Trump Signs Off on Fuel-Economy Rollback: 34.5 MPG by 2031, Formalized Monday

President Donald Trump said Saturday he has approved new fuel-economy standards for cars and trucks, teeing up the Transportation Department to formally announce the sharpest rollback of federal efficiency rules in years on Monday. The framework is expected to mirror December's proposal, which would hold the fleet average near 34.5 miles per gallon in model year 2031 — well below the roughly 50.4 mpg the Biden-era schedule required.

The Saturday announcement and the Monday signature

Trump made the announcement Saturday on Truth Social, writing that he had approved standards that "TERMINATE Sleepy Joe Biden and Pete Boot-EDGE-EDGE's ridiculous EV Mandate" and declaring it a "BIG DAY FOR AMERICAN AUTO WORKERS AND CAR BUYERS!" Transportation Secretary Sean Duffy previewed the formal move: "A major victory for America's auto workers is coming Monday."

He claimed automakers — naming General Motors, Ford and Stellantis — had expressed interest in expanding American production, and that "as much as $100 Billion is being invested in American Autos." He also thanked Duffy and Commerce Secretary Howard Lutnick. Those production and investment claims are Trump's own account; no independent confirmation from the automakers was available.

DOT is expected to formally announce the lower standards on Monday, September 28, with the final rule expected to track a December proposal that would cut the Biden-era efficiency schedule sharply. The announcement would cap a week in which the White House has made its autos posture explicit: build it in America, and build it without the emissions math the last administration imposed.

34.5 versus 50.4: what changes on paper

The December proposal would hold the fleet average near 34.5 miles per gallon in model year 2031 — down from roughly 50.4 mpg under the Biden-era schedule. It would retroactively revise down the 2022 standard, then require increases of only 0.25% to 0.5% a year through 2031.

Under the Biden schedule, passenger cars had to improve 8% a year in 2024 and 2025, 10% in 2026, and 2% a year from 2027 through 2031. The new framework effectively parks that climb: a fraction-of-a-percent annual rise instead of a multi-percent one, year after year.

The government's own math on the tradeoff

The Transportation Department's own estimates put the tradeoff in plain numbers: roughly $930 off the average new vehicle, about 100 billion more gallons of fuel consumed through 2050, $185 billion in additional national fuel spending, and carbon-dioxide emissions up about 5%.

Trump's pitch goes further than his department's arithmetic. "These new Standards will take the waste out of building cars in America," he wrote. "Americans will be able to buy safe, good cars at substantially LOWER PRICES, saving families thousands of dollars on a new, beautiful, and safe car!" DOT's estimate — $930 — sits well under the "thousands" in the president's post.

$4.48 a gallon: why the timing matters now

The rollback lands as American drivers are paying record September prices at the pump. The national average hit $4.48 a gallon Saturday, up from $3.16 a year earlier and $4.10 a month ago, per AAA data — a September record in the making and the highest ever for this time of year. In California, the average reached $6.33 a gallon Saturday, $1.84 more than a year ago, according to the New York Post citing AAA.

Gasoline prices have climbed since the U.S.-Israeli war with Iran began in late February. The practical effect of looser efficiency rules is straightforward: cars that burn more fuel per mile leave drivers more exposed to whatever the pump charges.

Congress cleared the runway first

Washington has been removing the old framework piece by piece. Congress already eliminated fines for automakers that miss the fuel-economy standards, saving the industry hundreds of millions of dollars, and last year blocked California from imposing stricter emissions limits on cars. In February, the EPA scrapped every federal limit on planet-warming pollution from cars, and the $7,500 federal tax credit for electric vehicles was repealed.

When DOT publishes the rule Monday, the first question is whether the final numbers track the December proposal. The second is how drivers — paying $4.48 a gallon — weigh a cheaper sticker against a bigger fuel bill.