Been looking into this further. Apparantly if your car already has an auxillary booster heater, to warm the engine on cold days, most of these can easily be turned into parking heaters. In other words a heater to warm the interior of the car without the engine running. Have looked on the Webasto website and it depends on your vehicle. If it already burns diesel its easier. An upgrade kit is required. Incase you were wondering why i am considering this its because i go camping and photographing in the winter!.