When launching a powerful executive sports model, manufacturers can get away with a lot. Their cars can often still succeed when saddled with catastrophic emissions, savage fuel economy, insurance bills that read like a Premiership footballer's pay slip and even crippling depreciation. The one thing they can't get by without is horsepower and lots of it. This is a power game and unless you're packing some serious numbers, you're going to fall by the wayside.

That's the position Audi's original S6 found itself in back in late 1999. Fronting up to the party with 'only' 340bhp just didn't cut the mustard at a time when rivals from BMW, Mercedes and Jaguar could all call on a whole lot more grunt. The sense of disappointment was palpable. What we didn't know then but do with the benefit of hindsight was that Audi would subsequently launch the RS6, a fire-breathing monster that packed 450bhp or, if you waited for the ultimate model, the RS6 Plus, a whopping 480bhp. With that in mind, we can forgive the latest S6 turning out a 'mere' 416bhp from its Lamborghini-sourced 5.2-litre V10 engine. You just know that if you want genuinely extreme horsepower, an RS6 version will be along in due course.

That's as maybe but let's take a good look at the car unveiled at the 2006 Detroit Auto Show. Available in saloon or Avant estate guises, the all-wheel drive S6 is a good deal more subtle than many would expect. The restyled single frame front grille and an additional centre air intake with bigger side inlets are what most will notice as the S6 looms large in the rear view mirror. Dawdle a little to admire the LED daytime running strip lights below the bumper and you'll probably get a testy flash of the xenon headlights. Pull to the inside and you'll get a glimpse of 19-inch five-armed Wing design alloys, gently flared wheel arches, aluminium effect door mirror casings and bigger side rubbing strips. As the S6 blows by you'll have to be quick to take in the integrated boot spoiler, the rear diffuser and the quad tail pipes, singing a song that's more Sant'Agata than Ingolstadt.

"With the S6, Audi aims to make exotic engineering exploitable"

Audi ploughed plenty of Euros into the development of the V10 engine that found its way into Lamborghini's Gallardo and few thought that this investment wouldn't come with some strings attached. As much as Lamborghini's brand managers would love exclusive dibs on this powerplant, the Germans pulled rank and fitted a version of it first to the S8 super saloon and now to the S6. It's not a direct transplant of the Gallardo's powerplant, as that engine is optimised for a small, lightweight sports car and features a power delivery that wouldn't make a good fit with the personality of a high end executive sports saloon. In short, it's just too peaky and aggressive. Therefore Audi have fitted a balancing shaft to improve refinement and have grafted on their FSI (fuel stratified injection) direct injection system to improve efficiency and responsiveness.

It's a lightweight piece of metalwork, tipping the scales at just 220kg, therefore helping the S6 avoid the rather turgid handling characteristics of many cars that feature large capacity front engines. The way the engine is tucked back a little further into the engine bay also promises better handling than the rather nose heavy old S6 V8. Some will be slightly crestfallen that the S6 isn't offered with a version of Audi's award-winning DSG twin-clutch sequential manual gearbox, especially as its fitment to Bugatti's 987bhp Veyron has blown the previous excuse that the 'box couldn't yet be set up for high power outputs null and void. Instead, the S6 gets a six-speed Tiptronic automatic transmission that offers smoother upshifts but less tactility to entertain keen drivers.

Many of the body panels are constructed from aluminium which helps keep the S6's all-up weight in check. This is a big car and tips the scales at 1,910kg in saloon guise which is more than a BMW M5 or a Mercedes E55 AMG, so one shudders to think how much the Audi would weigh with traditional steelwork. The bonnet, front bumper, bootlid and firewall are all constructed in aluminium, as is much of the suspension assembly. With a power to weight ratio of 218bhp per tonne, the S6 isn't going to be slow. Audi quote a sprint to 62mph of 5.2 seconds for the saloon with the Avant tacking on another tenth, with both cars electronically limited to a top speed of 155mph. Fuel economy is a not utterly eye-watering 21mpg.

With a 40:60 front/rear torque split, the S6 is set up to offer the keen driver some payback while still retaining that traditional Audi all-weather capability. The cabin remains one of the finest at any price in terms of ergonomics. Although much of the look and feel is reminiscent again of the A8, the dashboard features a binnacle and centre console that angles towards the driver. The quality of the cabin remains top notch but there's a little more style and colour contrast here, Audi finally recognising that the coal hole dark plastic look was just that little bit too nineties to cut it these days. Alcantara and leather trimmed seats with integral head restraints add a sense of purpose to the cabin, backed up by the 'S quattro' three-spoke leather trimmed steering wheel with aluminium effect Tiptronic gear shift paddles. The fascia and doors are inlaid with carbon fibre and the instrument panel features a special 'Flexmetallic' anthracite-coloured covering with S6 embossed dials, just in case you forget what you're piloting.

The S6 has always been a tricky car to pin down. It's a notch removed from the very top echelon of super sports saloons but is still gut wrenchingly rapid and capable. That said, the standard A6 4.2-litre V8 is no slouch. If you have a taste for exotic engineering, a very cool image and discreet dynamism, the S6 may be just the ticket.