X5 Sport: are you using the V600 snap-in adapter and connecting to the phone's antenna port on the back of the phone? Some X5s have the concealed bumper mounted antennas which would improve reception if connected to the phone via the snap-in adapter antenna port thereby improving the signal.

Newer USA X5s with Bluetooth no longer have the concealed bumper mounted antennas. This most likely why others may be experiencing poor signal quality inside the X5 vs. outside. The newer X5s with Bluetooth do not have a direct connection via the antenna port on the snap-in adapter to any vehicle mounted antenna(s). To support this operation, you would need to purchase the concealed bumper mounted antennas and connect them to the system. Without these antennas, you are connecting the antenna port of the phone to a dead short which will result in a situation worse than operating your phone with the regular antenna removed. The other option is to remove the antenna port from the snap-in adapter and use the snap-in only to hold and charge the phone. (That’s what I have done.) Even in this mode of operation, reception would be markedly improved from the previous and almost as god as operating outside the X5.

MJM