Changes to the Clean Air Act narrow and clarify which state vehicle standards are treated as covered by the federal waiver process. It explicitly defines state standards that limit the sale or use of new internal-combustion-engine vehicles by referencing an existing federal regulation definition (as of Jan 1, 2023), bars the EPA from treating later state amendments as already covered by earlier waivers, and requires the EPA to revoke any previously granted waivers covering the period from Jan 1, 2022 through enactment if those waivers do not meet the new definition.