You said "I really feel this is a serious safety issue"

If true, I suggest you file a complain with NHTSA, including your VIN.

NHTSA Complaint Link

Note a couple of things:

1) NHTSA is only interested in complaints that affect safety (I assume the steering would fit),

2) If you provide your VIN, they take it much more seriously. I believe one person actually got a response from BMW after doing this. (I assume NHTSA wrote a letter to BMW and BMW NA tracked him down to his dealer using the VIN).

This seems to be an all to frequent problem, and if NHTSA gets enough complaints, they will open an investigation which could lead to a recall and help a lot of unaware Z4 owners.