I don't think you will find the m-unit to be suitable for an auto as there simply aren't enough circuits to contend with the many functions in a car like, Wipers, Windows, Locks, etc.
Such luxuries! A 72’ 02 is extremely basic. No AC, locks and windows are manual, mechanical radiator fan, mechanical fuel pump, engine is carbureted, no rear defroster, very limited instrumentation - mine doesn’t even have a radio, haha. There are really only two circuits not found on a motorcycle which are the wipers, as mentioned, and the blower for the heater. Both are high current and would need to be separately fused and switched via relay anyways. But even then, the AUX outputs would be useful to supplying switching power for those circuits and would allow for keeping those items powered off until the engine is running. Besides simplifying the wiring a bit, it would add all the extra functionality that makes them so appealing for our old bikes - flexible lighting control, diagnostics/monitoring, adding an alarm and making it just that much harder to hotwire by throwing a computer in the mix
As far as the gauge is concerned, I guess more what I was getting at is that the oil, neutral, temp and even speed sensor (if you’ve got it mounted at the output shaft) are all going to be much closer to the main trunk of the harness and/or m-unit, which also has a bus output and is also aware of turn signal status. Even just a little breakout board could cut the gauge wiring down to just power and a single bus signal for those trying to conceal as much wiring as possible. It might be a diminishing returns sort of feature but I still think it would be *cool*, haha.
I know the real world performance of the m-button doesn’t lend a lot of confidence to their bus signal implementation, but perhaps that could be mitigated with properly shielded cable.
