Each Bentley Arnage R is fit with an all-aluminum, 400-horsepower, twin-turbo 6.75-liter V8 that produces an impressive 616 lb.-ft. of torque. All of the power is fed to the rear wheels through an aging four-speed adaptive automatic transmission. Bentley claims a 0-60 mph acceleration time of six seconds flat and a governed top-speed of 155 mph. At this price level one might expect at least a five- or six-speed transmission, especially with Mercedes-Benz and Lexus upping the ante in current models with seven- and eight-speed transmissions.