Yep, its a heat exchanger with the exhaust. Barely warm by the time I got home and the defroster didn't really do anything either.
I've often wondered how you warm up a hybrid car in the winter. I know this might not be environmentally friendly but when it's -20 out, we start our rides to warm up not just the engine but the inside and windows. So how do you do that in a car that is electric only? Or a Prius hybrid?