To get the best out of the standard Quattro all-wheel drive and the 40/60 front-to-rear torque split, specify the optional new sport differential, which distributes torque between the rear wheels in a progressively variable fashion. It works under trailing throttle and even when the gearbox is in neutral. As the vehicle turns in, the diff diverts most of the propulsion forces to the outer rear wheel. This reduces understeer, allows you to select a more moderate steering angle, and improves roadholding and directional stability.
To specify the sport diff, you must first opt for Audi Drive Select, which includes adjustable dampers and so-called Dynamic Steering. Drive Select offers three different tuning stages-comfort, normal, and dynamic-and the ability to dial in your preferred calibration of the engine, transmission, dampers, steering, and differential. Dynamic mode provides a nice mix of sharpness and balance, of tactility and feedback, of intuition and agility. It is still possible to deactivate stability control, but this move doesn't yield much anymore, because the front-to-rear and side-to-side torque flow is managed to perfection by a couple of electronically controlled gearsets. As a result, hard cornering is no longer a mix of more or less understeer. Instead, the nose turns in, the rear end tracks to match, and the ensuing four-wheel drift is easily modulated by throttle and steering in much smaller nuances than before.
The electronic damper control fitted to the S4 is a conventional system that varies the diameter of an orifice controlling the oil flow. More important than the switchable dampers are the changes made to the base A4 suspension. To reduce unsprung weight, Audi replaced certain chassis elements made of steel with aluminum. To limit unwanted body movements, the company fitted tauter springs and dampers, and it lowered the ride height by nearly an inch. These modifications are all welcome, but those who live in areas with smooth roads might pine for nineteen- or twenty-inch wheels, as the S4's wheelhouses certainly have room for them. Unfortunately, Audi of America won't offer anything other than the standard eighteen-inch rolling stock at launch.
Inside, the S4 is an A4 in monochromatic livery-black in the case of the car we drove. It sports redesigned instruments with gray faces, a special leather-wrapped steering wheel, comfortable and supportive power sport seats, and optional stainless-steel dashboard inlays. Inside and out, the new S4 is an undercover fast-lane warrior rather than a decaffeinated RS4.
Audi has created a product that is the epitome of efficiency. It is introverted in appearance and delivery but extroverted in character and ability. Call it pragmatic, if you wish. Call it multitalented, because that's what it is. Call it the reincarnation of the Q-ship. All it takes to enjoy it is to adjust to the S4's minimum-input, maximum-effect approach. And to hope that your stock portfolio allows you to consider buying one when it goes on sale here next fall.
On Sale: Late 2009
Price: $50,000 (est.)
Engine: 3.0L supercharged V-6, 333 hp, 325 lb-ft