The California Air Resources Board is proposing to change its regulations to ensure the state can continue to pursue more aggressive vehicle fuel efficiency standards if the Trump administration follows through with its proposal to freeze federal standards at current levels.

The CARB is accepting comments on its proposal and plans to take up the item at its Sept. 27-28 meeting, the board said in a news release and accompanying paper.

The Trump administration on August 2 proposed to suspend rules that would boost corporate average fuel economy, or CAFE, standards for cars and light-duty trucks and to revoke California's permit to set its own standards. The proposed rule, released by the U.S. Environmental Protection Agency and the Transportation Department's National Highway Traffic Safety Administration, would set up a showdown between the federal government and a number of states, led by California, over their right to set higher standards.

Under a deal the Obama administration reached with California and automakers nearly a decade ago, the federal government agreed to align its CAFE standards with California's more stringent requirements and ratchet up those standards for model years 2022-2025. The EPA's midterm review of the program during the final days of the Obama administration in 2017 reaffirmed the standards, but the Trump administration's EPA in April announced it would reconsider that finding.

Although California and the states that passed legislation to follow California's lead have not needed to exercise their ability to set their own standards since the national deal was reached, they do hold a federal waiver to set more stringent ones. Because those states account for roughly 40% of annual car sales in the U.S., California's standards effectively force car manufacturers to build to those specifications.

The states already have begun to fight the move. California, joined by 16 states and Washington, D.C., filed a lawsuit in May to block any rollback of the standards for the 2022-2025 model years. (State of California v. EPA, 18-1114)

The CARB in its Aug. 7 paper said weakening the unified national program "could substantially slow progress towards the emission reductions needed to address the serious threat climate change poses to California, the country, and the world, waste billions of gallons of gasoline, and cost consumer money on fuel."

Under the board's existing regulation, adopted in 2012, cars meeting federal standards for model years 2017-2025 are "deemed to comply" with California standards. The CARB proposed to revise that portion of the regulation to say that if the Trump administration changes its standards, then automakers wishing to sell cars in California after the 2020 model year would need to meet California's standards rather than any potentially weaker federal standards.

The CARB noted that auto manufacturers as well as Washington, D.C., and the 12 other states that have adopted California's regulations may need to modify their model-year plans and regulations in light of the Trump administration's proposal. The board said its proposed changes would "provide certainty in this context and ... allow appropriate time for necessary public processes and business decisions."

In the meantime, the CARB said it will also continue advocating for the Trump administration to reverse course on its proposal.