Used 2015 Audi S8

The 2015 Audi S8 provides the same seductive luxury as the regular A8 along with a thrilling turbocharged V8 and incredibly well-sorted handling. Essentially, it's a four-door rocket ship in the disguise of a sedately styled sedan.

If regular flagship luxury sedans don't quite get your blood pumping, Audi offers a solution: the 2015 Audi S8. The S8 is based on the regular A8 flagship and provides the same elegant driving experience, but it's got a huge helping of turbocharged V8 horsepower piled on top. The lap of luxury has perhaps never been this exciting.

How many horses, you ask? Try 520 of them, harnessed to a smooth and quick eight-speed automatic transmission. That's enough to take this big sedan from zero to 60 mph in just 3.6 seconds, which is as quick as many high-end sports cars. Equally remarkable is the exceptional refinement this V8 displays, as it's powerful right off idle and stays nearly silent during highway cruising. And should you desire to pilot the S8 on your favorite curving road, the pinpoint control afforded by the S8's exclusive sport-tuned air suspension may fool you into thinking you're driving a car two-thirds the size.

High-performance flagship sedans are a special breed, and each example deserves careful consideration. The 2015 Porsche Panamera lineup includes the wickedly fast Turbo model plus the naturally aspirated Panamera GTS; both are fantastic to drive. The 2015 Mercedes-Benz S63 AMG provides outlandish acceleration along with unbeatable cabin ambience. Nor will you go wrong with the sleek 2015 Jaguar XJR or the understated 2015 BMW Alpina B7. But the 2015 Audi S8 more than holds its own in this company, and it just might be the best all-around car in this class. It earns an Edmunds.com "A" rating.

The 2015 Audi S8 is a high-performance full-size luxury sedan offered in a single well-equipped trim level. Unlike the A8 on which it's based, the S8 does not offer the option of a longer-wheelbase variant.

Standard features include 21-inch alloy wheels, summer tires, a sport-tuned adaptive air suspension, full LED exterior lighting (headlights, running lights and taillights), automatic high beam control, a top-view parking camera system with front and rear parking sensors, a sunroof, auto-dimming and power-folding mirrors, a power trunk lid, soft-close power doors, keyless ignition and entry, diamond-stitched leather upholstery, four-zone automatic climate control, 22-way multicontour front seats (with massage, heating and ventilation functions), a power tilt-and-telescoping steering wheel and power rear side and rear window sunshades.

Infotainment features include a driver information center with a 7-inch screen between the gauges, a head-up display, Audi's Multi Media Interface (MMI) infotainment system with an 8-inch central screen, a navigation system, Bluetooth phone and audio connectivity and a 14-speaker Bose surround-sound audio system with a CD player, satellite radio, HD radio and an iPod interface. Also standard are Audi Connect (including enhanced Web-based navigation and information services, plus mobile WiFi capability), a blind-spot monitor and a basic collision mitigation system that includes pre-collision preparation measures and secondary automatic braking after a collision has been detected.

Some S8 options are grouped into packages. The Driver Assistance package features adaptive cruise control (with stop-and-go functionality) and a more advanced collision mitigation system with automatic pre-collision braking and active lane-keeping assist. The Cold Weather package includes a heated steering wheel, heated rear seats and a rear seat pass-through. The Full Leather package extends the already generous standard leather upholstery, while the Audi Design Selection packages include the Full Leather package and bundle unique trim elements into cohesive interior treatments.

Individual option highlights include different wheel designs, a sport exhaust system, a solar sunroof (which powers a ventilation fan to keep the car cool), a rear seat entertainment system (with dual screens and an additional MMI control panel), night vision assist (with pedestrian and animal detection) and a 19-speaker, 1,400-watt Bang & Olufsen surround-sound audio system.

Powering the 2015 Audi S8 is a twin-turbocharged 4.0-liter V8 that produces 520 hp and 481 pound-feet of torque. An eight-speed automatic transmission drives all four wheels through a standard all-wheel-drive system.

In Edmunds instrumented testing, the S8 accelerated from zero to 60 mph in 3.6 seconds, an extremely quick time for almost any car, let alone one this large. Yet the S8 somehow manages a respectable EPA fuel economy estimate of 20 mpg combined (17 city/27 highway). Only a select few cars are as fast and frugal as Audi's largest performance sedan.

Standard safety features for the 2015 Audi S8 include antilock disc brakes, stability control, front and rear parking sensors, a top-view camera, blind-spot monitoring, a collision alert (which detects potential collisions and engages certain passenger protection features), front seat side airbags, rear seat side airbags, full-length side curtain airbags, front knee airbags and Pre-Sense Basic and Rear (providing pre-crash vehicle preparation and post-crash automatic braking).

Optional via the Driver Assistance package is a collision mitigation system (Pre-Sense Plus) that monitors traffic and alerts the driver if it detects a potential collision. It can then apply the brakes (to a standstill when vehicle speed is below 20 mph) if a collision seems imminent and the driver hasn't reacted. Lane-keeping assist and a night vision camera are also available.

In Edmunds brake testing, an S8 equipped with the standard summer tires came to a stop from 60 mph in 105 feet. This is a very good distance for an elite sedan, though the Audi's brake pedal feel doesn't inspire as much confidence as some rivals. The pedal travel is surprisingly long, and the pedal itself is surprisingly soft. In a performance sedan of this caliber, we'd expect a shorter-travel brake pedal with a firmer feel.

Forget big-sedan standards. The 2015 Audi S8 is blindingly fast by any standard. The turbocharged V8 spools up so quickly that you almost forget it's a forced-induction power plant. The eight-speed automatic transmission heightens the effect by quickly and seamlessly cycling through the ratios, though the trade-off is a lack of smoothness in some situations. Use the manual paddle shifters to select gears yourself and you'll be rewarded with throttle blips on downshifts. We also like the electronically adjustable settings for the chassis and engine calibration, as they provide a useful degree of driver customization. The V8 engine sounds mean yet subdued when you put the pedal to the floor, and when you're cruising along at highway speeds, it settles into near silence.

With its standard all-wheel-drive system, well-tuned suspension and crisp steering response, the S8 handles like a smaller, lighter sedan. It's only around truly tight turns that you'll be reminded of the car's substantial size and weight, but even so, the S8 has the reflexes and grip to keep up with sports cars on challenging roads. In low-speed city traffic, the standard air suspension's ability to filter out harshness borders on magical, especially considering that the Audi S8 wears low-profile, 21-inch summer performance tires. In Comfort mode, you could easily fool people into thinking you were driving a regular A8.

Much like the A8 it's based on, the S8 has an excellent cabin design. Top-grade materials unite with expert craftsmanship and assembly to form one of the finest interiors in the automotive world. Comfort is exceptional, thanks to 22-way-adjustable front seats with numerous functions that ensure drivers of all shapes and sizes will find their happy place. Rear seat passengers won't feel left out either, as there's a wealth of head- and legroom for taller adults -- although some buyers would surely prefer a long-wheelbase S8 if Audi made one.

Audi's MMI interface is a boon for technophiles, as it controls a multitude of functions with its high-resolution screen and slick knob-based control layout. The menus may take a little more getting used to than some other high-end infotainment systems, but once you're acclimated, complicated tasks can be executed with ease. Also included is a remote touchpad that allows you to trace letters with your fingertips as a way of inputting or finding phone, music or navigation data. The software behind this system is starting to feel a little dated, though, as the navigation system isn't able to read street names aloud, while the standard WiFi is only capable of 3G speeds (versus 4G LTE in some other Audis). The price of the premium Bang & Olufsen surround-sound system may cause some initial sticker shock, but discerning ears will note that it is one of the finest audio systems on the market.

The one glaring fault in the S8 is its lack of trunk space. At 14.2 cubic feet, its cargo capacity is less than some midsize sedans and well below what's available in similarly sized rivals.