Well, I didn't do anything nice to my Defender today... it was -40 this morning.
I plug the truck in below -10, and I replaced the glow plugs a few months ago, so it did spring to life after a momentary complaint (3rd revolution instead of the first...)
After 5 minutes idling, I tried to move it. No dice. The transmission and transfer case fluids were goo. The alternator also wasn't happy, no output even after a few blips of the throttle. I gave it a few more minutes (heated seats are essential in these temps!) and then set off once I could get it in gear. Still no charge and no luck getting my doors to stay shut, I turned around and came home.
I put it on high idle for 15 mins and after that my doors closed, the truck ran like a top, and I made it to work without issue.
I need to build a garage....