The most powerful road-going Jaguar convertible ever – the 550 horsepower XK-RS concept car – was unleashed at the 2004 Chicago Auto Show on February 5, 2004.

Developed by Michigan-based Rocketsports Racing in cooperation with Jaguar North America, the XK-RS concept demonstrates how Jaguar’s luxury GT road car can be transformed into a thundering 200-mph supercar.

"At Rocketsports, we’re very familiar with Jaguar’s XKR sports car, having won the Trans-Am Manufacturers’ Championship two times with this beautiful, fast car," said Rocketsports Racing owner, Paul Gentilozzi.

"We think the XKR makes a great foundation for high-performance tuning. The XK-RS concept is just one dramatic interpretation of the many directions in which the car can be taken," he added.

Engineers at Rocketsports’ Lansing, Michigan workshop took the already-potent Jaguar AJ-V8 Trans-Am race engine and increased its displacement by stroking it out from 4.5 liters to 5.0 liters.

To ensure drivability, the engineers reinstalled an Eaton supercharger to deliver an estimated 550 bhp and 500 lb. ft. of torque, giving the car the power to accelerate from standstill to 60 mph in under four seconds, and take it to a top speed of 200 mph.

"Many of the lessons we learned in developing the 650 bhp normally aspirated Jaguar AJ-V8 race engine for the R-Performance XKR Trans-Am race car were incorporated in the engine for the XK-RS," explained Gentilozzi.

To make the car more involving for the sports car enthusiast, the standard six-speed ZF automatic transmission was replaced with a five-speed manual transaxle. Re-positioning the driveline weight to the rear of the car also results in a perfect 50:50 weight balance for improved handling.

Rocketsports also used the team’s considerable expertise in high-speed aerodynamics with its Jaguar XKR Trans-Am race cars, modifying the production XKR’s body to ensure ground-hugging stability at very high speeds.

Special underbody air tunnels running the length of the car were created, along with deeper front and rear spoilers, wider wheel arches and aero-style sill sections similar to those featured on the specially-developed XKR that starred in last year’s James Bond adventure, ‘Die Another Day’.

When tested in the wind tunnel, the changes are expected to result in a 100 percent increase in aerodynamic downforce at top speed compared to the standard car.

The production XKR’s suspension was also modified to ensure supercar handling. The changes include the addition of coil-over high-performance Penske shocks. To give the concept the kind of stopping power that matches its anticipated grip, R-Performance Brembo calipers with drilled rotors (13-inch front/12-inch rear) were added.

And no 200 mph supercar would be complete without a dramatic wheel and tire combination. The XK-RS comes fitted with three-piece wheels - center-lock 'Machiavelli Gotti' – 20-inch x 10-inch at the front, 20-inch x 11-inch at the rear – shod with high-performance Michelin Pilot tires.

Inside, the XK-RS features body-hugging Johnson Controls "Leap" seats clad in black leather with medium grey inserts.

To complete the bold appearance, the concept is painted in rich black lacquer. Along each side, Pearl Black Jaguar ‘leaper’ graphics echo those used on Rocketsports Racing’s XKR race cars.

"The XK-RS concept is one more example of our strong relationship with Paul Gentilozzi and Rocketsports Racing," said George Ayres, vice president of Marketing for Jaguar North America. "The XK-RS uses Rocketsports’ considerable race car expertise to create this dramatic, one-off concept car."

Paul Gentilozzi owns Rocketsports Racing and won the 2004 Trans-Am Driver's Championship. He is on the passenger side of the XK-RS.