Any advice about cars in cold weather, in general? Does anyone have a diesel car? How do you get it/keep it running when it gets super cold?
I have a diesel truck and a diesel car and grew up in the Great White North.
Didn't have the car at the time, but had the truck...
NEVER use Biodiesel in the winter, or at very least, make sure it's B20 or less and risk it.
Replace fuel filters twice as often in the winter. With my truck, that's every other oil change...so 2-3 times a winter. The o-rings are plastic and can warp, letting water in. Vehicle will start when water is frozen, run for 5-10 seconds until the ice melts, then sputter and die. You can almost always get it running and to your mechanic by priming the crap out of the fuel filter directly, but it's easier to avoid the issue and replace fuel filters often. Also, they clog faster in the winter since diesel gels.
The engine block heater is great, except when you live in an apartment complex that gets "annoyed" when you run an extension cord out the window to your vehicle. My vehicles have thus survived a few winters without the use of the block heaters. I let them warm up for a minimum of 10-15 mins before going anywhere when the temp is below 20. Never had a problem with starting. Yes, idling a diesel is not great for it, but neither is running it cold, so I choose to idle it and change the oil often.
Finally, when starting the diesel in extreme cold, run the glow plugs 2 or 3 times before making the engine turnover. In some vehicles this makes a huge difference; a lot of tractors won't start in super cold temps with just one flash of the glow plugs. Yes, you probably burn them out faster, but id rather replace those and have the vehicle start...and I have yet to have to replace a set of glow plugs.
Also, for anyone driving in the winter, invest in good tires. 4wd is wonderful, but as previously noted, doesn't help you stop. Good tires won't let you drive like an idiot on ice and slam on the brakes and expect to still stop, but they'll make a difference if you're driving cautiously. Slick tires with no tread on a slick road is a recipe for disaster. If you are already sliding or spinning, take your foot off the stupid brake. It'll just make you spin faster.