Several Audi automobiles have an available SD card slot in the stereo, allowing you to import audio directly from a computer into the music system. However, before you are able to use an SD card with the Audio car stereo, you need to format the flash storage device. If you don't, the car is (more than likely) unable to read or detect any of the saved music on the SD card.
Connect an SD card reader to your computer. These external readers plug directly into a USB port on the computer system.
Slide the SD card into the SD card reader. Momentarily a prompt window appears, stating the computer has detected a new, removable device. Close out all AutoPlay windows that appear on the screen.
Click the "Start" button on the desktop, then choose "(My) Computer" and right-click the removable device icon. From the pull-down menu choose "Format." This loads a new, format options window.
Click "OK" and the computer formats the SD card. If you want to back up any information on the card, you need to do so before selecting "OK," because once the card is formatted it is gone forever.