[JetStream]

Resistive heat is actually almost 100% efficient since virtually all the energy consumed is used to produce heat. The problem is that it takes a lot of energy to heat a cabin. What is 'waste heat' on an ICE is quite useful in the winter when trying to heat the inside of a car. I don't know the exact numbers but something like 40% of the energy produced by burning gasoline is waste heat in a normal ICE.

I agree 100% on the heat pump. They don't produce heat directly but only move heat from outside to inside. Unfortunately the mechanism in a R4P stops working at colder temps. At warmer temps, they move more heat than they take to operate so they use much less energy than a resistive heater.