Music that is copied onto a DVD+R disc will not play in a CD-playing car stereo. If, however, the car has a DVD function, it is possible to play music that way.
DVD+R discs are single-record discs that require finalization before the DVD is able to play in DVD players. These discs are primarily used for DVD purposes. If you want to play music in a regular car stereo, look for CD-R (or other variations of this type of optical disk drive) and copy music onto that. Both CD-R and DVD+R are classified as optical disk drives, however, their functions are different.