I drive a Prius. Not a plug-in, so the electricity argument doesn't apply.

Not an asshole driver, either. I keep it on cruise control, at or under the speed limit, do lots of coasting. I have a 55-mile roundtrip commute, over mountains, no less. I average about 43. My other car is a Passat TDI. It gets roughly the same mileage as the Prius, but is a much heavier, solid, fast car with plenty of room.