The US Department of Transportation finalized its plans today to weaken fuel efficiency standards, calling it “among the largest deregulatory actions under the second Trump Administration.”

It’s a nail in the coffin for Biden-era standards that would have required fleet average fuel economy to reach 50.4 miles per gallon by model year 2031. President Donald Trump’s plan requires 34.9 miles per gallon, not much higher than the 30.1-mile-per-gallon target previously set for model year 2024.

The Trump administration claims its plan would shave $1,300 off the average cost of a new vehicle, saving $138 billion over the next five years — though those figures have been disputed.

Automakers are pretty happy with the new rules. But consumer advocacy, health, and environmental groups are incensed. They argue that weaker fuel economy standards will wind up making Americans pay more at the pump, on top of increased healthcare costs and damages from climate change due to air pollution. The Biden administration’s standards that Trump trashed were expected to save $23 billion in fuel costs, and a car owner more than $600 in gasoline over the lifetime of a vehicle.

“For decades, fuel economy standards have ensured that new cars, SUVs and pickup trucks are more efficient, which saves lives and money,” the American Lung Association’s president and CEO, Harold Wimmer, said in an emailed statement. “There is no reason to weaken standards that are technologically feasible and have a direct benefit for the quality of the air people breathe.”