You can try scrubbing them with newspaper soaked in cheap white vinegar, the newspaper is mildly abrasive and the vinegar slight acidic that can many times dissolve the mineral deposits that stain the glass. However if the hard water has etched the glass there is no real solution--one of those services that buffs windshields might be able to help...
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq