This is what I remember about the flash drive in the E90 LCI. The glovebox USB port is only for transferring music from flash to the hard drive. I believe you can only transfer 4Gig at a time, with 12Gig of a available music storage. The hard drive catalogs the transfers separately (USB1, USB2, etc). You have to select each group group from internal storage separately along with CDs you have ripped with the CD drive. I'm not sure if playlists are supported from the hard drive USBx folders. Because all of the hard drive music is not catalogued together, I only use it for ripping CDs that friends have that I want to sample. Ripping CDs to AAC or MP3/LAME gives much better quality than the IDrive.
If you want to play music directly from USB flash you must use the console port. Playlists are supported here but most be formatted properly (just folder structure, no drive letters). The car seems to re-catalog the music every time you restart the car. The larger your flash drive the longer this takes (it's minutes, not hours). I used a 16Gig flash drive without a problem but it was no longer necessary (and too much trouble) once I got my iPhone.
Last edited by nospam; 11-25-2012 at 08:48 AM.