Hold onto your seats, Jaguar fans! The most powerful road-going Jaguar convertible ever - the 410kW XK-RS concept car – has been unleashed, but unfortunately, it will remain a one-off version.

Developed by Rocketsports Racing in co-operation with Jaguar North America, the XK-RS concept demonstrates how Jaguar's luxury GT road car can be transformed into a thundering 320km/h-plus supercar.

<br "The XK-RS uses Rocketsports' considerable race car expertise to create this dramatic, one-off concept car," said George Ayres, the US vice president of marketing for Jaguar.

Rocketsports Racing owner, Paul Gentilozzi, said: "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."

Engineers at Rocketsports' workshop took the already-potent Jaguar V8 race engine and increased its displacement by stroking it out from 4,5 litres to 5,0 litres.

To ensure drivability, the engineers reinstalled an Eaton supercharger to deliver an estimated 400kW and 678 N.m of torque, giving the car the power to accelerate from standstill to just about 100k/h in under four seconds, and take it to a top speed of 321km/h.

The standard six-speed automatic transmission was replaced with a five-speed manual transmission. Re-positioning the driveline weight to the rear of the car also resulted in a perfect 50:50 weight balance for improved handling.

Rocketsports also applied the team's considerable expertise in high-speed aerodynamics by modifying the production XKR's body to ensure ground-hugging stability at very high speeds.

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. Brembo calipers with drilled rotors were added to up the braking performance.

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

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.

To complete the bold appearance, the concept is finished in rich black sporting pearl black Jaguar 'leaper' graphics along each side.