Don’t laugh … it’s a really bad day when your car/truck decides to run …but the cab heater has stopped working … on a really cold day at minus 10 to 20 degrees Celsius (+14F to -4F in American) … your windshield basically becomes a frosty block of ice that will clear up for a minute after you scrape it before it forms a new layer of frost again.
I drove around for a week continually scraping the windshield to drive around town one winter a few years because of this. And if you are unlucky, police will stop you, ticket you and tell you to tow your vehicle home.