The engineering brief for the new 2020 Audi S8 is surely one of the most demanding in the automotive business.
Here’s a car that, on the one hand, must deliver top-shelf limousine-like qualities, with all the imbibing plushness, soft-riding comfort and soul-soothing refinement discerning customers expect.
But at the same time, the most outwardly sporting variant of Ingolstadt’s flagship four-door sedan is also expected to offer supercar-like performance, while engaging the driver with the sort of dynamic qualities to see off its premium brand rivals – all in a package stretching to over five metres in length and weighing all of 2230kg.
It’s a balancing act previous incarnations of the S8 attempted to achieve, but arguably failed to pull off with quite the same level of success as the high-end competition.
For this new one, Audi has left nothing to chance. Not only does the new S8 get a heavily reworked twin-turbocharged 4.0-litre V8 petrol engine featuring new mild-hybrid properties, but also the most advanced suspension Audi has ever placed in a production model.
With 420kW, power has been wound back by 25kW over the ultimate version of the third-generation S8 – the S8 Plus, which used a less heavily developed version of the same engine. But with up to 1.8bar of turbocharger boost pressure, torque has increased by 50Nm, now peaking at 800Nm on a band of revs between 2000 and 4500rpm.
To put this into perspective, the newly facelifted BMW M750i xDrive’s twin-turbocharged 4.4-litre V8 petrol engine delivers 390kW and 750Nm, while the Mercedes-Benz S63’s twin-turbocharged 4.0-litre V8 powerplant serves up 430kW and 900Nm.
The stronger reserves are sent through an upgraded eight-speed torque-converter-equipped automatic gearbox with a manual-shifting Tiptronic function. Plus, there's Audi’s quattro four-wheel-drive system, with a so-called sport differential that constantly varies the amount of drive sent to each individual rear wheel.
Depending on the conditions, up to 70 per cent of drive can be delivered to the front wheels. Alternatively, 85 per cent can also be apportioned to the rear wheels.
Audi makes big claims about the new S8’s efficiency. It boasts both a cylinder-on-demand system that automatically closes down one bank of cylinders on light throttle loads at urban driving speeds, and a new belt-driven 48-volt starter motor that operates in combination with a 0.47kWh lithium-ion battery and a recuperation system capable of harvesting up to 8kW of energy during braking and coasting. Together, they are claimed to reduce consumption by almost 0.8L/100km.
Yet despite the impressive energy-saving technology, combined-cycle fuel consumption has increased from a previous 10.0L/100km with the old S8 Plus to 11.4L/100km, giving the new S8 an average CO2 rating on the NEDC cycle of 260g/km.
It’s the suspension, though, that Audi is relying on to allow the new S8 to successfully achieve its dual roles. The new system, known as Predictive Active Suspension, uses a camera to scan the road and electromechanical actuators to constantly vary the ride height.
Each wheel can be separately loaded or relieved depending on the road conditions across five driving modes. In Comfort+, the suspension tilts the body into corners to reduce lateral forces.
In Dynamic, body roll is reduced to around half of that of a standard steel-sprung suspension, according to Audi.
As always, there’s little to tell the fourth-generation S8 apart from its less-sporty A8 sibling. Audi has a long history of delivering some of the most sought after understated performance sedans, and it is successfully employed here.
At standstill, the new model looks pumped, but subtly so, and without any obviously contrived design elements.
Among the unique touches is a new front bumper housing an S8-specific double-louvre grille, wider sills beneath the doors, aluminium-look mirror housings, and Audi’s signature S-model quad-tailpipe treatment at the rear.
When you open the driver’s door, the S8’s active suspension automatically raises the ride height by 50mm to ease entry.
As the door is closed, the air springs return to their nominal setting as the body is lowered again. It’s a nice touch that showcases the advanced underpinnings of the new Audi every time it is driven.
Inside, it’s a similar story to the exterior, with subtle updates to the standard A8 interior.
Subjectively, there’s precious little room for improvement in what remains one of the best interiors in any car at any price. But with a liberal covering of leather and Alcantara, combined with unique carbon fibre and aluminium trims, the new S8 manages to provide added appeal over and above its more standard stablemates.
Expensive looking and agreeably tactile materials combine with crisp and clear digital instruments, as well as a standard 10.1-inch touch display for the infotainment functions, a lovely multifunction steering wheel, and highly supportive sport seats to provide a truly first-class driving environment.
In the right conditions, the big Audi is brutishly potent with earnest step-off qualities and unrelentingly urgent in-gear traits. The brawny engine is the undisputed star of the show, with the sort of sledgehammer performance to propel it from standstill to 100km/h in a scarcely believable 3.9sec – or 0.1sec slower than the more powerful S8 Plus it replaces.
The slick-shifting eight-speed torque converter automatic gearbox and fast-acting quattro four-wheel-drive system also play an integral part in the explosive accelerative and top-shelf cruising abilities. Together with the engine, they form an intoxicating combination that is further enhanced by a convincingly realistic synthesised soundtrack played over the speakers.
Yet, as effective as it is under full load in Sport mode, the S8’s engine is also compellingly smooth on more measured throttle inputs in an altogether more relaxed Comfort+ mode.
In city driving, it proves wonderfully flexible even in Eco mode, where the cylinder-on-demand system closes down one bank of cylinders, essentially turning the engine into a four-cylinder unit for brief periods.
The most remarkable thing about the new S8, however, is the added agility brought by the adoption of Audi’s Predictive Active Suspension and Dynamic All-Wheel Steering system.
As well as varying the assistance acting on the steering of the front wheels, it adds a steering function to the rear wheels, which turn in the opposite direction to the front wheels at low speeds and in the same direction at higher speeds.
The upshot is a newfound level of communication and response. Despite its generous dimensions, you can place the new S8 with added precision and confidence in any given driving situation.
On more challenging roads, there’s a welcome liveliness and neutral character to the big Audi that was always found wanting in its predecessor.
With the predictive function to the suspension able to alter the characteristics of the damping up to 18 times per second, and an ability to lean into corners in a manner similar to a motorcycle, the new S8 is more composed and fluid. The trademark directional stability has also been improved, bringing added stability at higher speeds.
An added advantage of the adoption of rear-wheel steer is a reduction in the turning circle at low speeds – a development that facilitates manoeuvring during parking and low-speed urban driving. Primary ride quality is also improved. However, the S8 is still unsettled by larger transverse ruts and ridges.
Earlier incarnations of the S8 were persuasive ownership propositions. The problem as far as enthusiast drivers were concerned was they all lacked the inherent engagement that sets a truly great car apart from a merely good one.
As such, they never really rose to the challenge in a way Audi would have had us believe. Outstanding when charging flat out down an empty Autobahn, but somewhat detached on more challenging back roads.
This new model is different. It retains the traditional qualities that have made the S8 a car to cherish down through the years, but brings a whole new dimension in dynamic competence. It connects with the driver on a whole new level. On top of this, its advanced new suspension also provides the flagship Audi sedan with a newfound layer of comfort.