EPA Proposes to Delay Unattainable Biden-era Vehicle Standards, Projecting $1.7 Billion in Savings Public Comment DEADLINE TBD

May 15, 2026

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(U.S. Environmental Protection Agency) Today (May 14, 2026), U.S. Environmental Protection Agency (EPA) Administrator Lee Zeldin proposed another massive deregulatory action to restore consumer choice and make vehicles more affordable for all American families. EPA is proposing to delay the compliance deadlines for Biden-era emission standards for light-and medium-duty vehicles for two years until model year (MY) 2029 following the shift away from electric vehicles (EVs) after Americans overwhelmingly rejected the vehicles and auto companies have lost billions investing in them. EPA’s action is projected to save over $1.7 billion, providing hundreds of dollars saved per vehicle for American families.

“Freedom is the foundation of this nation, and this includes the freedom to choose the car you drive. The American people have been very clear; they do not want EVs forced upon them,” said EPA Administrator Zeldin. “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.”

The 2024 Tier 4 emissions standards for criteria pollutants were based on faulty assumptions by the Biden Administration that EVs would make up a significant percentage of MY 2027 and beyond fleets, causing the administration to set unrealistic emission standards for internal combustion engine (ICE) vehicles. In the intervening years since the Biden-Harris Administration established the 2024 Tier 4 emission standards, the assumptions about the trajectory of EVs have not come true. This makes the Tier 4 standards unattainable for manufacturers and drives up the cost of vehicles as they try to comply.

In response to low consumer appetite for EVs, and federal changes ending avenues used to force EVs onto Americans—including the Congressional Review Act disapproval of three California vehicle emission waivers—many major automakers are reducing their EV fleets and developments. Recently, General Motors announced a $4 billion investment to boost ICE vehicle production and a further “$6 billion charge to unwind some [EV] investments.” Similarly, Ford cancelled plans for electric SUVs and Stellantis announced it was scrapping its plug-in EV lineup, citing waning customer demand.

If finalized, manufacturers would continue to comply with the well-established and highly effective Tier 3 standards, which currently deliver substantial emissions reductions of up to 80 percent, for MY 2027 and MY 2028 vehicles. This would give adequate lead time for manufacturers to phase in Tier 4 standards with MY 2029 fleets that better fit consumer demand for less EVs.

Today’s announcement is Part 1 of a comprehensive review of the Tier 4 standards as EPA works to protect and bring back American auto jobs and fulfill President Trump’s agenda. In Part 2, EPA plans to reconsider the Tier 4 program, which may include proposed changes to the Tier 4 standards, implementation dates, phase-in schedules, and test procedures. EPA is committed to ensuring human health and the environment are at the forefront of all of the agency’s rulemaking, while also ensuring rules are practical for implementation by stakeholders.

EPA will hold a 45-day public comment period on today’s proposal. For more information, please visit EPA’s website here.

Background

Today’s announcement builds on the major vehicle and equipment wins delivered by Administrator Zeldin in his first year. On February 12, 2026, alongside President Trump, Administrator Zeldin announced the single largest deregulatory action in U.S. history with the repeal of the 2009 Endangerment Finding and all vehicle greenhouse gas regulations. In addition to saving American taxpayers $1.3 trillion, the final rule ended all off-cycle credits and eliminated EPA incentives for the start-stop button.

In early 2025, EPA transmitted to Congress three emission waivers granted to California by the Biden Administration. In June 2025, all Congressional Review Act resolutions disapproving the vehicle emission waivers were signed into law by President Trump, repealing EV mandates and restoring consumer choice.

The agency is also making great strides in addressing Diesel Exhaust Fluid issues harming American truckers and farmers and advancing Americans’ Right to Repair for nonroad diesel equipment. READ MORE

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Regulations for Emissions from Heavy Equipment with Compression-Ignition (Diesel) Engines (Environmental Protection Agency)
Revision of Tier 4 Criteria Pollutant Standards, Part 1: Amendments to Phase-In Schedule for Light-Duty and Medium-Duty Vehicles (Environmental Protection Agency)
IER Applauds EPA’s Proposal to Pause Biden-Era Tier 4 Vehicle Emission Standards Built on Faulty EV Assumptions (Institute for Energy Research)
US EPA proposes delaying enforcement of Biden vehicle pollution rule (Reuters)
EPA punts tailpipe emissions standards: The Trump administration argues automakers can't sell enough EVs to meet the Biden-era standard. EPA is planning a broader rewrite. (Politico Pro E&E NewsPM)

Excerpt from Environmental Protection Agency: On May 14, 2026, the U.S. Environmental Protection Agency proposed the first phase of a two-part rulemaking, this Part 1 action proposes to adjust the implementation timeline from model year 2027 to MY 2029 for the Tier 4 criteria pollutant standards for light- and medium-duty vehicles.

This proposal focuses on providing manufacturers and suppliers additional lead time to adapt to evolving market conditions, regulatory requirements, and feasibility challenges, while maintaining strong environmental protections. This proposal also reinforces the Agency’s commitment to protecting American workers, lowering costs for consumers, and restoring regulatory balance while continuing to deliver meaningful emissions reductions under the existing Tier 3 program.

This Part 1 action will provide the time needed for EPA to reconsider the longer-term Tier 4 standards in a future Part 2 rulemaking where EPA will address potential updates to Tier 4 standards and related program elements.

Documents Related to this Proposal

Fact Sheet: EPA Delays Unattainable Biden-era Tier 4 Criteria Pollutant Standards for Light-Duty and Medium-Duty Vehicles (pdf) (175.84 KB, May 2026, EPA-420-F-26-009)
Notice of Proposed Rulemaking (pdf) (846.49 KB, pre-publication, signed May 14, 2026)
Regulatory Impact Analysis (pdf) (1.14 MB, May 2026, EPA-420-D-26-001)

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Excerpt from Institute for Energy Research: The Institute for Energy Research (IER) today (May 14, 2026) praised the Environmental Protection Agency’s proposal to pause the Biden administration’s Tier 4 vehicle emission standards for model years 2027 and 2028. This pause will allow manufacturers to continue operating under the current, well-established Tier 3 standards while EPA undertakes a comprehensive reconsideration of the entire Tier 4 program.

Tom Pyle, President of the Institute for Energy Research, released the following statement:

“IER has long maintained that the Biden EPA’s Tier 4 standards were not designed to improve air quality—which Tier 3 already achieves—but to force electric vehicles on Americans who have made it clear they do not want them. It was always a purely regulatory mechanism built on wishful thinking. The Trump EPA is right to hit the pause button on this unnecessary regulatory hurdle. We urge EPA to use the comment period and Part 2 rulemaking to replace the Tier 4 program with standards that are legal and grounded in freedom of choice, for the good of all Americans.”

READ MORE

Excerpt from Reuters: In April 2024, Biden's EPA finalized a rule requiring significant reductions in so-called "criteria pollutants" emitted from passenger and commercial vehicles from the 2027 through 2032 model years.

The Sierra Club criticized the move to delay enforcement of more stringent limits on pollutants from gasoline-powered vehicles. The group said the reductions are "readily achievable using commonsense, low-cost technologies already used by many vehicles."

The Sierra Club added that EPA’s analysis "shows that delaying the standards would sharply increase harmful pollution, preventable illness, and premature deaths."

The Alliance for Automotive Innovation, a trade group representing General Motors (GM.N), opens new tab, Toyota Motor (7203.T), opens new tab, Volkswagen (VOWG.DE), opens new tab, Ford (F.N), opens new tab, Stellantis (STLAM.MI), opens new tab, Hyundai (005380.KS), opens new tab and others, said the EPA proposal "makes a lot of sense ‌given ⁠current market conditions."

The group's CEO John Bozzella said the Biden emission standards were "unachievable absent significant growth in electric vehicle sales" and would make gasoline-powered vehicles more expensive.

The Biden rules require a 50% reduction through 2032 for light vehicles and a 58% cut for medium-duty vehicles in the six so-called "criteria pollutants": ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide and lead.

In 2024, ⁠EPA estimated $13 billion in annualized benefits due to reduced emissions of criteria pollutants that contribute to the formation of soot and smog.

The Trump administration has taken a series of steps to roll back vehicle regulations. In February, it finalized its repeal of ⁠the "endangerment finding" for vehicles, a 2009 determination that greenhouse gas emissions endanger human health, which gave EPA authority to regulate emissions from vehicles.

In December, the Transportation Department proposed significantly reducing the fuel economy requirements from model years ⁠2022 to 2031, requiring 34.5 miles per gallon on average by 2031, down from 50.4 miles per gallon.

This year, Trump signed legislation that ended fuel economy penalties for automakers, and USDOT said they faced no fines dating back to the 2022 model year. READ MORE