Well that depends on country, year and engine cc. Can you provide more info?
The Audi A8 price ranges from $78,750 (base price of a 2012 Audi A8 NWB 4.2 FSI) to $169,202 (fully loaded A8 W12 6.3 FSI).
The 2011 Audi A8's engine produces 328 ft-lbs. @ 3500 rpm.
The 2009 Audi A8's engine produces 325 ft-lbs. @ 3500 rpm.
The 2004 Audi A8's engine produces 317 ft-lbs. @ 3500 rpm.
The 2008 Audi A8's engine produces 325 ft-lbs. @ 3500 rpm.
The 2003 Audi A8's engine produces 302 ft-lbs. @ 3000 rpm.
The 2013 Audi A8's engine produces 325 ft-lbs. @ 2900 rpm.
The 2001 Audi A8's engine produces 302 ft-lbs. @ 3000 rpm.
The 2010 Audi A8's engine produces 325 ft-lbs. @ 3500 rpm.
The 2006 Audi A8's engine produces 317 ft-lbs. @ 3500 rpm.
The 2012 Audi A8's engine produces 328 ft-lbs. @ 3500 rpm.
The 2014 Audi A8's engine produces 325 ft-lbs. @ 2900 rpm.