Another thing to think about: if plug-in electric cars catch on it will mean greater demand for electricity, less demand for gas.

FORBES: In Fuel Costs, Electric Cars Win

And the Chevrolet Volt plug-in hybrid has rebounded from the they-catch-on-fire debacle, with sales of 1, 462 in April.

FORBES: Meet The Incredible, Half-Sized Spark -- Chevy's Smallest Car Ever