Yes the BMW metallic paint is rock hard. I had some minor surface marring and used a 7424XP, orange pad and M105. Didn't do as good of a job as I wanted. I needed a stronger and smaller pad; for next time I bought a 4" backing plate and some yellow pads.
And lighting is absolutely critical ... I used sunlight but resorted to a flashlight for the sides of the car. PITA. Next time I will buy a 3M sun gun.
2011 BMW E92 335i, 6MT, Le Mans blue - Quaife LSD, JRZ RS Pro, JRZ camber plates, Eibach ERS, full M3 susp, custom toe arms, Powergrid end-links, SS brake lines, brake ducting, Michelin PSS, UUC SSK, ETS FMIC, ER CP, Perf. Exhaust, VAC RSIK, Sparcos; work by VAC Motorsports in Philadelphia