Hi,
I purchased an '06 A3 8 weeks ago and a rattling sound has developed within the last week. It is coming from the rear offside quarter and sounds like a rack of plates rattling under the rear seats.
I'm a little alarmed as it only has 26k on the clock but it has a warranty. It's going back to audi on Thursday to be identified, I'll update with diagnosis once I hear; I'm curious to know if its a similar issue.
D