Not too long ago, the Audi S6 derived its substantial motive force from a petrol engine that displaced 5.2-litres across 10 cylinders. The engine had essentially been plucked from the midriff of a Lamborghini supercar and squeezed, most probably with the aid of many shoehorns and much to and fro, into the unsuspecting engine bay of Audi’s mid-sized executive car.
The results were spectacular. That model only went off sale eight years ago, but these were very different and far more profligate times. If you want to understand exactly how different, you only need to know the Audi S6 is now powered by a 3.0-litre diesel.
PUT THE HAMMER DOWN
Really? That’s like confiscating Thor’s enormous hammer and handing him the sort of novelty tool your grandmother would use to chip the corner off a large slab of toffee. Given the remit of a car like this, however, a surprisingly potent turbodiesel motor and the very reasonable fuel economy that comes with it is arguably a better fit. What’s more, Audi reckons the latest S6 will manage more than 600 miles between fill ups, or double what the V10 model could achieve.
Fuel efficiency, of course, is behind this switch to diesel power. There are new powertrain technologies that can make a modern diesel engine far more compelling today than only a few years ago, too. Such as an electrically powered compressor, which makes the single turbocharger far more responsive than it would otherwise be. The new S6 also uses a 48-volt mild hybrid system, which recoups energy under braking, stores it in a small battery and uses it to power a motor that helps the combustion engine on its way. The small hybrid system isn’t potent enough to drive the car on its own, but it does help to improve fuel economy.
PLAYING A SUPPORTING ROLE
The S6 clearly plays a supporting role to the range-topping and more powerful RS6. It’s done so almost all its life. But as long as both the S6 and RS6 were driven by enormous petrol engines, the two cars served more or less the same purpose. Now, with the S6 powered by diesel and the forthcoming RS6 sticking with petrol, the two models sit more happily in the A6 model range, treading far less clumsily on one another’s toes.
And how about this? Diesel engines are known for their swollen torque outputs and this one is no different. It develops as much as 516lb ft, which is more than was produced even by the 5.2-litre petrol V10. In a large and heavy car, torque is more useful than power, so while 344bhp is a significant drop from the 444bhp you’d have found in this car’s immediate predecessor (that time powered by a twin-turbo petrol V8), out on the road the new S6 is no less rapid.
Audi reckons it’ll return 36mpg in mixed driving. First-hand experience says that’ll fall to around 22mpg when you really give the car a workout, which isn’t exactly parsimonious but a very handy improvement on the 10mpg you’d have got from the V10 model. Despite all its clever technology the 3.0-litre V6 still behaves like a diesel. It doesn’t rev particularly high or hard and the power band is narrow, but the mid-range muscle is beyond question, throttle response is good. It doesn’t even make the horrible clattery racket that comes to mind when you think of a diesel engine. In fact, with a little augmentation through the stereo it actually sounds quite pleasant. A bit like a rumbling petrol V8.
The eight-speed automatic gearbox is very good indeed, managing to be far smoother than a dual-clutch gearbox in normal driving while also offering every bit as much control and precision in manual mode as you could expect of this sort of machine. The quattro four-wheel drive system means there’s unimpeachable traction and stability at all times, but not the playful adjustability you’d get from a powerful rear-wheel drive car.
KNOW YOUR PLACE
The new S6 understands its role as well as any executive car on sale today. It doesn’t try to be thrilling to drive, favouring solid body control, security in wet conditions and predictability over an edgy handling balance. The standard fit coil springs (air springs are available on certain versions) keep the near two-tonne mass firmly under control when you thread the S6 through a sequence of bends, which means you really can hustle it. The steering, meanwhile, is one of Audi’s more convincing recent attempts, being consistently weighted and precise enough to allow you to place the car with confidence even along a narrow road.
The ride quality is good, if not quite creamy smooth, even on optional 21-inch wheels. On the motorway the car is calm and settled and although the S6 looks imposing from the outside, being only the same size as a BMW 5 Series it’s actually not at all intimidating or demanding to guide through town. This is a car that should be effortless to drive day-to-day, brisk in a straight line, competent when the road gets twisty and relaxing over a long journey. It is every one of those things, which means it hits its brief squarely on the nose.
Given how effective the new diesel engine is and how much less wasteful it is than the big petrol motors found in earlier models, it’s not at all unreasonable to declare this S6 the best of the lot. Can’t stand the thought of filling up from the black pump? At least there is still the RS6.
INSIDE THE 2020 AUDI S6
The S6’s cabin is so clinical and cool it borders on being sterile. A Mercedes-Benz interior is far more opulent, but this one feels as modern as any car cabin you’ll find anywhere. The pair of central touchscreens are beautifully rendered and easy to navigate. Touchscreens can often be irritating to use once on the move, but this one is perhaps the best you’ll come across because of its haptic feedback. Only when you press the screen hard enough does it respond (and give your finger a gentle buzz to let you know as much), which means you don’t ever accidentally brush your finger across the screen and press the wrong button. The interior quality, meanwhile, really is exceptional.
The S6 Saloon starts from £60,220 while the S6 Avant – or estate to the rest of us – costs from £62,745. It mightn’t have the heart of a supercar any longer, but the S6 is a more rounded machine than it’s ever been.
Audi S6 Saloon
Price: from £60,220. As tested £65,525
Power: 344bhp
0-62mph: 5.1 seconds
Top speed: 155mph
Fuel economy: 36.2mpg (combined)
AUDI S6 MODEL HISTORY
Audi S6 C4 (1994-1997)
Just like the present-day model, the Ur-S6 was available in either Saloon or Avant body styles. And while the latest version is offered with a petrol engine in other markets, the original came with a range of powerplants as well. Both petrol, buyers could choose between a turbocharged 2.2-litre inline five-cylinder with 227bhp, or a 4.2-litre V8 rated at 286bhp.
Audi S6 C5 (1999-2003)
By 1999 the V8 engine was the only option on the table, but power had swollen from 286bhp to 335. Whereas other Audi V8s of the same 4.2-litre capacity are tuned for high engine speeds and lots of power, this one was all about torque. It developed 310lb ft of the stuff at 3,400rpm, giving the S6 lusty, muscular performance.
Audi S6 C6 (2006-2011)
This was where Audi’s engineers and boardroom bigwigs briefly lost their minds. A paltry V8 was no longer deemed adequate for the S6, so in went a version of the normally-aspirated V10 that made the Lamborghini Gallardo one of the fastest cars on the road at the time. Again, the motor was tuned for mid-range torque rather than peak power, which equated to 429bhp and a walloping 398lb ft.
Audi S6 C7 (2012-2018)
Having rediscovered their senses, Audi’s suits had realised by 2012 that a 5.2-litre V10 wedged into a sizeable saloon or estate car inevitably meant for tragic fuel consumption. For the fourth-generation model, that engine was replaced by a far more efficient 4.0-litre V8 with a pair of turbos. Power was down fractionally but torque crept up a little, meaning the S6 was faster in the real world and not so ruinous for owners to run.
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