For quite some time, I was trying to understand how the radio on my car, sorted the mp3 files on my USB flash disk. I did notice it wasn't alphabetical, but couldn't figure out exactly how it sorted the files. Originally I thought it was based on the modification date, but it wasn't always right.
So after some months of trying to find out what was happening, I decided to research it. Seems Pioneer, even on post 2010 models, still uses sorting by FAT tables. I thought I was screwed since my 64GB flash disk is almost full on music, and I had no way of easily choosing what to hear, especially while driving.
Gladly I stumbled upon Drivesort, a small but super useful app, that (re)sorts the directories on the FAT tables alphabetically. I won't get into details, since if you understand what I'm talking about, you will easily find how Drivesort works.