Have you noticed if it disappears with window up/down?
I've been elbows deep in all my E46 door panels to do the window regulators and install speakers and there are all sorts of wonky cables, clips, brackets and gunk in there that could be loose or even slightly rubbing on each other. I assume the F10 has even more stuff in there.
2013 F10 535i M-Sport, Sophisto Grau, 6-speed MT
2011 E90 335i Sport, Jet Black, Sport Auto, Performance Edition
2002 E46 330i Sport, Jet Black, 5-speed MT, lots of upgrades
2001 E46 330Ci Sport, Steel Grey, 5-speed MT....and more
Last edited by Keyser Soze; 10-08-2012 at 03:19 PM.