Fuel Economy Standards Rolled Back: US Eases Mileage Rules

WASHINGTON, March 17, 2026 — The Trump administration on Monday finalized a sweeping rollback of federal fuel economy rules, replacing Biden-era mileage targets for cars and light trucks with significantly weaker standards. The new Corporate Average Fuel Economy (CAFE) rules lower the industrywide fleet average to roughly 34.5 miles per gallon in model year 2031, down from the 50.4 mpg required under the previous policy. The decision lands as the national average gas price sits at $4.47 a gallon and scientists warn that transportation remains the largest source of U.S. carbon emissions.

Trump has framed the change as a cost-cutting win for consumers and carmakers. In a Truth Social post on Saturday, he said the relaxed requirements would "take the waste out of building cars in America" and save families "thousands on a new, beautiful and safe car," while boosting domestic auto production. Transportation Secretary Sean Duffy had teased the announcement over the weekend, saying on X that the new rules would be made public Monday.

The CAFE program dates back to the 1970s energy crisis, when Congress ordered automakers to steadily improve how far new vehicles can travel on a gallon of gasoline. Successive administrations tightened the standards, most aggressively under Obama and Biden. Under the Biden-era framework, the National Highway Traffic Safety Administration (NHTSA) projected the average light-duty vehicle would need to hit 50.4 mpg by 2031. Monday's final rule resets that trajectory to about 34.5 mpg — a level analysts say most automakers can reach largely with existing internal-combustion technology.

The reversal underscores Trump's long-held skepticism of climate science. He has repeatedly called climate change a hoax and campaigned on the slogan "Drill, Baby, Drill," which he reprised at his 2025 inauguration and in speeches after declaring a national energy emergency. The phrase entered the political lexicon in 2008, when former Maryland lieutenant governor Michael Steele used it at the Republican National Convention to argue for American energy independence.

Federal projections illustrate the environmental cost. Compared with the Biden-era rules, the weaker standards would allow an additional 22,111 tons of carbon dioxide per year from new cars and light trucks by 2035, along with about 90 tons a year of fine soot particles and 4,870 tons a year of smog-forming nitrogen oxides and volatile organic compounds. Those pollutants are linked to asthma, heart disease and premature death, and they fall heaviest on communities near highways and freight routes.

Drivers encounter the change at an uncomfortable moment. The average new car in America sold for $50,089 in August, the first time the average crossed the $50,000 mark since December, according to Kelley Blue Book. Gasoline prices have climbed as Middle East tensions disrupt global fuel flows: the national average reached $4.47 a gallon on Sunday, up from $4.09 a month earlier, according to AAA. A car that burns more fuel per mile will make itself felt at the pump long before the new rules take effect in model year 2027.

The mileage rollback is one piece of a broader dismantling of clean-vehicle policy. Since taking office, Trump has also relaxed tailpipe emissions rules at the EPA, repealed fines for automakers that miss federal mileage targets and eliminated consumer tax credits of up to $7,500 for EV purchases. He has repeatedly described his agenda as killing an electric-vehicle "mandate," but no federal policy has ever required automakers to sell EVs. Biden's goal of making electric vehicles half of all new sales by 2030 was a nonbinding target, not a regulation.

The market is already sending mixed signals. Electric vehicles accounted for 6.5 percent of new-vehicle sales in February, down from 7.4 percent in all of 2025, according to automotive research firm Edmunds. The slide reflects weaker incentives and consumer concerns about charging infrastructure — trends that critics say the administration's policy signal will only reinforce.

Environmental groups reacted sharply. Dan Becker, director of the Center for Biological Diversity's Safe Climate Transport Campaign, said the final rule "ignores the feasibility of clean technology and the millions of fuel-efficient cars already on the road." He predicted consumers would pay for the rollback through higher fuel bills while oil and auto interests collect short-term profits. Katherine Garcia, director of the Sierra Club's Clean Transportation for All campaign, said the looser standards would "make driving more expensive too," and vowed the group would challenge the rule.

That challenge is likely to land in court. Environmental organizations and Democratic state attorneys general are expected to sue under the Clean Air Act, arguing that the mileage targets are illegally low given the costs and feasibility of cleaner technology. California, which has used Clean Air Act waivers for decades to set stricter vehicle standards, is expected to defend its own rules and could push automakers to follow them in the 14 other states that have adopted California's framework. The result could be years of litigation and a confusing patchwork of standards for manufacturers.

Automakers have greeted the rollback with mixed feelings. Looser federal targets cut near-term compliance costs, a relief for companies whose profits depend on trucks and sport-utility vehicles. But executives had also asked for stability: billions of dollars are already sunk into EV platforms and battery plants, and a regulatory pendulum that swings with each administration complicates product planning. The likely outcome, analysts say, is a two-track industry — efficient vehicles built for California and export markets, and larger, less efficient models for the rest of the country.

Internationally, the United States is moving against the grain. The European Union is enforcing binding CO2 limits that push automakers toward battery-electric and plug-in hybrid vehicles, and plans to end sales of new internal-combustion cars by 2035. China continues to tighten its fuel-consumption rules while expanding its EV export machine. Manufacturers competing globally must now satisfy divergent standards — a costly complication that the Trump administration acknowledges but dismisses as secondary to affordability.

NHTSA's own past analysis undercuts the cost-saving rationale. When the Biden-era standards were finalized in 2024, the agency estimated they would save 14 billion gallons of gasoline by 2050 and that higher upfront costs would be recouped through lower lifetime fuel spending. Gas prices have only risen since, yet Monday's rule walks away from those findings.

What comes next will play out in courtrooms, state capitals and the 2026 midterm campaign, where energy policy is already a central fault line. For motorists, the bottom line is straightforward: the average new car will burn more fuel than it would have under the previous rules, and the difference will show up every time the tank is filled. For the climate, the extra carbon dioxide, soot and smog will linger in the atmosphere for decades.