ICE always off

I'd be a little concerned about engine health, going months at a time without running the engine. Again, rather than strive for near-total lack of engiine use, I'd intentionally use it say once a week, and a lengthy run if possible. Having it sit idle for protracted times, punctuated by cold-starts and short runtimes, is not good for it.

Mighta been @bisco's issue.

 

I agree bout cold starts, put cold starting the engine can be put off at almost anytime, even in frigid temps as long as the Prime is pre-conditioned two or three times when it's below 14 F - not that the heat pump will provide any heat, but it will get it's gears and compressor turning and use some traction pack and wall charging at the same time. Then if gentle on the Go Pedal in EV, it's not to hard to find a mile or two where it's not uphill and or hwy speed to keep the load off the engine while it's warming up.

It could be a good thing to run the engine once a week when it's frigid cold, but if the driver doesn't need to there's not very many reasons why a driver should fire up the engine manually, except for HAVAC heat to the cabin. If there is a good reason, it will most likely show up on the MID as a message, than we'll all know for sure.

 

Somewhere in New Car Features, it indicated the defroster would demand engine heat if ambient temperature was below +15°C. Maybe you've been above that in Rome.

So basically it'll start the engine any time you might need to use the defroster.

 

Yes.

Assuming the "it" in "turn it on" is "the defroster".

(I thought at first your "it" was the car and you were going for an "I always need to use the defroster cos the weather's so bad" joke.)

 

If that’s every couple of weeks probably ok. An engine that has protracted down times will deteriorate. I’m by no means a mechanical engineer, but just speculating: oil residues will gum up, and cylinder walls maybe develop rust??

 

It would be more accurate to say the engine comes on with the defogger engaged when it is also calling for heat.

The longer the engine is off, the more time oil gets to drain down into the pan. that could lead to more metal to metal contact on start up, though additives cane reduce that. Depending on climate, humidity will works it way into the oil over time. There is also the coolant to consider. Portions of it and the oil might get depleted of protective additives within some sections of the loop. Want to mix them up periodically.

PHEVs should have a maintenance mode to use the engine to circulate the fluids, or up old gas. Whether the manufacturer has set those up correctly to prevent issues takes time to determine.