ViseeO Tune2air WMA1000 - Wireless Bluetooth Music Interface Adaptor for in-car iPod Integration (Audi, Volkswagen, Mercedes etc)
I have an Audi A5 2012, this device states that it works without interrupting Bluetooth calls, but it does.  Even when I am not using this device it's just plugged in to my car and I am on a call I hear a lot of static.  I have to completely disconnect the device to have a clear call.  This is not acceptable to me for a device worth $90.