The problem is iOS8. It is not compatible with many in-car media systems.
Last week I bought an iPhone 6. It will not connect to the media system in my 2011 Aston Martin V8 Vantage N420. My wife's iPhone 5S (with iOS 7 and the Apple 30pin to lighting adapter) and my previous iPhone 4S (also with iOS 7) would connect instantly and have full functionality. using a 30pin connection Apple suggested the following fixes for my iPhone 6:
1. Restore iPhone 6 to factory settings. I did this. It did not work.
2. "Update" my wife's iPhone 5S to iOS 8 to test if the problem is with iOS 8 (I resisted this at first because if iOS 8 was in fact the problem, I would have two phones that could not connect to my car - rather than one. Not really a solution).
3. Contact the car manufacturer. I did. They told me it was a problem with Apple.
In the interests of science I "updated" my wife's phone to iOS8. I say updated, but this proved to be a backward step. Following the "update" it refuses to connect to my car and now exhibits the exact same problem as my iPhone 6.
The problem is indeed with iOS8 based on this evidence.
The cynic or conspiracy theorist in me has come to the assumption that this is because Apple have recently created "Car Play" which they are trying to sell to car manufacturers. If you don't have car play, forgot about using your iPhone without serious hassle or difficulty.
I have ordered a ViseeO Tune2Air wma 1000 to see if this might help -- I will try to use it as a bluetooth interface between the phone and the in-car system. I don't hold out much hope and (if it does work) am sure the sound quality will suffer compared to cable connection so at best it is only a temporary fix (if it works).
I will be asking Aston Martin if they will be trying to update the software on the media systems and be able to apply that to my car in the future. I will also submit a suggestion on the Apple feedback page to ask them to fix iOS8. Failing both, I will probably get rid of my iPhone and switch to a less troublesome brand going forward. Unlikely to change the car simply because Apple have made it difficult (I suspect deliberately) for iOS8 to connect to systems that don't have Car Play.
Would be nice if things "just worked" But it doesn't just work really, does it Apple.