You won't be considering an Audi S6 if you want to shout about your performance pretensions. This car doesn't do that. In fact, over the years, it's got the whole business of not doing that down to a fine art. A lot of it's in the detail. Audi S cars have a reputation for styling subtlety and whether you order it as a saloon or an estate, this one is no exception.
For the record, this model is actually 16mm longer than a standard A6 - or 8mm longer if you're looking at the Avant estate version. First impressions though, are more likely to centre on the single frame sports aluminium front grille with its chromed horizontal double bars - a real work of art. There's more aluminium-style trim on the door mirrors (a classic S-brand touch), plus you get gorgeous sports alloy wheels, a subtle integrated boot spoiler and four chromed tail pipes surrounded by a grey diffuser. Most won't know what has just blown by and is disappearing into the distance.
The interior is similarly restrained but impressive. Everywhere you look, there's a beautiful blend of craftsmanship and technology. And a discreet reminder of what you've bought, with illuminated door sill trims and displays for the MMI and the driver information systems that highlight the S6 logo on start-up. A red ring adorns the start-stop button and there's an aluminum clasp surrounding the selector lever. The footrest, the pedals and the soft keys of the MMI operating system get a gleaming aluminum-style finish.
There's full leather of course and at the front, multi-way power-adjustable sports seats designed exclusively for this model. The three-spoke S quattro steering wheel has colour-contrasting stitching and a set of aluminum-look shift paddles just behind it. Beyond them, you view a set of bespoke instruments featuring grey dials with white needles.
What about luggage space? Well, at 530-litres in the saloon model, it's a little more than you'd get in a rival BMW 550i or Jaguar XF 3.0 S/C from this era and you can extend this to 995-litres by flattening the standard split-folding rear seats. But if you're likely to be doing that very often, then the Avant estate version will be a better bet. This provides 565-litres with all the seats in place - or up to 1,680-litres with the rear seats flat. As a halfway house between both body styles, Audi in this era also offered the S6's mechanical package as an S7 model, a car with a 535-litre boot that's extendable to 1390-litres.
This 'Type 4G' S6 generally has a good reputation for build quality and reliability, but there are a few things you'll need to look out for. We've heard reports that the electronic handbrake can sometimes get stuck. The infotainment screen that should power smoothly out of the dash top on start-up can sometimes get stuck too, so check that. Apparently the lock on the fuel filler cap has a history of sometimes breaking, so check that and make sure it opens properly. As for the air suspension, well the wishbones can apparently occasionally creak, especially over speed humps and potholes. This can, it seems, be fixed by installing wishbones borrowed from an Audi RS5; yes, really.
We came across a few reports of the electronic steering needing software updated. Audi's quattro 4x4 system should prove reliable and the engines have all been used extensively in other Audi models so there should be little cause for concern there. Look out for interior scuffs and alloy wheel scrapes. Otherwise, you shouldn't have much to fear, even from a high mileage example.
(approx based on a 2015 S6 - Ex Vat) An air filter costs in the £14 to £22 bracket. Front brake pads sit in the £45 to £60 bracket for a set but we came across pricier-branded items in the £70 to £131 bracket. You're looking at about £45 for a set of rear pads. Front brake discs sit in the £88 to £140 bracket, but for a pricier brand, you could be looking at as much as £213. For a rear pair of discs, you're looking in the £50 to £78 bracket, with pricier brands starting at around £100 upwards. A front brake calliper costs in the £195 bracket; rears cost in the £215-£293 bracket, depending on brand. A Rear shock absorber costs from around £40, with pricier brands in the £75-£90 bracket. A radiator costs around £150. Wiper blades cost in the £17 to £19 bracket.
If you're coming to this car expecting Brands Hatch for the boardroom, then you need to readjust your thinking a little bit. Sure, the twin turbo 4.0-litre TFSI V8 makes this car very, very fast, 550Nm of torque meaning that 62mph from rest is demolished in just 4.7s on the way to a top speed that would nudge 190mph were a restrictor not to cut in at 155mph. And it corners on rails, for reasons we'll explain in a minute. But it does all of this without making a song and dance about it. Truly, this is performance by stealth.
S6 prospects like it like that. Those that don't buy something else. It's as simple as that. But that something else is usually hamstrung as soon as the rain starts to fall or you've an icy morning to contend with. All the other-brand alternatives to this S6 quattro, you see, are rear wheel driven. There's a purity to that of course that a 4x4 layout doesn't have but Audi took steps to offer some of it in this 'Type 4G' fourth generation model by giving the set-up a rearward bias.
Couple all of that technology to a Tiptronic automatic gearbox with F1-style gearshift paddles and some of the most sophisticated traction control electronics yet devised and you have a car that'll be tough to beat in a traffic light grand prix. But what about around your favourite B road? Yes here too. Audi had already developed firmer sports suspension for the third generation version of this car and this MK4 model went a step further by including a self-locking differential with a sport differential on the rear axle. Thanks to this, during hard driving, the lion's share of the power flows to the outside wheel to literally push the car through the corner.
And there's more - much more. This S6 gets air suspension, a lowered set-up featuring variable damping which can alter the ride height of the body between three levels for what Audi claimed was a 'multi-faceted driving experience'. This set-up was designed to perfectly complement the optional dynamic steering (ask whether they car you're looking at has this) that adapts both its ratio and boost according to speed and uses slight, nearly imperceptible steering corrections to stabilise handling at the cornering limit.
Drive like this and you'll have selected the most focused of the modes available via the Audi drive select system - 'dynamic'. Or indeed set up your S6 for ultimate performance like a race driver would set up his racecar, via the 'individual' settings. If you're really throwing the thing about, you might want to switch the ESP stability control into its interim 'Sports' setting - which will give you a little more opposite lock leeway before all of the stability and traction controls kick in.
But of course on our traffic-clogged roads, the opportunities for such behavior are few and far between. Usually, you'll want to settle back and switch the system into 'auto' so it can adapt to your driving circumstances as the software thinks fit. Or perhaps you could click back into one of the more easygoing settings: 'comfort' (for a magic carpet air-suspended ride) or 'efficiency' (where all the vehicle's systems become frugally-minded).
It's when you're driving like this that you suddenly start to appreciate something. That this car is almost eerily quiet. And there's a reason for that. The engine deactivates four of its eight cylinders for extra efficiency on part-throttle at low speeds, at which point the car realises that you want greater refinement. In response, an Active Noise Cancellation system cuts in. Four microphones integrated into the headlining record noise in the cabin, which is then analyzed by a computer. If that computer detects intrusive sound elements, it broadcasts an antiphase sound through the stereo system speakers, which combines with the intrusive noise and largely cancels it out.
But of course, there are times when you do want noise - when you're powering through the gears and want to hear exactly what that twin turbo V8 can do. Audi understands that too, so there's a sound actuator in the exhaust system to emphasise the sonorous sound of this thumping 420PS powerplant under hard throttle. This unit was uprated to 450PS in later models.
That only leaves the brakes. This particular car features the expensive option of high performance ceramic discs, offering vastly improved temperature tolerance for the best possible resistance to brake fade and an operating life of up to 186,000 miles in everyday use - four times the lifespan of a steel disc. Just remember to budget for replacements.
It's tempting to dismiss this fourth generation 'Type 4G' S6 model on a number of grounds. For Audi owners, it's not as agile as an S4 that would save you plenty. And it's not as fast as the kind of RS6 from this era that wouldn't cost that much more. And that's before you even start to think about the talented opposition. But as soon as you do, you begin to realise that within its little market niche, this car is something quite special.
All its rivals are merely ordinary executive saloons with big petrol engines - there's no bespoke motorsport development. In other words, you can't have a proper M-powered BMW or AMG-developed Mercedes of this size for this kind of money. But you can have a fully-fledged S series Audi, purpose-designed by the performance specialists at quattro gmbh. And therein lies the appeal of this S6. Within its little segment, it's the genuine article.
It's also a very clever car indeed. Nearly 30 to the gallon from a car that, de-restricted, would reach 190mph? That's Active Cylinder Technology for you, technology that rivals currently can't match. But efficiency doesn't sell cars of this kind. No, you'll buy this S6 because of the way it makes you feel.
So what if an RS6 is faster? Or an M5 or an E63 come to that. Who cares if a BMW 550i or a Jaguar XFR are more overtly driver-orientated? This, in contrast, is the stealth bomber of the executive segment, the car that creeps in under the radar. In its era, it was the only one in its sector with 4WD. And the only one with Audi's S-inspired ring of confidence. Four rings in fact.