Temporary albeit annoying solution: with my infiniti, I had no problems with music track data streaming. My problem was with receiving calls via bluetooth: when I answered the call, the nav display would revert to whatever it was showing, rather than the active phone call screen which usually comes up, and the car was clearly not receiving the phone call, though on my phone the call was active. So I tried manually transferring the call to the car from my iphone (audio sources button, select "my-car" (infiniti's name for car bluetooth). The call transferred to the car, and everything worked fine. I then hung up, called the iphone 5 again, tried answering the call from the car, and it worked fine (ie, didn't have to go through the same manual transfer procedure from the phone). I turned the car off, on again, tried the same procedure, and it worked. So, even though, at least on your first call of the day the whole point of handsfree talking is lost, it does work on subsequent calls--At least you dont have to hold your phone to your ear for every call. Still need to try this a few times to see if it's consistent, and test both of our new iPhone 5s with my wifes MDX (nothing like the scientific method!). Will report back. At this point, based on so many other comments and threads, it seems like an iOS 6 issue, because others are reporting similar difficulties with older iPhones after updating iOS. Unfortunately, its much harder to get answers/solution points from infiniti than Apple. Apple will say any new iOS bluetooth problem is incompatible with the car's profile, and you'll never get any reliable answer at all from a car company.
