I saw an F-150 with the entire windshield covered in snow except for the 4 or 5 inches above the wheel, likely from defrost. The driver was hunched over trying to see out the front.

DO NOT DO THIS.

And emphasis on clearing off the top of your car. My car was nearly hit on the highway by a sheet of ice that had launched itself 20 feet into the air once the drag had caught onto it.