The engineering brief for the new 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 saloon 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 563bhp, power has wound back by 34bhp 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 37lb ft, now peaking at 590lb ft 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 523bhp and 553lb ft, while the Mercedes-Benz S63’s twin-turbocharged 4.0-litre V8 powerplant serves up 603bhp and 664lb ft.
The stronger reserves are sent through an upgraded eight-speed torque converter equipped automatic gearbox with a manual shifting Tiptronic function and 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 0.2mpg.