I must be doing something wrong.
Using the Apple maps app - the one that is crap - it gives me turn by turn directions through my Jeep's stereo. Mutes the music for the direction. Awesome.
I loaded the google maps ap yesterday, and while it said the sounds were activated, nothing through my stereo. But it also made sure that none of the music could stream either...
Any ideas? I have my iphone 4s connected via the USB cable. Works perfectly this way with everything apart from google maps.