[Ryland]

figure that my motor is 90% efficient and draws 6,000 watts gives me 600 watts of heat from the motor, my electric car came stock with duct work to cool the motor with a fan, after a few miles the motor gets hot enough that it starts to put out a little bit of warm air but not much, turn the fan off and you can smell that it is getting warm so active cooling for the motor is a must, but as I said it does not put out enough heat to be useful, a heat pump like this would help to concentrate the heat by cooling the motor and give more heat faster and with an electric car that is built for short trips instant heat would be nice.
As for a converter to run 4 12v peltier junctions off a 48v battery pack... a serise of 4 would be a perfect match for a 48 volt battery pack, no converter needed, just a switch that could handle 40-50 amps and for that I think I have a spare contactor that will work just fine.

Sure, I could run a resistive wire but for a 2,000 watt input I would only get 2,000 watts of heat out of it, I would get no cooling of the motor or other electronics and the only advantage that I could see would that it would be cheap, $120 for 4 junctions seems pretty reasonable for what it can do.

I'm thinking I might just get one junction for now, build an insulated box and try comparing a 500 watt resister wire to a 500 watt pelteir junction to see the heat out put in a controlled environment, a project like that is going to have to wait till winter fully sets in but is the best idea I have come up with for testing the heating ability.