You can drive an electric car with only two 12v car batteries!

[TheWraith]

15. Watt-hours determine range, voltage determines potential torque.

Although the voltage is a lot less important than the watt-hours in terms of overall performance, since you can eke a lot more power out of that kind of pack than the Volt does. Case in point, the Tesla Roadster runs on basically the same voltage range. It all depends on the engineering. Theoretically the most rawly efficient means would be electric motors directly in or attached to the wheels, allowing for the least waste of power in transmission, but with four wheels that gets expensive and it potentially exposes the electric motors to things like road salt that could damage them.