An Audi S8 doesn't exactly belong on a racetrack, in the same way that humans don't exactly belong in the same vicinity of ticked-off bulls charging down the street. So if we abandoned all reason and indulged in Audi's offer to shepherd an S8 around the Circuito de Navarra just outside of Pamplona, Spain, please forgive us. It must be something in the water.
The S8 is the sport-flavored variant of Audi's A8 flagship sedan. It is a massive four-door and it is supposed to be more engaging without compromising the cosseting luxury and attention to detail that define the A8. From five laps on a damp track, we can report that the S8 delivers accurate steering, excellent body control, and supreme stability. It is far more nimble and lithe than the Mercedes-Benz S63 AMG, as it should be since the Audi significantly lighter and shorter (the S8 only comes in standard-wheelbase form). Composed as it is, though, this is still a large car that will not be hurried through corners. Fortunately, the S8's hallmark is a furious engine that is eager to pick up the slack on the backside of the bend. Momentum conservation loses its significance and the mantra "slow in, fast out" takes on a new meaning when there's this much thrust on tap. No matter how slowly you enter a corner, the all-wheel-drive S8 charges through the back half and brushes the outside edge of the track with shocking speed.
That potency comes courtesy of an all-new engine, a twin-turbocharged, 4.0-liter V-8 that replaces the previous model's normally aspirated V-10. Audi has taken a cue from BMW and swapped the locations of the intake and exhaust ports so that exhaust gas flows toward the center of the engine. This allows the turbochargers to be moved into the valley of the engine's V and leads to shorter exhaust plumbing that improves engine responsiveness. Twin-scroll turbines also aid power delivery by eliminating the interference between exhaust-gas pulses. The torque curve hits its peak at just 1700 rpm and continues to deliver all 479 lb-ft up to 5500 rpm. While the 520-hp rating is less than that of Mercedes' 5.5-liter twin-turbo V-8, the S8's aluminum construction makes it nearly 600 pounds lighter and Audi claims a 0-to-62-mph time that's 0.2 second quicker at 4.2 seconds.
The engine steps off the line gracefully and spins smoothly to redline without the slightest hint of turbo lag. Working seamlessly with the crisp eight-speed automatic, the 4.0-liter is always ready to twist the tach needle to the right and launch the S8 down the road. The muffled growl under full throttle, smooth and deep, befits the engine's power and refinement. This engine will eventually be offered alongside the twin-turbo V-12 in the Bentley Continental range and will power the Audi S6 and S7, albeit in less powerful form, producing 420 hp. Our brief first drive of it in this S8 left us with nothing but positive impressions. The engine has the potential to be just as versatile as Audi's supercharged V-6, which is responsive enough for the S4, refined enough for the A6, and powerful enough for the Q7.
Would you like some fuel economy with that power?
Automakers don't raise engine output without simultaneously improving fuel economy these days, and Audi claims a 23 percent increase in mileage, which we estimate will translate to an EPA combined rating of 18 mpg versus 15 mpg for the previous S8. A portion of that gain is due to the smaller displacement engine, two fewer cylinders, and two additional gears in the automatic transmission. The rest can be attributed to specific fuel-saving technologies. During light-throttle cruising at moderate speeds, the V-8 engine is capable of running on just four of its cylinders. Cylinder on demand, as Audi calls it, isn't new (General Motors, Chrysler, and Honda have used it) but it's the first time Audi has employed the technology and it presented unique challenges to the luxury automaker.
Four-cylinder operation creates vibrations and noises that don't belong in a $100,000 sedan. To maintain the level of refinement found in the A8, engineers have developed innovative active engine mounts on either side of the engine that generate their own vibrations in opposition of the engine's shudder. Similarly, there's an active noise cancellation system that uses four microphones in the headliner and the subwoofer and four primary audio speakers to generate an audio signal that erases the low, quiet din that would otherwise be present in four-cylinder mode. European market cars will also be equipped with engine start-stop technology, a feature that eventually will make its way to our market but not for the S8's summer 2012 launch.
The high-tech chassis
Besides lapping a track, we also challenged the S8 on the back roads surrounding the Navarra Circuit and buzzed along Spain's highways. Several stretches proved too narrow or too tight to feel comfortable in a sedan this large moving at full speed. Instead, the S8 is at home zipping along large-radius sweepers with open sight lines and smooth transitions from left to right, or an open stretch of straight road where it can waft along effortlessly at triple-digit speeds.
Quattro all-wheel-drive, a torque-vectoring rear differential, and a nearly imperceptible variable-ratio steering system are all standard on the S8. Audi's Drive Select system can be set to comfort, auto, or dynamic mode, or an individual setting that allows for independent adjustment of the steering effort, shift calibration, throttle response, and suspension firmness, among other settings. A sport-tuned air suspension rides ten millimeters lower than the A8. Even in the stiffest setting, Audi has preserved the compliance you'd expect from an A8. So while body motions are tightly controlled, the ride on the standard 21-inch wheels is never jarring.
The same can't be said of the eight-speed automatic. It is generally well behaved with faultless decision-making and shift quality in the standard drive setting. Sport mode quickens cog-swapping, but it's fairly conservative when it comes to downshifting under braking. Calling the shots manually via the steering-wheel-mounted paddles introduces a speed and abruptness to the shifts that is occasionally unbecoming. That shift quality may be appropriate for the dynamic mode, but gear changes feel just as aggressive regardless of the Drive Select transmission setting.
Carbon-ceramic brakes are optional in Europe and Audi decision-makers are considering offering them in the U.S., which makes about as much sense as driving this car on the track. The high-performance brakes aren't just unnecessary; they're ill-suited to the S8's purpose. On a road drive in a carbon-ceramic-equipped car, light-pressure braking transitioned unpredictably between dull and abrupt. They're a boon on the track, but few S8 owners will drive to a level that taxes the standard brake system.
Separ8ing the S8 from the A8
The S8 receives only subtle tweaks to the A8's elegant styling and lush cabin to set it apart from the standard car. The exterior features a redesigned grille, new lower air intakes, tweaked side sills, a rear diffuser, matte aluminum mirror caps, and four oval exhaust tips. Inside, carbon-fiber and aluminum trim is standard on the dash and doors, although wood can be specified in place of the carbon. The highlight, though, is the 22-way adjustable sport seats for the driver and passenger with heating, ventilation, and massage capability. The rest of the cabin is familiar if you've been in an A8, A7, or A6. That is to say the ergonomics are intuitive, the materials are superb, the style is sophisticated, and the technology is progressive. Standard equipment includes Audi's excellent MMI infotainment system with a pop-up, eight-inch display, in-car wireless internet, and Google Maps imagery. The S8 will also introduce a feature that allows the driver to wave a foot under the rear bumper with the key in his pocket to automatically open the trunk.
Audi hasn't yet announced official pricing, but it appears the company will try to take advantage of the Mercedes-Benz S633 AMG's nearly $40,000 premium over the old S8 to justify a hefty price increase. Where the previous car listed for about $97,000, we expect the 2013 S8 to sticker for around $115,000, which would still undercut the Mercedes by roughly $20,000.
The fast and the fastidious
The larger and heavier the car, the more that the "performance variant" means the "speed variant." The S8 is no exception. The limits of physics and a desire to retain uncompromised luxury minimize the engineers' ability to meaningfully alter the car's agility. The S8 handles well and holds its own when driven hard, but like the S63 AMG and BMW's B7 Alpina, it is hardly the car for dissecting tight corners at the limits of adhesion.
It is the car for the driver who loves to go fast and who loves to do so without great effort. The S8 feels quick at any pace thanks to the swell of power that's always underfoot. It is also every bit as comfortable, stylish, and luxurious as the A8. The stellar powertrain is enough of a reason to succumb to the S8, but Audi has backed it with the chassis hardware to improve cornering composure without diluting the A8's refinement.
2013 Audi S8
Base price: $115,000 (est.)
Engine: 32-valve DOHC V-8
Displacement: 4.0 liters
Power: 520 hp @ 5800 rpm
Torque: 479 lb-ft @ 1700 rpm
Transmission: 8-speed automatic
EPA fuel economy: 18 mpg combined (est.)
Steering: Electrically assisted
Turning circle: 40.4 feet
Suspension, front: Control arms, air springs
Suspension, rear: Multilink, air springs
Brakes: Vented discs; ABS
Wheels: 21-inch aluminum alloy
Tires: Continental ContiSportContact 5P
Tire size: 275/35YR-21
Wheelbase: 117.9 in
L x W x H: 202.2 x 76.7 x 57.4 in
Cargo capacity: 18.0 cu ft
Weight: 4354 lb