Today an observation regarding pre-heating:-
My normal morning is pre-heating ON at 8:10 (by timer) and set off about 8:30, in a nice warm car.
This morning I had to drop my wife off earlier about 15 miles away, which meant i arrived home at about 8:00 with a flat battery.
Thought I would just boost the charge with what I could in the 30 mins before I left for work at 8:30, so connected charge cable and got a coffee.
At 8:30 got into a scorching hot car, with no additional charge showing (not sure how much I would have seen with 30 mins at 16A though)! It was so warm as soon as I turned car on the AC cut in to try and cool the car down to my set 21 degC!
I always have climate control set to 21degC, but the car was clearly a lot warmer than that when i got in.
Obviously I had arrived home from dropping off my wife, and car was already hot, and interior was at 21 degC.
I plugging the car in to charge, but that was over ridden when the pre-heating timer kicked in, which then continued to heat the car well over the 21 degC set temperature.
Exactly what happened i cant say, other than it seems the heater just heats at Maximum for duration of setting time!
Peter