The most elite S-Class sedan, the 2007 S65 AMG, needs no introduction according to Erin Riches at Edmunds. The link below provides her thoughts and several photos for your perusal:

Inside Line: 2006 Detroit Auto Show – 2007 Mercedes-Benz S65 AMG
What’s Edmunds’ Take?
Without an M version of the BMW 7 Series to battle, this car’s only real competition is the 552-hp Bentley Continental Flying Spur, and even it falls short of the S65’s performance. Mercedes remains the undisputed king of ultraluxury, ultrapowerful sport sedans. — Erin Riches