For petrolheads, the ‘S’ badge on an Audi serves as confirmation of a particular kind of performance: not just sheer straight-line speed, or brutal acceleration, but an overall dynamic capability that combines velocity and urge with finesse.

Not for these Audis the sledgehammer punch of the marque’s own RS models, or the unruliness of rival Mercedes- Benz’s AMG cars. The S-models manage to buff dynamic talent with the polish of luxury car sophistication.

This week, Audi introduced three new S-models to its South African passenger car line-up. All three are almost too big, and too bulky, to be considered performance cars. But then, their generous dimensions provide little indication of their underlying capabilities.

Perhaps the most conventional, but also most understated of the new S-car models is the S6. If, like me, you like the slightly chunky, understated A6 sedan, then its S6 off-shoot represents an irresistible and compelling alternative to more conventional performance car choices.

It’s the subtlety of the S6 that piques my interest. It looks more robust, more athletic than the standard car, but there’s nothing specific to confirm that impression. Like the trim but bulky silhouette of a tuxedo-clad bodyguard, the S6 is aggressive, even menacing, without having to be obvious about it.

Thus, the individual elements of the car’s exterior only come to light on close inspection: a restyled grille, deeper front airdam, subtly extended sills and a reshaped rear apron are among the core aspects, together with the large-bore exhaust tail pipes, bold brake callipers finished in black, and aluminium-look exterior mirrors.

Perhaps the most telling detail of all is in the wheels – massive 19-inch units are standard, but the example I’m looking at has even bigger 20-inch versions. They accentuate the S6’s low-slung stance, and fill the wheel arches to the brim.

Photo: The Audi A8

The S7 Sportback is the most svelte of the three new S-models. The concept of a four-door coupé remains inherently problematic, but the Audi’s take on that niche is more streamlined and more balanced than any of its rivals.

In S-guise, the car retains its low, curved roofline, its extended nose and its smooth profile. But like the S6, the additions of revised front and rear bumpers, lower sills, subtly flared wheel arches and bigger wheels create a ripple of muscle that suggests greater dynamic talent. In short, the effect may be understated, but the performance message is communicated with focus and clarity.

The S8 is by far the largest of Audi’s new S-machines. The marque’s largest sedan is usually an expression of opulence, offering heads of state and captains of industry a luxurious haven of peace and tranquillity, often best experienced from the rear seat.

But the S6 is meant to be driven by its owner, rather than by James the chauffeur. It’s one of a rare breed that links limousine luxury to sports sedan capabilities – and considerable capabilities they are. Again, the S-treatment provides for the necessary visual edge, so that the S8 looks more driving machine than VIP transport.

The engine is one of the real stars of the S models show. It’s at the heart of all three cars here, although the S8’s version is more powerful than its S6 and S7 Sportback brethren. And don’t be fooled by the plastic shroud that hides the big motor’s real bits – this is a living and breathing, red-blooded power unit.

For the S6 and S7 Sportback, the 4,0-litre V8, with its twin turbochargers neatly wedged into the V between the cylinder banks, has been tuned to deliver a 309 kW maximum power output, and 550 Nm of torque.

That considerable urge finds its way to all four wheels via a seven-speed dual-clutch S-tronic gearbox, and Audi’s quattro all-wheel drive system. Power and traction combine to deliver rapid acceleration and huge speed potential: both cars will reach 100 km/h from rest in under 5 seconds, and top speed is governed to 250 km/h.

The S8’s added bulk and mass require a more powerful version of the same twin-turbo V8. At 382 kW, the power hike is considerable, as is the torque peak’s jump to 650 Nm. Remember, the A8 remains one of the pioneers of lightweight aluminium construction, and despite its size, it’s less than 100 kg heavier than the more compact S6.

No wonder then that it’s the fastest member of the S-trio, with a 4.2 sec 0-100 km/h sprint time. That’s quicker than many a dedicated two-seater sports car…

Interestingly, the V8 has an additional talent not usually associated with high-powered mills: economy. The engine has the ability to shut off four of its eight cylinders when they’re not required, for instance when cruising at steady speeds, and that dramatically curtails its thirst for premium unleaded.

Photo: The Audi A7

Audi’s fuel consumption claims remain unrealistically frugal when compared to real-world experience, but the high-tech V8 is definitely more economical than expected, with similar reductions in CO₂ emissions terms.

While straight-line speed is only one facet of the S-model personality. Perhaps more important is how well these three cars cope with all the muscle at their disposal, and whether they’re as thrillingly competent in corners as they are on open stretches of ruler-straight roads.

The S7 Sportback’s inherent sophistication shines through in the way it understates its capabilities. Cosseted in an interior that’s easily at the very top of the luxury car class, the S7 driver always feels cocooned and comfortable. 

The cabin’s calm remains impenetrable, even when your right foot’s mashed the throttle to the floor, and the V8’s rumble tell you that every last horse is at a full gallop. Of course it’s rapid – the way the passing scenery becomes increasingly blurred confirms this. But there’s a lack of drama that some might consider disappointing, but others would consider confirmation of supreme competence.

As a rapid but surprisingly relaxed cross-country machine, the S7 Sportback has few rivals. If road conditions and legislation allowed, this Audi could effortlessly propel you from Johannesburg to Cape Town in less than a day.

But for me, there needs to be more involvement, and a more acute sense of dynamic intent. Despite its very similar underpinnings, the S6 delivers just that. It lacks the sleek attraction of the S7 Sportback’s slippery shape, but it feels edgier, and more involving. While the S7 Sportback wants you to relax, to savour the cabin’s amenities, the S6 places the experiential emphasis squarely on the performance on offer. The harder you drive, the better this car gets. At urban speeds, it champs at the bit, the V8 seeking every opportunity to show off its potential.

The glorious sound of the engine is somehow more apparent in the S6 too, and lowering the electric windows allows even more of its aural impact to be savoured. 

The S6 feels surprisingly wieldy when fed through a series of corners. It’s not a small car, and the kerb mass comes close to 1,9 tons, but it’s not unsettled by the inertia and the weight transfer extremes when you hammer it through the tight stuff, and on fast sweeps, it feels supremely in charge.

There’s more Jekyll and Hyde here than the always elegant S7 Sportback can muster: the former can roll up its sleeves and square up for a fight, while the four-door coupé just couldn’t be bothered with confrontation. But the S6 can also play the docile, luxury transport role, even if its edge of aggression remains omnipresent.

Photo: The Audi A5

Where does that leave the S8? The S-car flagship (by virtue of its size, and its R1,2-million price tag) could be mistaken for a symbol of excess, an over-the-top machine that might be a trump card favourite, but lacks relevance in an increasingly eco-aware world.

Well, let’s consider its dynamic credentials first, since it is an S-model member. And on that level, it’s the most surprising car here. Settle behind the wheel, press the start button, and trundle through town, and the S8 retains its limousine persona. 

Smooth, composed and regal, it will whisk its occupants from one side of the urban jungle to the next with supreme confidence, and in unruffled comfort. 

But give James the weekend off, and head for the twists and turns of a country road, and the S8 is almost instantly transformed into an altogether different animal. Even more so than the S6, the S8 shrinks around its driver, creating an illusion of agility and control completely at odds with its exterior dimensions.

Of course, Newton’s laws of gravity remain valid even when you’re piloting almost two tons of aluminium-sculpted, German-engineered, performance-focused sophistication, and in tighter twists, the sheer momentum of the beast will start overruling the driver’s intentions. But few owners will ever push the S8 that hard, anyway.

Perhaps because the S8 is so much more thrilling and rewarding to drive than one expects, is also the most compelling S-car of the three here. Few, if any, limo-level cars are able to successfully fuse true dynamic capability and opulent luxury. Rather than its long list of luxuries, it’s the S8’s breadth of capability that warrants its asking price.

Hard-core Audi fans will point to the equally hard-core RS models as the pinnacle of the marque’s performance car achievements. But to my mind, the less uncompromising, more balanced approach of the S-cars makes them ultimately more enjoyable. And in that context, the S6 is my personal pick of the trio here. DM