This will be the first winter with a Model S - how mild a UK winter will be is anyone;s guess, though I have always been intrigued by the section in the manual: "Using seat heaters to keep warm is more efficient than heating the cabin. To automatically limit the amount of power that the climate control system uses to maintain the temperature of the Battery and the cabin area, touch Controls > Driving > Range Mode > ON" Aware that getting the heating a bit hotter than 20C you need to turn Range Mode off, though any guidance for those who have used the seat heaters... ?? Do they make a big impact, and in what type of time? Typically would have 3-4 seats unoccupied in the morning - so better to crank them all on?, or better to use a combination of both seat heaters & vents? I also assume there are not other heating elements apart from rear window, as no side mirror heaters.