Also try paint polish. Chances are that the water spots are now etched in if you can't remove them. You may need a good glass polish and a machine.

X2

Also you might want to try 0000 steel wool and your favorite cleaner. It does work. If you are hesitant, try it on an out of the way place first or on an old beater.

I am also a fan of using Zaino Z-12 Glass Polish with a 4" pad on my Porter Cable.

Once you do get the spots off, i put liquid glass on my windows too when i apply it to the paint and it has a rain X effect. I think it lasts longer though.

what i noticed is that if you take it to a (touchfree) carwash, or if you wash it frequently a couple more times, dry the windows first. i started using a california water blade just to get the majority of the water off but if you let the hose run on the car its really not necessary cept for the hood and the windows/windshields. wash it a few more times and dry it quick, not in the sun.

this is what you need for anything. chrome wheels make them spotless, water spots on paint or windows say buy buy.

http://www.detailsupplyoutlet.com/item.htm?item_num=191
ive delt with pro for a very long time and they are a great company if you buy this buy a good bottle and sprayer from them also