As above, most CD writing software other than the one built into Windows has an option to burn music CDs, converting the files into the type needed for a standard CD player.
If the car has a standard head unit then it will be an RCD300. Only later versions of this head unit can play mp3 files from a CD, otherwise it's standard CDs only. As said by the first reply, these units say mp3 on them and have silver buttons rather than the earlier black buttons (however not all silver button RCD300s also have the mp3 function).