It would be interesting to know the efficiency of the Prius in this mode vs. my Saturn (4-cyl) with a 1500w inverter, or just a 1500kva portable generator.
My 1997 Escort will run the 5000 watt inverter at half its output (any more than that and the alternator can’t keep up) for 24 hours. it burns about 12 gallons of fuel in that time frame.
The main reason is the remote start will start and stop the engine as needed. So it works much like the prius system. however, I suspect the prius battery might be larger than the 2 I have in my car.