Used 2013 Audi S8

That the 2013 Audi S8 won't hang with the world's quickest performance sedans — like the Porsche Panamera Turbo and upcoming BMW M5 — doesn't even faze the car's technical project manager, Peter Dlab.

Dlab, sucking down a foie gras appetizer at the car's introduction in rural Spanish wine country, acknowledges that "it's not really that kind of car." And after driving the S8 through the region's isolated roads, we agree. Certainly, large sedans with track-worthy performance credentials are impressive, but the S8, which sublimely combines undeniable speed with opulent luxury, makes us question their value.

The new 2013 Audi S8, which utilizes the same aluminum chassis and suspension as the A8, is a luxury cruise missile targeted directly at the Mercedes-Benz S63 AMG. Audi's strategy, it seems, is to ignore the world's most dynamically potent sedans and focus instead on extravagance as much as performance. What we have here, then, is a massive luxury sedan that doesn't unravel when asked to hustle, but never concerns itself with that last tenth of a second.

Still Worthy
Even so, Audi still rented the Circuito de Navarra in Northern Spain to demonstrate the S8's dynamic abilities. And what we learned there about the big sedan's behavior is telling. Here's one you probably could have guessed: This 512-horsepower all-wheel-drive monster understeers around low-speed corners, which are plentiful on Circuito de Navarro. Build some speed, however, and the S8's technology can be put to real use.

In high-speed corners you'll witness unusually impressive behavior. Even the smallest lift while cornering gives the rear sport differential the message that you're ready for some rotation. It delivers by overdriving the outside wheel and effectively rotating the car enough to be unnerving at first. Repeat the endeavor, though, and you can predict when and how much to turn the car and the technique becomes as effective here as it is in the smaller S4.

Even the 15.8-inch front brake rotors and six-piston calipers are reliable in stopping the 4,354-pound machine. Upshifts are radically fast and smooth, while the body control is excellent thanks to a 10mm-lower ride height and stiffer air springs and dampers.

Also, Audi says the S8 will hit 62 mph in 4.2 seconds, which is only about half a second slower than the Panamera Turbo and a few tenths behind the smaller Cadillac CTS-V. We weren't able to test this claim, but our backside says it's probably close to reality. So, yes, the S8 is a for-real performance sedan — even if it's not the quickest one on the planet.

The Heart of the S8
You may have heard about the 2013 Audi S8's groundbreaking new engine — a 4.0-liter direct-injected twin-turbocharged V8 that produces 512 hp at 5,800 rpm and 479 pound-feet of torque at 1,700 rpm. The mill's power density — at 128 hp per liter — is higher than any other car in the class. It's a strategy based around economy as much as performance, and other technologies are rolled in to help. Cylinder deactivation — which makes the V8 into a V4 during low-load cruising — is present, as is a start/stop feature that kills the engine when idling. The start/stop feature, however, won't be available on U.S. models for at least the first model year.

On the road it's not the substantial power that makes the biggest impression, but rather the eight-speed automatic transmission, which manages to be both supremely smooth and rapid when executing full-throttle upshifts. It will click briskly through the first five gears during around-town cruising and it never made a poor selection when we slammed the throttle open to pass. Let it decide for itself when to shift and you'll experience one of the most effective automatic transmissions in the world.

Do the shifting yourself and it's less capable. Downshifts, when requested via the wheel-mounted paddles, are rev-matched but still upset the chassis when you brake for a corner. Whether this is a result of sloppy rev-matching or a powertrain not properly isolated from the chassis is difficult to discern. Also, because of the sheer number of gears, knowing which one to target for a particular corner isn't easy. And then there's the timeless problem shared with almost every manually shifted automatic transmission: aggressive downshifts — those that require a big dig into the throttle for proper rev matching — go largely ignored. As a result, corner exit speed is compromised.

Doesn't Matter Much
Whether this matters to potential S8 owners is a matter of debate, but it's the kind of thing one discovers when driving the car on a racetrack. It's this level of response, apparently, where Dlab and his team chose to draw the line between luxury and performance. And it seems like a perfectly appropriate stopping point. The 2013 Audi S8 is still mightily quick even if it leaves tight corners a gear higher than we'd prefer.

Audi Drive Select allows drivers a choice of Comfort, Auto or Dynamic modes when adjusting the chassis and powertrain. The system will configure throttle response, shift speed, steering weight, spring and damper settings (including adjusting ride height) and more. Alternatively, all Drive Select components can be adjusted individually.

Further enhancing the luxury side of the equation are engine mounts that deliver feedback 180 degrees out of phase with the engine's resonant frequency when in four-cylinder mode. The result, in combination with active noise cancellation via the audio system, makes the S8's cockpit an utterly smooth, silent place to conduct business. Like a rocket-powered safe room on wheels, there's little else on the road that rivals this sedan's mix of speed and silence.

Inside the Safe Room
At hand in the S8's interior are traditional high-end materials combined with striking levels of contemporary technology. Diamond cross-stitched leather covers the 22-way-adjustable front seats, which can be optionally ventilated and fitted with a massage function. Trim for the dash, doors and console can be had in either wood or carbon fiber (the real deal). The white-on-gray instrument cluster isn't high contrast but is surprisingly easy to read.

Audi Connect combines Google Earth 3-D graphics and voice-activated Web searches with the company's MMI navigation, which itself incorporates SiriusXM Traffic. The S8 is also a rolling WiFi hotspot.

Lest you get the idea that this sedan is somehow lacking in luxury, here are some amenities available to rear-seat passengers: power-adjustable seats with three-stage heating, individual climate control, power blinds, headrests with adjustable side bolsters and the ability to adjust the front passenger seat.

The Takeaway
It's too early to comment on several of the 2013 Audi S8's more critical details. Cost, for example, won't be announced until next May before cars begin shipping to the U.S. But our best guess has this performance model starting at a lower price than the W12-equipped A8. Call it roughly $115,000.

EPA fuel economy ratings, too, aren't yet prepared, although the car earns a 23-mpg average in the European drive cycle, which is very roughly equivalent to the EPA's "combined" rating in the U.S.

Even the carbon-ceramic brakes, which cut 44.1 pounds total from the big Audi, are yet to get the thumbs-up for the U.S. market. That one, we're told, will come down to whether a business case can be made for the costly option.

Perhaps the most telling detail regarding the S8's character is the fact that its press materials list the car's 155-mph governed top speed as a mere "formality." Formality or not, keeping pace with the top dogs of the autobahn — like the S63 AMG — will require more speed. We'd wager that speed is only a small electronic tweak away. And we're sure Mr. Dlab isn't losing any sleep over it.

Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.