We have the super awesome -40-something windshield wash here too, in Alaska. While we typically have a very, very dry winter - as the snow starts to melt from the salt and sand on the roads it is notorious for kicking up, mucking up, and effing up the windows with mud and small rocks, and thus small cracks. Blegh!

In the winter it takes my car about 20 minutes to warm up before I can leave my house, as I scrape the ice off of the windows outside. As soon as the oil gauge is high enough, and I can see everything through my windshield, I jump in - take off most of my layers, get nice and comfy, and put the heater on the "feet" setting so it's not on my face (I get SUPER car sick). The low setting is just enough to keep you room-temperature when you're in a long sleeve shirt, typically. Perfect! Then, if you need it back on the windshield as you're driving you can just bump it up again to the window, and on high for a little while or at least until it gets the job done.

Definitely the important thing to me is to NOT leave my coat on while I drive. Getting too warm, too fast, with warm air is a disaster waiting to happen. A nice long sleeve shirt, and I'm good. Then, in an emergency, my coat is already warmed up and sitting next to me to grab and go.