RS6

Good luck with the search, a couple of other things sprung to mind if buying approved used, ask the dealer for a full service breakdown of what's been done and whats due, for example the diff service is two separate items, you've got the sunroof schedule (if the car has one fitted) and filters are all separate too. From what I've seen, main dealers often have a '2 year warranty' offer on when buying used RS cars, so if they don't currently offer it, push to get it as a negotiation point, and finally pay close attention to the wings, they're aluminium and obviously prone to stone chipping, in some cases this can lead to bubbling and corrosion underneath the paint.