Document ID: EPA-HQ-OAR-2019-0307-0100
Agency: epa
Document Type: Proposed Rule
Title: Improvements for Heavy-Duty Engine and Vehicle Test Procedures
Posted Date: 2021-06-29T04:00Z

[Federal Register Volume 86, Number 122 (Tuesday, June 29, 2021)]
[Proposed Rules]
[Pages 34189-34194]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05305]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 1036 and 1037

[EPA-HQ-OAR-2019-0307; FRL-10018-51-OAR]

Improvements for Heavy-Duty Engine and Vehicle Test Procedures

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: This notice of proposed rulemaking includes corrections, 
clarifications, additional flexibilities, and adjustment factors to 
improve the Greenhouse gas Emissions Model (GEM) compliance tool for 
heavy-duty vehicles while more closely matching the outputs produced by 
the original GEM version 3.0 that was used to establish the 
CO2 standards for Model Years 2021 and later in the 2016 
Heavy-duty Phase 2 final rule. This document supplements the proposed 
rule published on May 12, 2020, which included a larger set of proposed 
revisions to modify and improve GEM. Most of the proposed revisions 
from that notice of proposed rulemaking are addressed in a final 
rulemaking published elsewhere in the Final Rules section of this issue 
of the Federal Register. Given the nature of this proposal, there will 
be neither

[[Page 34190]]

significant environmental impacts nor significant economic impacts for 
any sector.

DATES: 
    Comments: Comments must be received on or before August 30, 2021.
    Public Hearing: If anyone contacts us requesting a public hearing 
on or before July 6, 2021, we will hold an online hearing at 10 a.m. 
Eastern Standard Time on July 14, 2021.

ADDRESSES: 
    Comments: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0307, at http://www.regulations.gov. For detailed instructions 
on sending comments and additional information on the rulemaking 
process, see the ``Public Participation'' section of this document.
    Docket: EPA has established a docket for this action under Docket 
ID No. EPA-HQ-OAR-2019-0307. Publicly available docket materials are 
available either electronically at http://www.regulations.gov or in 
hard copy at Air and Radiation Docket and Information Center, EPA 
Docket Center, EPA/DC, EPA WJC West Building, 1301 Constitution Ave. 
NW, Room 3334, Washington, DC. Out of an abundance of caution for 
members of the public and our staff, the EPA Docket Center and Reading 
Room was closed to public visitors on March 31, 2020, to reduce the 
risk of transmitting COVID-19. Our Docket Center staff will continue to 
provide remote customer service via email, phone, and webform. We 
encourage the public to submit comments via https://www.regulations.gov 
or email, as there is a temporary suspension of mail delivery to EPA, 
and no hand deliveries are currently accepted. For further information 
on EPA Docket Center services and the current status, please visit us 
online at https://www.epa.gov/dockets.
    Public Hearing: Individuals are invited to notify EPA of interest 
in a public hearing; see FOR FURTHER INFORMATION CONTACT.
    Public Participation: Comments: All submissions received must 
include the Docket ID No. EPA-HQ-OAR-2019-0307 for this rulemaking. 
Follow the online instructions for submitting comments. Once submitted, 
comments received may be posted without change to https://www.regulations.gov/, including any personal information provided, and 
cannot be edited or removed from Regulations.gov. 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 http://www2.epa.gov/dockets/commenting-epa-dockets.
    Out of an abundance of caution for members of the public and our 
staff, the EPA Docket Center and Reading Room was closed to public 
visitors on March 31, 2020, to reduce the risk of transmitting COVID-
19. Our Docket Center staff will continue to provide remote customer 
service via email, phone, and webform. We encourage the public to 
submit comments via https://www.regulations.gov or email, as there is a 
temporary suspension of mail delivery to EPA, and no hand deliveries 
are currently accepted. For further information on EPA Docket Center 
services and the current status, please visit us online at https://www.epa.gov/.
    EPA continues to carefully and continuously monitor information 
from the Centers for Disease Control and Prevention, local area health 
departments, and our Federal partners so we can respond rapidly as 
conditions change regarding COVID-19.
    Docket: All documents in the docket are listed on the 
www.regulations.gov website. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy form through the EPA Docket Center 
at the location listed in the ADDRESSES section of this document.
    Public Hearing: If we hold a public hearing, we will announce 
detailed information about the hearing on our website https://www.epa.gov/regulations-emissions-vehicles-and-engines/supplemental-rule-improvements-heavy-duty-engine-and. Send requests for a hearing 
and questions about the status of a hearing to the contact identified 
in FOR FURTHER INFORMATION CONTACT.

FOR FURTHER INFORMATION CONTACT: Amy Kopin, Office of Transportation 
and Air Quality, Assessment and Standards Division, Environmental 
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 
telephone number: (734) 214-4173; email address: kopin.amy@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
II. Greenhouse Gas Emissions Model (GEM) Background
III. Proposed Updates to GEM
IV. Statutory Authority and Executive Order Reviews

I. General Information

Does this action apply to me?

    This action relates to companies that manufacture or sell new 
heavy-duty engines and vehicles as defined under EPA's CAA 
regulations.\1\ Regulated categories and entities include the 
following:
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    \1\ ``Heavy-duty engine'' and ``heavy-duty vehicle'' are defined 
in 40 CFR 1037.801.

------------------------------------------------------------------------
                                                          Examples of
         NAICS codes \A\             NAICS titles         potentially
                                                      regulated entities
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333618, 336111, 336112, 336120,   Other Engine        Motor vehicle
 336211, 336999.                   Equipment           manufacturers and
                                   Manufacturing,      engine
                                   Automobile          manufacturers.
                                   Manufacturing,
                                   Light Truck and
                                   Utility Vehicle
                                   Manufacturing,
                                   Heavy Duty Truck
                                   Manufacturing,
                                   Motor Vehicle
                                   Body
                                   Manufacturing,
                                   All Other
                                   Transportation
                                   Equipment
                                   Manufacturing.
------------------------------------------------------------------------
\A\ North American Industry Classification System (NAICS).

[[Page 34191]]

    This list is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. 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?

    This action proposes to amend the regulations that implement our 
air pollutant emission standards for heavy-duty engines and vehicles. 
The proposed amendments in this notice of proposed rulemaking include 
corrections, clarifications, additional flexibilities, and adjustment 
factors to the Greenhouse gas Emissions Model (GEM) compliance tool for 
heavy-duty vehicles. These amendments would modify the existing test 
procedure for heavy-duty highway engines and vehicles and apply to the 
measurement of CO2 emissions. EPA published a proposed rule 
on May 12, 2020 (85 FR 28153) (``Technical Amendments proposed rule''). 
EPA is issuing a final rulemaking (``Technical Amendments final rule'') 
relating to most revisions proposed in the Technical Amendments 
proposed rule, published in the Final Rules section of this issue of 
the Federal Register, titled ``Improvements for Heavy-Duty Engine and 
Vehicle Test Procedures, and other technical amendments,'' docket 
number EPA-HQ-OAR-2019-0307; FRL-10018-52-OAR.
    This action supplements the Technical Amendments proposed rule for 
only certain specific aspects of revising GEM by proposing several 
amendments to the model, after consideration of comments solicited and 
received on the Technical Amendments proposed rule, including a 
proposed revision to address concerns raised regarding potential 
stringency impacts that may result from changes to GEM.

What are the incremental costs and benefits of this action?

    This action is limited in scope and does not have significant 
economic or environmental impacts. EPA has therefore not estimated the 
potential costs or benefits of this notice of proposed rulemaking.

II. Greenhouse Gas Emissions Model (GEM) Background

    GEM is a computer application that estimates the greenhouse gas 
(GHG) emissions and fuel efficiency performance of specific aspects of 
heavy-duty vehicles. GEM uses several vehicle-specific inputs, such as 
engine fuel maps, aerodynamic drag coefficients, and vehicle weight 
ratings, to simulate vehicle and engine operation and model the amount 
of CO2 emitted over multiple duty cycles for tractors and 
vocational vehicles. The resulting CO2 values over these 
cycles are weighted by GEM to provide a composite GEM score. GEM 
version 3.0 was used to set standards in the Greenhouse Gas Emissions 
and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and 
Vehicles-Phase 2 (``Phase 2'') rulemaking (81 FR 73478). For purposes 
of determining compliance, composite GEM scores are compared to the 
applicable Phase 2 vehicle standard.
    In the Technical Amendments proposed rule, we proposed several 
amendments to GEM 3.0, including corrections, clarifications, and 
additional flexibilities in a revised version of the model, GEM 3.5 (85 
FR 28145). EPA also requested comment on whether any differences in GEM 
output values resulting from changes to the model would impact the 
effective stringency of the program and, if so, whether EPA should 
revise the GEM model itself or address such impacts via regulations 
(see 85 FR 28145).
    Comments received in response to the NRPM supported most of the 
proposed updates to GEM and requested additional revisions to further 
improve the model.\2\ The California Air Resources Board (CARB) 
provided comment on this topic, stating the importance of GEM results 
being consistent with the current program standards to avoid affecting 
program stringency. CARB recommended that EPA revise GEM in order to 
ensure stringency is maintained.\3\
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    \2\ See ``Improvements for Heavy-Duty Engine and Vehicle Test 
Procedures, and other Technical Amendments Response to Comments'', 
Publication Number: EPA-420-R-20-026, December 2020. Chapter 2 of 
the Response to Comments provides additional details on the 
amendments, clarifications requested by commenters, and our 
responses to most of the comments to the NPRM.
    \3\ California Air Resources Board, Docket number EPA-HQ-OAR-
2019-0207-0030.
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    After considering the comments received, EPA applied further 
potential changes to GEM 3.5 and released a new development version of 
GEM, GEM 3.7, to the public for download and review by stakeholders to 
evaluate and assess the performance of this revised model. GEM 3.7 
incorporated some corrections and improvements relative to the proposed 
version GEM 3.5, as noted in the corresponding memorandum in the 
rulemaking docket.\4\
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    \4\ Nelson, Brian. Memorandum to Docket EPA-HQ-OAR-2019-0307. 
``Development version of GEM and adjustment factors''. October 23, 
2020. Docket number EPA-HQ-OAR-2019-0307-0083. Also available 
online: https://www3.epa.gov/otaq/gem-p2v3.7-release-memo-2020-10-23.pdf.
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    While evaluating GEM 3.7, we found differences in the output values 
for some tractor and vocational vehicles compared to the output values 
from GEM 3.0 used to set the Phase 2 CO2 standards. To 
understand the differences between GEM 3.0 and GEM 3.7, we recreated 
the process used in 2016 to determine the numerical level of the Phase 
2 standards. Without an adjustment to the resulting GEM output value, 
these differences in GEM output values when compared to the Phase 2 
final rule could be considered an effective change in stringency. In 
light of GEM 3.7 output differences and considering CARB's comment, we 
identified adjustment factors in that same docketed memo that could be 
applied to the unrounded GEM 3.7 output to better ensure effective 
stringency of the standards is maintained.\5\
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    \5\ Id.
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    The Truck and Engine Manufacturers Association (EMA) requested 
additional time for its members to review the potential updates to the 
model in GEM 3.7 and evaluate the impact of the adjustment factors made 
available.\6\
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    \6\ Charmley, Bill. Memorandum to Docket EPA-HQ-OAR-2019-0307. 
``EPA discussions with the Truck and Engine Manufacturers 
Association, and with the California Air Resources Board, regarding 
Highway Heavy-Duty Technical Amendments.'' December 14, 2020. Docket 
Number EPA-HQ-OAR-2019-0307-0092.
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    As described in the Technical Amendments final rule, EPA released a 
revised version of GEM (i.e., GEM 3.5.1) that corrected three errors in 
GEM 3.5 and finalized provisions to specify GEM 3.5.1 without 
adjustment factors as the compliance tool for meeting Phase 2 
standards.\7\ GEM 3.5.1 includes the following updates to GEM 3.5:
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    \7\ See the notice of final rulemaking for ``Improvements for 
Heavy-Duty Engine and Vehicle Test Procedures, and other Technical 
Amendments'' published in the Final Rule's section of today's 
Federal Register, titled ``Improvements for Heavy-Duty Engine and 
Vehicle Test Procedures,'' docket number EPA-HQ-OAR-2019-0307; FRL-
10018-52-OAR.
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     Corrected duty cycle weighting factors for vocational 
vehicles in the Heavy Heavy-Duty Multipurpose subcategory.
     Corrected an idle map error when the cycle average engine 
fuel mapping procedure is used for all three drive cycles.
     Corrected a functional error that unnecessarily required 
manufacturers to include transmission power loss data when using the 
option to enter a unique (instead of default) k-factor for the torque 
converter.

[[Page 34192]]

III. Proposed Updates to GEM

    In this notice of proposed rulemaking, as detailed further in this 
section, we are proposing to revise GEM and to revise GEM's test 
procedures to include adjustment factors after consideration of 
comments solicited and received on the Technical Amendments proposed 
rule. We request comment only on these specific revisions and are not 
proposing changes to or seeking comment on any other amendments 
included in the Technical Amendments proposed or final rule.
    We are releasing GEM version 3.8 for notice and comment.\8\ The 
proposed GEM 3.8 allows additional compliance flexibilities and 
improves the vehicle simulation by incorporating the following 
improvements relative to GEM 3.5.1:
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    \8\ Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.8, 
December 2020. A working version of this software is also available 
for download at https://www.epa.gov/regulations-emissions-vehicles-and-engines/greenhouse-gas-emissions-model-gem-medium-and-heavy-duty.
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     Changed limits on engine input to allow small negative 
torque inputs.
     Corrected how GEM adjusts the idle fueling of the 
transient cycle by using the same idle duration time both for 
subtracting the idle fuel rate from the transient cycle average engine 
fuel map and for adding back in the simulated idle fuel rate.
     Added an option for vocational vehicles to input a value 
for neutral coasting in GEM and amend the related test procedure in 40 
CFR 1037.520(j)(1).
     Corrected manual and automated manual transmissions to 
perform clutched upshifts for Heavy HDV.
    We request comment on the revisions listed above.
    As noted in a memorandum to the docket, the resulting standards 
generated using GEM 3.8 in place of GEM 3.0 were, on average, 0.58 
percent lower for tractors and 0.20 percent higher for vocational 
vehicles, with the greatest difference (an increase of 1.3 percent) 
occuring in a few of the custom chassis standards.\9\ To ensure that 
these changes to GEM do not change the effective stringency of the 
Phase 2 CO2 standards, we propose a revision to the test 
procedures in 40 CFR 1037.520(o) to include a table of adjustment 
factors to be applied to the unrounded GEM 3.8 output to correct the 
differences. We request comment on this proposed revision to 40 CFR 
1037.520(o). EPA also requests comment on whether EPA should 
incorporate the adjustment factors directly into the GEM model, if EPA 
is able to develop a version of the GEM model which properly 
incorporates the adjustment factors.
---------------------------------------------------------------------------

    \9\ Sanchez, James, Memorandum to Docket EPA-HQ-OAR-2019-0307. 
Process of Using GEM to Set Vehicle Standards. December 4, 2020.
---------------------------------------------------------------------------

    We are proposing to incorporate by reference into the regulations 
the revised version, GEM 3.8, for manufacturers to demonstrate 
compliance with the Phase 2 standards, including obtaining a 
certificate of conformity and submitting end-of-year reports. For MY 
2021, we are proposing to allow use of GEM 3.5.1 under Sec.  
1037.150(bb) as an interim provision, but to limit this optional use of 
GEM 3.5.1 for demonstrating compliance with the Phase 2 standards, 
including obtaining a certificate of conformity and submitting end-of-
year reports, to MY 2021 vehicles only. A manufacturer who opts to use 
GEM 3.5.1 for MY 2021 is required to apply GEM 3.5.1 across its entire 
MY 2021 U.S.-directed production volume. We also propose to allow MY 
2021 data based on the use of GEM 3.5.1 to be used for carryover 
requests for certificates of conformity for MY 2022 and future years 
for qualifying vehicles under Sec.  1037.235(d); however, manufacturers 
would still need to use GEM 3.8 for end-of-year reporting for MY 2022 
and later. Under this proposal, GEM 3.8 would need to be used for all 
other certificates of conformity for MY 2022 and later. Due to the 
model improvements and flexibilities available in GEM 3.8 relative to 
GEM 3.5.1, we request comment on the appropriateness of requiring that 
GEM 3.8 be used for MY 2021 end-of-year reports even if MY 2021 
certificates of conformity were obtained using GEM 3.5.1. Finally, we 
are proposing that if an engine fuel map was run on an engine using a 
cycle generated from GEM 3.5.1 for MY 2021 and the manufacturer of that 
engine applies for carryover certification for MY 2022 or later, the 
manufacturer would not need to rerun the engine fuel map. We request 
comment on these requirements, allowable uses, and limitations proposed 
for each of these revised GEM model versions, including the use of GEM 
3.5.1 for MY 2021 and carryover applications.

IV. Statutory Authority and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at http://www2.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 not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget (OMB) 
for review.

B. 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. In 
making this determination, the impact of concern is any significant 
adverse economic impact on small entities. An agency may certify that a 
rule will not have a significant economic impact on a substantial 
number of small entities if the rule relieves regulatory burden, has no 
net burden or otherwise has a positive economic effect on the small 
entities subject to the rule. This action is designed to reduce testing 
burdens, increase compliance flexibility, and make various corrections 
and adjustments to compliance provisions; as a result, we anticipate no 
costs associated with this rule. We have therefore concluded that this 
action will have no net regulatory burden for directly regulated small 
entities.

C. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. This action imposes no enforceable duty on any 
state, local or tribal governments. Requirements for the private sector 
do not exceed $100 million in any one year.

D. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

E. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications as specified in 
Executive Order 13175. This rule will be implemented at the Federal 
level and affects engine and vehicle manufacturers. Thus, Executive 
Order 13175 does not apply to this action.

F. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because the EPA does not believe the environmental

[[Page 34193]]

health or safety risks addressed by this action present a 
disproportionate risk to children. There are no environmental health or 
safety risks created by this action that could present a 
disproportionate risk to children.

G. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution or Use

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

H. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR 
Part 51

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law 104-113, 12(d) (15 U.S.C. 272 note) 
directs EPA to use voluntary consensus standards in its regulatory 
activities unless to do so would be inconsistent with applicable law or 
otherwise impractical. Voluntary consensus standards are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
voluntary consensus standards bodies. NTTAA directs agencies to provide 
Congress, through OMB, explanations when the Agency decides not to use 
available and applicable voluntary consensus standards. This action 
involves technical standards.
    Except for the reference discussed below, the standards included in 
the regulatory text as incorporated by reference in 40 CFR part 1037 
were all previously approved for IBR and no change is proposed in this 
action.
    In accordance with the requirements of 1 CFR 51.5, we are proposing 
to incorporate by reference a new version of the Greenhouse gas 
Emissions Model (GEM), which we use for certifying heavy-duty highway 
vehicles to the greenhouse gas emission standards in 40 CFR part 1037. 
The model calculates emission rates for heavy-duty highway vehicles 
based on input values defined by the manufacturer. The model is 
available as noted in the amended regulations at 40 CFR 1037.810.

I. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes this action does not have disproportionately high 
and adverse human health or environmental effects on minority 
populations, low-income populations or indigenous peoples, as specified 
in Executive Order 12898 (59 FR 7629, February 16, 1994). Due to the 
small environmental impact, this regulatory action will not have a 
disproportionate adverse effect on minority populations, low-income 
populations, or indigenous peoples.

List of Subjects

40 CFR Part 1036

    Administrative practice and procedure, Air pollution control, 
Confidential business information, Environmental protection, Greenhouse 
gases, Labeling, Motor vehicle pollution, Reporting and recordkeeping 
requirements, Warranties.

40 CFR Part 1037

    Administrative practice and procedure, Air pollution control, 
Confidential business information, Environmental protection, 
Incorporation by reference, Labeling, Motor vehicle pollution, 
Reporting and recordkeeping requirements, Warranties.

Jane Nishida,
Acting Administrator.

    For the reasons set out in the preamble, we propose to amend title 
40, chapter I of the Code of Federal Regulations as set forth below.

PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVY-DUTY 
HIGHWAY ENGINES

0
1. The authority citation for part 1036 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.

0
2. Amend Sec.  1036.150 by adding paragraph (r) to read as follows:

Sec.  1036.150  Interim provisions.

* * * * *
    (r) Carryover fuel maps. You may use fuel maps from model year 2021 
engines for certifying model year 2022 and later vehicles using 
carryover provisions in Sec.  1036.235(d), even if the specified 
version of the GEM simulation tool to generate duty cycles for fuel 
mapping changes for those later model years.

PART 1037--CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES

0
3. The authority citation for part 1037 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.

0
4. Amend Sec.  1037.150 by adding paragraph (bb) to read as follows:

Sec.  1037.150  Interim provisions.

* * * * *
    (bb) Transition to updated GEM. Vehicle manufacturers may 
demonstrate compliance with Phase 2 GHG standards in model year 2021 
vehicles using GEM Phase 2, Version 3.5.1 (incorporated by reference in 
Sec.  1037.810). Each vehicle manufacturer must use a single version of 
GEM for all its model year 2021 families. Vehicle manufacturers may use 
GEM Phase 2, Version 3.5.1 for later model years only to certify 
vehicle families from model year 2021 that qualify for using carryover 
provisions in Sec.  1037.235(d).
0
5. Amend Sec.  1037.520 by revising the introductory text and paragraph 
(j)(1) and adding paragraph (o) to read as follows:

Sec.  1037.520  Modeling CO2 emissions to show compliance for 
vocational vehicles and tractors.

    This section describes how to use the Greenhouse gas Emissions 
Model (GEM) (incorporated by reference in Sec.  1037.810) to show 
compliance with the CO2 standards of Sec. Sec.  1037.105 and 
1037.106 for vocational vehicles and tractors. Use GEM version 2.0.1 to 
demonstrate compliance with Phase 1 standards; use GEM Phase 2, Version 
3.8 to demonstrate compliance with Phase 2 standards. Use good 
engineering judgment when demonstrating compliance using GEM. See Sec.  
1037.515 for calculation procedures for demonstrating compliance with 
trailer standards.
* * * * *
    (j) * * *
    (1) Intelligent controls. Enter 2 for tractors with predictive 
cruise control. This includes any cruise control system that 
incorporates satellite-based global-positioning data for controlling 
operator demand. For tractors without predictive cruise control and for 
all vocational vehicles, enter 1.5 if they have neutral coasting, 
unless good engineering judgment indicates that a lower percentage 
should apply.
* * * * *
    (o) Adjusting results for updated GEM. Adjust composite results 
from GEM Phase 2, Version 3.8 using the following equation to account 
for modeling changes relative to GEM Phase 2, Version 3.0:
[GRAPHIC] [TIFF OMITTED] TP29JN21.000

Where:

eCO2 = FEL CO2 Emissions from GEM.
AF = the adjustment factor from the following table:

[[Page 34194]]

       Table 10 of Sec.   1037.520--Adjustment Factors for Composite Results From GEM Phase 2, Version 3.8
----------------------------------------------------------------------------------------------------------------
                                                                           Adjustment factor
               Regulatory subcategory                -----------------------------------------------------------
                                                         MY 2022-2023        MY 2024-2026      MY 2027-and-later
----------------------------------------------------------------------------------------------------------------
Class 7 Day Cab Low Roof............................             -0.0104             -0.0090             -0.0094
Class 7 Day Cab Mid Roof............................             -0.0106             -0.0084             -0.0097
Class 7 Day Cab High Roof...........................             -0.0088             -0.0084             -0.0090
Class 8 Day Cab Low Roof............................             -0.0062             -0.0079             -0.0068
Class 8 Sleeper Cab Low Roof........................             -0.0014             -0.0015             -0.0016
Class 8 Day Cab Mid Roof............................             -0.0059             -0.0062             -0.0064
Class 8 Sleeper Cab Mid Roof........................             -0.0013              0.0000              0.0000
Class 8 Day Cab High Roof...........................             -0.0058             -0.0062             -0.0066
Class 8 Sleeper Cab High Roof.......................             -0.0013             -0.0014             -0.0016
Class 8 Heavy Haul..................................             -0.0076             -0.0080             -0.0062
Multi-Purpose Light HDV Compression-ignition........              0.0000             -0.0029              0.0000
Regional Light HDV Compression-ignition.............              0.0000              0.0000              0.0000
Urban Light HDV Compression-ignition................              0.0000              0.0000              0.0000
Multi-Purpose Medium HDV Compression-ignition.......             -0.0038              0.0000              0.0000
Regional Medium HDV Compression-ignition............              0.0000              0.0000              0.0000
Urban Medium HDV Compression-ignition...............             -0.0034             -0.0037              0.0000
Multi-Purpose Heavy HDV Compression-ignition........              0.0038              0.0041              0.0043
Regional Heavy HDV Compression-ignition.............              0.0000              0.0000              0.0000
Urban Heavy HDV Compression-ignition................              0.0065              0.0071              0.0037
Multi-Purpose Light HDV Spark-ignition..............              0.0000              0.0000             -0.0027
Regional Light HDV Spark-ignition...................              0.0000              0.0000              0.0000
Urban Light HDV Spark-ignition......................              0.0000              0.0000              0.0000
Multi-Purpose Medium HDV Spark-ignition.............              0.0000              0.0000              0.0000
Regional Medium HDV Spark-ignition..................              0.0000              0.0000              0.0040
Urban Medium HDV Spark-ignition.....................              0.0030              0.0032              0.0034
School bus..........................................             -0.0034             -0.0034              0.0000
Motor home..........................................              0.0000              0.0000              0.0000
Coach bus...........................................              0.0000              0.0000              0.0049
Other bus...........................................              0.0067              0.0067              0.0000
Refuse hauler.......................................              0.0096              0.0096              0.0034
Concrete mixer......................................              0.0125              0.0125              0.0127
Mixed-use vehicle...................................              0.0125              0.0125              0.0127
Emergency vehicle...................................              0.0123              0.0123              0.0125
----------------------------------------------------------------------------------------------------------------

0
6. Amend Sec.  1037.810 by revising paragraph (c) to read as follows:

Sec.  1037.810  Incorporation by reference.

* * * * *
    (c) U.S. EPA, Office of Air and Radiation, 2565 Plymouth Road, Ann 
Arbor, MI 48105, www.epa.gov.
    (1)(i) Greenhouse gas Emissions Model (GEM), Version 2.0.1, 
September 2012 (``GEM version 2.0.1''), IBR approved for Sec.  
1037.520.
    (ii) Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.5.1, 
November 2020 (``GEM Phase 2, Version 3.5.1''); IBR approved for Sec.  
1037.150(bb).
    (iii) Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.8, 
November 2020 (``GEM Phase 2, Version 3.8''); IBR approved for Sec.  
1037.520.
    (iv) GEM's MATLAB/Simulink Hardware-in-Loop model, Version 3.8, 
December 2020 (``GEM HIL model''); IBR approved for Sec.  1037.550(a).
    (2) The computer code for these models is available as noted in 
paragraph (a) of this section. A working version of the software is 
also available for download at https://www.epa.gov/regulations-emissions-vehicles-and-engines/greenhouse-gas-emissions-model-gem-medium-and-heavy-duty.
* * * * *
[FR Doc. 2021-05305 Filed 6-28-21; 8:45 am]
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