EPA Proposes Two-Year Delay of Biden-Era Tailpipe Emissions Rule

The EPA on Thursday proposed to push back the start date for a Biden-era rule that aimed to reduce emissions from vehicles, saying the standards were unrealistic and drove up costs.

The 2024 Tier 4 emissions standards were meant to clamp down on emissions that have been linked to heart disease, asthma, strokes, and other harmful conditions. The rule applied to new light- and medium-duty cars and trucks, and it was set to take effect in the 2027 model year.

If the Trump administration’s rule is finalized, the start date would be delayed until model year 2029. That would save American families more than $1.7 billion, according to the Environmental Protection Agency.

The Biden administration’s rule was based on “wishful thinking that EVs would make up most of model year 2027 and beyond fleets,” the EPA said in a statement. “That fairytale didn’t pan out because Americans are overwhelmingly rejecting EVs.”

If the rule is finalized, the EPA has said it may change the Tier 4 standards themselves, or amend the test procedures or phase-in schedules. Automakers would still have to comply with the previous emissions standards, known as Tier 3.

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

The Environmental Defense Fund has said the Biden standards would save the US more than $140 billion in health costs through 2055. The group also says automakers can easily meet the Tier 4 standards even in internal combustion engines by adopting widely-available filters or new engine designs. In a statement Thursday, the Sierra Club echoed those views, saying the standards are “readily achievable.”

“Tailpipe emission standards are not abstract policies,” said Katherine Garcia, director of the Sierra Club’s Clean Transportation for All campaign. “They are lifesaving protections grounded in science that protect communities across the country from toxic vehicle pollution.”

The announcement is the latest in a long series of auto emissions rollbacks by the Trump administration.

President Donald Trump’s July 2025 budget reconciliation bill zeroed out the civil penalty for automakers that fall short of meeting the Corporate Average Fuel Economy standards. The same bill also repealed a Biden-era $7,500 tax credit for new EV sales.

The EPA in February eliminated off-cycle credits that were used to implement the start-stop feature in vehicles. Zeldin said at the time that car makers “should not be forced to adopt or rewarded for technologies that are merely a climate participation trophy with no measurable pollution reductions.”

The Sierra Club has received funding from Bloomberg Philanthropies, the charitable organization founded by Michael Bloomberg. Bloomberg Law is operated by entities controlled by Michael Bloomberg.