My 2009 Ford Mondeo Clipper has a very nice "Max Heating" setting, where it both defrosts front and back windows, and sets the airco to max temperature, max fan speed. When I find my car windows frozen, I always first put the car in neutral, start it, rev up the engine to 2000 rpm a couple of times, and enable this "Max Heating" function. The car heats up, defrosts front and back windows while I scratch the side windows. I scratch back and front windows last, and it goes much easier this way.
A friend of mine told me I should turn off my headlights while letting the car defrost like this, to save the battery so it can heat faster/better. Does this really help? I thought heating was done using gasoline? (I see my fuel usage increase from 0,6 to 1,1 liters/100km running stationary)