Under the Clean Air Act, the Environmental Protection Agency (EPA) is establishing new, more protective emissions standards for criteria pollutants and greenhouse gases (GHG) for light-duty vehicles and Class 2b and 3 ("medium-duty") vehicles that will phase-in over model years 2027 through 2032. In addition, EPA is finalizing GHG program revisions in several areas, including off-cycle and air conditioning credits, the treatment of upstream emissions associated with zero-emission vehicles and plug-in hybrid electric vehicles in compliance calculations, medium-duty vehicle incentive multipliers, and vehicle certification and compliance. EPA is also establishing new standards to control refueling emissions from incomplete medium-duty vehicles, and battery durability and warranty requirements for light- duty and medium-duty electric and plug-in hybrid electric vehicles. EPA is also finalizing minor amendments to update program requirements related to aftermarket fuel conversions, importing vehicles and engines, evaporative emission test procedures, and test fuel specifications for measuring fuel economy.