Playing files from the external micro SD card in the car on my Sandisk Sansa Clip

I only appear to be able to access files from the memory on the player itself rather than from the external micro SD card when I have connected the player via a usb lead into my car’s audio system. I.e. the car audio system only displays tracks from the player not the external SD card. I can access files from the external SD card when listening to the player through headphones in the normal way.

Your car’s audio system can only see the player’s internal memory. If you have songs on an external memory card that you want to play in your car, I suggest you use a card reader plugged into the USB port for your system.

Thank you for your help.