I just want to make a quick comment on and update that must have happened on my Nexus 7 recently. I decided to try to Bluetooth streaming audio again in my car when wonder of wonders, it worked perfectly.
I no longer have the problem streaming from my audible book collection. What was the issue was that if I paused or stopped the Audible book from playing, when I tried to access it again later it would not connect. In fact, I was denied access to the book until I closed and restarted the Audible application. Now that is no longer in a problem. I'm so glad that finally started working again.