Heavy traffic on Interstate 5 in North County. Courtesy SANDAG

The Biden administration has finalized a reversal of a rule issued under former President Donald Trump that sought to pre-empt California’s vehicle emissions regulations.

The Department of Transportation announced before Christmas that it was issuing final rules rescinding the Trump action, which sought to bar the most populous state in the nation from setting vehicle rules that might conflict with the federal government’s authority to set Corporate Average Fuel Economy requirements.

The program, in place since 1975, sets vehicle fuel efficiency requirements.

“States can now actively pursue solutions to address the climate crisis and environmental challenges in their communities,” Transportation Secretary Pete Buttigieg said in a statement.

About two dozen U.S. states sued to block a pair of Trump actions that sought to remove California from vehicle emissions regulations, while major automakers had backed the effort. The Republican president often clashed with California.

Soon after Democrat Joe Biden was elected president in November 2020, General Motors reversed course and opted to no longer back the Trump administration’s effort to bar California from setting its own emissions rules.

The U.S. Environmental Protection Agency separately has moved to reverse the Trump administration’s 2019 decision to withdraw California’s legal authority to set vehicle emissions rules and set zero-emission vehicle mandates.

The EPA in 2013 granted California a waiver for its tailpipe greenhouse gas emissions and zero-emission vehicle regulations.

A total of 14 states have adopted California’s vehicle-emission rules and 11 have adopted its zero-emission vehicle mandates.

On Monday, the EPA finalized new vehicle emissions requirements through 2026 that reverse Trump’s rollback of car pollution cuts and will speed a U.S. shift to more electric vehicles. The rule will reduce U.S. gasoline consumption by 15% through 2050, the EPA said, or more than 440 million barrels.

If expressed in miles per gallon requirements, the EPA rules would result in real-world average for new cars and trucks of about 40 mpg in 2026, versus 38 mpg under the August proposal and 32 mpg under the Trump rules.

Biden wants 50% of all new vehicles sold in 2030 to be EV or plug-in hybrid models but has not endorsed California’s plan to phase out new gasoline-powered light-duty vehicles by 2035.

The Transportation Department next year is expected to finalize its rewrite of CAFE standards.

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