Supercharged XKR roars back

Jaguar’s supercharged XKR coupe and convertible have returned, this time boasting less weight, more power and torque, better performance and improved handling.

Compared with the current XK, the new supercharged machine, which debuts at this month’s London motor show, has an extra 116bhp and, according to Jaguar’s chief engineer, Mike Cross, it represents ‘the XK plus 30 per cent – the ultimate sports GT for the real world’.

Retaining the distinctive bonnet louvres that distinguished the original XKR, the new car’s exterior also features a fresh front bumper unit design with aluminium-mesh covers for the air vents, a revised lower rear bumper with cut-outs for the quad-tailpipes, aluminium ‘power vents’ on the sides, and exclusive alloy wheel designs in standard 19in and optional 20in rim sizes.

But it’s what’s under the skin rather than what adorns it that’s of greatest interest, and there have been extensive enhancements to all the car’s major components. The AJ-V8 engine retains its 4.2-litre capacity, but the addition of an Eaton supercharger boosts power to 410bhp at 6250rpm and hikes the torque peak to 413lb ft at 4000rpm. The gains over the previous supercharged XKR motor – which ran with 400bhp and 408lb ft of torque – have been made possible by enhancements to the induction system. It now features twin inlets to get a greater volume of air into the system in the first instance, while Variable Inlet Camshaft Timing (VICT) dispenses that air to the combustion chambers more efficiently, to the particular benefit of low-end torque.

At the opposite end of the combustion cycle, the XKR boasts what Jaguar calls ‘Active Exhaust’, a system that varies the flow of gas through the main silencer to create lower sound levels when cruising but the full-on V8 growl under heavy throttle loads. Jaguar has also managed to reduce the noise levels of the supercharger by 5dB so that its whine doesn’t intrude on the V8’s virtuoso performance.

On the subject of performance, the XKR coupe whistles up to 60mph from a standstill in 4.9sec, but rather more tellingly polishes off 50-70mph (a real-world performance measure) in just 2.5sec. The convertible accelerates only slightly slower and both cars are electronically limited to 155mph.

While some rivals have opted for automatically actuated manual gearboxes, Jaguar has stuck with a fully automatic transmission. Called Jaguar Sequential Shift (as used in the normally aspirated XK), it’s a six-speeder with paddle-shift operation and a choice of three shift modes. Jaguar claims that its 600 millisecond shift time whips the competition and ensures far smoother gearchanges.

Down at chassis level, the front spring rate is 38 per cent stiffer and the rear has been increased by 24 per cent. The XK’s two-stage adaptive damper system has been similarly recalibrated and a rear strut-brace added. There’s also more weight to the Servotronic power-steering system and revised settings for the Trac DSC traction and stability control system.

Also helping out on the handling front compared with the previous XKR, particularly in the case of the convertible, is the extra stiffness of the body structure (30 per cent and 40 per cent more rigid for the coupe and convertible respectively), which was designed from the outset to cope with the needs of a roofless shell.

In the cabin it’s a case of cosmetic upgrading, with sports seats and some XKR-specific trim treatments. A luxury ‘Sports’ interior option adds soft-grain leather that extends to the instrument panel, doors and centre console as well as the seat upholstery.

Prices for the new XKR, which is expected to go on sale later this year, will start from £67,495.