Switching the MIC and sunroof switch does work as well as upgrading the MIC to the new version. I have done both. The new MIC can be purchased from our good friend Tom at EAS.

http://www.europeanautosource.com/pr...roducts_id=307

It is $65.00...good deal.

Also the phone also plays a part. I have a Motorola V635 and a Treo 650. The sound quality on the V635 is much butter. This has to do with the firmware of the device. Palm recently released a new firmware for the Treo and one of the specific fixes was Bluetooth car kits.

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2011 550xi Carbon Black/Oyster, M-Sport, Premium Package, Technology Package, Electronic Damper Control, Dynamic Drive, Comfort Access, Active Seats, Surround Cameras

2013 X5 5.0 Space Grey/Black, M-Sport, Premium Package, Technology Package, Comfort Access, Surround Cameras