procedures detailed in this subpart to measure engine 
emissions over a specified duty cycle. Refer to subpart J of this part 
for field test procedures that describe how to measure emissions during 
in-use engine operation. Refer to subpart L of this part for 
measurement procedures for testing related to standards other than 
brake-specific emission standards. This section describes how to--
* * * * *
0
223. Amend Sec.  1065.510 by revising paragraphs (a) introductory text, 
(b) introductory text, (b)(4) through (6), (c)(2), and (g)(2)(i) to 
read as follows:


Sec.  1065.510  Engine mapping.

    (a) Applicability, scope, and frequency. An engine map is a data 
set that consists of a series of paired data points that represent the 
maximum brake torque versus engine speed, measured at the engine's 
primary output shaft. Map your engine if the standard-setting part 
requires engine mapping to generate a duty cycle for your engine 
configuration. Map your engine while it is connected to a dynamometer 
or other device that can absorb work output from the engine's primary 
output shaft according to Sec.  1065.110. Configure any auxiliary work 
inputs and outputs such as hybrid, turbo-compounding, or thermoelectric 
systems to represent their in-use configurations, and use the same 
configuration for emission testing. See Figure 1 of Sec.  1065.210. 
This may involve configuring initial states of charge and rates and 
times of auxiliary-work inputs and outputs. We recommend that you 
contact the EPA Program Officer before testing to determine how you 
should configure any auxiliary-work inputs and outputs. If your engine 
has an auxiliary emission control device to reduce torque output that 
may activate during engine mapping, turn it off before mapping. Use the 
most recent engine map to transform a normalized duty cycle from the 
standard-setting part to a reference duty cycle specific to your 
engine. Normalized duty cycles are specified in the standard-setting 
part. You may update an engine map at any time by repeating the engine-
mapping procedure. You must map or re-map an engine before a test if 
any of the following apply:
* * * * *
    (b) Mapping variable-speed engines. Map variable-speed engines 
using the procedure in this paragraph (b). Note that under Sec.  
1065.10(c) we may allow or require you to use ``other procedures'' if 
the specified procedure results in unrepresentative testing or if your 
engine cannot be tested using the specified procedure. If the engine 
has a user-adjustable idle speed setpoint, you may set it to its 
minimum adjustable value for this mapping procedure and the resulting 
map may be used for any test, regardless of where it is set for running 
each test.
* * * * *
    (4) Operate the engine at the minimum mapped speed. A minimum 
mapped speed equal to (951)% of its warm idle speed 
determined in paragraph (b)(3) of this section may be used for any 
engine or test. A higher minimum mapped speed may be used if all the 
duty cycles that the engine is subject to have a minimum reference 
speed higher than the warm idle speed determined in paragraph (b)(3) of 
this section. In this case you may use a minimum mapped speed equal to 
(951)% of the lowest minimum reference speed in all the 
duty cycles the engine is subject to. Set operator demand to maximum 
and control engine speed at this minimum mapped speed for at least 15 
seconds. Set operator demand to maximum and control engine speed at 
(951)% of its warm idle speed determined in paragraph 
(b)(3)(i) of this section for at least 15 seconds.
    (5) Perform a continuous or discrete engine map as described in 
paragraphs (b)(5)(i) or (ii) of this section. A continuous engine map 
may be used for any engine. A discrete engine map may be used for 
engines subject only to steady-state duty cycles. Use linear 
interpolation between the series of points generated by either of these 
maps to determine intermediate torque values. Use the series of points 
generated by either of these maps to generate the power map as 
described in paragraph (e) of this section.
    (i) For continuous engine mapping, begin recording mean feedback 
speed and torque at 1 Hz or more frequently and increase speed at a 
constant rate such that it takes (4 to 6) min to sweep from the minimum 
mapped speed described in paragraphs (b)(4) of this section to the 
check point speed described in paragraph (b)(5)(iii) of this section. 
Use good engineering judgment to determine when to stop recording data 
to ensure that the sweep is complete. In most cases, this means that 
you can stop the sweep at any point after the power falls to 50% of the 
maximum value.
    (ii) For discrete engine mapping, select at least 20 evenly spaced 
setpoints from the minimum mapped speed described in paragraph (b)(4) 
of this section to the check point speed described in paragraph 
(b)(5)(iii) of this section. At each setpoint, stabilize speed and 
allow torque to stabilize. We recommend that you stabilize an engine 
for at least 15 seconds at each setpoint and record the mean feedback 
speed and torque of the last (4 to 6) seconds. Record the mean speed 
and torque at each setpoint.
    (iii) The check point speed of the map is the highest speed above 
maximum power at which 50% of maximum power occurs. If this speed is 
unsafe or unachievable (e.g., for ungoverned engines or engines that do 
not operate at that point), use good engineering judgment to map up to 
the maximum safe speed or maximum achievable speed. For discrete 
mapping, if the engine cannot be mapped to the check point speed, make 
sure the map includes at least 20 points from 95% of warm idle to the 
maximum mapped

[[Page 17860]]

speed. For continuous mapping, if the engine cannot be mapped to the 
check point speed, verify that the sweep time from 95% of warm idle to 
the maximum mapped speed is (4 to 6) min.
    (iv) Note that under Sec.  1065.10(c)(1) we may allow you to 
disregard portions of the map when selecting maximum test speed if the 
specified procedure would result in a duty cycle that does not 
represent in-use operation.
    (6) Determine warm high-idle speed for engines with a high-speed 
governor. You may skip this if the engine is not subject to transient 
testing with a duty cycle that includes reference speed values above 
100%. You may use a manufacturer-declared warm high-idle speed if the 
engine is electronically governed. For engines with a high-speed 
governor that regulates speed by disabling and enabling fuel or 
ignition at two manufacturer-specified speeds, declare the middle of 
this specified speed range as the warm high-idle speed. You may 
alternatively measure warm high-idle speed using the following 
procedure:
    (i) Run an operating point targeting zero torque.
    (A) Set operator demand to maximum and use the dynamometer to 
target zero torque on the engine's primary output shaft.
    (B) Wait for the engine governor and dynamometer to stabilize. We 
recommend that you stabilize for at least 15 seconds.
    (C) Record 1 Hz means of the feedback speed and torque for at least 
30 seconds. You may record means at a higher frequency as long as there 
are no gaps in the recorded data. For engines with a high-speed 
governor that regulates speed by disabling and enabling fuel or 
ignition, you may need to extend this stabilization period to include 
at least one disabling event at the higher speed and one enabling event 
at the lower speed.
    (D) Determine if the feedback speed is stable over the recording 
period. The feedback speed is considered stable if all the recorded 1 
Hz means are within 2% of the mean feedback speed over the 
recording period. If the feedback speed is not stable because of the 
dynamometer, void the results and repeat measurements after making any 
necessary corrections. You may void and repeat the entire map sequence, 
or you may void and replace only the results for establishing warm 
high-idle speed; use good engineering judgment to warm-up the engine 
before repeating measurements.
    (E) If the feedback speed is stable, use the mean feedback speed 
over the recording period as the measured speed for this operating 
point.
    (F) If the feedback speed is not stable because of the engine, 
determine the mean as the value representing the midpoint between the 
observed maximum and minimum recorded feedback speed.
    (G) If the mean feedback torque over the recording period is within 
(01)% of Tmaxmapped, use the measured speed for 
this operating point as the warm high-idle speed. Otherwise, continue 
testing as described in paragraph (b)(6)(ii) of this section.
    (ii) Run a second operating point targeting a positive torque. 
Follow the same procedure in paragraphs (b)(6)(i)(A) through (F) of 
this section, except that the dynamometer is set to target a torque 
equal to the mean feedback torque over the recording period from the 
previous operating point plus 20% of Tmax mapped.
    (iii) Use the mean feedback speed and torque values from paragraphs 
(b)(6)(i) and (ii) of this section to determine the warm high-idle 
speed. If the two recorded speed values are the same, use that value as 
the warm high-idle-speed. Otherwise, use a linear equation passing 
through these two speed-torque points and extrapolate to solve for the 
speed at zero torque and use this speed intercept value as the warm 
high-idle speed.
    (iv) You may use a manufacturer-declared Tmax instead of 
the measured Tmax mapped. If you do this, you may also 
measure the warm high-idle speed as described in this paragraph (b)(6) 
before running the operating point and speed sweeps specified in 
paragraphs (b)(4) and (5) of this section.
* * * * *
    (c) * * *
    (2) Map the amount of negative torque required to motor the engine 
by repeating paragraph (b) of this section with minimum operator 
demand, as applicable. You may start the negative torque map at either 
the minimum or maximum speed from paragraph (b) of this section.
* * * * *
    (g) * * *
    (2) * * *
    (i) Perform an engine map by using a series of continuous sweeps to 
cover the engine's full range of operating speeds. Prepare the engine 
for hybrid-active mapping by ensuring that the RESS state of charge is 
representative of normal operation. Perform the sweep as specified in 
paragraph (b)(5)(i) of this section, but stop the sweep to charge the 
RESS when the power measured from the RESS drops below the expected 
maximum power from the RESS by more than 2% of total system power 
(including engine and RESS power). Unless good engineering judgment 
indicates otherwise, assume that the expected maximum power from the 
RESS is equal to the measured RESS power at the start of the sweep 
segment. For example, if the 3-second rolling average of total engine-
RESS power is 200 kW and the power from the RESS at the beginning of 
the sweep segment is 50 kW, once the power from the RESS reaches 46 kW, 
stop the sweep to charge the RESS. Note that this assumption is not 
valid where the hybrid motor is torque-limited. Calculate total system 
power as a 3-second rolling average of instantaneous total system 
power. After each charging event, stabilize the engine for 15 seconds 
at the speed at which you ended the previous segment with operator 
demand set to maximum before continuing the sweep from that speed. 
Repeat the cycle of charging, mapping, and recharging until you have 
completed the engine map. You may shut down the system or include other 
operation between segments to be consistent with the intent of this 
paragraph (g)(2)(i). For example, for systems in which continuous 
charging and discharging can overheat batteries to an extent that 
affects performance, you may operate the engine at zero power from the 
RESS for enough time after the system is recharged to allow the 
batteries to cool. Use good engineering judgment to smooth the torque 
curve to eliminate discontinuities between map intervals.
* * * * *
0
224. Amend Sec.  1065.512 by revising paragraph (b)(1) to read as 
follows:


Sec.  1065.512  Duty cycle generation.

* * * * *
    (b) * * *
    (1) Engine speed for variable-speed engines. For variable-speed 
engines, normalized speed may be expressed as a percentage between warm 
idle speed, fnidle, and maximum test speed, 
fntest, or speed may be expressed by referring to a defined 
speed by name, such as ``warm idle,'' ``intermediate speed,'' or ``A,'' 
``B,'' or ``C'' speed. Section 1065.610 describes how to transform 
these normalized values into a sequence of reference speeds, 
fnref. Running duty cycles with negative or small normalized 
speed values near warm idle speed may cause low-speed idle governors to 
activate and the engine torque to exceed the reference torque even 
though the operator demand is at a minimum. In such cases, we recommend 
controlling the dynamometer so it gives priority to follow the 
reference torque instead of

[[Page 17861]]

the reference speed and let the engine govern the speed. Note that the 
cycle-validation criteria in Sec.  1065.514 allow an engine to govern 
itself. This allowance permits you to test engines with enhanced-idle 
devices and to simulate the effects of transmissions such as automatic 
transmissions. For example, an enhanced-idle device might be an idle 
speed value that is normally commanded only under cold-start conditions 
to quickly warm up the engine and aftertreatment devices. In this case, 
negative and very low normalized speeds will generate reference speeds 
below this higher enhanced-idle speed. You may do either of the 
following when using enhanced-idle devices:
    (i) Control the dynamometer so it gives priority to follow the 
reference torque, controlling the operator demand so it gives priority 
to follow reference speed and let the engine govern the speed when the 
operator demand is at minimum.
    (ii) While running an engine where the ECM broadcasts an enhanced-
idle speed that is above the denormalized speed, use the broadcast 
speed as the reference speed. Use these new reference points for duty-
cycle validation. This does not affect how you determine denormalized 
reference torque in paragraph (b)(2) of this section.
    (iii) If an ECM broadcast signal is not available, perform one or 
more practice cycles to determine the enhanced-idle speed as a function 
of cycle time. Generate the reference cycle as you normally would but 
replace any reference speed that is lower than the enhanced-idle speed 
with the enhanced-idle speed. This does not affect how you determine 
denormalized reference torque in paragraph (b)(2) of this section.
* * * * *
0
225. Amend Sec.  1065.514 by revising paragraph (d) to read as follows


Sec.  1065.514  Cycle-validation criteria for operation over specified 
duty cycles.

* * * * *
    (d) Omitting additional points. Besides engine cranking, you may 
omit additional points from cycle-validation statistics as described in 
the following table:

  Table 1 of Sec.   1065.514--Permissible Criteria for Omitting Points
                  From Duty-Cycle Regression Statistics
------------------------------------------------------------------------
When operator demand is at its   you may omit . .
             . . .                      .                 if . . .
------------------------------------------------------------------------
   For reference duty cycles that are specified in terms of speed and
                              torque (f, T)
------------------------------------------------------------------------
minimum.......................  power and torque.  Tref <0% (motoring).
minimum.......................  power and speed..  fnref = 0% (idle
                                                    speed) and Tref = 0%
                                                    (idle torque) and
                                                    Tref-(2% [middot]
                                                    Tmax mapped) < T <
                                                    Tref + (2% [middot]
                                                    Tmax mapped).
minimum.......................  power and speed..  fnref < enhanced-idle
                                                    speed \a\ and Tref >
                                                    0%.
minimum.......................  power and either   fn > fnref or T >
                                 torque or speed.   Tref but not if fn >
                                                    (fnref [middot]
                                                    102%) and T Tref +
                                                    (2% [middot] Tmax
                                                    mapped).
maximum.......................  power and either   fn < fnref or T <
                                 torque or speed.   Tref but not if fn <
                                                    (fnref [middot] 98%)
                                                    and T < Tref-(2%
                                                    [middot] Tmax
                                                    mapped).
------------------------------------------------------------------------
For reference duty cycles that are specified in terms of speed and power
                                 (f, P)
------------------------------------------------------------------------
minimum.......................  power and torque.  Pref < 0% (motoring).
minimum.......................  power and speed..  fnref = 0% (idle
                                                    speed) and Pref = 0%
                                                    (idle power) and
                                                    Pref-(2% [middot]
                                                    Pmax mapped) < P <
                                                    Pref + (2% [middot]
                                                    Pmax mapped).
minimum.......................  power and either   fn > fnref or P >
                                 torque or speed.   Pref but not if fn >
                                                    (fnref [middot]
                                                    102%) and P > Pref +
                                                    (2% [middot] Pmax
                                                    mapped).
maximum.......................  power and either   fn < fnref or P <
                                 torque or speed.   Pref but not if fn <
                                                    (fnref [middot] 98%)
                                                    and P < Pref-(2%
                                                    [middot] Pmax
                                                    mapped).
------------------------------------------------------------------------
\a\ Enhanced-idle speed determined from ECM broadcast or practice cycle.

* * * * *
0
226. Amend Sec.  1065.545 by revising paragraphs (a) and (b) 
introductory text to read as follows:


Sec.  1065.545  Verification of proportional flow control for batch 
sampling.

* * * * *
    (a) For any pair of sample and total flow rates, use continuous 
recorded data or 1 Hz means. Total flow rate means the raw exhaust flow 
rate for raw exhaust sampling and the dilute exhaust flow rate for CVS 
sampling. For each test interval, determine the standard error of the 
estimate, SEE, of the sample flow rate versus the total flow rate as 
described in Sec.  1065.602, forcing the intercept to zero. Determine 
the mean sample flow rate over each test interval as described in Sec.  
1065.602. For each test interval, demonstrate that SEE is at or below 
3.5% of the mean sample flow rate.
    (b) For any pair of sample and total flow rates, use continuous 
recorded data or 1 Hz means. Total flow rate means the raw exhaust flow 
rate for raw exhaust sampling and the dilute exhaust flow rate for CVS 
sampling. For each test interval, demonstrate that each flow rate is 
constant within 2.5% of its respective mean or target flow 
rate. You may use the following options instead of recording the 
respective flow rate of each type of meter:
* * * * *
0
227. Amend Sec.  1065.610 by revising paragraph (c)(2) to read as 
follows:


Sec.  1065.610  Duty cycle generation.

* * * * *
    (c) * * *
    (2) A, B, C, and D speeds. If your normalized duty cycle specifies 
speeds as A, B, C, or D values, use your power-versus-speed curve to 
determine the lowest speed below maximum power at which 50% of maximum 
power occurs. Denote this value as nlo. Take nlo 
to be warm idle speed if all power points at speeds below the maximum 
power speed are higher than 50% of maximum power. Also determine the 
highest speed above maximum power at which 70% of maximum power occurs. 
Denote this value as nhi. If all power points at speeds 
above the maximum power speed are higher than 70% of maximum power, 
take nhi to be the declared maximum safe engine speed or the 
declared maximum representative engine speed, whichever is lower. Use

[[Page 17862]]

nhi and nlo to calculate reference values for A, 
B, C, or D speeds as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.107

Example:

nlo = 1005 r/min
nhi = 2385 r/min
fnrefA = 0.25 [middot] (2385-1005) + 1005
fnrefB = 0.25 [middot] (2385-1005) + 1005
fnrefC = 0.25 [middot] (2385-1005) + 1005
fnrefD = 0.25 [middot] (2385-1005) + 1005
fnrefA = 1350 r/min
fnrefB = 1695 r/min
fnrefC = 2040 r/min
fnrefD = 1212 r/min
* * * * *
0
228. Amend Sec.  1065.650 by revising paragraphs (a), (c)(2)(i), (3), 
(4)(i), and (6), (d)(7), (e)(1) and (2), (f)(1) and (2), and (g)(1) and 
(2) to read as follows:


Sec.  1065.650  Emission calculations.

    (a) General. Calculate brake-specific emissions over each 
applicable duty cycle or test interval. For test intervals with zero 
work (or power), calculate the emission mass (or mass rate), but do not 
calculate brake-specific emissions. Unless specified otherwise, for the 
purposes of calculating and reporting emission mass (or mass rate), do 
not alter any negative values of measured or calculated quantities. You 
may truncate negative values in chemical balance quantities listed in 
Sec.  1065.655(c) to facilitate convergence. For duty cycles with 
multiple test intervals, refer to the standard-setting part for 
calculations you need to determine a composite result, such as a 
calculation that weights and sums the results of individual test 
intervals in a duty cycle. If the standard-setting part does not 
include those calculations, use the equations in paragraph (g) of this 
section. This section is written based on rectangular integration, 
where each indexed value (i.e., ``i'') represents (or approximates) the 
mean value of the parameter for its respective time interval, delta-t. 
You may also integrate continuous signals using trapezoidal integration 
consistent with good engineering judgment.
* * * * *
    (c) * * *
    (2) * * *
    (i) Varying flow rate. If you continuously sample from a varying 
exhaust flow rate, time align and then multiply concentration 
measurements by the flow rate from which you extracted it. We consider 
the following to be examples of varying flows that require a continuous 
multiplication of concentration times molar flow rate: Raw exhaust, 
exhaust diluted with a constant flow rate of dilution air, and CVS 
dilution with a CVS flow meter that does not have an upstream heat 
exchanger or electronic flow control. This multiplication results in 
the flow rate of the emission itself. Integrate the emission flow rate 
over a test interval to determine the total emission. If the total 
emission is a molar quantity, convert this quantity to a mass by 
multiplying it by its molar mass, M. The result is the mass of the 
emission, m. Calculate m for continuous sampling with variable flow 
using the following equations:
[GRAPHIC] [TIFF OMITTED] TP28MR22.108

Example:

MNMHC = 13.875389 g/mol
N = 1200
xNMHC1 = 84.5 [mu]mol/mol = 84.5 [middot] 10-6 
mol/mol
xNMHC2 = 86.0 [mu]mol/mol = 86.0 [middot] 10-6 
mol/mol
nexh1 = 2.876 mol/s
nexh2 = 2.224 mol/s
frecord = 1 Hz

    Using Eq. 1065.650-5,

[Delta]t = 1/1 = 1 s
mNMHC = 13.875389 [middot] (84.5 [middot] 10-6 
[middot] 2.876 + 86.0 [middot] 10-6 [middot] 2.224 + . . . + 
xNMHC1200 [middot] nexh) [middot] 1
mNMHC = 25.23 g
* * * * *
    (3) Batch sampling. For batch sampling, the concentration is a 
single value from a proportionally extracted batch sample (such as a 
bag, filter, impinger, or cartridge). In this case, multiply the mean 
concentration of the batch sample by the total flow from which the 
sample was extracted. You may calculate total flow by integrating a 
varying flow rate or by determining the mean of a constant flow rate, 
as follows:
    (i) Varying flow rate. If you collect a batch sample from a varying 
exhaust flow rate, extract a sample proportional to the varying exhaust 
flow rate. We consider the following to be examples of varying flows 
that require proportional sampling: Raw exhaust, exhaust diluted with a 
constant flow rate of dilution air, and CVS dilution with a CVS flow 
meter that does not have an upstream heat exchanger or electronic flow 
control. Integrate the flow rate over a test interval to determine the 
total flow from which you extracted the proportional sample. Multiply 
the mean concentration of the batch sample by the total flow from which 
the sample was extracted to determine the total emission. If the total 
emission is a molar quantity, convert this quantity to a mass by 
multiplying it by its molar mass, M. The result is the total emission 
mass, m. In the case of PM emissions, where the mean PM concentration 
is already in

[[Page 17863]]

units of mass per mole of exhaust, simply multiply it by the total 
flow. The result is the total mass of PM, mPM. Calculate m 
for each constituent as follows:
    (A) Calculate m for measuring gaseous emission constituents with 
sampling that results in a molar concentration, x, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.109

Example:

MNOx = 46.0055 g/mol
N = 9000
xNOx = 85.6 [mu]mol/mol = 85.6 [middot] 10-6 mol/
mol
ndexh1 = 25.534 mol/s
ndexh2 = 26.950 mol/s
frecord = 5 Hz

    Using Eq. 1065.650-5:

[Delta]t = 1/5 = 0.2
mNOx = 46.0055 [middot] 85.6 [middot] 10-6 
[middot] (25.534 + 26.950 + . . . + nexh9000) [middot] 0.2
mNOx = 4.201 g

    (B) Calculate m for sampling PM or any other analysis of a batch 
sample that yields a mass per mole of exhaust, M, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.110

    (ii) Proportional or constant flow rate. If you batch sample from a 
constant exhaust flow rate, extract a sample at a proportional or 
constant flow rate. We consider the following to be examples of 
constant exhaust flows: CVS diluted exhaust with a CVS flow meter that 
has either an upstream heat exchanger, electronic flow control, or 
both. Determine the mean molar flow rate from which you extracted the 
sample. Multiply the mean concentration of the batch sample by the mean 
molar flow rate of the exhaust from which the sample was extracted to 
determine the total emission and multiply the result by the time of the 
test interval. If the total emission is a molar quantity, convert this 
quantity to a mass by multiplying it by its molar mass, M. The result 
is the total emission mass, m. In the case of PM emissions, where the 
mean PM concentration is already in units of mass per mole of exhaust, 
simply multiply it by the total flow, and the result is the total mass 
of PM, mPM. Calculate m for each constituent as follows:
    (A) Calculate m for measuring gaseous emission constituents with 
sampling that results in a molar concentration, x, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.111

    (B) Calculate m for sampling PM or any other analysis of a batch 
sample that yields a mass per mole of exhaust, M, using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.112

    (C) The following example illustrates a calculation of 
mPM:

MPM = 144.0 [mu]g/mol = 144.0 [middot] 10-6 g/mol
ndexh = 57.692 mol/s
[Delta]t = 1200 s
mPM = 144.0 [middot] 10-6 [middot] 57.692 
[middot] 1200
mPM = 9.9692 g

    (4) * * *
    (i) For sampling with a constant dilution ratio, DR, of diluted 
exhaust versus exhaust flow (e.g., secondary dilution for PM sampling), 
calculate m using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.113

Example:

mPMdil = 6.853 g
DR = 6:1
mPM = 6.853 [middot] 6
mPM = 41.118 g
* * * * *
    (6) Mass of NMNEHC. Determine the mass of NMNEHC using one of the 
following methods:
    (i) If the test fuel has less than 0.010 mol/mol of ethane and you 
omit the NMNEHC calculations as described in Sec.  1065.660(c)(1), take 
the corrected mass of NMNEHC to be 0.95 times the corrected mass of 
NMHC.
    (ii) If the test fuel has at least 0.010 mol/mol of ethane and you 
omit the NMNEHC calculations as described in Sec.  1065.660(c)(1), take 
the corrected mass of NMNEHC to be 1.0 times the corrected mass of 
NMHC.
    (d) * * *
    (7) Integrate the resulting values for power over the test 
interval. Calculate total work as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.114

Where:

W = total work from the primary output shaft.
Pi = instantaneous power from the primary output shaft over an 
interval i.
[GRAPHIC] [TIFF OMITTED] TP28MR22.115


[[Page 17864]]


[GRAPHIC] [TIFF OMITTED] TP28MR22.116

* * * * *
    (e) * * *
    (1) To calculate, mi, multiply its mean concentration, x, by its 
corresponding mean molar flow rate, ni. If the result is a molar flow 
rate, convert this quantity to a mass rate by multiplying it by its 
molar mass, M. The result is the mean mass rate of the emission, mi. In 
the case of PM emissions, where the mean PM concentration is already in 
units of mass per mole of exhaust, simply multiply it by the mean molar 
flow rate, ni. The result is the mass rate of PM, mPM. 
Calculate mi using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.117

    (2) To calculate an engine's mean steady-state total power, P, add 
the mean steady-state power from all the work paths described in Sec.  
1065.210 that cross the system boundary including electrical power, 
mechanical shaft power, and fluid pumping power. For all work paths, 
except the engine's primary output shaft (crankshaft), the mean steady-
state power over the test interval is the integration of the net work 
flow rate (power) out of the system boundary divided by the period of 
the test interval. When power flows into the system boundary, the 
power/work flow rate signal becomes negative; in this case, include 
these negative power/work rate values in the integration to calculate 
the mean power from that work path. Some work paths may result in a 
negative mean power. Include negative mean power values from any work 
path in the mean total power from the engine rather than setting these 
values to zero. The rest of this paragraph (e)(2) describes how to 
calculate the mean power from the engine's primary output shaft. 
Calculate P using Eq. 1065.650-13, noting that P, f, and T refer to 
mean power, mean rotational shaft frequency, and mean torque from the 
primary output shaft. Account for the power of simulated accessories 
according to Sec.  1065.110 (reducing the mean primary output shaft 
power or torque by the accessory power or torque). Set the power to 
zero during actual motoring operation (negative feedback torques), 
unless the engine was connected to one or more energy storage devices. 
Examples of such energy storage devices include hybrid powertrain 
batteries and hydraulic accumulators, like the ones illustrated in 
Figure 1 of Sec.  1065.210. Set the power to zero for modes with a zero 
reference load (0 N[middot]m reference torque or 0 kW reference power). 
Include power during idle modes with simulated minimum torque or power.
[GRAPHIC] [TIFF OMITTED] TP28MR22.118

* * * * *
    (f) * * *
    (1) Total mass. To determine a value proportional to the total mass 
of an emission, determine total mass as described in paragraph (c) of 
this section, except substitute for the molar flow rate, n, or the 
total flow, n, with a signal that is linearly proportional to molar 
flow rate, nj, or linearly proportional to total flow, n, as follows:
[GRAPHIC] [TIFF OMITTED] TP28MR22.119

    (2) Total work. To calculate a value proportional to total work 
over a test interval, integrate a value that is proportional to power. 
Use information about the brake-specific fuel consumption of your 
engine, efuel, to convert a signal proportional to fuel flow 
rate to a signal proportional to power. To determine a signal 
proportional to fuel flow rate, divide a signal that is proportional to 
the mass rate of carbon products by the fraction of carbon in your 
fuel, wC. You may use a measured wC or you may 
use default values for a given fuel as described in Sec.  1065.655(e). 
Calculate the mass rate of carbon from the amount of carbon and water 
in the exhaust, which you determine with a chemical balance of fuel, 
DEF, intake air, and exhaust as described in Sec.  1065.655. In the 
chemical balance, you must use concentrations from the flow that 
generated the signal proportional to molar flow rate, nj, in paragraph 
(e)(1) of this section. Calculate a value proportional to total work as 
follows:

[[Page 17865]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.120

* * * * *
    (g) * * *
    (1) Use the following equation to calculate composite brake-
specific emissions for duty cycles with multiple test intervals all 
with prescribed durations, such as cold-start and hot-start transient 
cycles:
[GRAPHIC] [TIFF OMITTED] TP28MR22.121

Where:

i = test interval number.
N = number of test intervals.
WF = weighting factor for the test interval as defined in the 
standard-setting part.
m = mass of emissions over the test interval as determined in 
paragraph (c) of this section.
W = total work from the engine over the test interval as determined 
in paragraph (d) of this section.

Example:

N = 2
WF1 = 0.1428
WF2 = 0.8572
m1 = 70.125 g
m2 = 64.975 g
W1 = 25.783 kW [middot] hr
W2 = 25.783 kW [middot] hr
[GRAPHIC] [TIFF OMITTED] TP28MR22.122

eNOxcomp = 2.548 g/kW [middot] hr

    (2) Calculate composite brake-specific emissions for duty cycles 
with multiple test intervals that allow use of varying duration, such 
as discrete-mode steady-state duty cycles, as follows:
    (i) Use the following equation if you calculate brake-specific 
emissions over test intervals based on total mass and total work as 
described in paragraph (b)(1) of this section:
[GRAPHIC] [TIFF OMITTED] TP28MR22.123

Where:

i = test interval number.
N = number of test intervals.
WF = weighting factor for the test interval as defined in the 
standard-setting part.
m = mass of emissions over the test interval as determined in 
paragraph (c) of this section.
W = total work from the engine over the test interval as determined 
in paragraph (d) of this section.
t = duration of the test interval.

Example:

N = 2
WF1 = 0.85
WF1 = 0.15
m1 = 1.3753 g
m2 = 0.4135 g
t1 = 120 s
t2 = 200 s
W1 = 2.8375 kW [middot] hr
W2 = 0.0 kW [middot] hr
[GRAPHIC] [TIFF OMITTED] TP28MR22.124

eNOxcomp = 0.5001 g/kW [middot] hr

    (ii) Use the following equation if you calculate brake-specific 
emissions over test intervals based on the ratio of mass rate to power 
as described in paragraph (b)(2) of this section:
[GRAPHIC] [TIFF OMITTED] TP28MR22.125

Where:

i = test interval number.
N = number of test intervals.
WF = weighting factor for the test interval as defined in the 
standard-setting part.
mi = mean steady-state mass rate of emissions over the test interval 
as determined in paragraph (e) of this section.
P = mean steady-state power over the test interval as described in 
paragraph (e) of this section.

[[Page 17866]]

Example:

N = 2
WF1 = 0.85
WF2 = 0.15
mi1 = 2.25842 g/hr
mi2 = 0.063443 g/hr
P1 = 4.5383 kW
P2 = 0.0 kW
[GRAPHIC] [TIFF OMITTED] TP28MR22.126

eNOxcomp = 0.5001 g/kW [middot] hr
* * * * *
0
229. Amend Sec.  1065.655 by revising paragraph (e)(1)(i) to read as 
follows:


Sec.  1065.655  Chemical balances of fuel, DEF, intake air, and 
exhaust.

* * * * *
    (e) * * *
    (1) * * *
    (i) Determine the carbon and hydrogen mass fractions according to 
ASTM D5291 (incorporated by reference in Sec.  1065.1010). When using 
ASTM D5291 to determine carbon and hydrogen mass fractions of gasoline 
(with or without blended ethanol), use good engineering judgment to 
adapt the method as appropriate. This may include consulting with the 
instrument manufacturer on how to test high-volatility fuels. Allow the 
weight of volatile fuel samples to stabilize for 20 minutes before 
starting the analysis; if the weight still drifts after 20 minutes, 
prepare a new sample). Retest the sample if the carbon, hydrogen, 
oxygen, sulfur, and nitrogen mass fractions do not add up to a total 
mass of 100  0.5%; you may assume oxygen has a zero mass 
contribution for this specification for diesel fuel and neat (E0) 
gasoline. You may also assume that sulfur and nitrogen have a zero mass 
contribution for this specification for all fuels except residual fuel 
blends.
* * * * *
0
230. Amend Sec.  1065.660 by revising paragraph (c)(1) to read as 
follows:


Sec.  1065.660  THC, NMHC, NMNEHC, CH4, and C2H6 determination.

* * * * *
    (c) * * *
    (1) Calculate xNMNEHC based on the test fuel's ethane 
content as follows:
    (i) If the content of your test fuel contains less than 0.010 mol/
mol of ethane, you may omit the calculation of NMNEHC concentration and 
calculate the mass of NMNEHC as described in Sec.  1065.650(c)(6)(i).
    (ii) If the content of your fuel test contains at least 0.010 mol/
mol of ethane, you may omit the calculation of NMNEHC concentration and 
calculate the mass of NMNEHC as described in Sec.  1065.650(c)(6)(ii).
* * * * *
0
231. Amend Sec.  1065.667 by revising paragraph (a) to read as follows:


Sec.  1065.667  Dilution air background emission correction.

    (a) To determine the mass of background emissions to subtract from 
a diluted exhaust sample, first determine the total flow of dilution 
air, ndil, over the test interval. This may be a measured 
quantity or a calculated quantity. Multiply the total flow of dilution 
air by the mean mole fraction (i.e., concentration) of a background 
emission. This may be a time-weighted mean or a flow-weighted mean 
(e.g., a proportionally sampled background). Finally, multiply by the 
molar mass, M, of the associated gaseous emission constituent. The 
product of ndil and the mean molar concentration of a 
background emission and its molar mass, M, is the total background 
emission mass, m. In the case of PM, where the mean PM concentration is 
already in units of mass per mole of exhaust, multiply it by the total 
amount of dilution air flow, and the result is the total background 
mass of PM, mPM. Subtract total background mass from total 
mass to correct for background emissions.
* * * * *
0
232. Amend Sec.  1065.672 by revising paragraphs (d)(3) and (4) to read 
as follows:


Sec.  1065.672  Drift correction.

* * * * *
    (d) * * *
    (3) For any pre-test interval concentrations, use the last 
concentration determined before the test interval. For some test 
intervals, the last pre-zero or pre-span might have occurred before one 
or more earlier test intervals.
    (4) For any post-test interval concentrations, use the first 
concentration determined after the test interval. For some test 
intervals, the first post-zero or post-span might occur after one or 
more later test intervals.
* * * * *
0
233. Amend Sec.  1065.680 by revising the introductory text to read as 
follows:


Sec.  1065.680  Adjusting emission levels to account for infrequently 
regenerating aftertreatment devices.

    This section describes how to calculate and apply emission 
adjustment factors for engines using aftertreatment technology with 
infrequent regeneration events that may occur during testing. These 
adjustment factors are typically calculated based on measurements 
conducted for the purposes of engine certification, and then used to 
adjust the results of testing related to demonstrating compliance with 
emission standards. For this section, ``regeneration'' means an 
intended event during which emission levels change while the system 
restores aftertreatment performance. For example, exhaust gas 
temperatures may increase temporarily to remove sulfur from an adsorber 
or SCR catalyst or to oxidize accumulated particulate matter in a trap. 
The duration of this event extends until the aftertreatment performance 
and emission levels have returned to normal baseline levels. Also, 
``infrequent'' refers to regeneration events that are expected to occur 
on average less than once over a transient or ramped-modal duty cycle, 
or on average less than once per mode in a discrete-mode test.
* * * * *
0
234. Amend Sec.  1065.695 by revising paragraph (a) to read as follows:


Sec.  1065.695  Data requirements.

    (a) To determine the information we require from engine tests, 
refer to the standard-setting part and request from your EPA Program 
Officer the format used to apply for certification or demonstrate 
compliance. We may require different information for different 
purposes, such as for certification applications, approval requests for 
alternate procedures, selective enforcement audits, laboratory audits, 
production-line test reports, and field-test reports.
* * * * *
0
235. Amend Sec.  1065.715 by revising paragraph (b)(3) to read as 
follows:


Sec.  1065.715  Natural gas.

* * * * *
    (b) * * *

[[Page 17867]]

    (3) You may ask for approval to use fuel that does not meet the 
specifications in paragraph (a) of this section, but only if using the 
fuel would not adversely affect your ability to demonstrate compliance 
with the applicable standards in this chapter.
* * * * *
0
236. Amend Sec.  1065.720 by revising paragraphs (a) and (b)(3) to read 
as follows:


Sec.  1065.720  Data requirements.

    (a) Except as specified in paragraph (b) of this section, liquefied 
petroleum gas for testing must meet the specifications in the following 
table:

        Table 1 to Paragraph (a) of Sec.   1065.720--Test Fuel Specifications for Liquefied Petroleum Gas
----------------------------------------------------------------------------------------------------------------
                Property                                     Value                      Reference procedure \a\
----------------------------------------------------------------------------------------------------------------
Propane, C3H8...........................  Minimum, 0.85 m\3\/m\3\...................  ASTM D2163.
Vapor pressure at 38 [deg]C.............  Maximum, 1400 kPa.........................  ASTM D1267 or ASTM
                                                                                       D2598.\b\
Butanes.................................  Maximum, 0.05 m\3\/m\3\...................  ASTM D2163.
Butenes.................................  Maximum, 0.02 m\3\/m\3\...................  ASTM D2163.
Pentenes and heavier....................  Maximum, 0.005 m\3\/m\3\..................  ASTM D2163.
Propene.................................  Maximum, 0.1 m\3\/m\3\....................  ASTM D2163.
Residual matter (residue on evaporation   Maximum, 0.05 ml pass \c\.................  ASTM D2158.
 of 100 ml oil stain observation).
Corrosion, copper strip.................  Maximum, No. 1............................  ASTM D1838.
Sulfur..................................  Maximum, 80 mg/kg.........................  ASTM D6667.
Moisture content........................  pass......................................  ASTM D2713.
----------------------------------------------------------------------------------------------------------------
\a\ Incorporated by reference; see Sec.   1065.1010. See Sec.   1065.701(d) for other allowed procedures.
\b\ If these two test methods yield different results, use the results from ASTM D1267.
\c\ The test fuel must not yield a persistent oil ring when you add 0.3 ml of solvent residue mixture to a
  filter paper in 0.1 ml increments and examine it in daylight after two minutes.

    (b) * * *
    (3) You may ask for approval to use fuel that does not meet the 
specifications in paragraph (a) of this section, but only if using the 
fuel would not adversely affect your ability to demonstrate compliance 
with the applicable standards in this chapter.
* * * * *
0
237. Revise Sec.  1065.790 to read as follows:


Sec.  1065.790  Mass standards.

    (a) PM balance calibration weights. Use PM balance calibration 
weights that are certified as NIST-traceable within 0.1% 
uncertainty. Make sure your highest calibration weight has no more than 
ten times the mass of an unused PM-sample medium.
    (b) Dynamometer, fuel mass scale, and DEF mass scale calibration 
weights. Use dynamometer and mass scale calibration weights that are 
certified as NIST-traceable within 0.1% uncertainty.
0
238. Amend Sec.  1065.901 by revising paragraphs (a) and (b)(3) to read 
as follows:


Sec.  1065.901  Applicability.

    (a) Field testing. This subpart specifies procedures for field-
testing engines to determine brake-specific emissions and mass rate 
emissions using portable emission measurement systems (PEMS). These 
procedures are designed primarily for in-field measurements of engines 
that remain installed in vehicles or equipment the field. Field-test 
procedures apply to your engines only as specified in the standard-
setting part.
    (b) * * *
    (3) Do not use PEMS for laboratory measurements if it prevents you 
from demonstrating compliance with the applicable standards in this 
chapter. Some of the PEMS requirements in this part 1065 are less 
stringent than the corresponding laboratory requirements. Depending on 
actual PEMS performance, you might therefore need to account for some 
additional measurement uncertainty when using PEMS for laboratory 
testing. If we ask, you must show us by engineering analysis that any 
additional measurement uncertainty due to your use of PEMS for 
laboratory testing is offset by the extent to which your engine's 
emissions are below the applicable standards in this chapter. For 
example, you might show that PEMS versus laboratory uncertainty 
represents 5% of the standard, but your engine's deteriorated emissions 
are at least 20% below the standard for each pollutant.
0
239. Amend Sec.  1065.910 by revising paragraphs (b) and (d)(2) to read 
as follows:


Sec.  1065.910  PEMS auxiliary equipment for field testing.

* * * * *
    (b) Locate the PEMS to minimize the effects of the following 
parameters or place the PEMS in an environmental enclosure that 
minimizes the effect of these parameters on the emission measurement:
    (1) Ambient temperature changes.
    (2) Electromagnetic radiation.
    (3) Mechanical shock and vibration.
* * * * *
    (d) * * *
    (2) You may install your own portable power supply. For example, 
you may use batteries, fuel cells, a portable generator, or any other 
power supply to supplement or replace your use of vehicle power. You 
may connect an external power source directly to the vehicle's, 
vessel's, or equipment's power system; however, you must not supply 
power to the vehicle's power system in excess of 1% of the engine's 
maximum power.
0
240. Amend Sec.  1065.915 by revising paragraph (d)(6) to read as 
follows:


Sec.  1065.915  PEMS instruments.

* * * * *
    (d) * * *
    (6) Permissible deviations. ECM signals may deviate from the 
specifications of this part 1065, but the expected deviation must not 
prevent you from demonstrating that you meet the applicable standards 
in this chapter. For example, your emission results may be sufficiently 
below an applicable standard, such that the deviation would not 
significantly change the result. As another example, a very low engine-
coolant temperature may define a logical statement that determines when 
a test interval may start. In this case, even if the ECM's sensor for 
detecting coolant temperature was not very accurate or repeatable, its 
output would never deviate so far as to significantly affect when a 
test interval may start.
0
241. Amend Sec.  1065.920 by:
0
a. Revising paragraphs (b)(2), (b)(4) introductory text, and 
(b)(4)(iii).
0
b. Removing paragraph (b)(5).
0
c. Redesignating paragraphs (b)(6) and (7) as (b)(5) and (6), 
respectively.

[[Page 17868]]

0
d. Revising newly redesignated paragraph (b)(6)(ii).
    The revisions read as follows:


Sec.  1065.920  PEMS calibrations and verifications.

* * * * *
    (b) * * *
    (2) Select or create a duty cycle that has all the following 
characteristics:
    (i) Engine operation that represents normal in-use speeds, loads, 
and degree of transient activity. Consider using data from previous 
field tests to generate a cycle.
    (ii) A duration of (6 to 9) hours.
* * * * *
    (4) Determine the brake-specific emissions and mass rate emissions, 
as applicable, for each test interval for both laboratory and the PEMS 
measurements, as follows:
* * * * *
    (iii) If the standard-setting part specifies the use of a 
measurement allowance for field testing, also apply the measurement 
allowance during calibration using good engineering judgment. If the 
measurement allowance is normally added to the standard, this means you 
must subtract the measurement allowance from measured PEMS emission 
results.
* * * * *
    (6) * * *
    (ii) The entire set of test-interval results passes the 95% 
confidence alternate-procedure statistics for field testing (t-test and 
F-test) specified in Sec.  1065.12.
0
242. Amend Sec.  1065.935 by revising paragraphs (d)(4) and (g) to read 
as follows:


Sec.  1065.935  Emission test sequence for field testing.

* * * * *
    (d) * * *
    (4) Conduct periodic verifications such as zero and span 
verifications on PEMS gas analyzers and use these to correct for drift 
according to paragraph (g) of this section. Do not include data 
recorded during verifications in emission calculations. Conduct the 
verifications as follows:
    (i) For PEMS gas analyzers used to determine NTE emission values, 
perform verifications as recommended by the PEMS manufacturer or as 
indicated by good engineering judgment.
    (ii) For PEMS gas analyzers used to determine bin emission values, 
perform zero verifications at least hourly using purified air. Perform 
span verification at the end of the shift-day or more frequently as 
recommended by the PEMS manufacturer or as indicated by good 
engineering judgment.
* * * * *
    (g) Take the following steps after emission sampling is complete:
    (1) As soon as practical after emission sampling, analyze any 
gaseous batch samples.
    (2) If you used dilution air, either analyze background samples or 
assume that background emissions were zero. Refer to Sec.  1065.140 for 
dilution-air specifications.
    (3) After quantifying all exhaust gases, record mean analyzer 
values after stabilizing a zero gas to each analyzer, then record mean 
analyzer values after stabilizing the span gas to the analyzer. 
Stabilization may include time to purge an analyzer of any sample gas 
and any additional time to account for analyzer response. Use these 
recorded values, including pre-test verifications and any zero 
verifications during testing, to correct for drift as described in 
Sec.  1065.550.
    (4) Verify PEMS gas analyzers used to determine NTE emission values 
as follows:
    (i) Invalidate any data that does not meet the range criteria in 
Sec.  1065.550. Note that it is acceptable that analyzers exceed 100% 
of their ranges when measuring emissions between test intervals, but 
not during test intervals. You do not have to retest an engine if the 
range criteria are not met.
    (ii) Invalidate any data that does not meet the drift criterion in 
Sec.  1065.550. For HC, invalidate any data if the difference between 
the uncorrected and the corrected brake-specific HC emission values are 
within 10% of the uncorrected results or the applicable 
standard, whichever is greater. For data that does meet the drift 
criterion, correct those test intervals for drift according to Sec.  
1065.672 and use the drift corrected results in emissions calculations.
    (5) Verify PEMS gas analyzers used to determine bin emission values 
as follows:
    (i) Invalidate data from a whole shift-day if more than 1% of 
recorded 1 Hz data exceeds 100% of the selected gas analyzer range. For 
analyzer outputs exceeding 100% of range, calculate emission results 
using the reported value. You must retest an engine if the range 
criteria are not met.
    (ii) Invalidate any data for periods in which the CO, 
CO2, and HC gas analyzers do not meet the drift criterion in 
Sec.  1065.550. For HC, invalidate data if the difference between the 
uncorrected and the corrected brake-specific HC emission values are 
within 10% of the uncorrected results or the applicable 
standard, whichever is greater. For data that do meet the drift 
criterion, correct that data for drift according to Sec.  1065.672 and 
use the drift corrected results in emissions calculations.
    (iii) For PEMS NOX analyzers used to determine bin 
emission values, use the following drift limits to verify drift instead 
of meeting the drift criteria specified in Sec.  1065.550:
    (A) The allowable analyzer zero-drift between successive zero 
verifications is 2.5 ppm. The analyzer zero-drift limit 
over the shift-day is 10 ppm.
    (B) The allowable analyzer span-drift limit is 4% of 
the measured span value between successive span verifications.
    (6) Unless you weighed PM in-situ, such as by using an inertial PM 
balance, place any used PM samples into covered or sealed containers 
and return them to the PM-stabilization environment and weigh them as 
described in Sec.  1065.595.
0
243. Amend Sec.  1065.1001 by:
0
a. Removing the definition for ``Designated Compliance Officer''.
0
b. Adding definitions for ``Dual-fuel'', ``EPA Program Officer'', and 
``Flexible-fuel'' in alphabetical order.
0
c. Removing the definition for ``Intermediate test speed''.
0
d. Adding a definition for ``Intermediate speed'' in alphabetical 
order.
0
e. Revising the definition for ``NIST-traceable''.
0
f. Adding definitions for ``No-load'' and ``Rechargeable Energy Storage 
System (RESS)'' in alphabetical order.
0
g. Revising the definition for ``Steady-state''.
    The additions and revisions read as follows:


Sec.  1065.1001  Definitions.

* * * * *
    Dual-fuel has the meaning given in the standard-setting part.
* * * * *
    EPA Program Officer means the Director, Compliance Division, U.S. 
Environmental Protection Agency, 2000 Traverwood Dr., Ann Arbor, MI 
48105.
* * * * *
    Flexible-fuel has the meaning given in the standard-setting part.
* * * * *
    Intermediate speed has the meaning given in Sec.  1065.610.
* * * * *
    NIST-traceable means relating to a standard value that can be 
related to NIST-stated references through an unbroken chain of 
comparisons, all having stated uncertainties, as specified in NIST 
Technical Note 1297 (incorporated by reference in Sec.  1065.1010). 
Allowable uncertainty

[[Page 17869]]

limits specified for NIST-traceability refer to the propagated 
uncertainty specified by NIST.
* * * * *
    No-load means a dynamometer setting of zero torque.
* * * * *
    Rechargeable Energy Storage System (RESS) means the components of a 
hybrid engine or vehicle that store recovered energy for later use, 
such as the battery system in a hybrid electric vehicle.
* * * * *
    Steady-state means relating to emission tests in which engine speed 
and load are held at a finite set of nominally constant values. Steady-
state tests are generally either discrete-mode tests or ramped-modal 
tests.
* * * * *
0
244. Amend Sec.  1065.1005 by adding a row in Table 1 of paragraph (a) 
for ``[kappa]'' in alphanumeric order and revising paragraphs (b), and 
(f)(1), (3), and (4) to read as follows:


Sec.  1065.1005  Symbols, abbreviations, acronyms, and units of 
measure.

* * * * *
    (a) * * *

                               Table 1 of Sec.   1065.1005--Symbols for Quantities
----------------------------------------------------------------------------------------------------------------
                                                                                               Units in terms of
         Symbol                 Quantity                Unit                Unit symbol          SI base units
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
[kappa].................  opacity............
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *
    (b) Symbols for chemical species. This part uses the following 
symbols for chemical species and exhaust constituents:

               Table 2 of Sec.   1065.1005--Symbols for Chemical Species and Exhaust Constituents
----------------------------------------------------------------------------------------------------------------
              Symbol                                                  Species
----------------------------------------------------------------------------------------------------------------
Ar...............................  argon.
C................................  carbon.
CH2O.............................  formaldehyde.
CH2O2............................  formic acid.
CH3OH............................  methanol.
CH4..............................  methane.
C2H4O............................  acetaldehyde.
C2H5OH...........................  ethanol.
C2H6.............................  ethane.
C3H7OH...........................  propanol.
C3H8.............................  propane.
C4H10............................  butane.
C5H12............................  pentane.
CO...............................  carbon monoxide.
CO2..............................  carbon dioxide.
H................................  atomic hydrogen.
H2...............................  molecular hydrogen.
H2O..............................  water.
H2SO4............................  sulfuric acid.
HC...............................  hydrocarbon.
He...............................  helium.
85Kr.............................  krypton 85.
N2...............................  molecular nitrogen.
NH3..............................  ammonia.
NMHC.............................  nonmethane hydrocarbon.
NMHCE............................  nonmethane hydrocarbon equivalent.
NMNEHC...........................  nonmethane-nonethane hydrocarbon.
NO...............................  nitric oxide.
NO2..............................  nitrogen dioxide.
NOX..............................  oxides of nitrogen.
N2O..............................  nitrous oxide.
NMOG.............................  nonmethane organic gases.
NONMHC...........................  non-oxygenated nonmethane hydrocarbon.
NOTHC............................  non-oxygenated total hydrocarbon.
O2...............................  molecular oxygen.
OHC..............................  oxygenated hydrocarbon.
210Po............................  polonium 210.
PM...............................  particulate matter.
S................................  sulfur.
SVOC.............................  semi-volatile organic compound.
THC..............................  total hydrocarbon.
THCE.............................  total hydrocarbon equivalent.

[[Page 17870]]

 
ZrO2.............................  zirconium dioxide.
----------------------------------------------------------------------------------------------------------------

* * * * *
    (f) * * *
    (1) This part uses the following constants for the composition of 
dry air:

                 Table 6 of Sec.   1065.1005--Constants
------------------------------------------------------------------------
         Symbol                 Quantity                 mol/mol
------------------------------------------------------------------------
[khgr]Arair............  amount of argon in dry                  0.00934
                          air.
[khgr]CO2air...........  amount of carbon                       0.000375
                          dioxide in dry air.
[khgr]N2air............  amount of nitrogen in                   0.78084
                          dry air.
[khgr]O2air............  amount of oxygen in                    0.209445
                          dry air.
------------------------------------------------------------------------

* * * * *
    (3) This part uses the following molar gas constant for ideal 
gases:

     Table 8 of Sec.   1065.1005--Molar Gas Constant for Ideal Gases
------------------------------------------------------------------------
                                                     J/([middot]K)
                                               (m\2\[middot]kg[middot]s-
        Symbol                 Quantity             \2\[middot]mol-
                                                   \1\[middot]K-\1\)
------------------------------------------------------------------------
R.....................  molar gas constant...                  8.314472
------------------------------------------------------------------------

    (4) This part uses the following ratios of specific heats for 
dilution air and diluted exhaust:

 Table 9 of Sec.   1065.1005--Ratios of Specific Heats for Dilution Air
                           and Diluted Exhaust
------------------------------------------------------------------------
                                                  [J/(kg[middot]K)]/[J/
         Symbol                 Quantity              (kg[middot]K)]
------------------------------------------------------------------------
[gamma]air.............  ratio of specific                         1.399
                          heats for intake air
                          or dilution air.
[gamma]dil.............  ratio of specific                         1.399
                          heats for diluted
                          exhaust.
[gamma]exh.............  ratio of specific                         1.385
                          heats for raw exhaust.
------------------------------------------------------------------------

* * * * *
0
245. Amend subpart L by adding a new center header ``VANADIUM 
SUBLIMATION IN SCR CATALYSTS'' after Sec.  1065.1111 and adding 
Sec. Sec.  1065.1113, 1065.1115, 1065.1117, 1065.1119, and 1065.1121 
under the new center header to read as follows:

Vanadium Sublimation in SCR Catalysts


Sec.  1065.1113  General provisions related to vanadium sublimation 
temperatures in SCR catalysts.

    Sections 1065.1113 through 1065.1121 specify procedures for 
determining vanadium emissions from a catalyst based on catalyst 
temperature. Vanadium can be emitted from the surface of SCR catalysts 
at temperatures above 550 [deg]C, dependent on the catalyst 
formulation. These procedures are appropriate for measuring the 
vanadium sublimation product from a reactor by sampling onto an 
equivalent mass of alumina and performing analysis by Inductively 
Coupled Plasma--Optical Emission Spectroscopy (ICP-OES). Follow 
standard analytic chemistry methods for any aspects of the analysis 
that are not specified.
    (a) The procedure is adapted from ``Behavior of Titania-supported 
Vanadia and Tungsta SCR Catalysts at High Temperatures in Reactant 
Streams: Tungsten and Vanadium Oxide and Hydroxide Vapor Pressure 
Reduction by Surficial Stabilization'' (Chapman, D.M., Applied 
Catalysis A: General, 2011, 392, 143-150) with modifications to the 
acid digestion method from ``Measuring the trace elemental composition 
of size-resolved airborne particles'' (Herner, J.D. et al., 
Environmental Science and Technology, 2006, 40, 1925-1933).
    (b) Laboratory cleanliness is especially important throughout 
vanadium testing. Thoroughly clean all sampling system components and 
glassware before testing to avoid sample contamination.


Sec.  1065.1115  Reactor design and setup.

    Vanadium measurements rely on a reactor that adsorbs sublimation 
vapors of vanadium onto an alumina capture bed with high surface area.
    (a) Configure the reactor with the alumina capture bed downstream 
of the catalyst in the reactor's hot zone to adsorb vanadium vapors at 
high temperature. You may use quartz beads upstream of the catalyst to 
help stabilize reactor gas temperatures. Select an alumina material and 
design the reactor to minimize sintering of the alumina. For a 1-inch 
diameter reactor, use 4 to 5 g of \1/8\ inch extrudates or -14/+24 mesh 
(approximately 0.7 to 1.4 mm) gamma alumina (such as Alfa Aesar, 
aluminum oxide, gamma, catalyst support, high surface area, bimodal). 
Position the alumina downstream from either an equivalent amount of -
14/+24 mesh catalyst sample or an approximately 1-inch diameter by 1 to 
3-inch long catalyst-coated monolith sample cored from the production-

[[Page 17871]]

intent vanadium catalyst substrate. Separate the alumina from the 
catalyst with a 0.2 to 0.4 g plug of quartz wool. Place a short 4 g 
plug of quartz wool downstream of the alumina to maintain the position 
of that bed. Use good engineering judgment to adjust as appropriate for 
reactors of different sizes.
    (b) Include the quartz wool with the capture bed to measure 
vanadium content. We recommend analyzing the downstream quartz wool 
separately from the alumina to see if the alumina fails to capture some 
residual vanadium.
    (c) Configure the reactor such that both the sample and capture 
beds are in the reactor's hot zone. Design the reactor to maintain 
similar temperatures in the capture bed and catalyst. Monitor the 
catalyst and alumina temperatures with Type K thermocouples inserted 
into a thermocouple well that is in contact with the catalyst sample 
bed.
    (d) If there is a risk that the quartz wool and capture bed are not 
able to collect all the vanadium, configure the reactor with an 
additional capture bed and quartz wool plug just outside the hot zone 
and analyze the additional capture bed and quartz wool separately.
    (e) An example of a catalyst-coated monolith and capture bed 
arrangement in the reactor tube are shown in the following figure:
[GRAPHIC] [TIFF OMITTED] TP28MR22.127

    (f) You may need to account for vanadium-loaded particles 
contaminating catalyst-coated monoliths as a result of physical 
abrasion. To do this, determine how much titanium is in the capture bed 
and compare to an alumina blank. Using these values and available 
information about the ratio of vanadium to titanium in the catalyst, 
subtract the mass of vanadium catalyst material associated with the 
catalyst particles from the total measured vanadium on the capture bed 
to determine the vanadium recovered due to sublimation.


Sec.  1065.1117  Reactor aging cycle for determination of vanadium 
sublimation temperature.

    This section describes the conditions and process required to 
operate the reactor described in Sec.  1065.1115 for collection of the 
vanadium sublimation samples for determination of vanadium sublimation 
temperature. The reactor aging cycle constitutes the process of testing 
the catalyst sample over all the test conditions described in paragraph 
(b) of this section.
    (a) Set up the reactor to flow gases with a space velocity of at 
least 35,000/hr with a pressure drop across the catalyst and capture 
beds less than 35 kPa. Use test gases meeting the following 
specifications, noting that not all gases will be used at the same 
time:
    (1) 5 vol% O2, balance N2.
    (2) NO, balance N2. Use an NO concentration of (200 to 
500) ppm.
    (3) NH3, balance N2. Use an NH3 concentration 
of (200 to 500) ppm.
    (b) Perform testing as follows:
    (1) Add a new catalyst sample and capture bed into the reactor as 
described in Sec.  1065.1113. Heat the reactor to 550 [deg]C while 
flowing the oxygen blend specified in paragraph (a)(1) of this section 
as a pretest gas mixture. Ensure that no H2O is added to the 
pretest gas mixture to reduce the risk of sintering and vanadium 
sublimation.
    (2) Start testing at a temperature that is lower than the point at 
which vanadium starts to sublime. Start testing when the reactor 
reaches 550 [deg]C unless testing supports a lower starting 
temperature. Once the reactor reaches the starting temperature and the 
catalyst has been equilibrated to the reactor temperature, flow NO, and 
NH3 test gases for 18 hours with a nominal H2O 
content of 5 volume percent.
    (3) After 18 hours of exposure, flow the pretest oxygen blend as 
specified in paragraph (b)(1) of this section and allow the reactor to 
cool down to room temperature.
    (4) Analyze the sample as described in Sec.  1065.1121.
    (5) Repeat the testing in paragraphs (b)(1) through (4) of this 
section by raising the reactor temperature in increments of 50 [deg]C 
up to the temperature at which vanadium sublimation begins.
    (6) Once sublimation has been detected, repeat the testing in 
paragraphs (b)(1) through (4) of this section by decreasing the reactor 
temperature in increments of 25 [deg]C until the vanadium concentration 
falls below the sublimation threshold.
    (7) Repeat the testing in paragraphs (b)(1) through (6) of this 
section with a nominal H2O concentration of 10 volume 
percent or the maximum water concentration expected at the standard.

[[Page 17872]]

    (8) You may optionally test in a manner other than testing a single 
catalyst formulation in series across all test temperatures. For 
example, you may test additional samples at the same reactor 
temperature before moving on to the next temperature.
    (c) The effective sublimation temperature for the tested catalyst 
is the lowest reactor temperature determined in paragraph (b) of this 
section below which vanadium emissions are less than the method 
detection limit.


Sec.  1065.1119  Blank testing.

    This section describes the process for analyzing blanks. Use blanks 
to determine the background effects and the potential for contamination 
from the sampling process.
    (a) Take blanks from the same batch of alumina used for the capture 
bed.
    (b) Media blanks are used to determine if there is any 
contamination in the sample media. Analyze at least one media blank for 
each reactor aging cycle or round of testing performed under Sec.  
1065.1117. If your sample media is taken from the same lot, you may 
analyze media blanks less frequently consistent with good engineering 
judgment.
    (c) Field blanks are used to determine if there is any 
contamination from environmental exposure of the sample media. Analyze 
at least one field blank for each reactor aging cycle or round of 
testing performed under Sec.  1065.1117. Field blanks must be contained 
in a sealed environment and accompany the reactor sampling system 
throughout the course of a test, including reactor disassembly, sample 
packaging, and storage. Use good engineering judgment to determine how 
frequently to generate field blanks. Keep the field blank sample close 
to the reactor during testing.
    (d) Reactor blanks are used to determine if there is any 
contamination from the sampling system. Analyze at least one reactor 
blank for each reactor aging cycle or round of testing performed under 
Sec.  1065.1117.
    (1) Test reactor blanks with the reactor on and operated 
identically to that of a catalyst test in Sec.  1065.1117 with the 
exception that when loading the reactor, only the alumina capture bed 
will be loaded (no catalyst sample is loaded for the reactor blank). We 
recommend acquiring reactor blanks with the reactor operating at 
average test temperature you used when acquiring your test samples 
under Sec.  1065.1117.
    (2) You must run at least three reactor blanks if the result from 
the initial blank analysis is above the detection limit of the method, 
with additional blank runs based on the uncertainty of the reactor 
blank measurements, consistent with good engineering judgment.


Sec.  1065.1121  Vanadium sample dissolution and analysis in alumina 
capture beds.

    This section describes the process for dissolution of vanadium from 
the vanadium sublimation samples collect in Sec.  1065.1117 and any 
blanks collected in Sec.  1065.1119 as well as the analysis of the 
digestates to determine the mass of vanadium emitted and the associated 
sublimation temperature threshold based on the results of all the 
samples taken during the reactor aging cycle.
    (a) Digest the samples using the following procedure, or an 
equivalent procedure:
    (1) Place the recovered alumina, a portion of the ground quartz 
tube from the reactor, and the quartz wool in a Teflon pressure vessel 
with a mixture made from 1.5 mL of 16 N HNO3, 0.5 mL of 28 N 
HF, and 0.2 mL of 12 N HCl. Note that the amount of ground quartz tube 
from the reactor included in the digestion can influence the vanadium 
concentration of both the volatilized vanadium from the sample and the 
method detection limit. You must be consistent with the amount ground 
quartz tube included in the sample analysis for your testing. You must 
limit the amount of quartz tube to include only portions of the tube 
that would be likely to encounter volatilized vanadium.
    (2) Program a microwave oven to heat the sample to 180 [deg]C over 
9 minutes, followed by a 10-minute hold at that temperature, and 1 hour 
of ventilation/cooling.
    (3) After cooling, dilute the digests to 30 mL with high purity 
18M[Omega] water prior to ICP-MS (or ICP-OES) analysis. Note that this 
digestion technique requires adequate safety measures when working with 
HF at high temperature and pressure. To avoid ``carry-over'' 
contamination, rigorously clean the vessels between samples as 
described in ``Microwave digestion procedures for environmental 
matrixes'' (Lough, G.C. et al., Analyst. 1998, 123 (7), 103R-133R).
    (b) Analyze the digestates for vanadium as follows:
    (1) Perform the analysis using ICP-OES (or ICP-MS) using standard 
plasma conditions (1350 W forward power) and a desolvating 
microconcentric nebulizer, which will significantly reduce oxide- and 
chloride-based interferences.
    (2) We recommend that you digest and analyze a minimum of three 
solid vanadium NIST Standard Reference Materials in duplicate with 
every batch of 25 vanadium alumina capture bed samples that you analyze 
in this section, as described in ``Emissions of metals associated with 
motor vehicle roadways'' (Herner, J.D. et al., Environmental Science 
and Technology. 2005, 39, 826-836). This will serve as a quality 
assurance check to help gauge the relative uncertainties in each 
measurement, specifically if the measurement errors are normally 
distributed and independent.
    (3) Use the 3-sigma approach to determine the analytical method 
detection limits for vanadium and the 10-sigma approach if you 
determine the reporting limit. This process involves analyzing at least 
seven replicates of a blank using the analytical method described in 
paragraphs (a) and (b)(1) of this section, converting the responses 
into concentration units, and calculating the standard deviation. 
Determine the detection limit by multiplying the standard deviation by 
3 and adding it to the average. Determine the reporting limit by 
multiplying the standard deviation by 10 and adding it to the average. 
Determine the following analytical method detection limits:
    (i) Determine the ICP-MS (or ICP-OES) instrumental detection limit 
(ng/L) by measuring at least seven blank samples made up of the 
reagents from paragraph (a) of this section.
    (ii) Determine the method detection limit (pg/m\3\ of flow or pg/g 
of the total combined mass of the recovered alumina, a portion of the 
ground quartz tube from the reactor, and the quartz wool) by measuring 
at least seven reactor blank samples taken as described in Sec.  
1065.1119(d).
    (iii) We recommend that your method detection limit determined 
under paragraph (b)(3)(ii) of this section is at or below 2 ppm (2 pg/
m\3\). You must report your detection limits determined in this 
paragraph (b)(3) and reporting limits (if determined) with your test 
results.
    (4) If you account for vanadium-loaded particles contaminating 
catalyst-coated monoliths as a result of physical abrasion as allowed 
in Sec.  1065.1115(f), use the 3-sigma approach to determine the 
analytical method detection limits for titanium and the 10-sigma 
approach if you determine the reporting limit. This process involves 
analyzing at least seven replicates of a blank using the analytical 
method described in paragraphs (a) and (b)(1) of this section, 
converting the responses into concentration units, and calculating the 
standard deviation. Determine the detection limit by multiplying the 
standard deviation by 3 and subtracting it from the average. Determine 
the reporting limit by multiplying the

[[Page 17873]]

standard deviation by 10 and subtracting it from the average.
    (i) Determine the ICP-MS (or ICP-OES) instrumental detection limit 
(ng/L) by measuring at least seven blank samples made up of the 
reagents from paragraph (a) of this section.
    (ii) Determine the method detection limit (pg/m\3\ of flow or pg/g 
of the total combined mass of the recovered alumina, a portion of the 
ground quartz tube from the reactor, and the quartz wool) by measuring 
at least seven reactor blank samples taken as described in Sec.  
1065.1119(d).
0
246. Amend subpart L by adding a new center header ``SMOKE OPACITY'' 
after the newly added Sec.  1065.1121 and adding Sec. Sec.  1065.1123, 
1065.1125, and 1065.1127 under the new center header to read as 
follows:

Smoke Opacity


Sec.  1065.1123  General provisions for determining exhaust opacity.

    The provisions of Sec.  1065.1125 describe system specifications 
for measuring percent opacity of exhaust for all types of engines. The 
provisions of Sec.  1065.1127 describe how to use such a system to 
determine percent opacity of engine exhaust for applications other than 
locomotives. See 40 CFR 1033.525 for measurement procedures for 
locomotives.


Sec.  1065.1125  Exhaust opacity measurement system.

    Smokemeters measure exhaust opacity using full-flow open-path light 
extinction with a built-in light beam across the exhaust stack or 
plume. Prepare and install a smokemeter system as follows:
    (a) Except as specified in paragraph (d) of this section, use a 
smokemeter capable of providing continuous measurement that meets the 
following specifications:
    (1) Use an incandescent lamp with a color temperature between (2800 
and 3250) K or a different light source with a spectral peak between 
(550 and 570) nm.
    (2) Collimate the light beam to a nominal diameter of 3 centimeters 
and maximum divergence angle of 6 degrees.
    (3) Include a photocell or photodiode as a detector. The detector 
must have a maximum spectral response between (550 and 570) nm, with 
less than 4 percent of that maximum response below 430 nm and above 680 
nm. These specifications correspond to visual perception with the human 
eye.
    (4) Use a collimating tube with an aperture that matches the 
diameter of the light beam. Restrict the detector to viewing within a 
16 degree included angle.
    (5) Optionally use an air curtain across the light source and 
detector window to minimize deposition of smoke particles, as long as 
it does not measurably affect the opacity of the sample.
    (6) The diagram in the following figure illustrates the smokemeter 
configuration:
    Figure 1 to paragraph (a) of Sec.  1065.1125-- Smokemeter Diagram.
    [GRAPHIC] [TIFF OMITTED] TP28MR22.128
    
    (b) Smokemeters for locomotive applications must have a full-scale 
response time of 0.5 seconds or less. Smokemeters for locomotive 
applications may attenuate signal responses with frequencies higher 
than 10 Hz with a separate low-pass electronic filter that has the 
following performance characteristics:
    (1) Three decibel point: 10 Hz.
    (2) Insertion loss: (0.00.5) dB.
    (3) Selectivity: 12 dB down at 40 Hz minimum.
    (4) Attenuation: 27 dB down at 40 Hz minimum.
    (c) Configure exhaust systems as follows for measuring exhaust 
opacity:
    (1) For locomotive applications:
    (i) Optionally add a stack extension to the locomotive muffler.
    (ii) For in-line measurements, the smokemeter is integral to the 
stack extension.
    (iii) For end-of-line measurements, mount the smokemeter directly 
at the end of the stack extension or muffler.
    (iv) For all testing, minimize distance from the optical centerline 
to the muffler outlet; in no case may it be more than 300 cm. The 
maximum allowable distance of unducted space upstream of the optical 
centerline is 50 cm, whether the unducted portion is upstream or 
downstream of the stack extensions.
    (2) Meet the following specifications for all other applications:
    (i) For in-line measurements, install the smokemeter in an exhaust 
pipe segment downstream of all engine components. This will typically 
be part of a laboratory configuration to route the exhaust to an 
analyzer. The exhaust pipe diameter must be constant within 3 exhaust 
pipe diameters before and after the smokemeter's optical centerline. 
The exhaust pipe diameter may not change by more than a 12-degree half-
angle within 6 exhaust pipe diameters upstream of the smokemeter's 
optical centerline.
    (ii) For end-of-line measurements with systems that vent exhaust to 
the ambient, add a stack extension and position the smokemeter such 
that its optical centerline is (2.50.625) cm

[[Page 17874]]

upstream of the stack extension's exit. Configure the exhaust stack and 
extension such that at least the last 60 cm is a straight pipe with a 
circular cross section with an approximate inside diameter as specified 
in the following table:

Table 1 to Paragraph (c)(2)(ii) of Sec.   1065.1125--Approximate Exhaust
                   Pipe Diameter Based on Engine Power
------------------------------------------------------------------------
                                                            Approximate
                Maximum rated horsepower                   exhaust pipe
                                                           diameter (mm)
------------------------------------------------------------------------
kW<40...................................................              38
40<=kW<75...............................................              50
75<=kW<150..............................................              76
150<=kW<225.............................................             102
225<=kW<375.............................................             127
kW> 375.................................................             152
------------------------------------------------------------------------

    (iii) For both in-line and end-of-line measurements, install the 
smokemeter so its optical centerline is (3 to 10) meters further 
downstream than the point in the exhaust stream that is farthest 
downstream considering all the following components: Exhaust manifolds, 
turbocharger outlets, exhaust aftertreatment devices, and junction 
points for combining exhaust flow from multiple exhaust manifolds.
    (3) Orient the light beam perpendicular to the direction of exhaust 
flow. Install the smokemeter so it does not influence exhaust flow 
distribution or the shape of the exhaust plume. Set up the smokemeter's 
optical path length as follows:
    (i) For locomotive applications, the optical path length must be at 
least as wide as the exhaust plume.
    (ii) For all other applications, the optical path length must be 
the same as the diameter of the exhaust flow. For noncircular exhaust 
configurations, set up the smokemeter such that the light beam's path 
length is across the longest axis with an optical path length equal to 
the hydraulic diameter of the exhaust flow.
    (4) The smokemeter must not interfere with the engine's ability to 
meet the exhaust backpressure requirements in Sec.  1065.130(h).
    (5) For engines with multiple exhaust outlets, measure opacity 
using one of the following methods:
    (i) Join the exhaust outlets together to form a single flow path 
and install the smokemeter (3 to 10) m downstream of the point where 
the exhaust streams converge or the last exhaust aftertreatment device, 
whichever is farthest downstream.
    (ii) Install a smokemeter in each of the exhaust flow paths. Report 
all measured values. All measured values must comply with standards.
    (6) The smokemeter may use purge air or a different method to 
prevent carbon or other exhaust deposits on the light source and 
detector. Such a method used with end-of-line measurements may not 
cause the smoke plume to change by more than 0.5 cm at the smokemeter. 
If such a method affects the smokemeter's optical path length, follow 
the smokemeter manufacturer's instructions to properly account for that 
effect.
    (d) You may use smokemeters meeting alternative specifications as 
follows:
    (1) You may use smokemeters that use other electronic or optical 
techniques if they employ substantially identical measurement 
principles and produce substantially equivalent results.
    (2) You may ask us to approve the use of a smokemeter that relies 
on partial flow sampling. Follow the instrument manufacturer's 
installation, calibration, operation, and maintenance procedures if we 
approve your request. These procedures must include correcting for any 
change in the path length of the exhaust plume relative to the diameter 
of the engine's exhaust outlet.


Sec.  1065.1127  Test procedure for determining percent opacity.

    The test procedure described in this section applies for everything 
other than locomotives. The test consists of a sequence of engine 
operating points on an engine dynamometer to measure exhaust opacity 
during specific engine operating modes to represent in-use operation. 
Measure opacity using the following procedure:
    (a) Use the equipment and procedures specified in this part 1065.
    (b) Calibrate the smokemeter as follows:
    (1) Calibrate using neutral density filters with approximately 10, 
20, and 40 percent opacity. Confirm that the opacity values for each of 
these reference filters are NIST-traceable within 185 days of testing, 
or within 370 days of testing if you consistently protect the reference 
filters from light exposure between tests.
    (2) Before each test and optionally during engine idle modes, 
remove the smokemeter from the exhaust stream, if applicable, and 
calibrate as follows:
    (i) Zero. Adjust the smokemeter to give a zero response when there 
is no detectable smoke.
    (ii) Linearity. Insert each of the qualified reference filters in 
the light path perpendicular to the axis of the light beam and adjust 
the smokemeter to give a result within 1 percentage point of the named 
value for each reference filter.
    (c) Prepare the engine, dynamometer, and smokemeter for testing as 
follows:
    (1) Set up the engine to run in a configuration that represents in-
use operation.
    (2) Determine the smokemeter's optical path length to the nearest 
mm.
    (3) If the smokemeter uses purge air or another method to prevent 
deposits on the light source and detector, adjust the system according 
to the system manufacturer's instructions and activate the system 
before starting the engine.
    (4) Program the dynamometer to operate in torque-control mode 
throughout testing. Determine the dynamometer load needed to meet the 
cycle requirements in paragraphs (d)(4)(ii) and (iv) of this section.
    (5) You may program the dynamometer to apply motoring assist with 
negative flywheel torque, but only during the first 0.5 seconds of the 
acceleration events in paragraphs (d)(4)(i) and (ii) of this section. 
Negative flywheel torque may not exceed 13.6 N [middot] m.
    (d) Operate the engine and dynamometer over repeated test runs of 
the duty cycle illustrated in Figure 1 of this appendix. As noted in 
the figure, the test run includes an acceleration mode from points A 
through F in the figure, followed by a lugging mode from points I to J. 
Detailed specifications for testing apply as follows:
    (1) Continuously record opacity, engine speed, engine torque, and 
operator demand over the course of the entire test at 10 Hz; however, 
you may interrupt measurements to recalibrate during each idle mode.
    (2) Precondition the engine by operating it for 10 minutes at 
maximum mapped power.
    (3) Operate the engine for (5.0 to 5.5) minutes at warm idle speed, 
fnidle, with load set to Curb Idle Transmission Torque.
    (4) Operate the engine and dynamometer as follows during the 
acceleration mode:
    (i) First acceleration event--AB. Partially increase and hold 
operator demand to stabilize engine speed briefly at (20050) r/min above fnidle. The start of this acceleration 
is the start of the test (t = 0 s).
    (ii) Second acceleration event--CD. As soon as measured engine 
speed is within the range specified in paragraph (d)(4)(i) of this 
section, but not more than 3 seconds after the start of the test, 
rapidly set and hold operator demand at maximum. Operate the 
dynamometer

[[Page 17875]]

using a preselected load to accelerate engine speed to 85 percent of 
maximum test speed, fntest, in (51.5) seconds. 
The engine speed throughout the acceleration must be within 100 r/min of a target represented by a linear transition between 
the low and high engine speed targets.
    (iii) Transition--DEF. As soon as measured engine speed reaches 85 
percent of fntest, rapidly set and hold operator demand at 
minimum and simultaneously apply a load to decelerate to intermediate 
speed in (0.5 to 3.5) seconds. Use the same load identified for the 
acceleration event in paragraph (d)(4)(iv) of this section.
    (iv) Third acceleration event--FGH. Rapidly set and hold operator 
demand at maximum when the engine is within 50 r/min of 
intermediate speed. Operate the dynamometer using a preselected load to 
accelerate engine speed to at least 95 percent of fntest in 
(102) seconds.
    (5) Operate the engine and dynamometer as follows during the 
lugging mode:
    (i) Transition--HI. When the engine reaches 95 percent of 
fntest, keep operator demand at maximum and immediately set 
dynamometer load to control the engine at maximum mapped power. 
Continue the transition segment for (50 to 60) seconds. For at least 
the last 10 seconds of the transition segment, hold engine speed within 
50 r/min of fntest and power at or above 95 
percent of maximum mapped power. Conclude the transition by increasing 
dynamometer load to reduce engine speed as specified in paragraph 
(d)(4)(iii) of this section, keeping operator demand at maximum.
    (ii) Lugging--IJ. Apply dynamometer loading as needed to decrease 
engine speed from 50 r/min below fntest to intermediate 
speed in (355) seconds. The engine speed must remain within 
100 r/min of a target represented by a linear transition 
between the low and high engine speed targets.
    (6) Return the dynamometer and engine controls to the idle position 
described in paragraph (d)(3) of this section within 60 seconds of 
completing the lugging mode.
    (7) Repeat the procedures in paragraphs (d)(3) through (6) of this 
section as needed to complete three valid test runs. If you fail to 
meet the specifications during a test run, continue to follow the 
specified duty cycle before starting the next test run.
    (8) Shut down the engine or remove the smokemeter from the exhaust 
stream to verify zero and linearity. Void the test if the smokemeter 
reports more than 2 percent opacity for the zero verification, or if 
the smokemeter's error for any of the linearity checks specified in 
paragraph (b)(2) of this section is more than 2 percent.
    (e) Analyze and validate the test data as follows:
    (1) Divide each test run into test segments. Each successive test 
segment starts when the preceding segment ends. Identify the test 
segments based on the following criteria:
    (i) The idle mode specified in paragraph (d)(3) of this section for 
the first test run starts immediately after engine preconditioning is 
complete. The idle mode for later test runs must start within 60 
seconds after the end of the previous test run as specified in 
paragraph (d)(6) of this section. The idle mode ends when operator 
demand increases for the first acceleration event (Points A and B).
    (ii) The first acceleration event in paragraph (d)(4)(i) of this 
section ends when operator demand is set to maximum for the second 
acceleration event (Point C).
    (iii) The second acceleration event in paragraph (d)(4)(ii) of this 
section ends when the engine reaches 85 percent of maximum test speed, 
fntest, (Point D) and operator demand is set to minimum 
(Point E).
    (iv) The transition period in paragraph (d)(4)(iii) of this section 
ends when operator demand is set to maximum (Point F).
    (v) The third acceleration event in paragraph (d)(4)(iv) of this 
section ends when engine speed reaches 95 percent of fntest 
(Point H).
    (vi) The transition period in paragraph (d)(5)(i) of this section 
ends when engine speed first decreases to a point more than 50 r/min 
below fntest (Point I).
    (vii) The lugging mode in paragraph (d)(5)(ii) of this section ends 
when the engine reaches intermediate speed (Point J).
    (2) Convert measured instantaneous values to standard opacity 
values, kstd, based on the appropriate optical path length 
specified in Table 1 of Sec.  1065.1125 using the following equation:
[GRAPHIC] [TIFF OMITTED] TP28MR22.129

Where:

kstd = standard instantaneous percent opacity.
kmeas = measured instantaneous percent opacity.
lstd = standard optical path length corresponding with 
engine power, in millimeters.
lmeas = the smokemeter's optical path length, in 
millimeters.

Example for an engine <40 kW:

kmeas = 14.1%
lstd = 38 mm
lmeas = 41 mm
[GRAPHIC] [TIFF OMITTED] TP28MR22.130

    (3) Select opacity results from corrected measurements collected 
across test segments as follows:
    (i) Divide measurements from acceleration and lugging modes into 
half-second intervals. Determine average opacity values during each 
half-second interval.
    (ii) Identify the 15 highest half-second values during the 
acceleration mode of each test run.

[[Page 17876]]

    (iii) Identify the five highest half-second values during the 
lugging mode of each test run.
    (iv) Identify the three overall highest values from paragraphs 
(e)(3)(ii) and (iii) of this section for each test run.
    (f) Determine percent opacity as follows:
    (1) Acceleration. Determine the percent opacity for the 
acceleration mode by calculating the average of the 45 readings from 
paragraph (e)(3)(ii) of this section.
    (2) Lugging. Determine the percent opacity for the lugging mode by 
calculating the average of the 15 readings from paragraph (e)(3)(iii) 
of this section.
    (3) Peak. Determine the percent opacity for the peaks in either 
acceleration or lugging mode by calculating the average of the 9 
readings from paragraph (e)(3)(iv) of this section.
    (g) Submit the following information in addition to what is 
required by Sec.  1065.695:
    (1) Exhaust pipe diameter(s).
    (2) Measured maximum exhaust system backpressure over the entire 
test.
    (3) Most recent date for establishing that each of the reference 
filters from paragraph (b) of this section are NIST-traceable.
    (4) Measured smokemeter zero and linearity values after testing.
    (5) 10 Hz data from all valid test runs.
    (h) The following figure illustrates the dynamometer controls and 
engine speeds for exhaust opacity testing:
BILLING CODE 6560-50-P

[[Page 17877]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.131


[[Page 17878]]


BILLING CODE 6560-50-C

PART 1066--VEHICLE-TESTING PROCEDURES

0
247. The authority citation for part 1066 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
248. Amend Sec.  1066.110 by revising paragraphs (b)(2)(i) and 
(b)(2)(v) introductory text to read as follows:


Sec.  1066.110  Equipment specifications for emission sampling systems.

* * * * *
    (b) * * *
    (2) * * *
    (i) For PM background measurement, the following provisions apply 
in addition to the provisions in 40 CFR 1065.140(b):
* * * * *
    (v) If you choose to dilute the exhaust by using a remote mix tee, 
which dilutes the exhaust at the tailpipe, you may use the following 
provisions consistent with good engineering judgment, as long as they 
do not affect your ability to demonstrate compliance with the 
applicable standards in this chapter:
* * * * *
0
249. Amend Sec.  1066.220 by revising paragraph (b) to read as follows:


Sec.  1066.220  Linearity verification for chassis dynamometer systems.

* * * * *
    (b) Performance requirements. If a measurement system does not meet 
the applicable linearity criteria in Table 1 of this section, correct 
the deficiency by re-calibrating, servicing, or replacing components as 
needed. Repeat the linearity verification after correcting the 
deficiency to ensure that the measurement system meets the linearity 
criteria. Before you may use a measurement system that does not meet 
linearity criteria, you must demonstrate to us that the deficiency does 
not adversely affect your ability to demonstrate compliance with the 
applicable standards in this chapter.
* * * * *
0
250. Amend Sec.  1066.415 by revising paragraph (e)(2) to read as 
follows:


Sec.  1066.415  Vehicle operation.

* * * * *
    (e) * * *
    (2) If vehicles have features that preclude dynamometer testing, 
you may modify these features as necessary to allow testing, consistent 
with good engineering judgment, as long as it does not affect your 
ability to demonstrate that your vehicles comply with the applicable 
standards in this chapter. Send us written notification describing 
these changes along with supporting rationale.
* * * * *
0
251. Amend Sec.  1066.420 by revising paragraph (b) to read as follows:


Sec.  1066.420  Test preparation.

* * * * *
    (b) Minimize the effect of nonmethane hydrocarbon contamination in 
the hydrocarbon sampling system as follows:
    (1) For vehicles at or below 14,000 pounds GVWR with compression-
ignition engines, account for contamination using one of the following 
methods:
    (i) Introduce zero and span gas during analyzer calibration using 
one of the following methods, noting that the hydrocarbon analyzer flow 
rate and pressure during zero and span calibration (and background bag 
reading) must be exactly the same as that used during testing to 
minimize measurement errors:
    (A) Close off the hydrocarbon sampling system sample probe and 
introduce gases downstream of the probe making sure that you do not 
pressurize the system.
    (B) Introduce zero and span gas directly at the hydrocarbon 
sampling system probe at a flow rate greater than 125% of the 
hydrocarbon analyzer flow rate allowing some gas to exit probe inlet.
    (ii) Perform the contamination verification in paragraph (b)(2) of 
this section.
    (2) For vehicles above 14,000 pounds GVWR with compression-ignition 
engines, verify the amount of nonmethane hydrocarbon contamination as 
described in 40 CFR 1065.520(f).
* * * * *
0
252. Amend Sec.  1066.710 by revising the introductory text, removing 
Figure 1, and adding paragraph (f) to read as follows:


Sec.  1066.710  Cold temperature testing procedures for measuring CO 
and NMHC emissions and determining fuel economy.

    This section describes procedures for measuring carbon monoxide 
(CO) and nonmethane hydrocarbon (NMHC) emissions and determining fuel 
economy on a cold day using the FTP test cycle (see Sec.  1066.801).
* * * * *
    (f) The following figure illustrates the cold temperature testing 
sequence for measuring CO and NMHC emissions and determining fuel 
economy:
BILLING CODE 6560-50-P

[[Page 17879]]

[GRAPHIC] [TIFF OMITTED] TP28MR22.132

BILLING CODE 6560-50-C
0
253. Amend Sec.  1066.815 by revising paragraph (d)(1)(ii) to read as 
follows:


Sec.  1066.815  Exhaust emission test procedures for FTP testing.

* * * * *
    (d) * * *
    (1) * * *
    (ii) Simultaneously start any electronic integrating devices, 
continuous data recording, and batch sampling before attempting to 
start the engine. Initiate the sequence of points in the test cycle 
when the engine starts. Place the vehicle in gear 15 seconds after 
engine starting, which is 5 seconds before the first acceleration.
* * * * *
0
254. Amend Sec.  1066.831 by revising paragraph (d) to read as follows:


Sec.  1066.831  Exhaust emission test procedures for aggressive 
driving.

* * * * *
    (d) For diesel-fueled vehicles, measure THC emissions on a 
continuous basis. For separate measurement of the city and highway test 
intervals as described in paragraph (c) of this section, perform 
separate calculations for each portion of the test cycle.
* * * * *
0
255. Amend Sec.  1066.835 by revising paragraphs (f)(1), (2), and 
(3)(iii) to read as follows:


Sec.  1066.835  Exhaust emission test procedure for SC03 emissions.

* * * * *
    (f) * * *
    (1) Ambient temperature and humidity. Measure and record ambient 
temperature and humidity in the test cell at least once every 30 
seconds during the sampling period. Alternatively, if you collect data 
of at least once every 12 seconds, you may use a moving average of up 
to 30 second intervals to measure and record ambient temperature and 
humidity. Control ambient temperature throughout the test sequence to 
(35.03.0) [deg]C. Control ambient temperature during 
emission sampling to (33.6 to 36.4) [deg]C on average. Control ambient 
humidity during emission sampling as described in Sec.  1066.420(d).
    (2) Conditions before testing. Use good engineering judgment to 
demonstrate that you meet the specified temperature and humidity 
tolerances in paragraph (f)(1) of this section during the 
preconditioning cycle and during

[[Page 17880]]

the vehicle soak period in paragraph (c)(6) of this section.
    (3) * * *
    (iii) Determine radiant energy intensity experienced by the vehicle 
as the average value between two measurements along the vehicle's 
centerline, one at the base of the windshield and the other at the 
bottom of the rear window (or equivalent location for vehicles without 
a rear window). This value must be (850 45) W/m2. 
Instruments for measuring radiant energy intensity must meet the 
following minimum specifications:
* * * * *
0
256. Amend Sec.  1066.845 by revising paragraphs (c) and (f)(3) to read 
as follows:


Sec.  1066.845  AC17 air conditioning efficiency test procedure.

* * * * *
    (c) Ambient conditions. Measure and control ambient conditions as 
specified in Sec.  1066.835(f), except that you must control ambient 
temperature during emission sampling to (22.0 to 28.0) [deg]C 
throughout the test and (23.5 to 26.5) [deg]C on average. These 
tolerances apply to the combined SC03 and HFET drive cycles during 
emission sampling. Note that you must set the same ambient temperature 
target for both the air conditioning on and off portions of emission 
sampling. Control ambient temperature during the preconditioning cycle 
and 30 minute soak to (25.0 5.0) [deg]C. For these same 
modes with no emission sampling, target the specified ambient humidity 
levels, but you do not need to meet the humidity tolerances. Note that 
solar heating is disabled for certain test intervals as described in 
this section.
* * * * *
    (f) * * *
    (3) Turn on solar heating within one minute after turning off the 
engine. Once the solar energy intensity reaches 805 W/m2, let the 
vehicle soak for (30 1) minutes. You may alternatively rely 
on prior measurements to start the soak period after a defined period 
of warming up to the specified solar heat load. Close the vehicle's 
windows at the start of the soak period; ensure that the windows are 
adequately closed where instrumentation and wiring pass through to the 
interior.
* * * * *
0
257. Amend Sec.  1066.1001 by adding definitions for ``Charge-
depleting'' and ``Charge-sustaining'' in alphabetical order and 
revising the definition for ``Test interval'' to read as follows:


Sec.  1066.1001  Definitions.

* * * * *
    Charge-depleting means relating to the test interval of a plug-in 
hybrid engine or powertrain in which the engine or powertrain consumes 
electric energy from the RESS that has been charged from an external 
power source until the RESS is depleted to the point that a test 
interval qualifies as charge-sustaining. The engine might consume fuel 
to produce power during a charge-depleting test interval.
    Charge-sustaining means relating to the test interval of a plug-in 
hybrid engine or powertrain in which the engine or powertrain consumes 
fuel to produce power such that the battery's net-energy change meets 
the end-of-test criterion of SAE J1711 or SAE J2711, as applicable 
(incorporated by reference in Sec.  1066.1010).
* * * * *
    Test interval means a period over which a vehicle's emission rates 
are determined separately. For many standards, compliance with the 
standard is based on a weighted average of the mass emissions from 
multiple test intervals. For example, the standard-setting part may 
specify a complete duty cycle as a cold-start test interval and a hot-
start test interval. In cases where multiple test intervals occur over 
a duty cycle, the standard-setting part may specify additional 
calculations that weight and combine results to arrive at composite 
values for comparison against the applicable standards in this chapter.
* * * * *
0
258. Amend Sec.  1066.1005 by revising paragraphs (b), (g), and (h) to 
read as follows:


Sec.  1066.1005  Symbols, abbreviations, acronyms, and units of 
measure.

* * * * *
    (b) Symbols for chemical species. This part uses the following 
symbols for chemical species and exhaust constituents:

       Table 2 to Paragraph (b) of Sec.   1066.1005--Symbols for Chemical Species and Exhaust Constituents
----------------------------------------------------------------------------------------------------------------
              Symbol                                                  Species
----------------------------------------------------------------------------------------------------------------
CH4..............................  methane.
CH3OH............................  methanol.
CH2O.............................  formaldehyde.
C2H4O............................  acetaldehyde.
C2H5OH...........................  ethanol.
C2H6.............................  ethane.
C3H7OH...........................  propanol.
C3H8.............................  propane.
C\4\ H10.........................  butane.
C5H 12...........................  pentane.
CO...............................  carbon monoxide.
CO2..............................  carbon dioxide.
H2O..............................  water.
HC...............................  hydrocarbon.
N2...............................  molecular nitrogen.
NMHC.............................  nonmethane hydrocarbon.
NMHCE............................  nonmethane hydrocarbon equivalent.
NMOG.............................  nonmethane organic gas.
NO...............................  nitric oxide.
NO2..............................  nitrogen dioxide.
NOX..............................  oxides of nitrogen.
N2O..............................  nitrous oxide.
O2...............................  molecular oxygen.
OHC..............................  oxygenated hydrocarbon.
PM...............................  particulate matter.
THC..............................  total hydrocarbon.

[[Page 17881]]

 
THCE.............................  total hydrocarbon equivalent.
----------------------------------------------------------------------------------------------------------------

* * * * *
    (g) Constants. (1) This part uses the following constants for the 
composition of dry air:

   Table 7 to Paragraph (g)(1) of Sec.   1066.1005--Constants for the
                         Composition of Dry Air
------------------------------------------------------------------------
         Symbol                 Quantity                 mol/mol
------------------------------------------------------------------------
xArair.................  amount of argon in dry                  0.00934
                          air.
xCO2air................  amount of carbon                       0.000375
                          dioxide in dry air.
xN2air.................  amount of nitrogen in                   0.78084
                          dry air.
xO2air.................  amount of oxygen in                    0.209445
                          dry air.
------------------------------------------------------------------------

    (2) This part uses the following molar masses or effective molar 
masses of chemical species:

    Table 8 to Paragraph (g)(2) of Sec.   1066.1005--Molar Masses or
               Effective Molar Masses of Chemical Species
------------------------------------------------------------------------
                                                       g/mol (10-
        Symbol                 Quantity        \3\[middot]kg[middot]mol-
                                                          \1\)
------------------------------------------------------------------------
Mair..................  molar mass of dry air                  28.96559
                         \1\.
MH2O..................  molar mass of water..                  18.01528
------------------------------------------------------------------------
\1\ See paragraph (g)(1) of this section for the composition of dry air.

    (3) This part uses the following molar gas constant for ideal 
gases:

 Table 9 to Paragraph (g)(3) of Sec.   1066.1005--Molar Gas Constant for
                               Ideal Gases
------------------------------------------------------------------------
                                                    J/(mol[middot]K)
                                               (m\2\[middot]kg[middot]s-
        Symbol                 Quantity        \2\[middot]mol-1[middot]K-
                                                          \1\)
------------------------------------------------------------------------
R.....................  molar gas constant...                  8.314472
------------------------------------------------------------------------

    (h) Prefixes. This part uses the following prefixes to define a 
quantity:

   Table 10 to Paragraph (h) of Sec.   1066.1005--Prefixes To Define a
                                Quantity
------------------------------------------------------------------------
         Symbol                 Quantity                  Value
------------------------------------------------------------------------
n......................  nano..................                    10\9\
[micro]................  micro.................                     10-6
m......................  milli.................                     10-3
c......................  centi.................                     10-2
k......................  kilo..................                    10\3\
M......................  mega..................                    10\6\
------------------------------------------------------------------------

0
259. Revise Sec.  1066.1010 to read as follows:


Sec.  1066.1010  Incorporation by reference.

    Certain material is incorporated by reference into this part with 
the approval of the Director of the Federal Register in accordance with 
5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than 
that specified in this section, the Environmental Protection Agency 
(EPA) must publish a document in the Federal Register and the material 
must be available to the public. All approved material is available for 
inspection at the EPA and at the National Archives and Records 
Administration (NARA). Contact EPA at: U.S. EPA, Air and Radiation 
Docket and Information Center, 1301 Constitution Ave. NW, Room B102, 
EPA West Building, Washington, DC 20460, www.epa.gov/dockets, (202) 
202-1744. For information on the availability of this material at NARA, 
email: [email protected], or go to: www.archives.gov/federal-
register/cfr/

[[Page 17882]]

ibr-locations.html. The material may be obtained from the following 
sources:
    (a) National Institute of Standards and Technology (NIST), 100 
Bureau Drive, Stop 1070, Gaithersburg, MD 20899-1070; (301) 975-6478; 
www.nist.gov.
    (1) NIST Special Publication 811, 2008 Edition, Guide for the Use 
of the International System of Units (SI), Physics Laboratory, March 
2008; IBR approved for Sec. Sec.  1066.20(a); 1066.1005.
    (2) [Reserved]
    (b) SAE International, 400 Commonwealth Dr., Warrendale, PA 15096-
0001; (877) 606-7323 (U.S. and Canada) or (724) 776-4970 (outside the 
U.S. and Canada); www.sae.org.
    (1) SAE J1263, Road Load Measurement and Dynamometer Simulation 
Using Coastdown Techniques, revised March 2010; IBR approved for 
Sec. Sec.  1066.301(b); 1066.305(a); 1066.310(b).
    (2) SAE J1634, Battery Electric Vehicle Energy Consumption and 
Range Test Procedure, revised July 2017; IBR approved for Sec.  
1066.501(a).
    (3) SAE J1711, Recommended Practice for Measuring the Exhaust 
Emissions and Fuel Economy of Hybrid-Electric Vehicles, Including Plug-
In Hybrid Vehicles, revised June 2010; IBR approved for Sec. Sec.  
1066.501(a); 1066.1001.
    (4) SAE J2263, Road Load Measurement Using Onboard Anemometry and 
Coastdown Techniques, revised May 2020; IBR approved for Sec. Sec.  
1066.301(b); 1066.305; 1066.310(b).
    (5) SAE J2264, Chassis Dynamometer Simulation of Road Load Using 
Coastdown Techniques, revised January 2014; IBR approved for Sec.  
1066.315.
    (6) SAE J2711, Recommended Practice for Measuring Fuel Economy and 
Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles, 
revised May 2020; IBR approved for Sec. Sec.  1066.501(a); 1066.1001.
    (7) SAE J2951, Drive Quality Evaluation for Chassis Dynamometer 
Testing, revised January 2014; IBR approved for Sec.  1066.425(j).

PART 1068--GENERAL COMPLIANCE PROVISIONS FOR HIGHWAY, STATIONARY, 
AND NONROAD PROGRAMS

0
260. The authority citation for part 1068 continues to read as follows:

    Authority:  42 U.S.C. 7401-7671q.

0
261. Amend Sec.  1068.1 by revising paragraphs (a)(2), (5), (6), (8), 
(9), and (13) and adding paragraph (a)(15) to read as follows:


Sec.  1068.1  Does this part apply to me?

    (a) * * *
    (2) This part 1068 applies for heavy-duty motor vehicles and motor 
vehicle engines we regulate under 40 CFR parts 1036 and 1037. This 
includes trailers. This part 1068 applies to heavy-duty motor vehicles 
and motor vehicle engines certified under 40 CFR part 86 to the extent 
and in the manner specified in 40 CFR parts 85, 86, and 1036.
* * * * *
    (5) This part 1068 applies for locomotives that are subject to the 
provisions of 40 CFR part 1033.
    (6) This part 1068 applies for land-based nonroad compression-
ignition engines that are subject to the provisions of 40 CFR part 
1039. This part 1068 applies for engines certified under 40 CFR part 89 
to the extent and in the manner specified in 40 CFR part 1039.
* * * * *
    (8) This part 1068 applies for marine compression-ignition engines 
that are subject to the provisions of 40 CFR part 1042. This part 1068 
applies for marine compression-ignition engines certified under 40 CFR 
part 94 to the extent and in the manner specified in 40 CFR part 1042.
    (9) This part 1068 applies for marine spark-ignition engines that 
are subject to the provisions of 40 CFR part 1045. This part 1068 
applies for marine spark-ignition engines certified under 40 CFR part 
91 to the extent and in the manner specified in 40 CFR part 1045.
* * * * *
    (13) This part applies for small nonroad spark-ignition engines 
that are subject to the provisions of 40 CFR part 1054. This part 1068 
applies for nonroad spark-ignition engines certified under 40 CFR part 
90 to the extent and in the manner specified in 40 CFR part 1054.
* * * * *
    (15) This part 1068 applies to portable fuel containers we regulate 
under 40 CFR part 59 to the extent and in the manner specified in 40 
CFR part 59, subpart F.
* * * * *
0
262. Revise Sec.  1068.10 to read as follows:


Sec.  1068.10  Practices for handling confidential business 
information.

    The provisions of this section apply both to any information you 
send us and to any information we collect from inspections, audits, or 
other site visits.
    (a) When you submit information to us, if you claim any of that 
information as confidential, you may identify what you claim to be 
confidential by marking, circling, bracketing, stamping, or some other 
method; however, we will not consider any claims of confidentiality 
over information we have determined to be not entitled to confidential 
treatment under Sec.  1068.11 or other applicable provisions.
    (b) If you send us information without claiming it is confidential, 
we may make it available to the public without further notice to you, 
as described in 40 CFR 2.301(j).
    (c) For submissions that include information that may be entitled 
to confidential treatment, we may require that you send a ``public'' 
copy of the report that does not include the confidential information. 
We may require that you substantiate your claim to confidential 
treatment for any items not contained in the public version. We will 
release additional information from the complete version of such a 
submission only as allowed under 40 CFR 2.301(j) and as described in 
this subpart and the standard-setting part.
    (d) We will safeguard your confidential business information (CBI) 
as described in 40 CFR 2.301(j). Also, we will treat certain 
information as confidential and will only disclose this information if 
it has been determined to be not entitled to confidential treatment as 
specified in Sec.  1068.11(c). The following general provisions 
describe how we will process requests for making information publicly 
available:
    (1) Certification information. We will treat information submitted 
in an application for certification as confidential until the 
introduction-into-commerce date you identify in your application for 
certification consistent with 40 CFR 2.301(a)(2)(ii)(B). If we issue 
the certificate after your specified date, for the purpose of this 
section the introduction-into-commerce date is the date we issue the 
certificate. After that date, we will treat information submitted in an 
application for certification as described in Sec.  1068.11.
    (2) Preliminary and superseded information. Preliminary and 
superseded versions of information you submit are covered by 
confidentiality determinations in the same manner as final documents. 
However, we will generally not disclose preliminary or superseded 
information unless we receive a request under 5 U.S.C. 552 that 
specifically asks for all versions of a document, including preliminary 
and superseded versions. We will consider a document preliminary if we 
have not reviewed it to verify its accuracy or if the reporting 
deadline has not yet passed. We will consider information superseded if 
you submit a new document or a revised application for

[[Page 17883]]

certification to replace the earlier version.
    (3) Authorizing CBI disclosure. The provisions of this section do 
not prevent us from disclosing protected information if you 
specifically authorize it.
    (4) Relationship to the standard-setting part. The standard-setting 
part may identify additional provisions related to confidentiality 
determinations. Note that the standard-setting part identifies 
information requirements that apply for each type of engine/equipment. 
If this section identifies information that is not required for a given 
engine, that does not create a requirement to submit the information.
    (5) Changes in law. The confidentiality determinations in this 
section and in the standard-setting parts may be changed through the 
processes described in 40 CFR 2.301(j)(4).
0
263. Add Sec.  1068.11 to read as follows:


Sec.  1068.11  Confidentiality determinations and related procedures.

    This section characterizes various categories of information for 
purposes of making confidentiality determinations, as follows:
    (a) This paragraph (a) applies the definition of ``Emission data'' 
in 40 CFR 2.301(a) for information related to engines/equipment subject 
to this part. ``Emission data'' cannot be treated as confidential 
business information and shall be available to be disclosed to the 
public except as specified in Sec.  1068.10(d)(1). The following 
categories of information qualify as emission data, except as specified 
in paragraph (c) of this section:
    (1) Certification and compliance information, including information 
submitted in an application for a certificate of conformity that is 
used to assess compliance.
    (2) Fleet value information, including information submitted for 
compliance with fleet average emission standards and emissions related 
ABT credit information, including the information used to generate 
credits.
    (3) Source family information. For example, engine family 
information or test group information would identify the regulated 
emission source.
    (4) Test information and results, including emission test results 
and other data from emission testing that are submitted in an 
application for a certificate of conformity, test results from in-use 
testing, production-line testing, and any other testing to demonstrate 
emissions. The information in this category includes all related 
information to characterize test results, document the measurement 
procedure, and modeling inputs and outputs where the compliance 
demonstration is based on computer modeling.
    (5) ABT credit information, including information submitted for 
current and future compliance demonstrations using credits under an ABT 
program.
    (6) Production volume, including information submitted for 
compliance with fleet average emission standards, compliance with 
requirements to test production engines/equipment, or compliance 
through ABT programs.
    (7) Defect and recall information, including all information 
submitted in relation to a defect or recall except the remedial steps 
you identify in Sec.  1068.510(a)(2).
    (8) Selective enforcement audit compliance information.
    (b) The following categories of information are not eligible for 
confidential treatment, except as specified in Sec.  1068.10(d)(1):
    (1) Published information, including information that is made 
available in annual and quarterly filings submitted to the U.S. 
Securities and Exchanges Commission, on company websites, or otherwise 
made publicly available by the information submitter.
    (2) Observable information available to the public after the 
introduction to commerce date.
    (c) The following categories of information are subject to the 
process for confidentiality determinations in 40 CFR part 2 as 
described in 40 CFR 2.301(j)(5).
    (1) Projected sales and production volumes.
    (2) Production start and end dates.
    (3) Detailed description of emission control operation and 
function.
    (4) Design specifications related to aftertreatment devices.
    (5) Description of auxiliary emission control devices (AECDs).
    (6) Plans for meeting regulatory requirements. For example, this 
applies for any projections of emission credits for the coming model 
year or determinations of the number of required repair facilities that 
are based on projected production volumes.
    (7) The following information related to deterioration factors and 
other adjustment factors:
    (i) Procedures to determine deterioration factors and other 
emission adjustment factors.
    (ii) Any information used to justify those procedures.
    (iii) Emission measurements you use to compare procedures or 
demonstrate that the procedures are appropriate.
    (8) Financial information related to the following items:
    (i) ABT credit transactions, including dollar amount, identity of 
parties, and contract information.
    (ii) Meeting bond requirements, including aggregate U.S. asset 
holdings, financial details regarding specific assets, whether the 
manufacturer or importer obtains a bond, and copies of bond policies.
    (9) Serial numbers or other information to identify specific 
engines or equipment selected for testing.
    (10) Procedures that apply based on your request to test engines/
equipment differently than we specify in the regulation. This applies 
for special and alternative test procedures. This also applies, for 
example, if we approve a broader or narrower zone of engine operation 
for not-to-exceed testing.
    (11) Information related to testing vanadium catalysts in 40 CFR 
part 1065, subpart L.
    (12) GPS data identifying the location for in-use emission 
measurements.
    (13) Information related to possible defects that are subject to 
further investigation (not confirmed defects).
    (d) If you submit information that is not addressed in paragraphs 
(a) through (c) of this section, you may claim the information as 
confidential. We may require you to provide us with information to 
substantiate your claims. If claimed, we may consider this 
substantiating information to be confidential to the same degree as the 
information for which you are requesting confidential treatment. We 
will make our determination based on your statements to us, the 
supporting information you send us, and any other available 
information. However, we may determine that your information is not 
subject to confidential treatment consistent with 40 CFR part 2 and 5 
U.S.C. 552(b)(4).
    (e) Applications for certification and submitted reports typically 
rely on software or templates to identify specific categories of 
information. If you submit information in a comment field designated 
for users to add general information, we will respond to requests for 
disclosing that information consistent with paragraphs (a) through (d) 
of this section.
0
264. Amend Sec.  1068.30 by adding a definition for ``Critical 
emission-related component'' in alphabetical order and revising the 
definition of ``Designated Compliance Officer'' to read as follows:


Sec.  1068.30  Definitions.

* * * * *
    Critical emission-related component means a component identified in 
appendix A of this part whose primary purpose is to reduce emissions or 
whose

[[Page 17884]]

failure would commonly increase emissions without significantly 
degrading engine/equipment performance.
* * * * *
    Designated Compliance Officer means one of the following:
    (1) For motor vehicles regulated under 40 CFR part 86, subpart S: 
Director, Light-Duty Vehicle Center, U.S. Environmental Protection 
Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
[email protected]; www.epa.gov/ve-certification.
    (2) For compression-ignition engines used in heavy-duty highway 
vehicles regulated under 40 CFR part 86, subpart A, and 40 CFR parts 
1036 and 1037, and for nonroad and stationary compression-ignition 
engines or equipment regulated under 40 CFR parts 60, 1033, 1039, and 
1042: Director, Diesel Engine Compliance Center, U.S. Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
[email protected]; www.epa.gov/ve-certification.
    (3) Director, Gasoline Engine Compliance Center, U.S. Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
[email protected]; www.epa.gov/ve-certification, for all the 
following engines and vehicles:
    (i) For spark-ignition engines used in heavy-duty highway vehicles 
regulated under 40 CFR part 86, subpart A, and 40 CFR parts 1036 and 
1037,
    (ii) For highway motorcycles regulated under 40 CFR part 86, 
subpart E.
    (iii) For nonroad and stationary spark-ignition engines or 
equipment regulated under 40 CFR parts 60, 1045, 1048, 1051, 1054, and 
1060.
0
265. Add Sec.  1068.50 to read as follows:


Sec.  1068.50  Adjustable parameters.

    (a) The standard-setting part generally requires that production 
engines, pre-production engines, and in-use engines with adjustable 
parameters meet all the requirements of this part for any adjustment in 
the physically adjustable range. This section refers to engines, 
because most adjustable parameters are integral to the engine even in 
the case of equipment-based standards. This section also applies for 
equipment-based adjustable parameters. The provisions of this section 
apply starting with model year 2024.
    (b) You must use good engineering judgment for all decisions 
related to adjustable parameters. We recommend that you ask for 
preliminary approval for decisions related to new technologies, 
substantially changed engine designs, or new methods for limiting 
adjustability. Decisions related to adjustable parameters include the 
following:
    (1) Determining which engine operating parameters qualify as 
adjustable parameters.
    (2) Establishing the adequacy of the limits, stops, seals, or other 
means used to limit adjustment.
    (3) Defining the physically adjustable ranges for each such 
parameter.
    (c) For purposes of this section, ``operating parameter'' means any 
feature that can, by the nature of its design, be adjusted to affect 
engine/equipment performance, including engine components that are 
designed to be replaced. For example, while bolts used to assemble the 
engine are practically adjustable (can be loosened or tightened), they 
are not adjustable parameters because they are not operating 
parameters. See paragraph (h) of this section for special provisions 
related to elements of design involving consumption and replenishment. 
A nonconsumable operating parameter is considered an adjustable 
parameter as follows:
    (1) An operating parameter is not an adjustable parameter if we 
determine it is not practically adjustable using available tools, as 
described in paragraph (d) of this section, or we determine that engine 
operation over the full range of adjustment does not affect emissions 
without also degrading engine performance to the extent that operators 
will be aware of the problem. Also, while spark plug gap and valve lash 
are practically adjustable operating parameters, they are not 
adjustable parameters because adjusting them does not affect emissions 
without also degrading engine performance.
    (2) The following specific criteria apply for determining whether a 
parameter is practically adjustable because it is permanently sealed or 
otherwise inaccessible:
    (i) Electronic components on circuit boards (such as onboard 
computers) are not practically adjustable if the board is encapsulated 
with a durable resin that adequately limits access to components on the 
board, consistent with paragraph (d)(1) of this section.
    (ii) Threaded fasteners (such as screws) on mechanically controlled 
engines are considered not practically adjustable if simple tools 
cannot be used to adjust the parameter once the head is sheared off 
after adjustment at the factory, or if the fastener is recessed within 
a larger, permanent body and sealed with a durable plug, cap, or cover 
plate that adequately limits access to the fastener, consistent with 
paragraph (d)(1) of this section.
    (iii) Bimetal springs on mechanically controlled engines are 
considered not practically adjustable if the plate covering the bimetal 
spring is riveted or welded in place or it is held in place with 
threaded fasteners meeting the specifications described in this 
paragraph (c)(2).
    (d) The following provisions apply for determining whether 
operating parameters are ``practically adjustable'':
    (1) A mechanically controlled parameter is considered ``not 
practically adjustable'' if adjustments with ordinary tools take more 
than 15 minutes or involve service parts that cost more than $30 for 
engines at or below 30 kW, or take more than 60 minutes or involve 
service parts that cost more than $60 for engines between 30 kW and 560 
kW. These costs are in 2020 dollars. Adjust these values for 
certification by comparing most recently available Consumer Price Index 
for All Urban Consumers (CPI-U) value published by the Bureau of Labor 
Statistics at www.usinflationcalculator.com. As used in this paragraph 
(d), the term ``ordinary tools'' includes hand tools, solvents, or 
other supplies that are reasonably available to the operator. Hand 
tools include screwdrivers, pliers, hammers, awls, wrenches, electric 
screwdrivers, electric drills, and any tools supplied by the 
manufacturer with the product. Any such items that are sold at hardware 
stores, automotive parts supply stores or on the Internet are 
considered available. The cost thresholds described in this paragraph 
(d)(1) do not include the cost of labor or the cost of any necessary 
tools or nonconsumable supplies; the time thresholds refer to the time 
required to access and adjust the parameter, excluding any time 
necessary to purchase parts, tools, or supplies or to perform testing. 
For engines at or above 560 kW, mechanically controlled parameters are 
considered ``practically adjustable'' if the parameter can be adjusted 
using any available tools. Determine the practically adjustable range 
of mechanically controlled parameters as described in paragraph (e) 
this section.
    (2) Electronically controlled parameters are considered 
``practically adjustable'' if they can be adjusted using any available 
tools (including devices that are used to alter computer code). 
Conversely, such parameters are not practically adjustable if you limit 
access to the electronic control units with password or encryption 
protection. You must have adequate protections in place to prevent 
distribution and use of passwords or encryption keys. We may exclude 
operating parameters (or narrow the adjustable range under paragraph 
(f)

[[Page 17885]]

of this section) where we determine that the operating parameters will 
not be subject to in-use adjustment or will be subject to a more 
limited in-use adjustment. Our approval may include conditions to 
ensure that the certified configuration includes adjustable ranges that 
reflect the expected range of in-use adjustment. This paragraph (d)(2) 
applies for engines with any degree of electronic control. Determine 
the practically adjustable range of electronically controlled 
parameters as described in paragraph (f) of this section.
    (e) A physical limit or stop is adequate for defining the limits of 
the practically adjustable range if it has the following 
characteristics:
    (1) In the case of a threaded adjustment, the threads are 
terminated, pinned, or crimped to prevent additional travel without 
such that the operator cannot bypass the physical limit or stop without 
causing damage for which the repairs would exceed the time or cost 
thresholds specified in paragraph (d)(1) of this section.
    (2) Operators cannot exceed the travel or rotation limits using 
ordinary tools without causing damage for which the repairs would 
exceed the time or cost thresholds specified in paragraph (d)(1) of 
this section. For example, if a vehicle has a shim, bushing, or other 
device to limit flow rates, range of travel, or other parameters to 
prevent operating outside of a specified range of engine or vehicle 
speeds, you must take steps to prevent operators or mechanics from 
removing, replacing, or altering those parts to operate at a wider 
range of engine or vehicle speeds.
    (f) Apply the following provisions to determine the practically 
adjustable range for electronically controlled parameters that can be 
adjusted by changing software or operating parameters (``reflashed''):
    (1) If an engine family includes multiple algorithms that can be 
selected or are easily accessible, consider each of the available 
settings to be within the practically adjustable range.
    (2) If you sell or offer to sell software or other products that 
could be used to reflash or otherwise modify the electronic control 
unit, consider all those settings to be within the practically 
adjustable range.
    (3) If your engines/equipment have other electronic settings that 
can be modified or accessed as described in paragraph (d)(2) of this 
section, consider all those settings to be within the practically 
adjustable range. The following engine systems and features illustrate 
examples of the types of electronic settings for which this paragraph 
(f)(3) applies:
    (i) Air-fuel setpoints for closed-loop fuel systems.
    (ii) Reductant flow systems.
    (iii) Base maps for fuel injection or spark timing.
    (iv) Exhaust gas recirculation maps.
    (g) We will make determinations regarding in-use adjustments of 
adjustable parameters under this section for certifying engines as 
follows:
    (1) Our determinations will depend on in-use maintenance practices 
conforming to the maintenance and service information you provide. For 
example, if your published maintenance instructions describe routine 
procedures for adjusting engines or if you or your dealers make 
specialized tools available to operators, we will conclude that such 
adjustments are likely to occur. Also, your maintenance and service 
information may not specify adjustable ranges that are broader than 
those that you specify in your application for certification.
    (2) We may review manufacturer statements under this section for 
certifying engines for a later model year if we learn from observation 
of in-use engines or other information that a parameter was in fact 
practically adjustable or that the specified operating range was in 
fact not correct. We may require you to include a new adjustable 
parameter or to revise your specified operating range for an adjustable 
parameter.
    (h) Except as provided in the standard-setting part and this 
paragraph (h), engines are not in the certified configuration if you 
produce them with adjustable parameters set outside the range specified 
in your application for certification. Similarly, engines are not in 
the certified configuration if you produce them with other operating 
parameters that do not conform to the certified configuration. The 
following provisions apply for adjustable parameters related to 
elements of design involving consumption and replenishment, such as DEF 
tank fill level and hybrid battery state of charge:
    (1) We will determine the range of adjustability based on the 
likelihood of in-use operation at a given point in the physically 
adjustable range. We may determine that operation in certain subranges 
within the physically adjustable range is sufficiently unlikely that 
the subranges should be excluded from the allowable adjustable range 
for testing.
    (2) Shipping new engines/equipment in a state or configuration 
requiring replenishment to be within the range of adjustability for a 
certified configuration does not cause a violation of the prohibition 
in Sec.  1068.101(a)(1).
    (i) In your application for certification, include information 
related to adjustable parameters as described in the standard-setting 
part and state that you meet the specifications of this section and 
provide supporting documentation for that statement as follows:
    (1) If your engine is designed with mechanically controlled 
adjustable parameters, state that they meet the specifications of this 
section for preventing in-use operation outside the intended physically 
adjustable range.
    (2) If your engine is designed with electronically controlled 
operating parameters that you consider ``not practically adjustable,'' 
state that you have restricted access to the electronic controls as 
specified in this section to prevent in-use operation outside the 
practically adjustable range.
    (j) We may inspect your engines at any time to determine whether 
they meet the specifications of this section. We may purchase engines 
for tesing, or we may ask you to supply engines for such inspections. 
We will inspect using ordinary tools and time limits specified in 
paragraph (d)(1) of this section and any available devices that alter 
computer code as specified in paragraph (d)(2) of this section. The 
inspection will determine the following:
    (1) If the adjustable parameter is limited to the physically 
adjustable range specified in the manufacturer's certification 
application.
    (2) If physical stops for mechanically controlled adjustable 
parameters can be bypassed using methods outlined in paragraph (d)(1) 
of this section.
    (k) Where we determine that you failed to identify something that 
should be considered an adjustable parameter, we may require you to 
treat the parameter as defective under Sec.  1068.501. If we determine 
you deliberately misrepresented the accessibility of the parameter or 
that you did not act in good faith, we may take action regarding your 
certificate as described in the standard-setting part (see, for 
example, 40 CFR 1054.255).
    (l) Nothing in this section limits the tampering prohibition of 
Sec.  1068.101(b)(1) or the defeat device prohibition of Sec.  
1068.101(b)(2).
0
266. Amend Sec.  1068.101 by revising paragraphs (a) introductory text 
and (b)(5) to read as follows:


Sec.  1068.101  What general actions does this regulation prohibit?

* * * * *
    (a) The following prohibitions and requirements apply to 
manufacturers of

[[Page 17886]]

new engines, manufacturers of equipment containing these engines, 
manufacturers of new equipment, and other persons as provided by Sec.  
1068.1(a), except as described in subparts C and D of this part:
* * * * *
    (b) * * *
    (5) Importation. You may not import an uncertified engine or piece 
of equipment if it is defined to be new in the standard-setting part 
with a model year for which emission standards applied. Anyone 
violating this paragraph (b)(5) is deemed to be a manufacturer in 
violation of paragraph (a)(1) of this section. We may assess a civil 
penalty up to $44,539 for each engine or piece of equipment in 
violation. Note the following:
* * * * *
0
267. Amend Sec.  1068.210 by revising paragraph (c) introductory text 
to read as follows:


Sec.  1068.210  Exempting test engines/equipment.

* * * * *
    (c) If you are a certificate holder, you may request an exemption 
for engines/equipment you intend to include in a test program.
* * * * *
0
268. Amend Sec.  1068.220 by revising paragraph (b) to read as follows:


Sec.  1068.220  Exempting display engines/equipment.

* * * * *
    (b) Nonconforming display engines/equipment will be exempted if 
they are used for displays in the interest of a business or the general 
public. The exemption in this section does not apply to engines/
equipment displayed for any purpose we determine is inappropriate for a 
display exemption.
* * * * *
0
269. Amend Sec.  1068.240 by revising paragraphs (a)(1), (b)(3), and 
(c)(3)(ii) to read as follows:


Sec.  1068.240  Exempting new replacement engines.

* * * * *
    (a) * * *
    (1) Paragraphs (b) and (c) of this section describe different 
approaches for exempting new replacement engines where the engines are 
specially built to correspond to an engine model from an earlier model 
year that was subject to less stringent standards than those that apply 
for current production (or is no longer covered by a certificate of 
conformity). You must comply with the requirements of paragraph (b) of 
this section for any number of replacement engines you produce in 
excess of what we allow under paragraph (c) of this section. You must 
designate engines you produce under this section as tracked engines 
under paragraph (b) of this section or untracked engines under 
paragraph (c) of this section by the deadline for the report specified 
in paragraph (c)(3) of this section.
* * * * *
    (b) * * *
    (3) An old engine block replaced by a new engine exempted under 
this paragraph (b) may be reintroduced into U.S. commerce as part of an 
engine that meets either the current standards for new engines, the 
provisions for new replacement engines in this section, or another 
valid exemption. Otherwise, you must destroy the old engine block (or 
confirm that it has been destroyed), or export the engine block without 
its emission label. Note that this paragraph (b)(3) does not require 
engine manufacturers to take possession of the engine being replaced. 
Owners may arrange to keep the old engine if they demonstrate that the 
engine block has been destroyed. An engine block is destroyed under 
this paragraph (b)(3) if it can never be restored to a running 
configuration.
* * * * *
    (c) * * *
    (3) * * *
    (ii) Count exempt engines as tracked under paragraph (b) of this 
section only if you meet all the requirements and conditions that apply 
under paragraph (b)(2) of this section by the due date for the annual 
report. In the annual report you must identify any replaced engines 
from the previous year whose final disposition is not resolved by the 
due date for the annual report. Continue to report those engines in 
later reports until the final disposition is resolved. If the final 
disposition of any replaced engine is not resolved for the fifth annual 
report following the production report, treat this as an untracked 
replacement in the fifth annual report for the preceding year.
* * * * *
0
270. Amend Sec.  1068.261 by revising paragraphs (b), (c) introductory 
text, and (d) introductory text to read as follows:


Sec.  1068.261  Delegated assembly and other provisions related to 
engines not yet in the certified configuration.

* * * * *
    (b) If you manufacture engines and install them in equipment you or 
an affiliated company also produce, you must take steps to ensure that 
your facilities, procedures, and production records are set up to 
ensure that equipment and engines are assembled in their proper 
certified configurations. For example, you may demonstrate compliance 
with the requirements of this section by maintaining a database showing 
how you pair aftertreatment components with the appropriate engines 
such that the final product is in its certified configuration.
    (c) If you manufacture engines and ship them to an unaffiliated 
company for installation in equipment and you include the price of all 
aftertreatment components in the price of the engine (whether or not 
you ship the aftertreatment components directly to the equipment 
manufacturer), all the following conditions apply:
* * * * *
    (d) If you manufacture engines and ship them to an unaffiliated 
company for installation in equipment, but you do not include the price 
of all aftertreatment components in the price of the engine, you must 
meet all the conditions described in paragraphs (c)(1) through (9) of 
this section, with the following additional provisions:
* * * * *
0
271. Amend Sec.  1068.301 by revising paragraph (b) to read as follows:


Sec.  1068.301  General provisions for importing engines/equipment.

* * * * *
    (b) In general, engines/equipment that you import must be covered 
by a certificate of conformity unless they were built before emission 
standards started to apply. This subpart describes the limited cases 
where we allow importation of exempt or excluded engines/equipment. If 
an engine has an exemption from exhaust emission standards, you may 
import the equipment under the same exemption. Imported engines/
equipment that are exempt or excluded must have a label as described in 
the specific exemption or exclusion. If the regulation does not include 
specific labeling requirements, apply a label meeting the requirements 
of Sec.  1068.45 that identifies your corporate name and describes the 
basis for the exemption or exclusion.
* * * * *
0
272. Amend Sec.  1068.310 by revising the introductory text and 
paragraph (e)(4) to read as follows:


Sec.  1068.310  Exclusions for imported engines/equipment.

    If you show us that your engines/equipment qualify under one of the 
paragraphs of this section, we will approve your request to import such 
excluded engines/equipment. You must have our approval before importing 
engines/equipment under paragraph (a) of this section. You may, but are 
not

[[Page 17887]]

required to request our approval to import the engines/equipment under 
paragraph (b) through (d) of this section. Qualifying engines/equipment 
are excluded as follows:
* * * * *
    (e) * * *
    (4) State: ``THIS ENGINE IS EXEMPT FROM THE REQUIREMENTS OF 
[identify the part referenced in Sec.  1068.1(a) that would otherwise 
apply], AS PROVIDED IN [identify the paragraph authorizing the 
exemption (for example, ``40 CFR 1068.310(a)'')]. INSTALLING THIS 
ENGINE IN ANY DIFFERENT APPLICATION MAY BE A VIOLATION OF FEDERAL LAW 
SUBJECT TO CIVIL PENALTY.''
0
273. Amend Sec.  1068.315 by revising paragraphs (a) and (h) and 
removing paragraph (i) to read as follows:


Sec.  1068.315  Permanent exemptions for imported engines/equipment.

* * * * *
    (a) National security exemption. You may import an engine or piece 
of equipment under the national security exemption in Sec.  1068.225.
* * * * *
    (h) Identical configuration exemption. Unless specified otherwise 
in the standard-setting part, you may import nonconforming engines/
equipment if they are identical in all material respects to certified 
engines/equipment produced by the same manufacturer, subject to the 
following provisions:
    (1) You must meet all the following criteria:
    (i) You have owned the engines/equipment for at least six months.
    (ii) You agree not to sell, lease, donate, trade, or otherwise 
transfer ownership of the engines/equipment for at least five years. 
The only acceptable way to dispose of the engines/equipment during this 
five-year period is to destroy or export them.
    (iii) You use data or evidence sufficient to show that the engines/
equipment are in a configuration that is identical in all material 
respects to engines/equipment the original manufacturer has certified 
to meet emission standards that apply at the time the manufacturer 
finished assembling or modifying the engines/equipment in question. If 
you modify the engines/equipment to make them identical, you must 
completely follow the original manufacturer's written instructions.
    (2) We will tell you in writing if we find the information 
insufficient to show that the engines/equipment are eligible for the 
identical configuration exemption. We will then not consider your 
request further until you address our concerns.
0
274. Amend Sec.  1068.325 by revising the introductory text and 
paragraphs (a) through (c), (e), and (g) to read as follows:


Sec.  1068.325  Temporary exemptions for imported engines/equipment.

    You may import engines/equipment under certain temporary 
exemptions, subject to the conditions in this section. We may ask U.S. 
Customs and Border Protection to require a specific bond amount to make 
sure you comply with the requirements of this subpart. You may not sell 
or lease one of these exempted engines/equipment while it is in the 
United States except as specified in this section or Sec.  1068.201(i). 
You must eventually export the engine/equipment as we describe in this 
section unless it conforms to a certificate of conformity or it 
qualifies for one of the permanent exemptions in Sec.  1068.315 or the 
standard-setting part.
    (a) Exemption for repairs or alterations. You may temporarily 
import nonconforming engines/equipment solely for repair or alteration, 
subject to our advance approval as described in paragraph (j) of this 
section. You may operate the engine/equipment in the United States only 
as necessary to repair it, alter it, or ship it to or from the service 
location. Export the engine/equipment directly after servicing is 
complete, or confirm that it has been destroyed.
    (b) Testing exemption. You may temporarily import nonconforming 
engines/equipment for testing if you follow the requirements of Sec.  
1068.210, subject to our advance approval as described in paragraph (j) 
of this section. You may operate the engines/equipment in the United 
States only as needed to perform tests. The testing exemption expires 
one year after you import the engine/equipment unless we approve an 
extension. The engine/equipment must be exported before the exemption 
expires. You may sell or lease the engines/equipment consistent with 
the provisions of Sec.  1068.210.
    (c) Display exemption. You may temporarily import nonconforming 
engines/equipment for display if you follow the requirements of Sec.  
1068.220, subject to our advance approval as described in paragraph (j) 
of this section. The display exemption expires one year after you 
import the engine/equipment, unless we approve your request for an 
extension. The engine/equipment must be exported (or destroyed) by the 
time the exemption expires or directly after the display concludes, 
whichever comes first.
* * * * *
    (e) Diplomatic or military exemption. You may temporarily import 
nonconforming engines/equipment if you represent a foreign government 
in a diplomatic or military capacity. U.S Customs and Border Protection 
may require that you show your written confirmation from the U.S. State 
Department that you qualify for the diplomatic or military exemption or 
a copy of your orders for military duty in the United States. We will 
rely on the State Department or your military orders to determine when 
your diplomatic or military status expires, at which time you must 
export your exempt engines/equipment.
* * * * *
    (g) Exemption for partially complete engines. The following 
provisions apply for importing partially complete engines and used 
engines that become new as a result of importation:
    (1) You may import a partially complete engine by shipping it from 
one of your facilities to another under the provisions of Sec.  
1068.260(c) if you also apply a removable label meeting the 
requirements of Sec.  1068.45 that identifies your corporate name and 
states that the engine is exempt under the provisions of Sec.  
1068.325(g).
    (2) You may import an engine if another company already has a 
certificate of conformity and will be modifying the engine to be in its 
final certified configuration or a final exempt configuration if you 
meet the labeling and other requirements of Sec.  1068.262. If you are 
importing a used engine that becomes new as a result of importation, 
you must meet all the requirements that apply to original engine 
manufacturers under Sec.  1068.262. You may sell or lease the engines 
consistent with the provisions of Sec.  1068.262.
* * * * *
0
275. Amend Sec.  1068.450 by revising paragraph (e) to read as follows:


Sec.  1068.450  What records must I send to EPA?

* * * * *
    (e) We may post test results on publicly accessible databases and 
we will send copies of your reports to anyone from the public who asks 
for them, consistent with Sec.  1068.11.

[[Page 17888]]

0
276. Amend Sec.  1068.601 by revising the introductory text and 
paragraph (b) to read as follows:


Sec.  1068.601  Overview.

    The regulations of this chapter involve numerous provisions that 
may result in EPA making a decision or judgment that you may consider 
adverse to your interests. For example, our decisions might require you 
to pay penalties, or you might consider that our decisions will limit 
your business activities or put you at a competitive disadvantage. As 
specified in the regulations in this chapter, this might involve an 
opportunity for an informal hearing or a formal hearing that follows 
specific procedures and is directed by a Presiding Officer. The 
regulations in this chapter generally specify when we would hold a 
hearing. In limited circumstances, we may grant a request for a hearing 
related to adverse decisions regarding regulatory provisions for which 
we do not specifically describe the possibility of asking for a 
hearing.
* * * * *
    (b) For other issues where the regulation allows for a hearing in 
response to an adverse decision, you may request an informal hearing as 
described in Sec.  1068.650. Sections 1068.610 through 1068.630 
describe when and how to request an informal hearing under various 
circumstances.
* * * * *
0
277. Add Sec.  1068.630 to read as follows:


Sec.  1068.630  Request for hearing--allowable maintenance.

    (a) Any manufacturer may request an informal hearing as described 
in Sec.  1068.650 in response to our decision to identify allowable 
maintenance associated with new technology as part of the certification 
process.
    (b) You must send your hearing request in writing to the Designated 
Compliance Officer no later than 30 days after we publish our decision 
in the Federal Register. If the deadline passes, we may nevertheless 
grant you a hearing at our discretion.
    (c) Your hearing request must include the information specified in 
Sec.  1068.610(d).
    (d) We will approve your request for an informal hearing if we find 
that your request raises a substantial factual issue in the decision we 
made that, if addressed differently, could alter the outcome of that 
decision.
0
278. Redesignate appendix I to part 1068 as appendix A to part 1068 and 
amend newly redesignated appendix A by revising the introductory text 
to read as follows:

Appendix A to Part 1068--Emission-Related Components

    This appendix specifies emission-related components that we 
refer to for describing such things as emission-related warranty or 
maintenance or requirements related to rebuilding engines. Note that 
inclusion of a component in Section III of this Appendix does not 
make it an emission-related component for engines/equipment that are 
not subject to evaporative emission standards.
* * * * *

Appendix II to Part 1068--[Redesignated as Appendix B to Part 1068]

0
279. Redesignate appendix II to part 1068 as appendix B to part 1068.

Appendix III to Part 1068--[Redesignated as Appendix C to Part 1068]

0
280. Redesignate appendix III to part 1068 as appendix C to part 1068.

PART 1090--REGULATION OF FUELS, FUEL ADDITIVES, AND REGULATED 
BLENDSTOCKS

0
281. The authority citation for part 1090 continues to read as follows:

    Authority:  42 U.S.C. 7414, 7521, 7522-7525, 7541, 7542, 7543, 
7545, 7547, 7550, and 7601.

0
282. Revise Sec.  1090.1550 to read as follows:


Sec.  1090.1550  Requirements for gasoline dispensing nozzles used with 
motor vehicles.

    The following requirements apply for any nozzle installation used 
for dispensing gasoline into motor vehicles:
    (a) Nozzles must meet the following hardware specifications:
    (1) The outside diameter of the terminal end must not be greater 
than 21.3 mm.
    (2) The terminal end must have a straight section of at least 63 
mm.
    (3) The retaining spring must terminate at least 76 mm from the 
terminal end.
    (b) The dispensing flow rate must not exceed a maximum value of 10 
gallons per minute. The flow rate may be controlled through any means 
in the pump/dispenser system, as long as it does not exceed the 
specified maximum value.

[FR Doc. 2022-04934 Filed 3-16-22; 4:15 pm]
BILLING CODE 6560-50-P