What software did you use? I tried that in an '06 650i. It played MP3 CDs fine but not an MP3 DVD. I have since switched to an iPod. 1600 songs on an 8GB nano for the new 550i.Worked like a charm! Takes a few minutes for the system to choke down all those files, but it's nice to have just one disk with a massive music collection on it.
I hope that helps someone out there who didn't know.