It takes a keen eye to spot the subtle visual differences that separate the new Audi S4 Avant from its less powerful and considerably cheaper sibling, the A4 Avant. Four exhaust pipes, skimpy side skirts and brushed aluminium door mirror covers are the only indications that this is in fact a Q-car, a veritable wolf in sheep's clothing.
A medium-size estate car, the S4 Avant is handsome, but in a rather modest, no-frills kind of way. With its huge goatee of a front grille and LED eyeliner on its headlights, it is unmistakably an Audi, but it is bereft of any aggressive styling cues that would hint at its BMW 335i-bashing performance.
Not only does it outperform its arch rival, the 335i, it will give BMW M3 owners a fright and run with minor league Porsche 911s. The key to this is Audi's new supercharged 3 litre V6 that replaces the previous model's 4.2 litre V8 in the interests of less weight, better fuel consumption and lower emissions.
Audi has not used a supercharged engine since the fabulous Auto Union racing cars of the 1930s. The new V6 produces 333 bhp and a towering 440Nm of torque, 90 per cent of which is available over a wide rev range for outstanding overtaking.
Audi's direct fuel injection system, TFSI (the T confusingly standing for turbocharged), not only provides better control of the fuel/air mix for increased efficiency, it also cools the cylinders allowing a higher compression ratio to be used for more power.
The power is transferred to all four wheels via Audi's seven-speed S-tronic dual clutch gearbox. Just as with other dual-clutch systems, such as Volkswagen's DSG or Porsche's PDK, the gearbox can be used as an automatic or operated manually via the steering wheel paddles. Because the gearbox is mechanical, as opposed to the fluid coupling of an automatic, gear changes are crisp and instantaneous, taking less than 0.2 seconds from cog to cog whether in automatic or manual mode. When driving hard, downshifts are accompanied by a satisfying blip of the throttle adding to the smoothness and sportiness of the experience.
