A-ha, I knew I'd seen those wheels somewhere before. Pangster gave the site permission to publish a few of his write ups in our article system. Jolly nice chap he was about it too!
I think it's for adding a little vibration to the seat area for your pleasure!! BMW thinks of everything to please their drivers and passengersSound good!
Just a question @Lee:
Why does the Poweflex bush have a round hole in it and the OEM version a more oval looking hole?