Funny:
I have 3 headsets - Jawbone ERA, Plantronics Voyager Legend, and now (post iPhone 5) a Bose. None of them work well with the iPhone 5, but did work well with my 4S. Same with my 2013 CR-V - can make calls, but can't answer. After doing some research on the internet, it appears that others are having the same problem. So... it's going to be up to the every company or manfacturer that makes a bluetooth system to fix the problem (other than Apple, which does make "the blue tooth system" in the iPhone 5).
It's funny, on one forum a guy said (and I'm paraphrasing): "the iPhone 5 doesn't work with any of these cars; I wonder if we could sue all of these car manufacturers."
The question is this: whose responsibility is it to make functional the bluetooth features advertised by Apple? The Bluetooth system in my car works perfectly with the 4S (running iOS6), as do my headsets. The iPhone 5 doesn't work properly with anything.
BTW: Between my wife, my 4 year old, and I we own 19 pieces of Apple hardware: 1. a Mac Pro; 2+3. 2x 15" rMBP; 4+5+6. 3 ipads; 7. 1 ipad mini; 8+9. two UMBPs; 10+11+12 3 x iphone; 13+14+15. 3 x AEX; 16. Time Machine; 17. the original powerbook; and who knows what else I can't remeber (I edited this because I just remembered that I own 2 apple tvs). I am also a member of the ADC (OS X).
I been with Apple for a long time. I have been very loyal to Apple. I am entitled to say that is Apple's responsibility to make its own products work - but that Kool-Aid sure is sweet, ain't it?