That part is just the hitch receiver. You will still need the factory rear cross member.
I had the Invisihitch (Rack option; $615) installed on my car for $200 at a local body shop. I would highly recommend this as an option. You can do the install yourself if you have the time. Here is the thread on it:
http://f15.bimmerpost.com/forums/sho...ght=invishitch