General Motors joined Fiat Chrysler and Toyota on Monday in siding with the Trump administration on the rules. Ford and Honda aligned with BMW and Volkswagen in July in sidestepping the administration to craft a deal with California that raised standards for gas mileage and emissions. California's size -- its economy would rank fifth among the world's largest -- gives its regulations significant heft among automakers, who benefit from uniform standards that allow them to sell each model in as broad a market as possible.
"Thank you @GM, @FiatChrysler_NA, @Toyota, and @GloblAutomkrs for standing with us for Better, Cheaper, Safer Cars for Americans," Trump tweeted. "California has treated the Auto Industry very poorly for many years, harming Workers and Consumers. We are fixing this problem!"
The Department of Transportation and Environmental Protection Agency moved to block California's authority to set its own standards in September. "No state has the right to impose its policies on the rest of the country,” Transportation Secretary Elaine Chao said at the time.
California Gov. Gavin Newsom blamed the administration's action on a political vendetta and promised to fight it.
"California won’t ever wait for permission from Washington to protect the health and safety of children and families," he said. "While the White House has abdicated its responsibility to the rest of the world on cutting emissions and fighting global warming, California has stepped up."