The main purpose of this legislation is to extend the authorization for certain alternative fuel and clean vehicles to use high occupancy vehicle (HOV) lanes. This is aimed at promoting the use of environmentally friendly vehicles and encouraging more people to choose these options for their transportation needs. The key provision of this legislation is the extension of the current authorization period for alternative fuel and clean vehicles to access HOV facilities. Specifically, it changes the expiration date from September 30, 2025, to September 30, 2031.