I didn't get this with the Golf but the Rocco develops a whistling noise which is noticeable when I have the window down, it's coming from the gap between the door and the mirror, if I put my hand there the whistle stops. The noise only appears for speeds over 60kmph. Not the worst thing in the world but it is a bit annoying when you have the windows down. Is this a common thing? Not really sure how to fix it - apart from having my hand there everytime!