OK, I'm going to assume cracking the window about 1 cm on the leeward (hopefully) side of the vehicle is going to stand me in good stead.

So what are my options?
(Liquid) alcohol stove - too dang dangerous if I bump it over
Sterno - sounds like a good option, yes?
Candle - maybe not as safe as Sterno, but in some type of "candleier" maybe a pretty good bet. Candles do put out soot some times
Gas (butane/isobutane/propane) - no spill risk, but pretty high heat. Fire risk? Definitely don't want a spindly stove; you'd want something steady.
Coleman Fuel - no way in heck. Way to hazardous.
Kerosene - safer than Coleman, but I still can't see it

So maybe Sterno is actually the best heat for a car followed by candles as a second? Is this fair to say?

Yes, if I've got plenty of gas and my tail pipe is clear, the car's heater is great, and a plug in cigarette lighter electric heater would be great if you're willing to risk discharging your batter, but if I've got to fall back to something inside the car, what do you think?

I don't have any experience with portable catalytic propane heaters. Are those the better way to go?

HJ