Regulatory Announcement

EPA Issues Amendments to the 

Heavy-Duty Highway Greenhouse 

Gas Rule and Other Nonroad 

Provisions 

The U.S. Environmental Protection Agency (EPA) and the 

National Highway Traffic Safety Administration (NHTSA) are 

adopting amendments to the agencies’ respective rules addressing 

Greenhouse Gas Emissions Standards and Fuel Efficiency Standards 

for Medium- and Heavy-Duty Engines and Vehicles. EPA and NHTSA 

are adopting amendments to correct inconsistencies and add clarifications 

to the current rules’ text. These amendments eliminate duplicative 

reporting requirements, reduce inadvertent minor differences between 

the EPA and NHTSA programs regarding such matters as voluntary 

early model year compliance, better align testing procedures to market 

realities, and reduce unnecessary testing burdens. 

This action also separately amends EPA regulations addressing mobile 

source emissions other than greenhouse gases. These other amendments 

include exemption provisions for new replacement engines, technical 

hardship provisions for nonroad diesel engines, fuel line permeation 

test procedures for large nonroad spark-ignition engines, and other 

amendments for small nonroad spark-ignition engines. 

EPA and NHTSA are accepting comment on this action, and EPA 

is also publishing EPA-specific amendments in a parallel notice of 

proposed rulemaking. EPA’s proposed rule would be used to address 

public comments, as needed. 

Office of Transportation and Air Quality 

EPA-420-F-13-001 

May 2013 
Regulatory Announcement

Background 

After the 2011 publication of the heavy-duty greenhouse gas and fuel efficiency rules, EPA and 

NHTSA began an extensive outreach effort to aid in the rules’ implementation. In the course 

of these efforts, the agencies received comments on specific aspects of the rules. In some cases it 

became clear that minor amendments to the rules would help to clarify the rules’ intent or make 

them more effective. The amendments adopted here are largely based on these implementation discussions, and the agencies are jointly taking this action to maintain a single, harmonized 

national program. This joint action will facilitate an expedited compliance process by allowing 

engine and vehicle certifications, based on the amendments, to occur directly after publication. 

In addition, EPA is adopting other amendments to address issues in the following five areas: 

Replacement Engines: EPA is adopting modifications to the replacement engine provisions 

to allow on a limited basis the practice of replacing engines with engines that are cleaner, 

but not certified to the most stringent standards. EPA is also revising the regulations to help 

ensure the proper use of this exemption. 

Nonroad Technical Hardships: EPA is revising technical hardship provisions to allow for 

wider Agency discretion to provide additional allowances for equipment manufacturers to 

transition to Tier 4 standards, based on individual circumstances involving exceptional 

difficulties in the availability of compliant engines. 

Transition Program for Marine Equipment Manufacturers: EPA is addressing a potential 

supply issue of compliant engines for marine installation during the transition to new emission standards for land-based engines by temporarily allowing marine equipment manufacturers to use allowances if a compliant marine engine is not available. 

Large Spark Ignition (SI) Engine Fuel Lines: EPA is modifying the regulation to allow fuel 

lines for Large SI engines to meet either the 1996 or 2004 version of SAE J2260 to address a 

fuel line supply issue. 

Small Spark Ignition (SI) Amendments: Through 2019 EPA is aligning an optional certification fuel to California’s Phase 3 gasoline for small SI nonroad engines, along with equivalent stringency standards. 

What are the Economic and Environmental Impacts? 

The regulatory changes in this action provide clarification and guidance and will have no cost 

impact. Similarly, these regulatory changes will have no environmental impact, except for the 

potential delay in the Tier 4 implementation schedule of a limited number of nonroad diesel 

engines. 

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Regulatory Announcement

For More Information 

You can access the direct final rule, the proposed rule and related documents on EPA’s Office of 

Transportation and Air Quality (OTAQ) Web site at: 

www.epa.gov/otaq/highway-diesel/regs.htm 

and 

www.epa.gov/otaq/climate/regs-heavy-duty.htm. 

For more information on these and related rules, please contact EPA through EPA OTAQ 

Public Inquiries at: 

www.epa.gov/otaq/oms-cmt.htm 

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