Electric car power consumption
Found this for the old GM EV-1.
Table puts power consumption for cruise plus maximum AC at about 8.7 kW.
Just off the net, I found a truck APU with a 3-cylinder diesel that turns out 6 kW at 0.3 gallons per hour. Probably a worst-case for weight and such.
A Honeywell RE100 APU for business jets uses a turbine. It weighs 83 lbs., and generates 23 shaft horsepower. I would need an efficiency figure for a generator to see how much electrical power would come out the other end. I didn't see a figure for fuel consumption--compared to the fuel consumption of the jet engines, it's probably considered noise.