Jaguar roars at its fastest speed

British car maker Jaguar has revamped its flagship XF model to produce the firm's fastest vehicle yet.

The new XFR is powered by a supercharged 5.0-litre V8 engine, developing 510 horsepower. Electronic limits built into the car mean it normally has a top speed of 155mph, though it can accelerate from standstill to 60mph in just 4.7 seconds.

To promote the XFR, Jaguar took a prototype to the legendary Bonneville Salt Flats, in Utah, for a secret speed trial.

With small aerodynamic and safety modifications to meet the requirements for a Bonneville run, the XFR recorded a top speed of 225.675mph - beating Jaguar's previous speed record of 217.1mph set in the XJ220 in 1992.

The speeds were achieved without changes to any engine components and with a standard six-speed automatic transmission.

The extra power was achieved by remapping the electronic control unit, modifying air intake and exhaust systems and revising supercharger settings.

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