Editor's note: An earlier version of this report should have more clearly stated that litigation arguing for weaker or flat federal fuel economy standards was filed by the Competitive Enterprise Institute, not the Alliance for Automotive Innovation.
A legal battle over the Trump administration's new fuel efficiency standards has begun, with 23 states and the District of Columbia filing a lawsuit last week challenging the administration's decision to weaken yearly benchmarks.
The new rules require 1.5 percent annual increases in vehicle fuel efficiency through 2026. Under former President Barack Obama, emissions standards would have tightened by 5 percent each year. The final rule takes effect June 29 and requires the U.S. vehicle fleet to average 40.4 mpg by the 2026 model year.
In the lawsuit, the multistate coalition argues the final rules unlawfully violate the Clean Air Act, the Energy Policy and Conservation Act, and the Administrative Procedure Act.
The California Air Resources Board — represented in the lawsuit by state Attorney General Xavier Becerra — said the EPA and NHTSA also sidestepped congressional requirements in passing the rules and "used a faulty and flawed analysis, unfounded assumptions and made statistical errors to manipulate data in support of their conclusions."