My car is now a few years old, and has lost the new car smell. Even so, at the end of the summer there is still a film on the inside of the car windows. It could be residual outgassing from synthetic components still depositing itself on all the inside surfaces, even though you can't smell it any more. It could be simply being on the road.
Whatever it is, it looks kinda disgusting, and what's more, it's dangerous, as the film lights up when hit by sunlight, so you can't look through the windshield.
I didn't really feel like using Windex again, nor was I in the mood for vigorous scrubbing with dishwashing liquid. Internet to the rescue! There's bound to be someone who has figured out a safe way to clean new car gook off your windshield.
It's fun to read people's homemade solutions (no pun intended) and try to figure out the chemistry of what makes it work. I settled on a recipe from Crunchy Betty, who is seriously into clean: clean food, clean toiletries, clean house. By "clean" I mean chemically clean.
This one has water (that's safe to drink); rubbing alcohol (that's not safe to drink but you can handle it with your bare hands); vinegar (I put that in my food regularly); and corn starch (I bake with that). I like it when a cleaner contains only stuff I have in my kitchen anyway, and is free of ingredients I can't pronounce.