The perfect APU (with current technology).

After all of the research that I have done to get this site up and running, I have come to see the advantages and shortcomings of a lot of idling alternatives. I have come up with the characteristics of what would make the best APU. It would surely be expensive, but if you are spending enough money to buy a small car, you want it to be right.

1. Start with a Kubota engine.  Great dealer network, a long service interval, and a reputation for reliability.  Optionally 2 cylinders for a liteweight model or a 3 cylinder for a no comprimise model.
2. A 6000 watt generator.  This would give you plenty of power for a rooftop A/C if you have a large sleeper.
3. The APU would be tied into the main engine but would have shutoff valves in case one or the other springs a leak.  Optional separate APU radiator and Webasto/Espar coolant heater for those who don’t like the engine tied in.
4. Auto start/stop for cabin temperature, low battery, block temperature, and a day/hr timer.  All of these settings would need to be ajustable.
5. Heat would come from a Webasto or Espar diesel fired heater.  These are incredibly efficient at around .04 gallons per hour and their reliablity is bankable.
6. A/C would come from a rooftop unit, back of wall unit, under bunk unit, or under floor unit.  Some of these are not commercially available, but the technology exists for a company like Dometic, Carrier, or Coleman to easily create one.  This would eliminate the need for ducting, one of the biggest capacity thieves of current A/C units.  Any one of these units should be repairable cheaply or completely replaceable for under $500.
7. As many parts as possible would be non-proprietary.  You should be able to replace the alternator, air filter, oil filter, fuel filter, and belts from Wal-Mart or any auto parts store in under one hour.

Because of the non-proprietary nature of the APU service locations would be plentiful.  It would also be simple enough that a owner or general service person could work on it.  The only proprietary part on the unit would be the electronics.

I know that it isn’t possible for a given APU to be perfect for everyone, but with a non-proprietary, open approach, additions or options would make the purchase the best choice for more situations.