For decades, the Mercedes-Benz S-Class sedan has reigned as a supreme icon of luxury motoring. The S-Class is usually the first to receive Mercedes' latest technological and safety gadgets, giving us mere mortals a glimpse of things to come. This tradition continued with this iteration of the flagship sedan. The S550 also has power, ride and comfort fit for a monarch, but the fiendishly complicated controls can be a royal pain. For the S550, a 429-hp, 4.6-liter twin-turbo V8 is mated to a seven-speed automatic transmission. All-wheel-drive was an available option.