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EPA Seeks Delay on Stricter Emissions Rules for Certain Vehicles
Proposal Pushes 2-Year Delay for New Limits for Light-Duty and Class 3 Vehicles
Key Takeaways:
- EPA has proposed delaying stricter emissions standards for light-duty and Class 3 medium-duty vehicles until model year 2029.
- The standards would cut nonmethane organic gases plus NOx limits by 50% for light-duty vehicles and 58% to 70% for medium-duty vehicles.
- EPA will take public comments for 45 days and plans a broader reconsideration of Tier 4 standards, timelines and procedures.
The Environmental Protection Agency has proposed delaying stricter emissions standards for light-duty and Class 3 medium-duty vehicles until model year 2029 as part of a wider rollback of Biden-era pollution regulations.
The Trump administration promised in 2025 to revisit or rewrite a swath of climate regulations, including changes to tailpipe emissions for heavy-duty trucks and engines.
Now, EPA is set to review the 2024 Tier 4 emissions standards for pollutants such as nitrogen oxides, particulate matter and volatile organic compounds from passenger cars, pickup trucks and lighter commercial vehicles including cargo vans and some small box trucks under the proposed two-year delay.
The 2024 Tier 4 emissions standards for light- and medium-duty vehicles, which would be phased in between 2027 and 2030, as written, would include:
- A nonmethane organic gases (NMOG) plus NOx standard of 15 milligrams per mile (mg/mi) by MY 2032 for light-duty vehicles, a 50% reduction from the Tier 3 rule established in 2014.
- An NMOG+NOx fleet average level of 75 mg/mi by MY 2033 for medium-duty vehicles, representing a 58% to 70% cut from the Tier 3 standards of 178 mg/mi for Class 2b vehicles and 247 mg/mi for Class 3 vehicles.
EPA will hold a 45-day public comment period on the proposal.
The Trump EPA continues its historic deregulatory approach as @epaleezeldin announced a proposal to delay the compliance deadlines for Biden-era emission standards for light-and medium-duty vehicles for two years until model year (MY) 2029, which were unattainable due to the… — U.S. EPA (@EPA) May 15, 2026
EPA Administrator Lee Zeldin pitched the review and potential delay as an initiative that would restore customer choice and make vehicles more affordable, adding that American consumers were not interested in buying electric vehicles.
“This proposal aims to return EPA regulations to reality, restoring consumer choice, protecting good-paying American jobs and strengthening the nation’s global competitiveness while the agency works to reconsider the Tier 4 standards,” Zeldin said.
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Zeldin
Zeldin added that Tier 4 emissions standards were based on “faulty assumptions by the Biden administration” that EVs would make up a significant percentage of MY 2027 and beyond fleets, which he said led to unrealistic emissions standards for internal combustion engine vehicles.
EPA said the announcement was Part 1 of a review of the Tier 4 standards. Part 2, it said, would see the agency reconsider the Tier 4 program, which EPA said may include proposed changes to the Tier 4 standards, implementation dates, phase-in schedules and test procedures.
Meanwhile, heavy-duty truck and engine manufacturers expect EPA to release a draft of its long-awaited notice of proposed rulemaking on possible changes to its existing NOx emissions rule for model-year 2027 engines by the end of June.
The agency is expected to leave in place a requirement that NOx emissions from heavy-duty trucks fall to 35 milligrams per horsepower-hour from 200 mg/hp-hr, but the trucking industry is still waiting for clarity on key details, including warranty requirements.
Heavy-duty truck manufacturers have warned that the NOx rule could raise new vehicle prices by more than $10,000.
