There seems to he some confusion over what works and doesn't using and iPhone over BT. Wireless audio (A2DP) has always been supported. You can fire up any app that plays audio and it will send the audio signal through your car stereo.
What iOS lacks (that Android enjoys) is Serial Port Profile (SPP), which allows your stereo to connect to the internet brought your phone. The difference here is that you can actually control apps on your stereo interface. Pandora will not only show you the artist and song title (and album art?), but it will also give you the option to create and edit stations and thumbs up/down songs.
iOS 8 does not add SPP and so anything beyond audio is still going to require a cable connection.