Environmental groups filed a lawsuit on Friday against the Trump administration over its rollback of vehicle fuel efficiency standards, saying the move will increase gasoline consumption and boost prices at the pump for U.S. motorists. 

“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, Sierra Club’s Clean Transportation for All Director, said in a statement. 

The new Trump administration rules, announced on Monday, changed the Corporate Average Fuel Economy standards, which dictate how many miles per gallon vehicles must be able to travel. Under the revised standards, automakers must achieve a fleetwide average of 34.9 miles per gallon by 2031, down from a projected 50.4 miles under rules previously implemented by the Biden administration.

In announcing the new CAFE standards, the Department of Transportation said it will lower the average upfront cost of new vehicles by $1,300, cut annual oil consumption and give automakers more choice regarding the types of cars they manufacture. Transportation Secretary Sean Duffy also said the revamped rule will blunt the “illegal mandate that forced automakers to produce more expensive electric vehicles that American families didn’t want.”

But the groups behind the lawsuit allege that reducing fuel efficiency will raise costs for drivers and increase vehicle emissions, a leading cause of climate change. 

“Consumers need more fuel-efficient choices when considering new cars, and they deserve vehicles that get more miles per gallon and miles per dollar,” Robert Weissman, co-president of Public Citizen, a consumer advocacy group and a plaintiff in the suit, said in a statement. 

Other groups joining the legal action include the Center for Biological Diversity’s Climate Law Institute, Conservation Law Foundation and Environmental Defense Fund.

A typical passenger vehicle emits 4.6 metric tons of carbon dioxide, a major greenhouse gas, per year, according to the Environmental Protection Agency. As of 2022, the most recent year for which data is available, the transportation industry accounted for 28% of total U.S. greenhouse gas emissions, the agency says.

The national average price for a gallon of gasoline on Friday was $4.40, up from $3.16 a year ago and from roughly $2.98 just before the Iran war started in late February. 

The environmental groups filed the petition for review on Friday in the U.S. Court of Appeals against Duffy and Jonathan Morrison, the administrator of the National Highway Traffic Safety Administration, which sets the CAFE rules. 

The Transportation Department and NHTSA did not immediately respond to a request for comment by The Associated Press.

Fuel economy requirements have been in place since the energy crisis of the 1970s, and over time, have led to improved average efficiency in vehicles.