If the switch to diesel has left you concerned that the new S4 might be short of accelerative potency compared with its petrol-powered predecessors, worry not. This new S4 TDI is no damp squib. Audi’s claimed 0-62mph time of 4.8sec appears to be realistic or, if anything, a touch conservative. Even with its fuel tank brimmed and no launch control system in sight, our test car managed to hit 60mph from a standstill in 4.6sec.
More intriguing, however, is that the S4’s 0-60mph time not only beats that of the 349bhp petrol-engined S5 Coupé we road tested in 2017 (4.9sec), but it also eclipses the 5.3sec time set by the Ford Mustang Bullitt (admittedly on a damp track) with its gargantuan 5.0-litre 453bhp V8. Of course, the deep, bassy grumble of the S4’s oil-burning V6 is nowhere near as characterful or appealing as the noise made by either of those petrol engines, but such a comparison highlights just how effective this new four-wheel-drive diesel performance car is judged strictly in terms of outright shove.
With a C63 S-rivalling 516lb ft of torque on tap between 2500rpm and 3100rpm, its mid-range punch and overall flexibility are dramatic, too. Even with the crankshaft spinning at 2000rpm, you’re aware of sitting on an immense well of accelerative force, and as the revs rise towards 3000rpm, the tidal manner in which the S4 sucks you towards the horizon gets only more uncanny. Locked in fourth gear, the Audi was able to accelerate from 30mph to 70mph in 5.2sec – a whole second quicker than the old S5. Above 3500rpm, mind you, the car’s appetite for speed grows markedly less insatiable.
There are a few small flies in the ointment, though, the first concerning the eight-speed transmission. Even when supplemented by that 48V mild-hybrid architecture, it’s not quite as responsive to your inputs as you’d like. Part-throttle response is particularly unenthusiastic and it takes a proper shunt of the righthand pedal to initiate kickdown.
When you’re simply trying to pull away from the lights in a swift yet controlled manner, the S4’s almost binary reactions to your inputs don’t always make for the smoothest progress.
Less irritating are the brakes, which, while undoubtedly effective, feel a touch numb and over-assisted. At speed, you don’t really notice the immediacy with which a prod of the brake pedal will begin to slow the car, but around town, this lack of finesse can again act as an impediment to smooth progress.