The low speed vibratory rattle I had on mine (as well as a squeaking noise when turning s/wheel) was the bushing on the steering rack where the s/column attaches.
BMW fitted a new rack, as the bushing is integral with the rack, so not cheap if the car is out of warranty.
2011 135i M-Sport Coupe DCT ~ Bluewater:Coral Red | BMWP CF spoiler & BMWPE | Birds B1 suspension | Forge FMIC | Hartge footrest | Alufelgen CS7
2017 X5 4.0dSE on order
1932 Ford 3 window Coupe hot rod