I ran the math one time on the cost to charge vs. gasoline, based on numbers from a Motor Trend article and my own electric bill. It did look like you’d save a fair amount to use electricity, everything being equal. I don’t remember exactly but it seemed like electricity was about 75-80% cheaper than $3 gas. But if I recall, those numbers assumed better performance of the Volt than I’ve heard about lately. And it didn’t account for battery replacements. Also, it doesn’t count the in-elasticity of supply of electricity. If electric cars were widely adopted and electrical demand shot up in a short period, not only would the cost have to increase, but we’d see blackouts and probably some kind of rationing like they do with AC in the summer. Government should have learned from the CA 1990 ZEV law that just because you pass it doesn’t mean the technology exists to get you there.
Don’t forget the increased registration fees for automobiles which don’t pay gasoline taxes at the pump.