Bluetooth dissconnecting in car

By burritolove My IP6 and my wifes IP6+ (to a lesser extent) both disconnect and reconnect very frequently in the car. our 5S’s did not have this problem. has something changed, is this a known problem?
i would say if i take a call over the cars bluetooth i will connect/disconnect 4-5 times in the course of a 30 minute call.

Source: MacRumours