Water Repellant Windows

Hi MaggieMay, to be honest I don't think they could do this with a windshield. The wipers are going to rub on it until it comes off.
Aquapel will rub off over time and take 10 mins to reapply. The side windows see very little water so it will last a long time. Aquapel does as well. But the constant rubbing of the glass by the wipers will degrade it over time, even if it's built into teh glass itself.
Someone posted about the Lotus Blossom effect and that's what it is. There are products being worked on that will allow rain to clean skyscrapers in much the same way.
Someday the rain will wash your car clean with no soap. The paint will be hydrophobic.
Although I think a black car will still look dirty even after you wash it.