I haven't ever run the numbers on this. To be honest, I suspect that the specific carbon footprint of an all-electric car will depend largely on where it is used (and thus where it is recharged). Around here, for example, we get our power from TVA. Some of that is hydroelectric, which would represent a particularly low carbon footprint. Memphis, however, is mainly fed from a coal-fired TVA plant. Rinse and repeat that sort of analysis for any location you want. Then compare that with a hybrid's carbon footprint or some of the other alternate energy vehicles (as I recall, LP had some really impressive benefits over standard gasoline, although fuel availability makes it mainly a fleet vehicle option).