People of northern descent, do you hate getting into a cold car and the few minutes it takes to heat your car up? (Sorry diesel owners, it may take hours for you) I've often wondered why cars don't use resistance heaters instead of blowing air from the coolant. Basically, these heaters would be hot as soon as your car is turned on. It's basically a little space heater inside each of the vents.

Does anybody know why these aren't used?