Great looks and light weight characterise the new Jaguar XK coupe and convertible. But these are are no stripped out lightweight supercars aimed at people wanting a near-racer. They are very highly-equipped cars aimed squarely at the luxury end of the supercar market, powered by a 4.2 liter V-8.
Let's start with the first bit of good news: the new Jaguar XK is a great looking car, and is quite a lot different from the previous model. You've got this deep chin, with its own air intakes, both for the radiator and brakes, then the traditional oval of Jaguar sports cars. The headlamps aren't very original, but then there is long hood – designed to help reduce any injury to a pedestrian who should get in the way – and the long, flowing coachroof merging into a sharp back end. Elegant and cool, this makes a distinctive supercar.
Then there is the convertible, which retains a fabric hood to give plenty of luggage space – a folding steel roof takes up oodles of space - and that, too, looks a million dollars, open or closed. Some roadsters look pretty odd with the roof up, but not the Jag. Incidentally, the roof is made of three layers: a waterproof outer, a sound and heat insulating inner layer, and a smart inner roof lining. This design should overcome two of the problems of convertibles – noise and water coming in.
So, we start off with two great looking cars, which are lighter than the old XK, but which don't win any medals in aerodynamics; the coupe manages a Cd of 0.337 and the convertible 0.354. A class act is nearer 0.30 for a coupe.
Light body gives better acceleration
Thanks to the aluminium body, which is about 20% lighter than the steel XK, the new car accelerates quicker, with a 0-60 mph of 5.9 seconds, against 6.1 seconds. That's a difference you'll hardly notice, but a step in the right direction. The car is limited to 155 mph.
The XK has a true all-aluminum monocoque body, as on the XJ, in which all the panels are stressed.
This is different from the use of an aluminum frame with separate panels as on the Aston Martin V8 Vantage, Audi A8 and newer Ferraris. It could be slightly lighter than a car with an aluminum frames, so long as the other cars don't have aluminum skin panels. As with all aluminum bodies, you get better energy absorption than steel – in other words, you will crash a little more safely.
V-8 engine almost the same
Initially, the XK is available with a 4.2 litre V-8, slightly modified from the previous unit to improve response, and to give a little more power – 300 bhp at 6,000 rpm, which is up form 294 bhp. Torque is also up slightly at 310 lb ft (420 Nm) at 4,100 rpm. The quad-cam V-8 has variable valve timing – which Jaguar more correctly calls variable camshaft timing as the timing of the camshafts is varied as on most engines.
Apart from giving a better spread of power – and now used on quite lowly engines in not-very-hot hatches – variable timing allows heavy exhaust gas recirculation which is needed to reduce emissions to meet new regulations. So, the V-8 ought to be giving more power than before? No, because it has had variable timing for some time.
Even so, it is now easy to get a lot of power from engines without supercharging, so the 71 bhp per litre of the XK is hardly supercar power – more suitable for the Jag sedans. These days, 80 bhp per litre, or 335-340 bhp, would seem more in the ballpark for this type of car. True, a supercharged engine will be coming for power freaks, and that will be up around the 400 bhp level, making the car very quick.
Now Jaguar drivers get paddle shifting
Jaguar has not offered a manual transmission for decades, and those they did use were not brilliant, so they have stuck with the six-speed slush-box automatic, but with a difference. Now you get paddles on the steering wheel to allow quick manual shifting, which you can use in manual or D or sport. The difference is that in manual the shifts are faster. The controller is designed to adapt both to road conditions and driving style, so it should suit you however you drive.
Incidentally, Jaguar claims that the overall shift time of its box is quicker than that of the BMW and Ferrari sequential boxes because there is no interruption to the transfer of torque – as one clutch disengages, the other engages. It will certainly be much smoother than the BMW M5, which has a jerky shift when you are not hurrying. In practice, once you've got 300 bhp or more, a full automatic delivers the goods so long as you have a good manual over-ride. The previous XK lacked that.
Aluminum panels, extrusions and castings
Jaguar is a leader in the production of aluminum bodies, following on from the research done between Ford and Alcan in the 1990s, and it has moved forward with the XK. The body consists mostly of aluminum sheet, but also includes some extrusions and castings in areas where either extra local strength was needed, or where the shape was so complex that fabricated sheet was not practical.
Also, like the Audi A8, the panels and other body components are joined together by epoxy adhesives and self-piercing rivets. There is no structural welding at all – just one cosmetic weld where it produces an invisible seam. Extrusions are used for the main box section members, and castings are used for the mountings of the engine, transmission and suspension. Castings are also used for the suspension towers.
Jaguar claims that the new body has twice the durability of the steel one, and the new body is undoubtedly a fine structure. Real progress.
A true lightweight supercar
But what about the weight, I hear you ask? Jaguar has done quite a good job, but fell foul of the desire to make the car a bit bigger. No cunning 'packaging' to get more space into an existing size and shape here. The new body is an inch longer and two inches wider.
Therefore, the weight reduction is less than it might have been. Also, as with all modern cars, especially in the luxury class, they've loaded the car with all sorts of 'extras'.
Body 19% lighter than steel
The body shell of the convertible weighs 632 lb (287 kg), which is a weight reduction of 19% over the slightly smaller steel one. A world-class lightweight aluminum structures should be 25% lighter than a comparable steel one, and this one wold probably achieve 20-22% like for like.
The new XK weighs in at 3,513 lb (1,595 kg), which doesn't sound bad, but is only 5.4% lighter than the old car. The target with an aluminum body is 10% weight reduction, so this must be rated as slightly disappointing, partly because of the extra bits and pieces Jaguar's bosses – and other bosses - think new cars should have to keep ahead, especially in the USA.
But how does it compare with the competition? Very well, as you can see in the Table. It weighs only 50 lb more than the Aston Martin V8 Vantage, which is 16 inches shorter, whereas a difference of 100-250 lb would be more likely. The XK is 260 lb lighter than the BMW 650, which is quicker and fairly spacious, and 550 lb less than the Mercedes-Benz SL500. The 650 does offer real competition.
The XK also weighs 180 lb than the Maserati GranSport, about the only 2+2 V-8 supercar that the XK can be compared with directly. It weighs 115 lb less than the Aston Martin DB9, which has a heavy V-12 engine.
But the real shocker is that it weighs 500 lb less than the Ferrari Scaglietti, which is the same size, but has a heavier engine, and more staggering is that the XK weighs 381 lb less than the Mercedes-Benz SLR McLaren! Not only is the SLR McLaren slightly smaller but it has a carbon fiber body, reckoned to the lightest way to build a car! So in the real world, the XK is a real lightweight champion.
Double wishbone suspension
Jaguar has retained its legendary double wishbone front and rear suspension with anti-roll bars each end, and as before these are mounted on substantial sub-frames – of aluminum. At the front, very long stub axle carriers, which extend right up above the tires are used. The top wishbone, which is triangular pivots on the stub axle carrier almost above the tire, which gives good geometry and lighter loads than you get with shorter stub axle carriers. The spring/damper units are mounted in towers.
At the rear, the drive-shaft still serves as the upper wishbone, a method which works well and also reduces weight, although it does limit geometry somewhat, but not so you'd notice.
Brakes are larger than before, and you can choose 18, 19 or 20 inch wheels, and the rear tires are fatter than the front ones. The steering is the latest Sensotronic system which gives more assistance at low speed than at high speeds – more or less standard on cars of this class.
Sporty handling is standard
However, although Jaguar has thrown its cap into the luxury end of the market, its engineers could not resist giving the car more sporty handling than previously. So expect to be able to the throw the XK about a bit. The front-engine, rear drive layout does give balanced handling, although the XK has slightly more weight at the front - the ratio is 52.6% front:47.4% rear – than the much more expensive Aston Martins or Ferrari Scaglietti.
The interior looks very neat, particularly with the aluminum trim, with the usual twin speedo/rev-counter in a binnacle and a smart three-spoke wheel. Most of the minor controls are grouped in the center console, the touch-screen giving you quick control over many functions.
Plenty of electronics
Needless to say there are plenty of electronic gizmos to help you on your way, starting with an improved version of the Jaguar automatic variable damping, traction control and stability control. The stability control has an extra function so that when you want to corner faster you select Trac DSX, and the threshold is set higher, allowing you to hang the tail out.
Cruise Control is standard, but Jaguar's excellent adaptive cruise control is available, of course. Rear parking aids are standard so you don't back into things – but the penalty is those annoying beeps when you're sliding past something at a safe distance.
Inside, you get full dual-zone air conditioning, high-spec audio with six-CD changer in the dash and a Bluetooth-compatible communication system. Volume and answer controls for the telephone are on the steering wheel.
Among the external features are the latest bi-xenon headlamps, which are truly brilliant, so you can see that driving the new XK is going to be a great experience.
How do I rate it? On what we know now, I'm sure the car will be great to drive, and will come with a very high specification to compete with anything in the luxury high-performance market. I mean, it makes the Mercedes-Benz SL class look ridiculously overweight and clumsy, but will have a harder time fighting the BMW 650 except that it looks a hundred times better..... And that is the XK's trump card. It's a beauty.
