I have a Nissan Sentra with built in bluetooth, and I am having problems since getting the new iphone. I synced mine with no problems, but when someone calls, the phone vibrates and then only after a couple of "rings" the car display says bluetooth but there is still no audible ringing at all. The phone was not in silent mode. With my 3G, as soon as a call came in, it would silence my radio and the car would ring to let me know of an incoming call. Anyone having similiar issues with their car bluetooth? Thanks.