If you live somewhere cold heating your air cooled Volkswagen van can be a problem. This Youtube video comes from Canada and shows the clever installation of a Mikuni diesel heater. The great thing about this heater is that it vents exhaust outside unlike, for example, a Coleman Sportcat heater which is not for use when the vehicle is moving. Also, the Coleman camping heaters generate a lot of moisture and use up oxygen, instructions recommend proper ventilation. The Mikuni requires it’s own fuel and the performance looks amazing pumping out a lot of heat, maybe there could be a control vent that would aim some of it at the engine compartment before starting the engine on a snowy day.
Footnote: below is a warning from the Coleman Sportcat heater manual. Great little units, perhaps best suited to tent use.