I would think the best solution is to invest in a car heater that doesn't require the engine to run. They exist, but require electrical power from the battery to power the fan. But according to Webasto, they're really designed to heat your cold car for a short period of time, not keep it warm for long periods. Except that the fan will eventually drain the battery I see no reasons why you can't run a Webasto system for hours and hours. Not actually having tried this - except in a military vehicle years ago - I would ask someone with actual practical experience. Not cheap, though.


Pure propane canisters is probably a good solution. They're heavy steel containers, probably a lot less fragile than propane/buthane containers. And the performance in low temperatures is very much better than propane/butane stoves.

The dangers of fumes (co poisoning) is nothing a little ventilation can't solve. Open the window ever so slightly and close the excessive hole with a towel.



About propane/butane canistersThey're really too fragile for long term bumping around in the trunk. You need to solve that problem, which really shouldn't be too hard.


And propane/butane canisters aren't really well suited for cold. They work well if your vehicle inside isn't really that cold, i.e. you need to fire them up to keep it reasonably comfortable. Try firing them up at temperature below freezing and you're in for an unpleasant experience. My pyromanic practice of feeding liquid propane/butane to a stove with pre-heating loop is not really for the faint at heart, but it improves the performance in low temperatures.