The move has triggered a backlash among congressional Democrats historically allied with the auto industry and has angered some consumers, one of whom tweeted, "Boycott Time!" While another said, "GM to the planet: Drop dead."  Meanwhile said the Trump administration, as it said last year
it wanted to freeze fuel efficiency at 2026 levels required by the Obama-era regulations, has decided to propose requiring car companies to improve fuel efficiency at a rate of 1.5 percent a year, according to senior federal officials who spoke about the condition of anonymity because the rule is not yet published.
The proposed rate is far slower than 4.7 percent a year in existing federal regulations, and is slower than the 3.7 percent rate that would be required in the agreement between California and four other manufacturers. .
The proposed rollback is likely to deepen political divisions. In an interview, rep suggested. Debbie Dingell (D-Mich.) That she and other lawmakers would push to introduce stricter mileage for the industry through legislation.
"The action this week by some of the car companies means that Congress will not ignore the transportation sector," she said, "and something is going to happen at Congress on fuel economy standards."
So far, President Trump is likely to block such legislation. Margo Oge, who headed the Environmental Protection Agency's Office of Transportation and Air Quality from 1
994 to 2012 and who helped negotiate Obama-era fuel standards, said carmakers' decision to support the administration would have consequences if Democrats take back the White House in 2020.
"When Democrats enter the White House, they will not forget what these companies have done," she said.
The companies that intervened on behalf of the Trump administration this week insisted that they were not taking political sides but wanted rather to see the federal government and California compromise on a single national mileage standard – a compromise that has not been ted in view.
But the Obama administration had set a standard in a 2009 agreement, the federal government and California. Trump's return is what will enrich that conformity.
The industry has been in a drag match for several months.
In July, California signed an agreement with Ford, Honda, Volkswagen and BMW in North America to raise the average fleet efficiency to about 50 kilometers per gallon by model year 2026. At that time, state governments expected other large companies to sign soon on.
But Trump officials have been actively trying to undermine that deal, according to several administration and industry officials by reaching out to car makers who had been lying on the fence and launching antitrust probes by the four who made the deal.
National Economic Council Director Larry Kudlow's office repeatedly pushed several companies aside with the White House, according to two people familiar with the talks. Trump himself raised the issue with GM boss Mary Barra in September.
Especially foreign firms had been wary of angering the president for fears of retaliatory tariffs, according to four people familiar with the case. Senior Toyota officials participated in talks with California officials earlier this year, according to two individuals, but did not reach a final deal.
Meanwhile, car companies are concerned that California may make it difficult for them to sell in the state or find other ways to punish them, said a person familiar with the calls. There was no explicit threat to the White House companies, this person said, "but Trump has much more power and can do a lot more harm if he wants to."
Ultimately, the coalition of automakers that encountered the White House in the lawsuits included Subaru and Nissan, along with GM, Toyota and Fiat Chrysler. They said they agreed that setting combustion economic standards is the federal government's purpose.
The outcome of the case can have major consequences for the planet. The transport sector accounts for more greenhouse gas emissions than any other in the United States, after exceeding the electric power sector in recent years.
The administration has sought to reverse federal requirements that increase the average mileage of cars and light trucks from 37 mpg to about 51 mpg by the year 2025, former President Barack Obama's most important climate rule. But the administration had not yet completed the restitution because it was still trying to formulate a formula that shows the benefits of the rule would outweigh the costs, according to two senior federal officials
But the White House is pushing ahead with attempts to strip California of its right to put out pipe discharges on their own, the authority the state has had for decades under a dispensation in the Clean Air Act. California helped the broker to the first carbon limits on cars a decade ago, and its stricter standards have been adopted by 13 other states and the District of Columbia.
GM spokeswoman Jeannine Ginivan declined to comment on the meeting between Barra and Trump, but said in an email that the company is still committed to improving fuel efficiency and "an all-electric future."
In a statement, Toyota insisted that it sign the legal action "not as a plaintiff or defendant, and not to favor any political party," but rather to say how fuel standards are being used around the country. "That's why we decided to be part of this legal case," the company said. "Doing so does not diminish our commitment to the environment."
Mary Nichols, chair of the California Air Resources Board, said in an interview that she was disappointed that companies like Toyota would join the administration, given that the state accounts for 20 percent of the firm's US market.
"There are more prizes on the road out here than the rest of the country," she said.
Nichols is not the only one to express disappointment this week. Many car owners have complained on social media and through emails to the companies.
"So much for an eco-friendly brand," one person tweeted to Subaru.
"For a company that is apparently committed to environmental protection, you came a long way," another customer wrote to Toyota. "We have two Hondas, and I suppose we get a third."