Days after the U.S. Transportation Department announced a new rule to reduce fuel economy standards for cars and light trucks, a coalition of 26 Democratic-led states and cities sued the Trump administration, alleging the change is illegal.
The coalition says the rule violates the Energy Policy and Conservation Act that first established fuel economy standards more than 50 years ago in response to the 1973 oil crisis.
“When we have been confronted in the past with an oil shock or constrained supplies on global energy markets, we came together collectively as a country, understanding that we had to not only conserve energy but work with industry to increase fuel economy standards in a way that both conserved the amount of energy we’re using as a nation but also put more money back into the pockets of drivers and families,” New Mexico Attorney General Raul Torrez said at a news conference announcing the lawsuit. “That fundamentally is what we were trying to do with this action.”
New Mexico is among the plaintiffs in the case against the National Highway Traffic Safety Administration, NHTSA Administrator Jonathan Morrison and Transportation Secretary Sean Duffy.
Filed in the United States Court of Appeals for the First Circuit in Boston, the case challenges a rule Duffy announced Monday to reduce the Corporate Average Fuel Economy, or CAFE, standards that establish how far a new vehicle must travel on a gallon of gasoline.
Under the final rule, the standard is now 34.9 miles per gallon for passenger cars and light trucks for the 2031 model year — down from a projected 50.4 miles per gallon under rules put in place during the Biden administration.
Duffy said the move was made to keep car-buying affordable by reducing the average cost of a new vehicle by $1,300 and to help automakers produce cars the public wants to buy.
The new rule reverses a final regulation the Biden administration implemented in 2024 to push carmakers to build more electric vehicles so they could meet increasing fuel economy standards. The Biden-era rule required cars to be 10% more efficient for the 2026 model year and increase efficiency 2% annually from 2027 to 2031.
Responding to Spectrum News’ request for comment about the lawsuit, the Transportation Department sent a quote from Duffy: “Joe Biden and Pete Buttigieg illegally twisted mileage standards to create an electric vehicle mandate — jacking up car prices for American families and forcing manufacturers to produce vehicles no one wanted. I’m proud to stand with President Trump to say that those days are over. This administration understands the freedom of every American family starts with affordable cars. That’s why our new standards will make that dream more achievable by letting auto manufacturers produce the cars that fit families’ needs at a lower price.”
The industry trade group representing Ford, General Motors, Hyundai, Toyota and other major carmakers praised the new rule, saying it will preserve consumer vehicle choice and keep the U.S. auto industry globally competitive.
The Union of Concerned Scientists, however, characterized the rule as a giveaway to oil and gas companies. It said CAFE standards have saved consumers over $32 billion since the Iran war began and pushed up gas prices, and that any reduction in upfront vehicle costs would be outweighed by higher fuel expenses over the vehicle’s lifespan.
Friday’s lawsuit contends that NHTSA used defective analyses about vehicle affordability, vehicle sales, fuel savings and vehicle safety in determining the new standards. Under the previous fuel economy standards, the states and cities who filed the case say consumers would have saved almost $200 billion in fuel.
“Gas prices don’t stop at the pump,” California Attorney General Rob Bonta said at Friday’s news conference. “They raise the cost of moving food and goods, and that raises prices at the store. This rollback isn’t only bad for Americans’ wallets; it’s illegal.”
California led the lawsuit that also includes the attorneys general of Arizona, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin and the District of Columbia. The city of Chicago, the city and county of Denver, the city of New York, and the city and county of San Francisco are also plaintiffs.
In a separate case, the Center for Biological Diversity, the Conservation Law Foundation, the Environmental Defense Fund and Public Citizen, along with the Sierra Club, filed a petition for review Friday in the U.S. Court of Appeals against Duffy and Morrison.
“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,” Katherine Garcia, director of the Sierra Club’s Clean Transportation for All campaign, said in a statement.
The Associated Press contributed to this report.