There are six trims within the Audi A8 family. The standard-wheelbase A8 is offered with either a 3.0L V6 or 4.0L V8 form. The 3.0L model utilizes a supercharged 3.0L V6 that makes 333 horsepower and 325 pound-feet of torque, and is capable of accelerating to 60 mph in 5.5 seconds. Meanwhile 4.0L twin-turbocharged V8 makes 420 hp and 444 lb-ft of torque and can rocket to 60 mph in just 4.7 seconds. Long-wheelbase A8 L models are the way to go for rear-seat comfort. They add about five inches of overall length and wheelbase--most of which provides added legroom in back. Long-wheelbase models are offered with a choice of the short-wheelbase's 3.0L supercharged V6 and the 4.0L turbo V8. A new-for-2014 3.0L turbocharged diesel V6 makes 240 horsepower and helps make some impressive fuel economy numbers. The top of the range is a special, limousine-like 6.3L W12 engine that makes 500 hp and 463 lb-ft of torque. The Audi S8 variant is the pick for the performance-minded. It packs a special high-output version of the 4.0 TFSI, making 520 hp and 481 lb-ft of torque--good for an almost incredible, supercar-like 0-60 time of 3.9 seconds. Throughout the A8 and S8 lineups, acceleration, all-weather traction, and overall handling stability are aided by Audi's quattro all-wheel drive system. In the S8, a sport differential is added to the system to aid high-performance handling and stability, and an adaptive damping suspension helps make the most of its handling and added responsiveness without negatively affecting ride quality. Upgraded ventilated disc brakes--6-piston in front--help give the S8 stronger stopping performance to match its high-speed potential, and showy 21-inch wheels are included in that model. Separately, a Sport Plus package adds an adaptive air suspension plus dynamic steering, the sport differential system, and summer performance tires. Throughout, an Audi Drive Select system also allows the driver to adjust throttle and transmission response as well as steering feel and other characteristics, with Comfort, Auto, Dynamic or Individual settings. No matter the A8 model, it has a luxurious interior that matches the best of both classic executive-car cabins with some of the fine, almost custom-look details of bespoke ultra luxury cars. Interior trims include matte-brushed aluminum, ash brown wood, layered oak wood, or Carbon Atlas in the S8, and heating, ventilation and massage are included in the front seats in the S8. A8 V6 and V8 models come with fuel-saving start/stop technology that automatically turns the engine off when the vehicle is stopped at a light and automatically restarts, almost instantaneously, when the brake is released. EPA fuel economy ratings range from a high of 24 mpg city and 36 mpg highway for the TDI model to 13/21 mpg for the W12-powered 6.3L model. 6.3L models stand out from the rest of the model lineup. It offers an available Executive Rear Seat package with recline, a footrest, massage and heating and cooling. A rear entertainment system is also offered on that model and includes Bluetooth wireless headphones and can even project map displays to passengers. The navigation displays in the A8 lineup are unique. The Audi Connect system can display panoramic views as well as 3D Google Earth views, plus live traffic information from SiriusXM Traffic. The system also includes mobile hot-spot capability, through its built-in data connection, as well as Google Voice Local Search plus other information apps. Even base 3.0L models include Audi connect, a rear-window electric sunshade, a garage-door opener, Bluetooth connectivity, Bose surround sound, a dual-zone climate-control system, proximity entry and ignition and a power sunroof. Noteworthy extras include new LED headlamps with a high-beam assistant, available on the A8, standard on the S8 and W12 models, the Sport plus package and a new Sport Design package that upgrades the look and feel of A8 3.0L or 4.0L models. The optional Bang & Olufsen Advanced Sound system packs 1,400 watts and 19 speakers in all.