[miker98038]

If you google “rear window defroster” you’ll come up with some pictures. Most are little fan units but there one that’s and electric grid you stick on. I had one of those in the back window of a little foreign wagon back in the 70’s. It didn’t work as well as the ones built into the glass, but it worked to take moisture off the inside of the window. Not so much for snow or ice. I also had a car with a small 12v fan mounted on the rear package tray (there when I bought it). It worked too. But in Seattle, and my cars usually parked inside, fog was a result of getting in a cold car when you were wet. The heater blew the rain off you, and warmed the car, then the moisture fogged all the windows. But if you didn’t start them as soon as you started the car, they would take forever to clear a fogged window. Best bet was to stop it from happening. Colder climates and frost outside, not so sure.

None of them was like a modern car.