I modified a cheapie *mart heater (resistive coil + fan) for the Citicar. It worked OK from the traction pack, but I only used it once or twice as a heater. It tended to kill my wh/mile. (used about 10% more power) With only six batteries, it makes a difference...
I modified it (again!) and it is now in service as a defroster. It only needs to be on for a minute or two, and works much better than paper towels