US EPA References and Calculations

To determine annual GHG emissions per passenger vehicle, the following methodology was used: vehicle miles traveled (VMT) was divided by average gas mileage to determine gallons of gasoline consumed per vehicle per year. Gallons of gasoline consumed was multiplied by carbon dioxide per gallon of gasoline to determine carbon dioxide emitted per vehicle per year. Carbon dioxide emissions were then divided by the ratio of carbon dioxide emissions to total vehicle greenhouse gas emissions to account for vehicle methane and nitrous oxide emissions.
Calculation

Note: Due to rounding, performing the calculations given in the equations below may not return the exact results shown.

8.81*10-3 metric tons CO2/gallon gasoline * 11,856 VMT car/truck average * 1/19.7 miles per gallon car/truck average * 1 CO2, CH4, and N2O/0.971 CO2 = 5.46 metric tons CO2E /vehicle/year