The Audi S6 is the only Volkswagen Group model so far to use the revolutionary new twin-turbo V-8 paired with the firm’s twin-clutch transmission. The technical merits of the design allow the S6 to beat the remarkable sub-4-second sprint stats achieved by the larger S8 despite packing 100 fewer horsepower.

The transition from the luxury A6 to the S6 is a comprehensive redesign of nearly all the car’s key mechanical systems and components. The exterior style barely moves forward from the A6 S-line but does include a number of S6-exclusive elements, like the giant quad exhaust system, and deeper fascias and bumpers.

The S6 raises the bar on every aspect of the standard A6’s performance. It also changes the car’s competitive set from BMW 535i and Mercedes E350 models up to the Porsche Panamera and the new E63 AMG 4Matic. For 2014, the S6 has some reshuffled option packages and a new Black Optics trim pack to increase car’s road presence.

The Porsche Panamera is the S6’s biggest competitive threat for buyer attention. Does the Audi->ke14 have the chops to dethrone the ranking AWD performance sedan king?

Click past the jump for the full review of the Audi S6 with info on the new-for-2014 features and options.

Exterior

The S6’s exterior styling is in an uncomfortable no-man’s land at the top of the A6 food chain but clearly less aggressive than the RS6 Avant above it. Similar to the current A5/S5/RS5 line, the S6 shares all critical body panels with the A6 and doesn't get any of the RS-style fender flares, 3D Quattro badging in the lower grille, or the latest huge twin oval exhausts in the rear.

With the current S6’s subtle details the only ways to differentiate the model on the road, the value proposition changes from showy cruiser into sleeper performance monster. For all the extra drama in the BMW M6 GranCoupe’s styling, there is a large segment of buyers who prefer to walk more softly.

The black optics package looks sharp with the gloss-black grille housing and a total chrome delete for the rest of the body. For ultimate Q-car appeal, the black pack also ditches the aluminum mirror housings in favor of body-colored items. There’s no question that the changes help make the look more menacing.

The other changes versus the A6 include the V8T badges on both front fenders and S6-exclusive psuedo-foglamps in the lower bumper region. While these look like projector foglights, they are actually the radar and camera arrays for the 2014's active safety tech and night vision.

The brake calipers are painted black with an S6 emblem, and the car has deeper and sharper rocker panel extensions.

The S6 comes with standard Xenon Plus headlights that include the LED running lights. Full-LED lamps are optional and significantly enhance the car’s style over the boring projector-beam bi-xenons.

Versus the Porsche, the Audi->ke14 loses points by sharing so many styling details with the A6 that costs just $42,000 in base trim. Versus the E63 AMG, the Audi simply looks like an older design but has similar performance mods like the quad exhaust visible in places.

Finally, the red-trimmed S6 badge lives in the grille where lesser models would have nothing or a simply chrome Quattro badge.

2014 Audi S6 Exterior Dimensions:

2014 Audi S6 Exterior Standard Features:

- Audi S exterior appearance (Platinum Gray Matte Audi Singleframe grille, unique front/rear fascia and side sills, Aluminum-optic front/rear blade fins, exterior side mirror housings and integrated rear spoiler)

- Adaptive xenon plus headlights with LED daytime running light technology

- Automatic headlights

- LED taillight technology and rear fog lights

- Power-adjustable, auto-dimming, heated exterior side mirrors with memory

- Quad exhaust outlets

- LED indicator light technology integrated into the exterior side mirrors

- Heated windshield washer nozzles

- 8.5-by-19-inch Five-parallel-S-spoke design wheels with 255/40 summer performance tires

2014 Audi S6 Exterior Options:

- Metallic/pearl/crystal effect paint

- Full LED headlights ($1,400)

- Black optics package

- Estoril Blue crystal effect paint

- 8.5-by-20-inch Five-parallel-star-spoke design wheels with 255/35 summer performance tires

Interior

The corporate sharing is less of a problem inside the S6, due to the extremely high standard of base A6 sedans. The S6 comes at an $11,000 premium versus loaded A6 S-line models and puts about half of that money into including more standard features.

The S6 now includes MMI Navigation and the upgraded Bose audio system as standard. It also packs new, sportier 12-way power seats that buyers can order with very handsome quilted leather for the seat bases.

The fine-grain Ash trim replaces dark Walnut for the S6 but options also include: brushed aluminum, carbon-fiber or layered Oak options (see gallery below). The layered Oak was new for 2013 and is seen on the above photo.

Super-premium 22-way power seats are an S6-exclusive option. The S6 has a touch of added cache, via the exclusive illuminated door sills with an S6 logo, unique S6-branded welcome screen graphics and new grey gauge faces with white needles and yet more S6 badges.

The S6’s biggest changes for 2014 are the inclusion of the driver assistance package that brings adaptive cruise control. The S6 also bundles a number of other systems into the Innovation package that includes night vision and a heads-up display projection on the windshield.

The S6 also includes active noise cancellation via the Bose stereo – something not offered on lesser A6 sedans.

2014 Audi S6 Interior Dimensions:

2014 Audi S6 Interior Standard Features:

- Three-spoke multifunction sport steering wheel with shift paddles

- MMI Nav Plus – eight-inch display screen with S6 graphics; Audi connect with Google Earth navigation, six-month trial connectivity period included; BLUETOOTH streaming audio

- S6-specific gray instrument cluster with white needles and S6 emblem

- Leather seating surfaces

- Twelve-way power front S Sport diamond quilting seats with S6 embossing on front seats including four-way power lumbar adjustment and front integrated headrests with driver memory

- Audi music interface with iPod integration includes one cable for iPod connection

- Bose Premium Surround Sound system with AudioPilot: 14 speakers including center speaker and subwoofer with total output of 630 watts

- BLUETOOTH wireless technology preparation for mobile phone

- SD card slot with 32GB capacity (dual slots)

- 40:60 split folding rear seat

- Three-step heated front seats

- SiriusXM Satellite Radio with 90-day trial subscription; SiriusXM Traffic with four-year subscription

- Voice control system (controls cellular phone, CD, radio and navigation), includes speech-to-text engine

- Fine grain natural Ash brown decorative inlays

- Aluminum-optic surrounding of air vents, window & seating switchgear and vent controls

- Five 12V power outlets (two in front / two in backseat / one in trunk)

- Power glass sunroof with slide/tilt function, sunshade and pinch protection

- Automatic four-zone climate control system

- Ambient Lighting plus: LED Interior lights in front and rear headliner with fade-in & fade-out feature, time delay and automatic switch on when key is withdrawn from ignition

- Advanced key: Doors can be locked and unlocked without active use of the car’s ignition key; the engine is started with a button on the center console next to the gear shift knob, without the need to insert ignition key

2014 Audi S6 Interior Options:

- Four-spoke multifunction leather wrapped steering wheel

- Topview camera system

- Head-up display: Optical system of mirrors projects driving-related information directly into the driver’s field of vision

- Night vision assistant with pedestrian detection

- Bang & Olufsen Sound System with 15 speakers and 1,300 watts ($5900)

- Brushed aluminum decorative inlays

- Layered Oak decorative inlays

- Driver assistance package ($2,500): adaptive cruise, blind-spot assist and parking sensors

- Innovation package ($5,650): all Driver assistance pack items, plus: HUD, night vision, top-view camera system, active lane assist

- Heated rear seats ($450)

- Comfort Seats option ($1,900): 22-way power sport seats

Drivetrain, Suspension and Brakes

If half the upgrade cost went into extra interior equipment, it is hard to see how Audi can afford to make the extensive mechanical changes while staying within budget. The biggest news is the engine and transmission setup that is unseen elsewhere in the Audi->ke14 range.

The S6 runs a slightly detuned version of the twin-turbo 4.0-liter V-8 that also appears in everything from the Bentley Continental GT to the Audi S8.

In S6 trim, the engine produces 420 horsepower and 406 pound-feet of torque. This is down 100 horsepower versus the engine’s output in the S8, but is achieved largely through electronics and not mechanical differences in the design.

The engine still offers the stump-pulling torque that makes it so impressive elsewhere. The S6 reaches its giant torque peak only 500-rpm above idle at 1,400 rpm. Paired with the faster-reacting dual-clutch transmission, the car is officially quoted at 4.5 seconds to 60 mph, but times in the low 4’s or high 3's are more realistic.

The S-tronic 7-speed DSG gearbox also offers instant responses from the shift paddles and is more obedient in extremely fast conditions.

The S6 comes only with huge steel brakes and not the pricey carbon-ceramic option on Euro S6 models. The size of the front rotors is a gigantic 15.7 inches and ensures the S6 can stop as hard as it goes.

These big brakes are absolutely critical when you consider that the S6 has gained more than 600 pounds compared with a front-drive A6 CVT. Versus a 3.0T Quattro, the S6 is still 400 pounds heavier. Where is all that weight? In the nose. This adversely affects weight distribution as well as fuel economy and, typically, suspension settings.

Using a S6-exclusive air suspension means the Audi team does not have to make the ride settings so hard and unforgiving in comfort mode. The dynamic mode increases control in corners but will be a rarely-pushed button on most choppy American freeways and city centers.

2014 Audi S6 Mechanical Details:

Safety

The related Audi A6 is a Top Safety Pick from IIHS with “Good” scores across the board. The car has not yet gone through the full NHTSA testing program but is expected to perform very well. The car comes with six standard airbags with two extra optional in the rear doors.

Like the A6, a comprehensive safety package on the S6 includes all the required electronic systems to keep passengers safe. The night-vision camera offers a valuable safety addition for drivers who live in rural and suburban areas where unseen wildlife on the road can cause high-speed impacts.

Another shout-out for the A6/S6's power-operated child door locks controlled via the driver's seat. No more stopping and fumbling in the rear doorjambs to flip the manual child lock switch. Also, no more unhappy adults who discover they cannot open the rear doors from the inside.

Pricing

The S6 comes in only the top Prestige trim level with a base price of $71,900. Audi’s Navigation and 630-watt stereo are included as standard, but the worthwhile LED headlights and Innovation package take the price into the $81,000 ballpark.

Competition

2014 Porsche Panamera

The Panamera competes with the Audi on performance and the pricing overlaps near the top $80,000 S6 prices. The Porsche's performance at this level is significantly slower than the Audi. Upgrades in engines and trim can easily double the Panamera's base price.

Being at the bottom of the Panamera range means even the cheapest Porsche's seem very expensive on the road.

2014 Mercedes-Benz E63 AMG 4Matic

Nearly all future V-8 AMG models in the United States are expected to include 4Matic AWD as standard equipment starting with this fall's new E63 and winter's S63. The AWD enhances the AMG's launch abilities and nearly matches the S6 with a 3.9-second 0-to-60 mph time versus 4.5 for the rear-drive model with the same power.

The V-12 S65 AMG and SL65 AMG remain rear-drive for the time being.

Conclusion

The S6 offers nearly all the pace of its RS sibling but does without the RS6’s flamboyant styling and track-ready suspension. Whether this is a plus or a minus will depend on individual buyer priorities for the car.

Despite lacking the RS6's rock-hard suspension, the S6 will still demolish nearly all racetracks and be far more comfortable doing so than the RS6. It will not be as exciting in or outside the car, however, because the S6 lacks visual and aural drama.

Then again, new fenders and a wilder exhaust would’ve pushed the S6 close to $90,000. As it stands just above $70,000, the S6 is incredible value. That engine and gearbox alone probably cost $20,000 to install, so buyers are basically getting nearly all the interior options, an air suspension and the mild styling tweaks for free.

The car is quicker than the Porsche but lacks some of the more-expensive Panamera’s exclusivity and gravitas at the valet stand. The S6’s standard Quattro all-wheel-drive also makes it more viable than the M5 in any state that gets snow.

The battle will heat up again as the new 2014 4Matic-equipped E63 AMG and (expected) 2015 xDrive BMW M5 arrive in the near future.

Until then, the S6 is the ultimate sleeper supercar.