Corporate Average Fuel Economy (CAFE) standards require US automakers to meet average fuel-efficiency targets across the vehicles they sell.

Congress created the program in the 1975 Energy Policy and Conservation Act. The law says the agency must set standards at the “maximum feasible” level.

Stronger standards save drivers money at the pump, reduce gasoline consumption and cut pollution. Supporters cite 64 billion gallons of gasoline saved and $35 billion in consumer savings under existing rules.

The current fight is over a final rule that weakens the standards. Twenty-seven states, counties and cities sued, arguing the new five-year targets are lower than what the US fleet already achieved in 2021.

The states also argue the agency removed electric vehicles from its calculations and glossed over nearly $220 billion in driver fuel savings. The case is in the First Circuit. Congress set the program to push automakers toward efficiency. Supporters say every gallon saved keeps fuel dollars in drivers’ pockets, not at the pump.