Washington — In a high-profile rebuke against the Trump administration's efforts to roll back stringent gas-mileage rules, Ford and three other major carmakers have reached an agreement on fuel economy rules with California.

Under the terms of the deal, negotiated directly between the California Air Resources Board and Ford Motor Co., Volkswagen AG, Honda Motor Co. and BMW AG, the carmakers would voluntarily increase the average fuel economy of their fleets to about 50 miles per gallon by the end of the 2026 model year.

The move comes in the face of the Trump administration's two-year push to freeze fuel-mileage rules at about 39 mpg for model years 2021 to 2026. The White House has also pushed to revoke a longstanding waiver allowing California and other states to set their own stricter auto emissions standards.

“Ensuring that America’s vehicles are efficient, safe and affordable is a priority for us all,” the four automakers, which together sell nearly one-third of vehicles in the United States, said in a joint statement. “A 50-state solution has always been our preferred path forward and we understand that any deal involves compromise. These terms will provide our companies much-needed regulatory certainty by allowing us to meet both federal and state requirements with a single national fleet, avoiding a patchwork of regulations while continuing to ensure meaningful greenhouse gas emissions reductions.”

U.S. Environmental Protection Agency spokesman Michael Abboud slammed the agreement, saying, "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."

In a tweet directed at President Donald Trump, California Gov. Gavin Newsom, a Democrat, said his state and the four automakers are providing leadership on climate change that he said has been missing from the White House.

In a statement, he called 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,” he said.

The White House declined to comment.

The National Highway Traffic Safety Administration vowed to continue its push for national rules that would relax mpg rules. It said the Trump administration's proposal does not prohibit any auto manufacturer from building highly fuel-efficient vehicles.

Ford in particular has been a frequent target of environmental groups who argued the company paid lip service to believing in the importance of improving the fuel economy of its cars, but has lobbied behind the scenes to relax the rules.

Rachel McCleery, a Ford spokeswoman, said the new deal shows the Dearborn automaker supports a "50-state solution" to the mpg debate and believes "this agreement is the best path forward to protect the environment, consumer affordability and the short- and long-term health of the industry.

"We have been pursuing One National Program, and failing that, a negotiated settlement for regulatory certainty," McCleery said. "This voluntary agreement provides environmental benefits not only for California, but for the nation as a whole."

Jeannine Ginivan, a spokeswoman for General Motors Co., said the automaker has not joined the voluntary agreement with California because its "focus remains on working with all parties on a solution that would involve a 50-state solution and a national electric-vehicle program."

Fiat Chrysler Automobiles said in a statement it is "committed to continuing the improvement of our fleet fuel economy" and is reviewing details of the new agreement. But it did not commit to joining the pact.

"We have been clear throughout the federal rulemaking process that the current standards need to be adjusted to reflect changing conditions in the marketplace, and today's announcement acknowledges that is true," FCA said.

Under the deal made public Thursday, Ford, VW, Honda and BMW agreed to increase the average fuel economy of their fleets from 2021 levels by 3.7% per year, reaching an average of nearly 50 mpg by 2026. If the Trump administration is successful in its effort to roll back the Obama-era mpg standards, other automakers would be bound by less restrictive federal rules.

The Trump administration announced last year its intention to ease stringent gas-mileage rules that would have required fleets averaging nearly 55 miles per gallon by 2025. The administration proposed a freeze in the mandate after 2020, touching off a fierce battle with California, which helped craft the Obama-era rules.

The two sides attempted to negotiate a potential agreement, but the White House announced in February it was pulling out of the talks and moving forward with its proposed freeze.

Thirteen states and Washington, D.C., have adopted California’s mileage rules, meaning automakers could be left with one set of rules for a quarter of the country and another set for the remaining states.

Revoking California's waiver, which is ensconced in the Clean Air Act, would require an act of Congress that is unlikely while the U.S. House is under the control of House Speaker Nancy Pelosi (D-Calif.).

Automakers cheered the decision to reopen the so called midterm review they were promised when the Obama-era gas mileage rules were agreed to in 2011. But they hoped the Trump administration would quickly reach an agreement with California to prevent a lengthy legal battle that would leave mileage requirements for the next half-decade in limbo.

"I hope this can be a catalyst to get everybody back at the table," U.S. Rep. Debbie Dingell, D-Dearborn, a member of the U.S. House Energy and Commerce Committee, said Thursday in a phone interview, noting her preference for an industry-wide deal.

Luke Tonachel, director of clean vehicles and fuels at the Natural Resources Defense Council, said the agreement reaffirms the authority of California and other states to set pollution standards that protect the public.

“The agreement clearly demonstrates that the Trump administration’s rollback, which has no technical or legal rationale, is doomed," Tonachel said. "The administration should drop its senseless and harmful plan that would make cars pollute more and cost drivers more at the pump.”

Rebecca Lindland, founder of RebeccaDrives.com, an auto-industry and car review website, said the agreement with Ford, VW, Honda and BMW "reaffirms California’s authority over fuel-economy standards."

But she said the deal "does not address the real issue of consumer preference, which continues to be for SUVs and pickup trucks."

"The regulations push fuel-efficiency onto the market, rather than the consumer pulling on hybrids, electrics and smaller, more fuel-efficient cars," Lindland said. "Ideally, the industry will reach an agreement across the board on one single federal standard that maximizes fuel efficiency within market realities.”

klaing@detroitnews.com

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Twitter: @Keith_Laing