This tool models only emissions savings from operating an electric vehicle, not vehicle manufacture. Carbon emissions savings are approximated by comparing driving-related emissions over five years for an electric or plug-in hybrid vehicle assumed to charge only at home, to the driving-related emissions for a gasoline vehicle with the fuel efficiency (MPG) entered by you, the user of this tool.
Gasoline emissions are calculated at 19.6 lbs. of carbon dioxide per gallon of gas and electricity-related emissions from charging are calculated as the carbon dioxide emitted per kWh of energy consumed by your local grid (given your zip code), as per grid carbon intensity data from the U.S. Energy Information Administration (EIA) for your state.