(Vehicles classes are shown in Table 10.4.) Data on the key traffic-related variables (vehicle registration distribution, annual mileage accumulation rate, and the distribution of vehicle miles of travel) are input by vehicle class and roadway type- Local data on mileage accumulation are typically more difficult to obtain because odometer readings are typically not recorded on an annual basis unless an inspection and maintenance program is operational in the region under study. MOBILE6 outputs the emission rates (g/vehicle-mile) for three pollutants: HC, NO,, and CO.