There are car audio receivers that allow playback of MP3 files recorded onto DVD discs.
I know that sony makes such a unit, but I’m equally sure that
the other makers, Alpine, Pioneer, Clarion, etc, have head
units that do the same.
I use DVD-R discs to archive my mp3 files against the potential
(inevetible) failure of a hard drive.
I just started doing the same thing for archiving my .wav files.
when you are used to recording mp3’s on CD-R’s it’s
more than a little amazing to see just how few discs
it takes when using DVD-R’s… but then again I
suppose you already realize that