Unfortunately, GM's support for usb and sd card for music comes up a bit short. For both my Cadillac and our new Envision, a stick or card containing multiple folders cannot be played in its entirety without intervention. Start playing a song in a folder, and you're stuck in that folder until you intervene. Our Lincoln had a "repeat" option that could be turned off, GM doesn't.
So, cd player does this just fine, except that I'll have to burn multiple cd's.