BMW previously unveiled a feature where it makes use of the iPod Out functionality on the iPhone in order to control the gadget via a iPod-like display menu to be integrated with BMW iDrive interface concept. It allows the driver to make use of BMW iDrive Controller to control and search through your phone. Unfortunately it seems that all this will be put on hold if you plan to drive a BMW and own the new iPhone 5 as the new 8-pin will no longer work with this iPod Out functionality even though you might use the converter to convert the new 8-pin into 30-pin.
The adapter will still function for music, postcast and other audio application using the new Lightning adapter together with the 1/8 inch audio jack. Just iPod like interface will not be available.
Take a look at the video on previously introduced iPod Out feature from BMW.