WASHINGTON, D.C.: New vehicles sold in the United States will face lower fuel-efficiency requirements under standards finalized by the Trump administration on September 28, a change the Transportation Department estimates will reduce vehicle costs but increase fuel consumption and carbon dioxide emissions for decades.

The new rules set a fleetwide average of 34.9 miles per gallon (14.7 km per liter) by 2031, down from the 50.4 miles per gallon (21.4 km per liter) required under standards adopted by former President Joe Biden.

The change is part of the administration's effort to make it easier for automakers to sell gasoline-powered vehicles. It comes as U.S. drivers face sharply higher fuel prices following the start of the U.S.-Israeli war with Iran at the end of February.

In 2024, the Biden administration finalized rules intended to encourage automakers to produce more electric vehicles as fuel-efficiency requirements increased. Those rules raised the required fuel efficiency for cars by eight percent annually for model years 2024 and 2025, 10 percent for 2026 and two percent annually from 2027 through 2031.

The Alliance for Automotive Innovation, which represents General Motors, Toyota, Volkswagen, Hyundai, Ford and other major automakers, welcomed the new standards, saying the government "made the right call to better align fuel economy standards with the law and current market conditions."

The trade group said the Biden rules "effectively required a switchover to electric vehicles that was out of step with market realities and customer demand."

Environmental group the Sierra Club said it would fight the rollback.

"Americans need relief from high costs, but instead Trump is giving automakers a free pass on pollution and handing families the bill, at the pump and with their health," the group said.