The best piece is the back area (croupon) where the grain is particularly even with cracks or scars due to injuries rare. Audi discards the outermost region of each hide again for quality control reasons.

The very high grade leather from the core of the bull's back is used in all areas of a car seat where fine, smooth appearance and high robustness are most important – on the headrest, in the shoulder area, in the important lower seat squab area and on the side bolsters and seatbacks on the entry side.

http://www.autoblog.com/2009/08/07/bovine-blues-audi-bullish...