Quick-swap windshield

This windshield would be twice as tall as necessary. At the push of a button it would scroll up or down, or it could automatically move as parts of it are melted by the car's heater. The lowest parts would be under the hood where even if it may frost up, it's not going to be subject to rain, snow, or warm moist air on the inside. So it should be nearly transparent and if not, a lot easier to defrost. The top of the car can have a special container designed to protect the windshield when scrolled up and to heat it (and drain any water) when the car is running.