Why does it use the VW Phaeton's steel chassis instead of the Audi A8's chassis?
Aluminum construction has benefited the Audi A8 and the new Jaguar XJ. For example, the long-wheelbase 2005 XJ weighs 53 pounds more than than normal XJ yet is 5 inches longer. The 2005 Jaguar Super V8 weighs over 800 pounds less than a BMW 760Li.