High tech, high style, and high hopes for Jag's new coupe and convertible
By D. John Booth
Both the coupe and convertible will be lighter than the competition from BMW and Mercedes. Some might argue the XK will look better, too.
Think your job is impossible? That your customers are wretchedly demanding? Or that the standards your industry is held to are the reason for that early hair loss? Well, take a Kleenex, pal — at least you're not an automotive engineer. Just ask Peter Matkin, chief of vehicle engineering for Jaguar's all-new 2007 XK8 coupe and convertible.
Case in point: Jags, of course, are supposed to showcase elegance and sophistication, so Matkin and his team spent an incredible amount of time engineering the XK's chassis, interior and sound absorption materials to make the new sports car's cabin as calm and peaceful as possible.
But did he get thanks? Oh, noooo.
"Well, I like the fact that it's quiet and all that at cruise," went the refrain, "but it's supposed to be a sports car, right? When I floor it, then, I want some bite. You know, some growl from that big V8 engine."
Back to the drawing board went Matkin's team. Many car companies would have simply fiddled with the exhaust system, employing the same rpm-dependent valves that open up the mufflers for more noise. But Matkin's propeller heads went even further, running a tube from the XK's intake manifold through the bulkhead to the recesses of the dashboard behind the radio controls. On the end of this long resonance chamber, they molded in a little 25mm diaphragm, turning the whole thing into a speaker so that at specific rpm and load conditions, it pipes in just the right amount of intake roar. The official title for the little doohickey is "intake feedback system," but Matkin calls it the "Bark Tube." Too right.
As satisfying as righting soniferous wrongs is, Matkin takes the most satisfaction from the engineering that went into the XK's third-generation aluminum frame. "It was, by far, the most difficult but most rewarding part of the project," he says, pointing out that the XK's all-aluminum chassis needed new bonding techniques and features with more extrusions and castings than the XJ, which is predominantly formed from sheet stampings.
This might sound like a lot of techno-garble that you don't really need to know about. But the switch to aluminum is one of the essential reasons that the new XK appears poised for success.
And yet it will be, by all estimations, affordable. You see, not only do those extrusions make the XK coupe's frame the stiffest in its segment (ahead of the BMW 645 and Mercedes-Benz SL — both granitelike examples of chassis engineering) but extrusions require very little investment in tooling, saving Jaguar big bucks in the research and development phase. The pieces may be costlier to produce, but since the XK will be a relatively low production run, it still saves Jaguar precious development resources, something in short supply back in Coventry these days.
From computer screen to showroom
And while on the subject of costs, Matkin claims that the entire XK design was performed on a computer, with only the cloth roof of the convertible, prototyped during the initial design phase, falling outside this system. "Everything came out pretty much exactly as the computer predicted," explains Matkin, "and we saved lots of money not having to build so many test vehicles."
Is all this technological innovation worth the trouble? Well, let's see: An XK coupe weighs in at 3,671 pounds (the convertible is 3,759 pounds). By comparison, a BMW 650i coupe tips the scales 143 pounds heavier (the convertible XK weighs a whopping 518 pounds less than the 650 ragtop). And an SL500 is a hefty 306 pounds heavier than the XK ragtop. Take my word for it — that lighter weight makes a huge difference.
Or listen to Matkin's more adroit explanation. "Get the basics right," says the chief engineer, "and the rest is relatively easy. And a light weight, extremely stiff chassis is exactly where you want to start."
Matkin explains that a stiffer chassis allows firmer suspension settings, which creates superior road-holding without sacrificing any refinement or ride quality. "The base XK's all-wheel independent Computer Active Technology Suspension (CATS) is actually almost as stiff as the last-generation XKR's, yet ride is not at all compromised."
It also helps Jaguar tune the steering to levels of precision and feedback that Matkin hopes will surpass even perennial segment leader, BMW.
Powering this exceptional chassis is Jag's AJ-V8 4.2-liter. Unlike the chassis, the 4.2 is essentially a carryover with a little electronic fuel injection fiddling to raise peak power to 300 hp. That's 60 less than the latest version of BMW's 6 Series. Despite that deficit, the lightweight XK coupe is just 0.6 second slower to 100 kilometers an hour (62 mph).
Even Matkin admits it could use a few more ponies, noting that "with such a great chassis, even the base XK could easily handle substantially more power." Expect that to come in short order with an XKR version, and don't be surprised if it boasts more than the current model's 390 hp.
As for the transmission, it's the same six-speed automatic that Jaguar's been using for some time now, but Matkin says it's been calibrated for quicker and more positive gear changes. More noticeable is the absence of Jaguar's trademark J-gate, replaced with steering-wheel-mounted paddle shifters.
Comfort, convenience and cockpit engineering
Owners of the current XK who are less than enamored of its rather cramped quarters are going to love the new car's cabin. Though it is but barely half an inch longer overall — and still retains its 2+2 seating format — the new XK claims 2.13 inches more front legroom, 0.8 inch more headroom and a whopping 1.4 inch more shoulder room. The extra width is particularly noticeable as your legs are no longer butting up against the transmission tunnel or being skewered by a parking brake lever.
Unlike the exterior, which possesses Jaguar's trademark organic, feline appeal, the XK's interior is pure techno. And the British — yes, the British — have delivered a centralized computer that isn't an infernal pain in the you-know-what to operate. Unlike the complicated systems in German luxury automobiles (BMW's iDrive, Mercedes' COMAND and Audi's MMA), Jaguar's Driver Information Center system works through a touchscreen and is extremely easy to decipher and use. Audio, climate control and even seat heater controls are easy to find and free of needless over complication and diabolically difficult menus. Our only complaint is that the radio's manual station-changing function automatically returns to "seek-scan" every time you use it, and you can't set manual operation as the default command. There is, of course, a navigation system as well.
Those electronically minded will also appreciate the optional Alpine audio system that features Dolby Pro Logic II Surround Sound, eight speakers and 520 watts of power. When that's off, you can chat via a built-in communication system that works wirelessly with Bluetooth mobile phones. Personally, I like the "do not disturb" mode that inhibits incoming calls, especially while tossing the XK into corners like the very devil is chasing me.
Though the new XK gets all the de rigueur safety aids like multiple airbags (including side curtain airbags) and traction and stability control, the truly nifty safety innovation is something we're not likely to get, at least right away, in North America. Europe is implementing new standards for pedestrian impacts, and the most difficult of these to meet is the frontal collision. The problem is the damage caused when a human's head hits the hood. The bonnet itself doesn't do the damage. But when a heavy skull deforms the relatively flimsy hood a few inches, it abruptly comes in contact with the engine (usually the intake manifold) which does serious damage.
Jaguar's solution is to have sensors in the front bumper that determine if a pedestrian has indeed been struck and then triggers two pyrotechnical charges that instantaneously lift the front hood, providing extra distance between engine and head. In effect, the hood becomes the exterior equivalent of an airbag: The hood's sheet metal may not be as soft, but it's a damn sight more accommodating than a solid 400-pound piece of metal and plastic.
When all is said and done, the 2007 Jaguar XK will sell on its shape. To these eyes, it looks gorgeous, the only styling faux pas being the body-color "power vents" along the front fenders rather than the polished aluminum version of the Advanced Lightweight Coupe concept car. But that's easily forgotten when peering at those lovely rear haunches and the gracefully sloping silhouette — it's a constant reminder of the new XK's alloyed blend of the stylist's art and the engineer's craft.
Using computers to design the XK's body-in-white improved the coupe's power-to-weight ratio by 10 percent, yet increased its stiffness by more than 30 percent.
The stiffer construction afforded by the Lightweight Vehicle Technology allowed Jaguar to calibrate the Computer Active Technology Suspension more aggressively, for improved handling without sacrificing ride quality.