In the planning stage of the rallycross project, the S1 became the car of choice relatively soon. According to team boss Ekström, the subcompact car with its short wheelbase is perfectly suited for the sometimes very narrow rallycross circuits and, thanks to its very good traction and sophisticated suspension, is in contention for victory on fast tracks as well. Aside from these factors, the start is particularly crucial in rallycross, with as many as six cars battling each other in the races. The narrow circuits frequently offer only limited overtaking opportunities following the start.
Under the hood, a two-liter turbo engine provides the required power. The transverse inline-four unit delivers 560 HP and develops approximately 750 Nm of torque which, in spite of its 45-mm air restrictor, makes this engine a similar brute as the one used in the old Group B monster, although the vehicle’s weight is only 1.3 metric tons – including the driver.
Gears are manually shifted using a sequential six-speed transmission. Thanks to the unit’s short gear ratio combined with its extreme ability to transmit power to the wheels and systematic lightweight design the all-wheel-drive rocket catapults the driver from 0 to 100 km/h in 2.5 seconds. Not even Formula 1 cars accomplish this in less time. Top speed is 210 km/h, which is enough on the short straights in rallycross racing.
Obviously, as far as its exterior is concerned, the car features aerodynamic modifications. Large wheel arch cutouts and flared fenders, a roll cage, louvers and a massive rear double wing transform the fast city car into a rallycross monster bursting with vigor. The large air scoops in front of the rear wheels supplying the radiator installed at the rear end with fresh air are a special characteristic. There is a good reason for this unusual arrangement. If the radiator sat at the front, gravel and mud would obstruct air supply and cause the engine to overheat.
For the car’s exterior design, Ekström and his team deliberately attempted to take cues from the legendary Audi S1 quattro from the 1980s. As a result, the fenders of the Audi S1 EKS RX quattro are “slightly sharper and more angular than those of the other rallycross cars,” according to Ekström. However, the regulations are very strict in this respect. The width of the racing version may differ from the road-going car by a maximum of seven centimeters. In terms of length, they even have to be identical.
Another specialty in rallycross are the specification tires supplied by the U.S. manufacturer Cooper. “We have a cut slick that’s very soft. In other series, you’d call it a qualifyer,” says Ekström. Due to the soft compound and the hand-cut tread, it is possible to drive on gravel rallycross tracks nearly as fast as on tarmac. In order to lose as little time as possible even while cornering the Audi S1 EKS RX quattro cockpit includes a special eye-catcher: an oversized handbrake projecting upward at a steep angle and directly installed next to the gear knob. When used, the handbrake decouples the rear wheels from the drivetrain, causing them to break traction and slide out. This makes it possible to drift through the tightest turns.