Just thought I would share the issue I was having with my iPhone6 and the built in Maps app on iOS v8.3.
I couldn't play back audio thru the 8.4A system even after enabling the HFP (Hands Free Profile) option in the Maps settings on the iPhone. The option was disabled to start and even after setting up Uconnect bluetooth again on the iPhone it wouldn't work.
I had to "forget this device" for Uconnect as well as remove phone from bluetooth settings in the 8.4A system. Turned off bluetooth on iPhone. Set it all back up normally and Nav voice in the Maps app started playing thru the vehicle's audio system. Woohoo!
Just wanted to post this in case anyone came across similar issue.