^ You guys got it. Quick detailers will cause swirls, and the rear bumper is especially bad because the particles are highly abrasive (brake dust and such). As much as that "dust layer" bugs me, I always wait and do a full wash.
2015 ///M3 | BSM/Full Black/CF | DCT | Silver 19s | Executive | Lighting | DAP | Adaptive Suspension | HK | Enhanced USB | Tint
Past BMWs: 2014 550i, 2013 M3 ZCP, 2012 535i, 2011 E90 335i, 2009 E90 M3, 2008 X5, 2006 330i, 2004 330i