Yeh I knew it is based on the A8.
It gets build by the same company sortof. VW, Audi, Porsche, Seat and Skoda all are part of the VAG or Volkswagen Auto Group. Loads of models share parts. The Pheaton uses the same bottomplate/suspension if I recall correctly. U see it in more cars, the Interior of a Seat Leon is almost identical to a VW Golf.
U buy a Lancer Evo to race, U get a $65,000 VW for luxery and comfort. (and speed too btw, the W12 is awesome