Originally Posted by Weasel

Try this, when you're sitting there at idle in gear with the vibration happening... try just barely hitting the gas to raise the RPM only 50 to 100 rpm. You'd be amazed what a difference a few RPM makes at idle. If that does indeed smooth it out you could ask the dealer to raise the RPM by 50 through a test plan in the diagnostic equipment. I've fixed quite a few BMWs with the same vibration at idle doing this.