Been detailing cars since I was 14 years old . Best way to get rid of water spots is to WAIT, yes wait, for the body to cool down, particularly after a drive, or if left outside in the sun. Then wash the car .... at night. Sunlight isn't your friend. I'm talking 9, 10, 11pm. Heck I'll wash my car at 1am. Wipe/dry the car down with microfiber cloths. Then clay the body, followed by a coat of polish like Meguiar's, then one (or two) coats of wax. Best/faster results with an orbital buffer. Didn't I mention doing all this at night? Use detail spray inbetween washes/waxes.
2011 E92 335i 6MT (Space Gray/Coral): M-Sport / Premium / Convenience / Navi / L7 / InvisiGuard / Dinan Exhaust & Pedals
2011 CR-Z EX 6MT, 2008 GSX-R600
RETIRED: 2008 Dinan M5 SMG, 2006 330i 6MT, 2006 Dinan 550i 6MT, 1992 Accord EX 5MT