SD memory cards are typically used by digital cameras and computers. These devices work in a similar manner as flash drives and it is possible to store only music on the card. Because SD cards are becoming more widely used, more devices are beginning to accept SD memory cards. This includes car stereo systems. Although it is only possible to use an SD card with a car stereo that has a built-in SD card port it is going to function just like a connected MP3 player.
Insert the SD card into the SD card slot on the car stereo system.
Power on the stereo, if it is not yet on. If the stereo is on when you insert the SD card slot it automatically detects the SD card.
Press the "SD" button on the car stereo. This turns the stereo to read the SD card (if it did not automatically detect the SD card when inserting it into the system).
Press "Play" and the car stereo begins to play the music on the SD memory card. You may skip in between songs with the back and forward buttons (just like with a CD or MP3 player).