Where once the S4 Avant was powered by a normally aspirated 4.2-litre V8, then a turbo 3.0-litre V6, these days, it's pulled along by a mild hybrid 3.0-litre TDI diesel unit that produces 347PS and 700Nm of pulling power, good enough to get this car from rest to 62mph in just 4.8s, which is only a tenth slower than the previous 3.0-litre TFSI V6 petrol unit could manage. Top speed, as before, is artificially pegged at 155mph. The engine utilises a large turbo, which is partly driven by a little electric compressor, as well as exhaust gases. Audi claims that this set-up minimises the effects of turbo lag, with the system being automatically activated whenever the requested engine load exceeds the capabilities of the turbocharger.
To go with this change of engine, Audi has upgraded this car in a number of other areas, adding in Progressive steering, refining the sports suspension and incorporating a revised chassis platform, which controls the car's quattro 4WD system. The transmission remains an 8-speed Tiptronic auto unit, but this set-up's impressively quick-reacting and smooth. Not so good is the lowered 'S' Sports suspension, which will be rather over-firm for some, though you can improve it by paying extra for a 'CDC' 'Continuous Damper Control' system that can be tweaked via the settings of the standard 'drive select' driving dynamics system. As well as also altering steering weight, throttle response and stability control thresholds, the 'drive select' modes can also influence the optional 'Quattro Sport differential' system, which constantly varies the amount of drive to each of the rear wheels for extra cornering traction.