Mine is possessed with rattles when it is very cold. It gets better as it warms up but it is not completely quiet. I chalk it up to there not being a perfect car no matter what the price.
Current: 2014 F10 M5
Previous: 2015 F80 M3, 2013 E92 M3, 2013 F10 M5, 2009 E90 M3, 1998 E36 M3