Environmental Groups Sue Trump Administration Over Rollback of Car Mileage Standards

A coalition of five environmental and consumer advocacy groups sued the Trump administration on Friday over a new federal rule that sharply loosens how far cars and light trucks must travel on a gallon of gasoline, arguing the rollback will cost drivers money and worsen air pollution at a moment when gas prices are already near historic highs.

The Sierra Club, the Center for Biological Diversity's Climate Law Institute, the Conservation Law Foundation, the Environmental Defense Fund and Public Citizen filed a petition for review in the U.S. Court of Appeals against Transportation Secretary Sean Duffy and Jonathan Morrison, the administrator of the National Highway Traffic Safety Administration. The agency finalized the rule, formally titled the Safer Affordable Fuel-Efficient Vehicles Rule III, in the Federal Register on September 30.

What the Rule Changes

The Corporate Average Fuel Economy program, known as CAFE, sets the minimum fleetwide mileage automakers must hit each model year. NHTSA's new standards call for a combined industry average of roughly 34.9 miles per gallon for passenger cars and light trucks by model year 2031, down from the 50.4 mpg trajectory NHTSA had projected under standards finalized during the Biden administration. Under the new schedule, passenger-car requirements rise only 0.9% a year through 2029 before climbing to 1% a year through 2031, a far slower pace of tightening than the prior rule required.

The Transportation Department has defended the change as a correction to what it calls an unworkable mandate. The revamped rule, Duffy said, will blunt an "illegal mandate that forced automakers to produce more expensive electric vehicles that American families didn't want," according to a CBS News account of the announcement. The department said the looser standards would lower the average upfront cost of a new vehicle by $1,300, cut annual oil consumption and give automakers more flexibility over which kinds of vehicles they build.

The Numbers Behind the Fight

The plaintiffs counter with the administration's own projections. According to their joint statement announcing the lawsuit, NHTSA's own analysis shows the weaker standards will push Americans to spend more than $1,600 more on fuel over the life of a vehicle and will add more than 121 billion gallons of fuel consumption through 2050. The groups say the standards they are defending would otherwise have saved 64 billion gallons of gasoline and delivered $35 billion in savings to consumers over the lifetimes of the vehicles covered, even before the latest run-up in prices at the pump.

That run-up is real. The national average price for a gallon of gasoline stood at $4.40 on the day the lawsuit was filed, up from $3.16 a year earlier and roughly $2.98 just before the war with Iran began in late February, CBS News reported. Transportation already ranks as the second-largest household expense after housing, accounting for roughly 17% of average spending, according to the groups' filing. The Environmental Protection Agency has estimated that a typical passenger vehicle emits 4.6 metric tons of carbon dioxide a year, and that transportation accounted for 28% of total U.S. greenhouse gas emissions in 2022, the most recent year for which the agency has published data.

A Program Born of an Earlier Energy Crisis

CAFE standards date to the energy crisis of the 1970s, when Congress first ordered automakers to improve mileage to curb the country's dependence on imported oil. The targets have tightened and loosened along with the party in the White House ever since, and this is not the first time a rollback has ended up in court. During Trump's first term, a similar effort to ease federal mileage rules known as the SAFE Vehicles Rule drew a lawsuit from roughly two dozen states, including Oregon and Washington, which argued the rollback rested on flawed data and violated the Clean Air Act. Duffy signaled his intent to revisit the Biden-era targets almost as soon as he took office in early 2025, directing his department to begin unwinding what he described as a de facto electric-vehicle mandate.

Who Feels the Change

The rule reaches well beyond Washington. New-car buyers face a trade-off between the lower sticker prices the administration promises and the higher fuel bills the plaintiffs project over a vehicle's lifespan. Automakers, who had lobbied for relief from the steeper Biden-era targets, broadly welcomed the rollback as easing their product planning. Oil refiners stand to benefit from the higher gasoline demand the new standards are projected to generate. And communities near highways and ports, which advocacy groups say bear a disproportionate share of vehicle-tailpipe pollution, are the ones Friday's lawsuit says will be left breathing dirtier air as the rule takes hold.

Dueling Arguments

"With gas prices at historic highs, Trump picked the worst possible time to roll back federal mileage standards," said David Pettit, an attorney at the Center for Biological Diversity's Climate Law Institute, in the coalition's statement. "Oil companies will profit from less efficient cars, but drivers will take a hit to their wallets and our kids will breathe dirtier air."

"It is unlawful for Trump to turn back the clock on fuel-efficient cars, forcing drivers to waste more money on gas and communities to breathe toxic air," said Katherine Garcia, director of the Sierra Club's Clean Transportation for All program.

Robert Weissman, co-president of Public Citizen, said "consumers need more fuel-efficient choices when considering new cars, and they deserve vehicles that get more miles per gallon and miles per dollar," while James Crowley, a senior attorney at the Conservation Law Foundation, argued that "as the needle drops toward empty, more grocery and rent money goes into the tank." The Transportation Department and NHTSA did not respond to a request for comment on the lawsuit from the Associated Press, which first reported the filing.

What Happens Next

The case now moves through the normal course of appellate review, in which the plaintiffs will ask the court to find that NHTSA's rulemaking violated the Energy Policy and Conservation Act, the 1975 law underlying the CAFE program, and acted arbitrarily by ignoring the agency's own cost and emissions projections. Similar fights over mileage rules have taken years to resolve in the past, often outlasting the administration that wrote the challenged rule, and this one is unlikely to move any faster. In the meantime, the new standards remain in effect, meaning automakers can begin designing model-year 2031 vehicles to the looser targets while the litigation plays out in the background of a presidential term already defined, in part, by fights over energy and the cost of living.