The high-tech sportscar’s overall concept is based on the DTM car: the safety bodys-hell has gull-wing doors, a spaceframe and various exceptionally rigid components reinforced with carbon fiber. Its 4.0-liter V8 engine, with four valves per cylinder, drives the rear wheels through a sequential-shift six-speed, transaxle gearbox. The wheels are suspended on double wishbones and there are carbon-fiber disk brakes at the front and rear. In the course of development work, however, at least half of the cars compo-nents were either modified or redesigned for road use. ‘We shifted the accent from pure functionality for racing application to one that could embrace the new tasks that the car would face in its road-going form,’ says Opel’s design director for compact cars, Martin Smith. Of this project, which was brought to such a rapid conclusion, he says: ‘I was highly impressed by the way the technical, design and marketing people worked together so constructively.’
In place of the 18-inch wheels called for by the DTM championship regulation, the X-Treme runs on 20-inch wheels of new OPC design; like their counterparts on the competition car, they have central fastenings. An equally dramatic visual aspect of this new high-performance car is its specially-created fiery red eight-coat paint finish.
Trimmed to a higher standard with the aid of Alcantara and brushed aluminum, the car’s interior conveys a strong impression of high-grade technology, sports character and perfect workmanship. As with the DTM version that acted as a model for this car, the seat shells are reinforced with carbon fiber, but for the road user they are of course upholstered to a much higher level of comfort. The driver and front passenger are pro-vided with five-point seat belt harnesses. The steering wheel is the same as used in the new Opel Speedster, and just as with the DTM racer, there is a central instrument display that keeps the driver informed of the car’s principal technical functions.
In order to give the car an ideally positioned center of gravity, the four-liter V8 engine in the X-Treme is located behind the front axle, as in the DTM racing version; the driver and front passenger seats have been moved back to accommodate. The engine, with four valves per cylinder, delivers its vast reserves of power to the rear wheels by way of a carbon-fiber reinforced clutch, a sequential-shift six-speed, transaxle gearbox and a mechanical-action limited-slip differential. As in the racing version, straight-cut gears are used and there is no synchromesh, but the gear teeth have chamfered flanks to make the shift action easier. The same form of ignition shutdown is provided, so that the driver of this civil version can make power-on shifts between the gears.
Most details of the road-going car’s suspension are shared with the racing car. Double wishbone suspension at front and rear guarantees precise wheel location, and drivers can emulate DTM stars such as Manuel Reuter or Joachim Winkelhock by choosing their own personal suspension set-up, since the stabilizers and the shock-absorber bump and rebound settings can be varied. The immensely powerful brakes are another feature of the race car that have been applied unaltered. Ventilated, carbon-fiber rein-forced brake disks and six-piston aluminum calipers are the secret of the car’s amazingly short stopping distances.
The engine, with its dry sump lubrication, doesn’t have to withstand thousands of prac-tice and race miles without any attention; as a result it is allowed to run up to a maxi-mum speed 850 revolutions a minute higher than its competition counterpart, yet de-velops a maximum power output only 18 horsepower lower, namely 326 kW (444 hp) at 7350 rpm, more than enough to catapult this red-painted rocket’s to a place among the extreme high performers’, as its name implies. Acceleration from a standstill to 100 km/h takes no more than four seconds, and the top speed is beyond the 300 km/h mark.