If the smears are on the outside of the glass, please tell me, how is a towel on the inside of the car is going to affect anything?

 

Yes, the smears have been on the outside of the glass, and I wondered the same thing.

 

It's definitely from the product on the top. I would start by washing the top well and drying it with a microfiber. Then see what happens after that. if you treat the top wipe the product in well and let it dry in the sun. Then wipe it off again.

 

Stop using Windex which is known to cause streaks. Try Invisible Glass which has no ammonia in it or a detailing site glass cleaner.

 

Bingo, windex has ammonia in it which causes streaking. Use Invisible glass as mentioned and wipe dry with 2 microfiber towels. One to wipe off excess and one to follow up. Never had an issue with mine using this method.

 

I get the same smears on my rear window after the top has been down. I use only Invisible Glass or just plain water to clean mine.