I'm going to snap a shot tomorrow and post it here. Actually it doesn't really matter whether I set the iDrive language to English / Chinese. Either way, the chinese, Japanese, Korean or whatever names of the songs should be correctly displayed but .....there is one prerequisite.
Every mp3 file should have a "tag" that specifies the title, artist, album, genre etc of the song. The iDrive system does seem to rely on this to identify each song or to allow you to search your collection according to the different parameters specified within that"tag". Even if your mp3 file name was shown correctly on your computer, it may still contain non-UTF-8 characters for the song title within the mp3's tag. If that's the case, most likely you will see all sort of #$%^^#$% for your song title, artist's name, Genre etc.
mp3 tag's WIKI
So you have to check the tag for each mp3 file to make sure they contain the correct UTF-8 characters under different headings.
Try to follow this guide if you're using iTune
Or if your system is Windows, download this "Mp3tag" from here to edit the tag
PS: even if your iDrive doesn't allow you to change the system language to something other than English, the above should still work if the system is truely UTF-8 compliant. BTW you can attach a jpg file for the album cover to each song by editing the tag
I have all my songs stored in a ScanDisk USB key. Sometimes when I turned on the system, it just failed to recognise the USB key and I have to reinsert it into the USB slot and wait for a few sec before the iDrive was able to recognise the key again. Some other times, it just automatically jumped to the song I was listening last time when I turned off the car. Very annoying... I will bring this to my dealer's attention when my next service is due. Hopefully not hardware related....