Heater? What heater?
In my hybrid, I can't get into EV mode until I reach 161F water temp. Seems like I get to that temp about the time I pull into the parking lot at my destination. And, that's with a full rad block and an EBH.
Of course, it has been 10F for most of the last 2 months!
So, my heater stays off most of the time...
Eph