Audi: S is for stunning

Despite all-aluminium construction, the S8 is a fairly substantial machine at 1975kg. Photo / Supplied

The paint is hardly dry on the Circuito de Navarra, Los Arcos. Opened in 2010, the main speed circuit is a 4km, 15-turn roller-coaster ride of a track set in the sparse countryside of northeast Spain. It's built to full Formula One specification, but also serves as a driver training, sports and corporate facility. Does it all.

Navarra is a new-money circuit hosting the launch of a new-money car: the latest Audi S8. The S8 may be the priciest model in the A8 series, says Audi, but it's also one typically purchased by younger, more overt types than those who opt for the regular A8.

You might not glean that merely by looking at the car: it's surprisingly understated, although it wears the expected S-badging, slightly more garish grille and bumper treatments and quad exhausts.

But there's a good reason why we've come to a racetrack. The S8 has the kind of ludicrous performance that can barely be contained on a public road: 0-100km/h in just 4.2sec. Seriously. Despite the outrageous turn of speed, Audi places just as much emphasis on the S8's improved fuel efficiency (10.2 litres per 100km) and luxury fitout.

German carmakers are generally pretty serious. But it seems that Ingolstadt company people have a sense of humour. Possibly. Entry point to Spain is Pamplona - famous for the running of the bulls. The previous S8 had a 5.0-litre V10 petrol engine borrowed from Audi's own raging bull brand, Lamborghini. The new one doesn't.

The all-new engine powering the S8 has two less cylinders and a litre less capacity than the old V10. It's also 15 per cent more powerful, with an astonishing 382kW/650Nm - produced with the help of a pair of twin-scroll turbochargers. Audi has taken a leaf out of BMW's book by placing the turbos and exhaust hardware between the V8 engine's two cylinder banks, improving efficiency and saving space.

The economy (23 per cent better than the old V10 model) is courtesy of cylinder-on-demand technology, which shuts down four of the eight pots under light load, reduced internal friction and stop-start.

At full throttle, there's a polite, increasingly present growl from the V8 - about the same time that the eight-speed gearbox is getting ready to shift into hyperdrive. Any other time, the S8 is near-silent because it has two technologies new to Audi: Active Noise Control (ANC) and active engine mounts. ANC is an elaborate arrangement that operates when the S8 is in four-cylinder mode. It's there to prevent the car sounding like ... well, a four-cylinder sedan. It analyses the engine sound coming in the cabin and sends real-time acoustic signals to the audio speakers to cancel it out.

All of this technology will be shared with the forthcoming S6 and S7 models, which will also be powered by the new 4.0-litre V8. As will the Bentley Continental GT from next year.

Despite all-aluminium construction, the S8 is a fairly substantial machine at 1975kg. I can only imagine the V8 will be detuned for the smaller, lighter S6/S7, because an Audi sedan going any faster than this one seems downright dangerous. The scariest thing about the S8's ferocious pace is that it doesn't feel particularly fast, because the power delivery is so linear and the cabin so quiet. Put your foot down, glance at the speedometer - lift-off, heart palpitations.

In all other respects, this car's not dramatically different to the standard A8. Even inside, which remains staggeringly luxurious and well-finished. The S8 does feature unique Carbon Atlas trim (yes, it's real carbon fibre) and the option of Moon Silver upholstery. Which is very silvery. There are also two bespoke exterior colours: Daytona Grey and Prism Silver.

After seven laps - two behind an R8 GT pace car, five all to myself - and one missed corner after the 200km/h main straight, I bring the S8 in. Really, a racetrack is no place for a two-tonne luxury sedan. Circuito de Navarra corners are not the S8's friend. No surprise there.

However, the track does provide the opportunity to experience the strangest combination of supercar performance and refinement/luxury. It's a confusing car in some respects: it's natural to think such a fast car should be more sporting or that such a refined limousine should be a bit less ferocious in its acceleration. But this is a flagship-showcase after all.

The $275,000 S8, which arrives in New Zealand mid-2012, could well be Audi's ultimate "because we can" car.