I would recommend using the California Water Blade. It eliminates most of the water spots. Your water could also be the cluprit. Try a good soap, or 3m Imperial Hand Glaze. That stuff works magic...
ECIS Intake | Shark Injector | Scorpion Exhaust | PG2 style rims, YOKOHAMA AVS ES100 235/40/18 | M3 Lip Spoiler | OEM Clears | Hamann Eyelids | M-Technik Front | M-Technik Sides | M-Aero Rear | 50% Tint | M3 Dead Pedal | MOMO Aluminum Pedals | UUC Gauges |Titanium Shadow Painted Trim