I have no issues with my 13 550ix.... drives great no vibration at any speed below 135 mph.... ( havent been faster than that yet ) hope you get it resolved....

__________________
2013 550ix, Alpine white, M Sport package (me)
2012 X5 35ix, Saphire black metalic, (wife),
2006 325i , space gray (daughter)

Retired:
2009 535i
2007 335i