The Trump administration on Monday released new fuel efficiency mandates that weaken stringent rules implemented under President Biden.

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President Trump pitched the changes, which he announced in December, as a way to boost the domestic auto industry and lower consumer costs. He made the original announcement standing alongside several auto executives.

“These new Standards will take the waste out of building cars in America,” Trump said in a social media post Saturday. “That means LOWER PRICES, saving families thousands on a new, beautiful, and safe car — Far better than the Environmental Monsters that we were building heretofore.”

The new rule lowers the fuel-economy requirement for 2031 model-year vehicles to 34.9 miles per gallon from about 50 miles per gallon under the Biden administration. Current requirements are about 30.1 mile per gallon for model year 2024.

Trump has long criticized the Biden-era rules, which were part of a set of policies to spur production and purchases of electric vehicles. EV production and sales have plummeted as a consequence of Trump administration policies, and the new changes also come as elevated fuel prices are sending ripples through the broader U.S. economy.

Trump, whose party is struggling in the polls ahead of the November midterm elections, has been under pressure to do more to address concerns about rising prices for consumer goods, particularly as oil prices have remained persistently high since the start of the Iran war.

U.S. Transportation Secretary Sean P. Duffy said in a statement that the rules will end the “illegal mandate that forced automakers to produce more expensive electric vehicles that American families didn’t want.”

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“With our commonsense standards in place, we are making the American dream affordable again, putting safer cars on the road, and investing in the American autoworker,” Duffy said.

The lowered standards represent a major win for the auto and oil industries that complained the Biden-era requirements push the bounds of available technology and effectively discourage the sale of traditional gasoline-powered vehicles in favor of electric models.

However, the changes also come as diesel prices set a record high and gasoline prices reached their highest level ever for September, extending a rally driven by the Iran war and Russia’s invasion of Ukraine.

Trump administration officials are studying a range of options aimed at curbing soaring fuel prices, fueled in part by political impetus as rising cost of living is undermining Republicans’ odds of retaining control of Congress after the November midterm elections. Banning diesel exports has been floated as an option, though energy experts say such a step would only offer short-term relief and eventually drive costs even higher.

“With Americans struggling to afford gasoline that is more than $4 a gallon, the Trump administration is going to force them to pay more at the pump,” said Atid Kimelman, an attorney at Natural Resources Defense Council, an environmental nonprofit group. “Oil companies will get a windfall from gutting the fuel economy standards, but the rest of us are going to be handing over more of our hard-earned paychecks to fill up the tank.”

This is a developing story and will be updated. Mijares Torres writes for Bloomberg. Bloomberg writer Ari Natter contributed to this report. Times staff writer Hayley Smith contributed to this report.

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