One problem related to sway bar has been reported for the 2007 BMW Z4. The most recently reported issues are listed below.
1. Rear sway bar mount loosens over time. 2. Rear sway bar mount may fall off if not tightened every ~5k miles. Adversely affects vehicle handling, especially in emergency maneuvers. Noticeable increase in vehicle understeer, 3. Replaced rear sway bar mount (it had fallen off) and used loctite on bolts.