UPDATE 2-U.S. EPA to relax fuel efficiency standards for autos

(Adds quotes from Pruitt, auto trade group and environmentalist)

WASHINGTON, April 2 (Reuters) - The Trump administration on Monday rejected an Obama-era plan to make automobiles more fuel efficient, opening up a long process to weaken current standards and putting California and the federal government on a collision course over vehicle emissions.

Scott Pruitt, the administrator of the Environmental Protection Agency, said in a statement that the standards on model year 2022 to 2015 vehicles were not appropriate and should be revised.

The Obama administration set the average fleet-wide fuel efficiency standards "too high" and "made assumptions about the standards that didn't comport with reality," Pruitt said. He did not offer any specifics on revising them.

The standards called for roughly doubling by 2025 the average fuel efficiency of new vehicles sold in the United States to about 50 miles (80 km) per gallon, and were seen by proponents as a way to spur innovation in clean technologies.

California, which has long held a right to impose stricter standards on vehicle emissions of some pollutants than federal rules under a waiver granted by the EPA, is prepared to sue the EPA if it tries to weaken the standards, state Attorney General Xavier Becerra said last week.

That has set up a battle between California, the most populous U.S. state and a massive car market, and the administration of U.S. President Donald Trump on the future of vehicle efficiency.

California's waiver from the EPA to impose its own efficiency standards is being reexamined, the EPA said in the release. Pruitt is a big proponent of states' rights to regulate themselves but opposes California's push for greener cars.

It is in "America's best interest to have a national standard," Pruitt said in the release, adding that he looks forward to partnering with California to finalize a national standard.

Automakers, which want to avoid a patchwork of rules that would add costs to engine manufacturing, praised the EPA's move.

"The best way to achieve our collective goals is under a single national program that provides an aggressive but achievable pathway, a variety of compliance tools, and factors in the role of customers," John Bozzella, president and chief executive officer of the Association of Global Automakers, said.

Environmentalists decried Pruitt's decision, saying the stricter standards would slash emissions of the greenhouse gas carbon dioxide and cut fuel costs for consumers. Proponents of the corporate average fuel economy standards, or CAFE, say they have led to big gains in auto technology and that relaxing them could eventually hurt sales of U.S. cars in European and Asian countries that are moving toward mandates for electric cars.

Relaxing the standards would "take America backward by jeopardizing successful safeguards that are working to clean our air, save drivers money at the pump, and drive technological innovation that creates jobs," said Luke Tonachel a clean vehicles advocate at the Natural Resources Defense Council. (Reporting by Timothy Gardner Additional reporting by David Shepardson Editing by Diane Craft and Leslie Adler)