A burned CD may not play in your car's CD player for a number of reasons, all of which have to do with the media type (e.g., CD-R, CD-RW, or DVD-R), the music format, the burning method, and the capabilities of the head unit. Some head units are more sensitive than others, and some recognize a limited set of file types. You may be able to burn CDs that play in your car by changing the type of media you use, the brand or model of CDs, or the file type.
Why Old Car Radios Won't Play Burned CDs
The two types of burnable CDs are CD-Rs, which can be written to once, and CD-RWs, which can be written to multiple times. CD-Rs are usually the better choice for troublesome head units. This used to be a bigger problem than it is now, and is more likely to be the source of the problem if the head unit is old.
Some CD-R music discs contain special disc application flags that allow you to use them in standalone CD recorders. They are not needed when burning music with a computer. In some cases, manufacturers put "for music" labels on lower quality discs, which can cause additional problems.
You can burn music files in two formats: as audio CDs or as data CDs.
