Here's my 2 cents.
This is my first winter of having a car computer.
A month or so ago the hard drive wouldn't spin up (too cold).
My solution is: I have to plug in the car so it will start so why not split the plug in cable and use an interior heater.
I don't need the interior to be hot, but warm enough that I'm not doing damage to the computer when it starts.
I put in a simple in car heater, plugged through a "thermo cube"
Keeps the interior at zero (32F) even through the -30 to -40 days.
Cost is $20 plus the heater and some cord splitters.
works for me. Hope it helps for you.