If you preheat the cabin and the battery using the HV battery, how is your efficiency then?
De-Ice should only take 10 minutes if you set the temperature to 25°C and will have consumed 1kWh.
Preheating the battery will take 20-25 minutes on an SE SR and can be scheduled in the app. It will have consumed between 1 and 2 kWh depending on how cold the pack is. You could then warm up the cabin a further 10 minutes and it will bring the interior up to a comfortable range around 19-20 degrees.
If you do the above, what is your energy consumption like on your commute?
Granted, you will have consumed between 2 and 4 kWh before your trip: that’s on top of the presumably 6 to 7 kWh that your trip will consume once everything is warmed up properly.
That will cost you £3.52 assuming you are charging at the fixed rate and including charging losses. So your commute is going to be equivalent to 2.2 litres of petrol, which is slightly under half a gallon. I don’t know how far it is but looks like 20-25 miles, you are doing 50mpg when the temps are below 5 degrees.
50mpg for say 3 months of the year.
Nearer 80-90 mpg the rest of the year.
Maybe I miscalculated something in the above calculations but give it a try.