The four-door Mercedes-Benz S550 rules the luxury sedan pack at $87,525. Its COMAND navigation/audio/phone/voice control system sets many of the interior functions including the climate, lighting, mirrors and security system. The company's largest passenger car is less green than it is great, getting only 14/21 mpg city/highway, but the V-8's 382 horsepower kicks in quietly and smoothly, going from 0 to 60 in 5.4 seconds. Features include a safety system that tightens seat belts before impact and closes the sunroof if a rollover is detected. Other options include Distronic Plus, a radar-based cruise control system; infrared night-view that transfers pictures to the COMAND display; 11-chambered pneumatic seats; and a rearview camera and blind-spot assistance. Other sedans of this ilk are the Audi A8, BMW 750i and Lexus LS.Jill Amadio is an international award-winning automotive journalist and author.