96 eagle talon has one, and it needs it. It is more of a hatch though.
I think all cars should have it though it would look weird on some passenger cars. Anyway, as an example just this morning there's mist/fog on the rear window because of the temp here. It doesn't matter what kind of vehicle it is. You don't notice it until you're about to back up. Engage a wiper, wait for the rear defrost, or get out of the car? You choose.