I have a 2006 S4 Avant with similar problems. The Bluetooth in the car will initially connect with my Audiovox 6600 but will then quickly disconnect. It usually reconnects a few seconds to minutes later. To add to the quandry, I have Verizon as my carrier, which has had its own share of Bluetooth issues. I was thinking of changing to the T-Mobile MDA. It appears to be compatible according to the most current list in the above post. Any help would be greatly appreciated. Thanks.