If my PHEV has a PTC heater, it certainly isn't doing much.
1) My engine always turns on ANY time that the engine coolant is cold and the heater is on, even if the climate control is set to a temp barely warmer than ambient temp.
2) The vents do not blow warm air until the engine coolant is warm.
3) The temperature of the air coming out of my vents almost always exactly correlates with the coolant temperature indicated on my dashboard display. There is never a time where the vents blow warm air and the engine coolant is cold, it seems to be physically impossible.
4) The engine only shuts off while the heater is running if the coolant reaches normal running temp. But then it immediately kicks back on once the coolant temp drops.
If anything, a PTC heater (if it exists) is nothing more than a mild "booster" for the heat coming out of the vents, increasing the temperature by maybe a barely noticeable 5 degrees F, at most.
All that said, I'm not one of the people complaining about it. The effect on my MPG has been negligible. I'm still getting 45mpg in HEV mode on average, with 80 miles of daily driving. Since I do plug it in every night, I'm getting more like 60-65mpg when using combined EV/HEV modes, even with the engine doing its thing to keep my cabin warm. That's not much different than what I was getting during the summer and fall.
Last edited by cockedandglocked; 12-13-2018 at 06:14 PM.