This April 23, 2019 file photo shows gas prices are displayed at a Shell station in Sacramento, Calif. Four major automakers have reached a secret deal with California to increase gas mileage and greenhouse gas emissions standards, bypassing the Trump administration's plan to freeze standards at 2021 levels, according to two people briefed on the matter. (AP Photo/Rich Pedroncelli, File)

Four major automakers on Thursday announced they had reached a deal with California to produce more fuel-efficient cars for the US market, an end run around the Trump administration which is seeking to freeze mileage standards.

California negotiated the agreement with Ford, Honda, Volkswagen and BMW in secret, and said it provided a 50-state solution that would avoid a patchwork of regulations from arising across the country.

"California, a coalition of states, and these automakers are leading the way on smart policies that make the air cleaner and safer for us all," California Governor Gavin Newsom said in a statement. "I now call on the rest of the auto industry to join us, and for the Trump administration to adopt this pragmatic compromise instead of pursuing its regressive rule change.

"It's the right thing for our economy, our people and our planet."

Last year, President Donald Trump's administration proposed a rule to axe tougher mileage and greenhouse gas emissions requirements for light-duty cars enacted by his predecessor Barack Obama.

But California, which exercises considerable clout in the auto industry as the country's wealthiest state, announced its intention to set its own regulations.

"These terms will provide regulatory stability, preserve vehicle affordability for customers, reduce compliance costs and result in increased environmental benefits," the manufacturers said in a statement.

The agreement envisages reducing greenhouse gas emissions by 3.7 percent each year from 2022 through 2026.

In this Dec. 10, 2015, file photo, vehicles make their way westbound on Interstate 80 across the San Francisco-Oakland Bay Bridge as seen from Treasure Island in San Francisco. Four major automakers have reached a secret deal with California to increase gas mileage and greenhouse gas emissions standards, bypassing the Trump administration's plan to freeze standards at 2021 levels, according to two people briefed on the matter. (AP Photo/Ben Margot, File)

Under the framework, by 2026, new models would meet a standard of 50 miles per gallon (4.7 liters per 100 kilometers), against the 37 mpg current level—just one year later than the target set under the Obama administration, Newsom's office said.

It added that the framework also supports California's long-term goals of transitioning to electric vehicles.

'Recklessness of Trump administration'

"This is an important breakthrough that will ensure the United States continues to make progress in addressing what is now our largest source of global warming pollution," said Dan Lashof, US director of the World Resources Institute.

"It demonstrates beyond any doubt the recklessness of the Trump administration's efforts to push the nation backwards on climate, regardless of how it harms families or businesses."

Mary Nichols, who heads the California Air Resources Board, said in a statement that the liberal state would move ahead on its own in pushing for more fuel efficient cars if the White House fails to support the measure.

"This agreement represents a feasible and acceptable path to accomplishing the goals of California and the automobile industry," she said.

But the Environmental Protection Agency, which has spearheaded efforts to undo Obama-era measures on vehicle emissions, scoffed at the deal.

"This voluntary framework is a PR stunt that does nothing to further the one national standard that will provide certainty and relief for American consumers," EPA spokesman Michael Abboud said in a statement sent to AFP.