@Will B I was pulling your leg a little. Once the engine runs, the heat is mostly from the engine coolant. In that case it would be "free" except if it's cold enough outside so the engine will perpetually run to produce it. In that case it's not. On cold-ish temps, the best way to heat is with the seats heater and the steering wheel heater. Goes to you own cold resistance of course. Mine is quite high. When it's very cold outside, i will try to run the engine on charge mode (23-25 it's doable, feature removed in 26 models..) so the engine oil gets fully warmed up and humidity/raw fuel gets out of it. In that time, heat is mostly free as the engine produces loads of it. When in hybrid mode, heat will be produced by a mix of heatpump and engine but if cold enough, it will force the engine to run. Not if it's hot enough outside however. Depends on loads of different conditions i can't enumerate right now..
Like most threads, it'll probably quiesce for a while eventually, then somebody with the same question will find it five or ten years later, and post on it, and somebody else will post "hey, do you know you just posted on a ten-year-old thread?!" and the person will post "sure, but it's about my question" and it'll go on from there.
If you love what you're doing - you'll never work a day in your life says most of the loafers on welfare for life - other people's money. Why work & get oneself some dignity & self-respect
You must not be a capitalist. Externalize your risks and costs. You don't get rich by spending your own money.