The Audi S8 is a limousine with a dark side, the polar opposite to the sedate hybrids that glide near-noiselessly around the city. It is the anti-Uber, with nigh-on 600 horsepower pumped out by a twin turbo-charged V8 and, in this special ‘Plus’ model, an indecently high top speed that places it squarely in supercar territory. Yet all this drama is cloaked with a stylish, sober façade, the power lurking beneath the long, subtly fluted bonnet. In truth, you needn’t deploy it all and simply revel in the hush and refinement of Audi’s flagship saloon.

Unlike the raucous AMG variants of Mercedes’ S-Class, the S8 is more subdued. It’s a titanically fast car that you don’t feel the urge to thrash and delivers a far better experience when it’s just wafting along serenely. The V8 is an especially emotive engine; tuned right it produces a deliciously waffly exhaust note that has come to define a certain type of brutish, heavyweight performance. Pushed hard, it will roar, but overall it’s been tuned to stay discrete, not diabolical. The same engine is also found in Bentley’s GT V8S, but Audi recently hinted that their most recent V8 might also be their last, as the anachronistic combination of noise, emissions and raw power slowly fades into history.

It’s certainly at odds with the S8’s otherwise high-tech demeanour. The big limousine sector is traditionally a tech showcase and an all-new A8 and S8 will appear in the next 18 months. Unfortunately, this knowledge unwittingly highlights the current car’s shortcomings. The dashboard design has been usurped by other Audis, with their digital ‘virtual cockpits’, and although the interior still oozes quality, the MMI (multi-media interface) has become less, not more, intuitive, with the passing years, as the ubiquity of touchscreen interaction seeps successfully into car design. Audi might argue that tactile feedback is the way to go, but while the rotary dial and button combination clicks and twirls with satisfying precision, more often than not you dial something in the wrong direction.

These are minor quibbles about what is undeniably an impressive and desirable machine. S8 buyers care not for what others think, preferring to focus on the sensation of stealth, the knowledge of hidden power and the majestic solidity of Audi’s build quality.