During this time, Walkinshaw had been developing a road-going concept based on the 1988 Le Mans winning XJR-9 that was used to test the longevity of composite materials over many thousands of miles. Known as XJR-9R, it was this test mule that would prove the basis for the XJR-15. Despite the XJ220's impending arrival, Walkinshaw convinced Jaguar to back the project and a new jointly owned company (JaguarSport) was formed to manufacture a batch of 50 XJR-15's. Although clearly designed to be the ultimate road-going supercar, the XJR-15 was marketed as a racer to avoid creaming off prospective XJ220 customers. The price for each car was $960,000 and buyers were able to sign up for a one-make series if they so wished. Grid slots would be limited to 16 cars, the 1991 JaguarSport Intercontinental Challenge consisting of three rounds supporting the F1 races at Monaco, Silverstone and Spa Francorchamps. Included in the purchase price was full race prep and maintenance for the series but any damage would have to be paid for by the owners.

At the heart of the XJR-15 was a beautifully manufactured carbonfibre and Kevlar composite monocoque chassis based on the Le Mans-winning XJR-9 of 1988. However, neither the design or construction were identical. The tub was modified to accomodate two occupants in reasonable comfort whereas for Group C the passenger seat was little more than a token gesture to satisfy the rule makers. For road use, the ride height had to be increased which in turn would have negated the XJR-9's underbody ground effects so these were greatly reduced for the XJR-15. Suspension was full racing geometry with pushrods at the front actuating horizontally mounted spring/damper units and outboard dampers and springs mounted within the wheels at the rear. The engine and transmission acted as a stressed member bolted to the rear bulkhead upon which the rear suspension was hung. Drivers could adjust the front anti-roll bar (there wasn't one at the rear) along with the brake balance at both ends. Each corner saw AP four-pot calipers installed with 13-inch cast-iron ventilated discs, 17-inch OZ forged alloy wheels (9.5 front / 13 rear) and Pirelli P Zero tyres.

The engine was a naturally aspirated 5993cc 60° V12 with aluminium-alloy block and heads. A combination of two earlier race motors, the bottom end came straight from Group C whilst the top end and air intake system had previously been used on the Group A XJS racers built by TWR in the mid eighties. Equipped with Cosworth forged alloy pistons, sequential Zytec electronic engine management, Lucas electronic ignition and a forged EN40B steel crankshaft with Holset harmonic damper, the engine produced 450bhp at 6250rpm and 420 lb ft of torque at 4500rpm. Compression was set at 11.0:1 and the reduced torque from the XJR-15's engine required the use of a six rather than five-speed gearbox. This manual transmission with straight-cut gears was built in-house by TWR, the power being delivered via a triple plate carbonfibre clutch. A five-speed synchromesh 'box was offered as a $75,000 option.

Peter Stevens was responsible for designing the XJR-15's sultry bodywork, this being manufactured from lightweight composite and carbonfibre materials throughout. With hardly a straight line to be found anywhere, Stevens' curvaceous creation made the XJ220 look like a barge which must have been a headache for Jaguar's marketing men. The basic form was complimented by shapely cooling ducts carved out from the nose and sides plus covered headlights positioned just below supplemntary pop-up items. Simple, elegant and beautiful, the XJR-15's only obvious concession to creating downforce was a colour-coded fixed rear spoiler. All 50 cars were originally painted 'XJR Blue'.

XJR-15 chassis 020