Why not just leave the car turned ON? You'd have to put a rubber band around the button on the shifter to full the car into thinking it was NOT in Park, or it would turn off after 1 1/2 hrs or so. This would be a lot easier; you could lock it and nobody would know it was running, and the the 12v would be kept charged by the DC-DC converter. The measly .3kWh would be negligible for the traction battery.Yeah, I have come to the same conclusion.