You can go outside for a few minutes, long enough to get from your heated car to the heated building. You're screwed if you break down, though.
You just have to wrap up well.
I have a forty below rated parka that folds up into its hood, like a football size, which I keep in my car for emergencies.
Also I have a massive sleeping bag which I can use to supplement the need if the giant parka is not adequate or if you have others to protect. I also keep a "go bag" of necessaries, like paper goods, some light cooking equipment, can openers, several cans of staples like beans and heavy soups, a few sterno cans that will last for many hours, matches, water (which may need to be thawed by the streno cans or the heat of the car's engine), a few other blankets and gloves. Everything fits into a gym bag, except for the parka, bed roll and blankets.
I keep my car tank above three quarters full during this time of year. I drive carefully and I do not feel fear in challenging winter, as long as I am so prepared.
Most fear a slide off on an icy country road, being not found for days. I am prepared for such as that.
