If your bluetooth audio cuts out a lot..
... it is probably due to WiFi being turned on.
In my Jeep, I connect my phone via bluetooth to my Sony BT-3700U to listen to music, podcasts, etc. If WiFi is turned on in the Captivate, the audio cuts out often. When I turn WiFi off, it's really smooth and uninterrupted.
It might be due to the phone trying to search for WiFi connections on the road... it's just faster to turn WiFi off altogether.