When first installed the ringing sound was not clear and muffled, it only connected when the phone was placed directly over the centre console. The Bluetooth antenna looks like its installed at rear left compartment over the left wheel I managed to pull the cushion from the left rear seat next to the seat belt out to locate the BTA. The Bluetooth antenna appears to be black and bolted to the chassis of the car.

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BMW X5 E53 4.4i 2006 AWD