I have a plug-in hybrid Ford Fusion Energi, and the car automatically switches to use the internal combustion engine (rather than the battery) when the gas has been in the tank for a certain time.
Not sure how long this is, because I take enough highway trips to burn a tank of gas every 2 months or so.
That’s a clever feature. My office has a Kia Niro plug-in hybrid in the motor pool that I’m certain hasn’t been driven in the past year; I should probably go see if it’ll boot up and run. I should glance though the operator’s manual and see if a similar feature is mentioned, as well.