benjammin...thanks for the video...I'm not an outdoors person, so a large volume of hot water was not a requirement... I do like to fool around with gadgets, so when I encountered the topic of the Swiss Ranger Volcano stove a couple of years ago, picked up a pair ($20)... and as mentioned before, opened up the feed hole to accept first a Trangia stove, and later for a can of Sterno.. this gives me a heat source in my remain overnight kit for my car...the tapered sides of the .5L cup works similar to the Kettle as it also is heated by the stack heat... very light, and works with a variety of fuel sources... the scorching is from a paraffin, lamp wick stove reminiscent of what I used a half century ago in the Scouts...

I am not sure I would want to use a trangia burner, or sterno, for that matter , for heating of a car interior - carbon monoxide is just as insidious as it is deadly.
Even used for cooking, it is better to do it outside.