What you may be seeing as water spots on the exterior side of the glass, may be just water spots. I have them on my 96 RS. It is caused by acid water. Acid water or rain is prevalent in New Jersey because of all the refineries and coal buring power plants. And other industial factories. I use RainX to clean all the dirt and grime off of the glass and then use something like Glass Wax of years ago. I might be dating myself. Remember during Christmas back in the Sixties. Some of us as kids would use stencils and pink Glass Wax to decorate our windows for the Holidays. Try It! What do you got to lose.

 

If the 50/50 water vinigar solution does not work try a super fine rubbing compound and a buffer.

 

We use clay bar to get things out like that. As an alternative to rain x we use Aquapel ($12/application) or claybar the window and wax it for $6. Rain x deterorates the wipers. If they are really stubborn, we use body shop prep.

 

Clay bar works great on glass, I just wax the glass with the same Mothers cleaner wax that I wax the car with. It's cheeper anyway. Also, after you wash the car, rinse it a second time with filtered water instead, it will reduce waterspots significantly.

 

I don't have any of that fancy stuff on hand but I had the same issue and just sprayed the t's really good with foamy window cleaner and took a blade to it, looks good and no scratches or water marks anymore.

 

Ive read that buffing with a chrome polish does wonders... soon as weather breaks I have to do it to all my windows cause they are spotted ALL OVER... and as 91Z said about Jersey, thats where my car was bought and had sat for awhile under a cheap none waterproof car cover.

 

yeah mines the same way i think its the tint

 

Are the spots on the inside or outside? If its on the outside its probably a build up of hard water spots, try waxing it then cleaning it with automotive glass cleaner.