My Range Rover L322 diesels have had parking heaters ...so when you get up on a cold morning ...look out the bedroom ..if looks cold press the remote and within 30 mins -nice and toasty !

Also have one fitted in the back of my defender 90 ..but has to be programmed on a timer ...getting into a defrosted 90 is even better ...normally your trying to prise open the door with a shovel because they are frozen shut !!