hah, I had a Webasto or similar heater in my 1968 VW 'baja bug'.... burned gasoline, and got hot enough to melt your sneakers.
when I scrapped that car due to it falling apart from 15 years of abuse, the guy who bought it pulled the heater and installed it in his VW van camper, and the car chassis ended up on blocks in his rural back yard with a belt off one rear wheel running a water pump. i ran into him about 5 years later, he said that nearly-blown motor was /still/ chugging along at idle running the pump.