Engine number
WARNING: This page is about a different car, the 2006 Audi A8, 2005 Audi A8, and 2004 Audi A8. However, it is still accessible from the selected car via links, so may be relevant.
The engine number ("engine code" and "serial number") are stamped on left side of cylinder block.
In addition, a sticker with "engine code" and "serial number" is affixed to timing belt cover.
The engine code is also included on vehicle data plate.