Emissions for this analysis were binned into three main vehicle groups: LDVs, MDVs, and HDVs, with all other vehicle types (including motorcycles, motorhomes, and buses) grouped together as "Other" (Table ). Fleet information is derived from detailed data from the California Department of Motor Vehicles, the California Highway Patrol, the International Registration Plan Clearinghouse, and the National Transit Database . EMFAC is therefore capable of providing a reasonable representation of distinct activity and emissions patterns for specific vehicle fleets.