Last year I bought a new GMC Envoy Denali that happened to come with heated seats. Finally getting the chance to use them in winter I've come to the conclusion that they could be an excellent winter survival tool. Here's why:

Unlike the cars regular heater, it doesn't require the engine to be running to create heat, nor does it require a long amount of time for the engine to warm up. This means, as long as you have battery power you have plenty of heat.

Therefore, you don't need to risk carbon monoxide poisoning constantly running the car in snow or using some kind of open flame in the vehicle. All you need to do is keep the seat heaters on, throw a blanket over yourself, and start the vehicle every hour or so to make sure the battery doesn't drain too far. Much safer if you're stuck on the side of the road over night in the cold.

I tested this out last night when it was about 20*f and snowing out and it kept me warm for over an hour no problem. Normally, I go for the most stripped out vehicle possible (only reason I got a Denali was for the V8's towing rating), but from now on my daily driver will have seat heaters.