This is something I have never even thought about 'till now.
I can remember running my 52 GMC truck, before I sold it, in the winter, heater howling, 6 volt motor on a 12 volt system and having that warm and toasty feeling as I motored along the road.
So that is a just a dream now with the stock heater system in my suburban? It makes sense with the extra space and all....
Sniffle sniffle....