California regulator threatens ban on gasoline engines

California’s top environmental regulator is threatening to enact tougher pollution rules that could include a ban on vehicles that burn petroleum-based fuels in retaliation for the Trump administration’s plan to relax vehicle emission standards.

The move — which would be a first in the U.S. — marks an escalation in the clash between Washington and Sacramento that would increase uncertainty for carmakers in the nation’s biggest auto market.

California has already gone to court to fight the Trump administration’s determination that current vehicle emission and fuel economy standards are too stringent. Now, California Air Resources Board Chairman Mary Nichols is arguing that the state will match any relaxation of federal auto rules with its own more stringent anti-pollution requirements on everything from fuel to the refineries producing it.