Whether your built-in car stereo (newer cars) has a USB port (somewhere hidden) or you have installed a third part car stereo (older cars) with the USB port on its face, YES, you can use a USB stick to play music in your car. You can even use a HARD DISK drive. Most players, however, do NOT support NTFS file system, so you have to have your USB device formatted in the FAT32 file system. If you finally use an external hard disk you must create a FAT32 partition for the car stereo to recognize and play the music in it.