2007 Audi S8 Review

Specifications

A German Performance Limo with the Power of a Bull

As if the technologically advanced and ultra-luxurious A8 W12 isnt an adequate range topper, Audi has decided to raise the bar in the exclusive high-performance luxury sedan market segment. How, you may ask? Theyve done it by shifting the A8s exquisite balance of luxury and performance towards the performance end of the spectrum with the all-new S8.

After developing and producing the new supercar-bashing RS-4 sedan, quattro GmBH, Audis in-house tuning firm, promptly turned its efforts towards a new project; transforming the highly dynamic, three-year old A8 into a large vehicle capable delivering the thrill of a sports sedan and true driving enjoyment in a vehicle often used to chauffeur others around - and to do so without sacrificing an ounce of comfort.  I dont know about you, but this challenge seems as difficult - if not more - than those outlined for the RS4.

With millions upon millions of dollars poured into its flagship sedan, the A8 benefits from unique technologies limited to this top-tier model. Aside from the small-series production A2 subcompact, no other Audi features lightweight ASF (Audi Space Frame) aluminum construction and adaptive air suspension. Of course, the sublime Quattro all-wheel drive system and a full range of gasoline and diesel engines cant be forgotten. Combining these elements together, Audis performance team couldnt have asked for a better base to start with.

The biggest news to come with the announcement of the S8 is its motor. As much of a mechanical masterpiece as the 6.0-liter W12, including the potential in twin-turbocharged form as noted by applications in the Bentley Continental series, Audi has opted for a different engine altogether. Under the hood lies, not an upgraded version of the RS4s 4.2-liter FSI V8, nor a biturbo V8 engine as with the RS6, but rather a V10 engine borrowed from Italian subsidiary and supercar-maker, Lamborghini.

A significant number of changes have been made to this thoroughbred ten cylinder, giving it a completely new set of characteristics; after all, an executive sedan is vastly different than a sports car, with priorities centering on refinement and ease of operation. Enlarged bore and stroke increases displacement to 5.2 liters (up from 5.0 liters), satisfying the requirement for more torque, while the addition of FSI direct injection bumps the compression ratio to 12.5:1, improving efficiency while reducing emissions and fuel consumption. The engine also includes two-stage variable valve timing on intake and exhaust manifolds.

Despite the countless advancements that normally yield a greater horsepower count, the outcome is the opposite, a horsepower drop from 500 to 450. Instead, the gains are in torque, where a useful increase of 22 lb-ft of torque is seen, making for a total of 398 lb-ft compared to 376 lb-ft in the Gallardo. Furthermore, different internal components and governing electronics have been added so that the car now produces peak pull at a less peaky 3,500 rpm, as opposed to the baby bulls 4,500 rpm. To boot, the S8 features a linear torque curve, with 90 percent of max twist accessible from 2,300 rpm.

Having learned a thing or two about improving dynamics from the RS4, the S8 features a revised version of the quattro AWD system with an asymmetrical torque split. Rather than the 50:50 were accustomed to seeing, the car features a 40:60 split to reduce understeer and create a more neutral rear wheel drive bias. The system can still juggle torque, directing a max of 85 percent to the rear and 65 percent to the front if needed.

Meanwhile, the six-speed Tiptronic automatic gearbox features a shorter final ratio which enables a W12-matching 5.0 seconds for the sprint to 60 mph. Unsurprisingly, there are no ill effects to top speed, given that it is electronically governed to 250 km/h.

To match the additional power of the motor, the A8s aluminum air suspension has been upgraded as necessary. The car now rides 20 mm lower with firmer springs and dampers, though the ride height and comfort levels are adjustable through the MMI control system. New rubber bushings and a tweaked steering system aim to further improve body control and overall feel. As for stopping power, conventional discs have been upgraded to 385 mm front and 335 mm rear carbon ceramic brakes for increased performance, lower unsprung weight and reduced maintenance.

As with the past S8, identification on the road will amount to little more than a guessing game. Changes are stealth-oriented and minor, including S trademarks that include brushed metal mirrors, metal trim on the door handles, S8 badges, quad tailpipes and 20-inch wheels inspired by the Le Mans Quattro concept, wrapped in 265/35 ZR 20 tires. The S8 makes its world debut at the Tokyo Motor Show this week, and will be available late 2006 at a price of 97,500 euro (est. $117,000 USD).