I mended a thing and it worked!
A few weeks ago a few replies on my comment sparked my interest for in-car audio in my 2006 Audi A3. My old solution for streaming music was an FM transmitter which worked but the quality was rather bad and sometimes my phone disconnected out of the blue. After a bit of research on forums and on YouTube I found a solution: a small bluetooth device from Bluemusic which connects to the cd changer pin on the back of the radio. Delivery was super fast as was the installation. It took only 10 minutes to hook the reciever up. The audio quality is good so far and no comparison to my old FM transmitter at almost the same cost! If you want to listen to your music in your car without having an AUX jack or installing a gaudy looking aftermarket radio this is the best possible solution in my opinion.