Why doesn't my CD-R play on my car CD player?
If you have a factory CD player, an old aftermarket CD player, or a cheap aftermarket CD player it most likely is not CD-R compatible or your music is in a format that the player doesn't support such as; AAC, WMA, and a few others. Your only option would be to get a new CD player that is compatible with mp3 cds, or if your stereo supports an external CD changer(alot of radios do, even factory radios) you can get a CD changer that supports mp3 cds, or just live with only listening to regular cds in your car.
To get a better idea of your options you should go to your local car audio shop and talk to them about your issue.
Also there is a possibility that you have a defective disk, burner, or had a problem when your disk was burned(happens alot). Try the disk in another player(not a computer).
Aftermarket= did not come on the car originally.