On my 2010 w/ Nav I Hooked up an iPhone 5 using Bluetooth (as I always have with my 4S). When not listening to anything and using the new Turn by Turn in Apple Maps, the Bluetooth seems to cut off some of the spoken directions every time. What is strange is that if I am listening to something via Bluetooth then the spoken directions are not cut off at all. Anyone else?
Wouldn't surprise me too much - for example, when I've used Siri in the past, the car usually cuts off the acknowledgement beep when I activate it. Or when I answer a call, I get cut off unless I wait for a second or so between answering the call and starting to talk. So far, I've only used the turn-by-turn directions while also listening to music, which (as you noted) works just fine. I doubt this is a problem unique to the iPhone 5 (I have a 4S). Maybe you should get a track of silence and listen to that on repeat to make sure the directions don't get cut off.
It's probably a timing issue where the phone starts streaming the audio before the system is ready for it. You could run a silence track like macman suggested.
Androids had the same issue on bluetooth using nav but it was fixed in the latest version. I'm guessing with the way Apple Maps is right now that this is last on their fix list.
