My 1969 semi-automatic Bug had a gas heater. A design flaw with it was that the gas line from the fuel tank ran on the outside of the vehicle, under the left front fender.
After several years of being exposed to road salt, the line developed a small hole. I was at the drive in, just before the movie started, and saw a bright light outside the car. It was actually a fire that was burning on my vehicle, reflected in the hub cap of the vehicle beside me. The guy saw it, started his car and tore out of there, taking the speaker with him.
I went into the confection stand and grabbed a fire extinguisher.
I got rid of the car shortly after that.
The up side was that the heat was instantaneous, and worked without the engine running.
