mclean:
Maybe I have restricted concentration bandwidth, but I find having a phone conversation on the hands-free phone in my car really reduces my perception of what's happening on the road. I would have thought audio books would be the same.
No different for me than listening to talkback or some other spoken radio. Sometimes I find I've zoned out of the audio for a while and have to skip back a bit, but that's also no different than when I'm reading a book and find myself down 3/4 of a page with no memory of what I've read :) Good thing about it is if I want to skip forward or back then the steering wheel audio controls work fine so I'm not having to touch my phone (Which I won't do in the car either way).