The JaguarDrive Selector rotary shifter to “S” and set the “Dynamic Mode” switch — then put right foot to floor, and the formerly docile luxury coupe becomes a snarling beast. It leaps forward at the rate of a 4.6 second 0-60 time, to an electronically-limited top speed of 155 mph if in an appropriate location, and the once-mellow V8 rumble becomes a sharp, menacing howl. Suddenly it’s not all that far from its GT2 ALMS competition derivative.

Except that it is fully capable of providing sumptuous luxury transportation for two people for as long as necessary, and it easily deals with city and commute traffic. The 2011 Jaguar XKR may not be completely domesticated, but it is civilized. Quite.

If the 2011 versions of Jaguar’s XK series — the naturally-aspirated XK and supercharged XKR, both in coupe and convertible styles — look little different from the 2007 models that heralded the second generation of the venerable British manufacturer’s quintessential grand tourers, look more closely.

As of model year 2010, and continuing to 2011, there are detail changes to front and rear styling, LED taillamps and turn signal repeaters integrated into the outside rearview mirrors. Typical mid- product cycle refresh material… Inside are a myriad of changes, each minor to moderate but adding to a pleasant upgrade. Again, though, mid-product cycle changes. Except for that JaguarDrive Selector.

Which connects, electronically, to a six-speed ZF automatic transmission. Which in turns connects to the newest iteration of Jaguar’s AJ-V8 engine. The AJ-V8 Gen III is the significant attribute of the newest XK that serves notice to its competition.In both atmospheric and forced-induction form, it is more powerful, more compact, and more efficient. And larger in displacement, to 5.0 liters from the previous 4.2 and original 4.0.

Direct fuel injection, variable cam phasing on all four camshafts, and other advances see significant increases in power — to 385 horsepower for the XK engine and 510 for the XKR — and a US LEV II emissions rating and, when driven modestly, commendable fuel economy. Foot to the floor as noted above, debit the entertainment budget and enjoy. YMMV, as the saying goes.

During a short but intense week with a new XKR Coupe, I was able to enjoy both sides of its performance personality. It is, at heart, a definitive grand touring machine. Meaning a car made for easily and comfortably traveling long distances, at speed. Highway cruising was effortless, relaxing, even, with little demand on the drivetrain. Any need to change speed at speed, whether up or down, was met immediately — top gear roll-on is ferocious, even in regular D mode, and four huge vented antilock discs are fully capable. Backroads, aka “sports car” roads? Again, happy Jaguar habitat, although wide sweepers are preferred to really tight corners as this is a large car. City and commute traffic? No stumbles, no fuss. But when a little adrenaline is needed, press the right buttons and it’s right there.

APPEARANCE

The second-generation XK heralded new design cues for Jaguar when it debuted in model year 2007, more angular than the original but still unmistakably Jaguar. Much of that look showed up on the XF and the newest XJ. It’s appropriately elegant, and announces performance with classic British understatement. A bit more chrome trim, a new front bumper design, LED taillights, and a revised spoiler highlight the XKR’s 2011 styling refresh.

COMFORT

As outside, multiple small detail enhancements bring the newest XKR up to date without compromising its grand touring elegance and comfort. Most apparent is the JaguarDrive shift knob in the console. A little quirky? Yes, and so was the old J-gate shift in years past. Jaguar tradition… and the knob works simply and easily. A full suite of audio options are now standard equipment, with minijack, USB, and iPod interfaces in addition to AM, FM, and Sirius satellite radio and CDs. New instruments, with lit red needles on white numbers, grace the dash. Stitched leather covers the seats, steering wheel rim, instrument panel, and door panels.

Jaguar does burled walnut trim in the classic British manner, but textured aluminum is found in the XKR — appropriately, considering the car’s construction and character. Front seats are multi-adjustable, completely powered, and provide top-notch comfort and support. The “+2″ rear buckets are best though of as extra luggage space, as headroom limits occupant size to under 4′ 6″ in the coupe. Solid construction ensures no rattles from the large hatch, which ensures easy luggage loading and a surprisingly good capacity. Which is only fair, as this is a car that can go the distance, quickly and comfortably.

SAFETY

The 2011 Jaguar XKR protects its passengers with structural strength, front, side, and thorax airbags, huge antilock vented disc brakes, and a multi-mode dynamic stability-control system.

RIDE AND HANDLING

Thanks to its light and rigid aluminum chassis structure, the XKR feels solid on the road, and is appropriately quiet and refined. That structure also benefits the big cat’s ride and handling, providing sturdy attachment points for its fully-independent suspension. Befitting its sports specification, the XKR’s springs are stiffer than the XK’s.

The Adaptive Dynamics system continuously varies the shock damping to allow for both good ride comfort – even on poor road surfaces and even with the ultra low-profile 255/35 ZR20 front, 285/30 ZR20 rear tires – and minimal body roll in fast cornering. It is a capable, high-performance machine so don’t expect luxury-car softness.

Grip is tremendous, a given with with the huge contact patches, and steering and brake effort is moderate. At just under 4000 pounds, the new XKR coupe is a large, heavy car that responds best to a smooth driving. Long-distance, high-speed touring? That’s what “grand touring” is all about, and that is the XKR’s element.

PERFORMANCE

Jaguar’s new “Gen III” 5.0-liter AJ-V8 engine has the same aluminum alloy, dual overhead cam, 32 valve architecture as its predecessors, but is significantly different and more compact. The block casting is all-new, and high-pressure die-cast with cross-bolted main bearings for strength and light weight. High-pressure direct fuel injection is used for the first time in a Jaguar, allowing higher compression for increased efficiency and power.

Variable cam phasing on all four camshafts is actuated by valve torque, not oil pressure, for quicker reaction to driver demands. The naturally-aspirated engine has intake cam profile switching and a variable-length inlet manifold; the supercharged R variant has a more-efficient Roots supercharger, twin air-to-water intercoolers, and a redesigned, more efficient intake manifold. The result is 510 horsepower (at 6000-6500 rpm) and 461 lb-ft of torque between 2500 and 5500 rpm.

That strong, flat torque curve is why the car responds immediately, at all times, and doesn’t need to work hard for results. That, and the six-speed ZF 6HP28 automatic transmission, newly upgraded to handle the extra torque, ensure commendable fuel economy considering the power — EPA ratings are 15/22, and I got an honest 18 even indulging in use of all 510 horses more than a few times. Adaptive shift logic ensures performance minimal fuel use in normal driving.

In “D”, use of the manual-shift paddles allows over-ride, and automatic shifting resumes shortly. In “S”, it’s manual all the way, with rev-matching downshifts that emulate an automated manual gearbox. Stepping smartly on the loud pedal of a supercharged Jaguar has always made me hear Pink Floyd’s “Interstellar Overdrive” in my mind’s ear; with the new engine it’s through Marshall stacks at 11.

The benefits of the XK’s lightweight but incredibly stiff and strong chassis are already acknowledged. Not only does this architecture bring dynamic benefits thanks to its torsional rigidity, it also offers excellent safety and crash repair features – and provides the ideal base to optimize performance across the board, including fuel economy and CO2 emissions.The all-new AJ-V8 Gen III engines are the most efficient Jaguar has ever produced. They deliver significantly more power and torque than the previous generation of engines: 510bhp and 461lb-ft of torque in the new supercharged XKR and 385bhp and 380lb-ft in the XK Portfolio.

Price: $82,150 – $88,150.

Invoice: $74,757 – $80,217.

Performance

In naturally aspirated form, the new AJ-V8 Gen III 5.0-liter engine delivers 385bhp and 380lb-ft of torque – respectively 26 and 23 percent more than its 4.2-liter predecessor. The XKR’s supercharged 5.0-liter AJ-V8 Gen III R delivers a mighty 510bhp and 461lb-ft of torque – improvements of 23 and 12 percent respectively over the supercharged 4.2-liter engine.

On the road, while maximum speed remains under electronic control at 155mph, these power and torque gains allied to the lightweight aluminum body architecture of the XK dramatically reduce acceleration times. For the naturally aspirated XK Portfolio, 0-60mph is reduced from 5.9 to 5.2 seconds; for the supercharged XKR, 0-60mph is reduced from 4.9 to 4.6 seconds.

The supercharged XKR is also impressively efficient, with an average consumption of 23.0mpg and a CO2 rating of 292g/km – an improvement over the previous XKR – and a remarkable 16 and 17 percent better, respectively, than the equivalent figures for the BMW M6. Crucially, however, the XK also continues to better its closest rivals on economy and CO2 ratings, with an average consumption of 25.2mpg and a CO2 figure of 264g/km – a seven percent improvement on the equivalent figures for the Mercedes-Benz SL500.

Interior

Contemporary, sporting luxury, exceptional quality of craftsmanship and Jaguar’s renowned attention to detail are the keynotes of the new XK range’s enhanced interiors. The cabin is clean, elegant, spacious and remains entirely in harmony with the sporty character of the revised exterior. The luxury character of the new XK range, however, is guaranteed, regardless of the customer’s choice of body style – hard-topped coupe or fabric-roofed convertible. Both benefit from the inherent strength of Jaguar’s lightweight aluminum architecture, which means that as well as being the lightest body structure in its class, the XK Portfolio and XKR’s shells also have the highest torsional strength. And that exceptional rigidity, with or without a fixed roof, means creak and rattle-free refinement on virtually any surface, however unforgiving.

Beyond that, the convertible’s triple-lined fabric roof gives a level of fit and stability even at very high speeds that minimizes wind noise and other road noise and includes a luxurious interior finish almost indistinguishable from a fixed roof. In addition, XK Portfolio and XKR models feature luxurious Jaguar Suedecloth headlining as standard.

It can, however, be powered up or down at the touch of a button in less than 18 seconds. And when it is lowered, the convertible’s flush-folding roof retracts completely into the bodywork behind the rear seats, under a smooth cover that retains the elegant, sporty lines of the car. Nor does the convertible compromise the new XK range’s safety, for its roll-over protection system, which remains hidden unless it is needed, deploys instantaneously as necessary to provide occupants with the highest levels of protection.

For both coupe and convertible, the latest trim and feature enhancements are highlighted by the JaguarDrive Selector™, which is very neatly and elegantly packaged in the center console. The welcome to the car is also enhanced by new, bright treadplate inserts. Many of the other changes emphasize very high levels of Jaguar craftsmanship with new jewel-like touches. The three-spoke §teering wheel now has a leather-wrapped lower spoke and Jaguar’s striking ‘growler’ badge. The new XKR’s instruments now further emphasize its performance character with red pointers, while all models adopt a new white illumination for their instruments.

New heated and cooled front seats are standard equipment on the new XK Portfolio and available on XKR with the optional R Performance interior. The XKR features 10-way seat adjustability for both driver and passenger seats, with heating and memory functions as standard and unique R seat style. The XK Portfolio and XKR with the optional R Performance interior have 16-way adjustable seats with heating and memory functions, adjustable side bolsters and new cooled seats as standard.

The door casings are even more luxuriously crafted than before, with saddle-stitched lines and a new interlayer to give a softer touch to the top shoulder of the casing. The leather door pulls also introduce twin-needle stitching and a soft-feel interlayer. In each door, the modified seat switch pack now includes single-piece chrome ‘highlight’ switches.

Exterior

Visible changes on the new XK Portfolio and XKR reflect the significant changes under the skin. Carefully revised exteriors take the seductive, powerful, elegant lines that define Jaguar’s new design language and interpret them for a dramatically beautiful 2+2 sports car whose shape is even more taut, powerful and athletic. Evoking the essence of performance long before it moves, the new XK family shape is unmistakably ‘new-school’ sporting Jaguar: wholly contemporary, finely sculpted, efficiently packaged and precisely detailed.

‘The current XK was the first car to signify a new generation of Jaguars – cars that have honed our image every bit as successfully as the original XK120 or E-type. Now the new XK range reinforces that message. The cars’ visual agility and beautiful lines have been enhanced with a distinctive new front end, rear lights and revised body styling that gives every model even more presence.’

The exterior changes for both the naturally aspirated XK Portfolio and the supercharged XKR are highlighted by a distinctive and purposeful new front bumper design, new LED rear lights and a new lower rear bumper spoiler. New LED rear light clusters incorporating fog lamps plus twin reversing lamps (rather than the previous single units) give every car in the new XK range a unique ‘night time signature’, while LED technology is also included in the integrated side repeater and approach lamps in the new exterior mirrors. Every car in the new XK range also features new engine covers and revised, body-colored side power vents.

Beyond the shared changes, subtle differences in detail distinguish each of the three models in the new XK range. Both the naturally aspirated XK Portfolio and the supercharged XKR display purposeful front bumper features with stylish, chrome-detailed inserts and further chrome detailing to the upper mesh grille. The XKR is set apart by also featuring chrome on its lower mesh grille – which is finished in black on the XK Portfolio model. All models now feature chrome detailing on window surrounds and rear signature blade, and in addition the XKR comes with a new rear bumper spoiler that is finished in body color and a revised tailpipe design further emphasizing its sporting performance.

Power And Economy

One of the key features of the new engines is an industry-first, centrally-mounted, multi-hole, spray-guided fuel injection system, delivering fuel at a pressure of up to 150bar directly to the cylinder. This substantially contributes to improved low-speed, dynamic response. The positioning of the injectors ensures fuel is precisely delivered to the center of the combustion chamber, maximizing air-fuel mixing, and improving combustion control. Fuel is delivered via twin, high-pressure fuel pumps that are driven via auxiliary shaft in the all-new engine block.

The charge cooling effects of the direct-injection fuel system have allowed the compression ratio of the naturally aspirated engine to be raised to 11.5:1, further improving the engine economy. The supercharged engine also benefits from an increase from 9.0:1 in the previous 4.2-liter to 9.5:1. During the engine warm-up phase, the combustion system employs multiple injection mode strategies to deliver 50 percent more heat for fast catalyst warm-up and substantially reduced emissions.

Safety

Jaguar’s Emergency Brake Assist is standard on the new XK and Advanced Emergency Brake Assist is fitted to all models with Adaptive Cruise Control (ACC). Advanced Emergency Brake Assist uses the ACC radar to calculate distance from and speed of approach to the vehicle ahead and pre-charges the brake-line pressure to minimize impact speed if a collision is predicted – with an audible warning to the driver.

For the occupant, every car in the new XK range includes front, side and thorax airbags, incorporating new technology which reduces the load on the occupant’s body if the front airbag is deployed. Jaguar’s Adaptive Restraint Technology System checks for seat occupation, seatbelt use, seat position, and the direction and severity of any impact, and uses all that information to determine the appropriate level of airbag deployment in any incident. Additionally, Jaguar’s Protec front head restraint system protects against whiplash in the event of a rear impact.