Cold weather affecting predicted range

[Barrie1956]

In cold weather, I can quite understand that putting the heater on will cost me a chunk of my EV range. That's only to be expected. I'll see the range drop by about 6 miles. However, what I can't get my head around is that turning on the heater also causes the ICE to run. Again, I can kind of see the logic of this, using the waste heat from the engine. But the EV range stays at its "compromised" level, even though the ICE is providing the heat AND driving the car!! What am I missing?

 

[PHEV07]

What Year is your vehicle and what temperatures are you driving in?