Winter in Alaska where we live can be so harsh! No matter where you live, though, scraping ice off of your car in the early morning is just no one's idea of fun. This is the BEST WAY to keep your windshield frost free.
Wipe the windows and windshield of your vehicle down with white vinegar, undiluted, after you park your car for the night. This will prevent frost from building on your car, and who doesn't LOVE that?