It seems to me that everything that I have read has had to do with a number of European cars and luxury cars, such as BMW, Mercedes, Audi. I'm not saying that is necessarily the problem, but once the phones are released and iOS are released, it is up to the vehicle and other accessory manufacturers to bring their devices into compliance with the phone software for them to work.
I feel fortunate, as my 2012 Hyundai has worked with my old 4s and the sofware it had on it, and when I purcased my 5s in October, it worked just find for it as well. No problems connecting, or maintaining connections. While it seems as though there are a lot of issues, it really isn't widespread. Good luck trying to find a solution.