Depends on which deck you have.
The 6 disk unit plays MP3's, it says mp3 on the face of the unit.
The Nav unit also does.
My stock deck was the single CD unit and did not play MP3 CD's, but it did have an aux jack that an iPod could be plugged into.
I bought the 6 disk MP3 compatable unit off a member here for $125.
Its a 10 minutes swap...couple screw and clips