This Web form estimates the cost and carbon savings achieved by the combination of a purchase of a plug-in hybrid car and simultaneous conversion of house electricity from fossil fuels to renewables. Start the calculation by changing the value in any of the boxes. Then change other input defaults to values appropriate for your situation, first using a traditionally powered car and electricity source in your location, and then for a plug-in hybrid car with renewable house electricity. Hover your mouse over the Details buttons for more information on each line. Details on default values are given here and limitations of the calculation are given here. Output values are given in red.
This calculator accompanies the article How I Bought a New Car, Saved Thousands, and Slashed My Carbon Footprint by Eric D. Feigelson, published by the Moshannon Group of the Pennsylvania Sierra Club, February 2015.