It's probably the same problem I have been reporting ( type "jerky" in the search to find it ).Have you tried reversing any distance in your S5 ?? I have to reverse down the road up my drive to the garage. Not wanting to slip the clutch, I find the car either kangaroos or goes balls out backwards and takes some controlling. my neighbours know to keep clear when I get back from work. No other car I've owned has been quite so brutal in reverse. Anyway my real concern is the clutch judder as it pulls away in reverse gear, is this characteristic or common to S5's ???