Different sources of electricity have different environmental impact, but at least you can have a good idea of where your utility gets power from. At the same t

Different sources of electricity have different environmental impact, but at least you can have a good idea of where your utility gets power from. At the same time, you don't know if your gas came from tar sands or easy to get (but dwindling) shallow Californian oil. There is an electric equivalent mpg called mpg-e: http://www.edmunds.com/fuel-economy/decoding-electric-car-mpg.html http://www.edmunds.com/fuel-economy/decoding-electric-car-mp...