By 1989, Tom Walkinshaw recognised that Jaguar's large, naturally aspirated V12 engines were losing ground to the compact, high-powered forced-induction units deployed by rivals such as Mercedes-Benz, particularly in shorter sprint events. The Rover V64V 3.5-litre V6 engine, originally engineered for the MG Metro 6R4 rally car, offered an attractive solution: at just 143 kg it was significantly lighter than the V12, while its architecture was well suited to turbocharging.
Jaguar developed two variants of the engine. A 3.0-litre version, fitted with twin Garrett turbochargers, was intended for Jaguar's companion IMSA car, the XJR-10, and produced 650 horsepower. The 3.5-litre variant destined for the World Sports Prototype Championship produced 750 horsepower at 7,500 rpm with boost applied. Designer Tony Southgate created a new chassis around the engine — a compact carbon fibre and Kevlar monocoque that evolved from the architecture of the XJR-8 and XJR-9, incorporating double wishbone suspension with push-rod actuated dampers at both ends. The rear suspension was mounted outboard to free additional volume for ground-effect tunnels. Two distinct body configurations were produced for the car's two championship programmes.
The XJR-11 made its competitive debut in July 1989 at Brands Hatch. It faced immediate and formidable opposition from the Sauber-Mercedes cars — the C8 and C9 — which deployed similarly powerful V8 engines in what was dubbed the 'Silver Arrows' campaign. Jan Lammers and Patrick Tambay drove the XJR-11 to sixth place on its first outing, a result that offered some promise but also revealed the gap to the front-running Mercedes machines.
Reliability proved to be the XJR-11's fundamental weakness throughout its career. The car suffered recurring mechanical failures that prevented it from converting competitive pace into results. It was deliberately excluded from the Le Mans 24 Hours programme; instead, TWR developed the separate XJR-12 for that event, retaining the proven naturally aspirated V12 for the longer endurance race.
The car managed only a single outright victory across both the 1989 and 1990 seasons, that win coming at Silverstone in 1990. New technical regulations introduced for the 1991 World Sports Prototype Championship rendered the car ineligible to compete, bringing its brief career to an end. With one victory from multiple seasons of effort, it was regarded as one of the least successful sports prototypes produced under the TWR programme.
The XJR-11's engine was a 90-degree V6 in aluminium alloy construction, displacing 3,498 cc with a bore and stroke of 94 mm by 84 mm. The twin overhead camshaft heads carried four valves per cylinder, with Bosch fuel injection and twin Garrett turbochargers providing forced induction. Peak power output in World Sports Prototype Championship trim was 750 hp at 7,500 rpm. The chassis used AP Racing cross-ventilated brake discs with six-piston calipers at both ends. Power-to-weight ratio was quoted at 0.83 hp per kilogram, and the car's top speed was rated at 229 mph (369 km/h).
Despite its competitive shortcomings, the XJR-11 left a significant indirect legacy. The 3.5-litre twin-turbocharged V6 engine developed for the car was subsequently adapted and used in the Jaguar XJ220 road car, connecting the failed prototype programme to one of the most celebrated — and controversial — supercars of the early 1990s. The car demonstrated that TWR was willing to pursue radical technical solutions under competitive pressure, even when results proved elusive.