The main purpose of this legislation is to modify the Clean Air Act to ensure that regulations concerning vehicle emissions do not restrict the availability of new cars and trucks. The goal is to maintain a diverse selection of vehicles for consumers while still addressing air quality concerns. Key provisions of the legislation include specific changes to the Clean Air Act. It clarifies that any future regulations related to vehicle emissions cannot require the use of particular technologies or lead to a decrease in the number of new vehicles available based on their engine types.