Like Bananachipz said - Opticoat !!! research it. It's a permanent sealant like product that is professionally applied that is like a second clear coat. It won't come off even with multiple washes, etc. Only way to remove it is to polish it off. When it rains the water just beads off and it is much easier to keep it clean. Not cheap but you never have to wax again.
I'm picking our car tomorrow and it's getting an Opticoat treatment the following weekend.
2013 328i Sport Line, Mineral Grey, Black, custom order sport auto, custom order variable steering, opti-coated!!
2014 Carrera S, Agate grey, black int, 7spd manual, sport PASM, sport chrono, sport seats plus, sport exhaust combined with Sharkwerks bypass pipes - on order