From 1988 to 1993, a special high performance XJR-S version equipped with the HE V12 engine was produced by the newly formed JaguarSport, a separate company owned in a ratio of 50:50 by Jaguar and TWR Group Limited specialising in developing high performance Jaguar sports cars. The car had a distinctive body kit, special alloy wheels, a unique suspension system utilising modified coil springs and Bilstein shocks, a luxurious interior with Connolly Autolux leather along with walnut wood trim, and handling improvements. The first 100 of these cars were named "Celebration Le Mans" to commemorate Jaguar's 1988 win at the 24 Hours of Le Mans and were only sold in the UK. Between 1988 and 1989, a total of 326 XJR-S cars were produced with the engine which has a power output of . After September 1989, the displacement of the engine was increased to and it was now equipped with Zytek fuel injection and engine management system. This was different from the standard 6.0-litre engine used in the late XJS models and was unique to this model. The power output was raised to at 5,250 rpm and of torque at 3,650 rpm due to a higher compression ratio of 11.0:1, a new forged steel crankshaft, increased bore and forged alloy pistons. A modified air intake system and a low loss dual exhaust system was also standard on the model. The engine was mated to the 3-speed GM400 automatic transmission utilising a recalibrated valve body and had faster shift times. The car was equipped with Dunlop D40 M2 tyres for better grip. These modifications resulted in a top speed of . During a comparison test conducted by Motorsport magazine in 1997, the XJR-S outperformed the other competitors which included a BMW 850i, Porsche 928 GT and a Ferrari Mondial.