When I got my Model 3 back in February, I simply took the thumb drive out of my Model S and installed into the Model 3. However, I noticed right away for the vast majority of my MP3 files, it would give a playback error message. Only the FLAC files played properly and about 10 MP3 files (out of 260). So I brought the car into the service center this past week to have a rattle addressed and also had them look at this issue. They tried my thumb drive in another Model 3 and it didn't play in that car either and when they tried their own music, they said it played fine. So they wrote off the issue as saying my music was corrupt (even though I specifically mentioned the music played fine on the Model S). So after taking the car home, I did a close comparison to the few MP3 files that played and those that didn't. After a bit of troubleshooting, I noticed it was a tag issue! If the files had ID3v1, ID3v2.3 and APEv2 tags, it wouldn't play them. I used a program called Mp3tag to clear all tag data from the files and import it back in using the file names for artist/song info. This removed the APEv2 and just left ID3v1 and ID3v2.3 tagging info. Sure enough, they all play now (at least the ones I've tested so far)! I've sent an E-mail back to the service center to have them raise a formal bug complaint on this and specified the tag info. Hopefully they will get this working like the Model S/X system. So if you have issues with MP3 playback, I would check the tagging on them.