WARNING: This page is about a different car, the 2014 Audi A8 Quattro. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Removing Engine Cover
Courtesy of AUDI OF AMERICA, LLC
-- Carefully pull the engine cover off the bolts one after the other -arrows-. Do not remove the engine cover on one side or in a jerking manner.