Jaguar XKR, More Power To The Big Cat

Mighty powerful, suave and stylish that's the new Jaguar XKR. Here's a supercar designed to be at home in the country club or the open road. The XK series has been around for quite some time now, but is it the car that they early Jags were? Well, yes and no. It retains the flowing lines of those early models - despite the fact that the shape of the coupe is so like the Aston Martin DB7 it's uncanny. The convertible somehow looks more like you'd expect a Jag to look. This XKR is a big car, though, with the accent on luxury rather than taut all-out performance.

Some would say it's too big and soft to be a supercar, but the performance of the superb supercharged V-8 of the XKR pushes it right up there in the supercar league. Still, the car is big for a two-seater coupe; OK, I know it has two seats in the back, but it's really for two. The XKR is as big as the BMW 645 coupe, and weighs about 250 lb more. Boy does it need a diet - and no doubt its successor will do so. Jaguar now has plenty of experience in developing and building lightweight cars, as the superb aluminum XJS shows, and we can expect that method to be used to reduce weight.

Despite its size, the XKR is no overweight weakling. The new supercharged engine sees to that. This supercar can reach 60 mph in 5.2 seconds - almost half a second less than the new BMW 645Ci. What about the top speed? Well, like the BM its politically correct and is limited to a gentlemanly 155 mph. The old E-Type wasn't much slower.

Supercharged V-8 gives masses of power

Still, the XKR combines an excellent and very powerful engine with a six-speed automatic and the Big Cat's proverbially refined suspension. Let's start with the engine. To give a bit more torque, it has been enlarged from 4.0 to 4.2 liters, and the XKR unit is supercharged not turbocharged, but supercharged with a mechanically driven 'charger. Why Like Mercedes-Benz, Jaguar learned years ago that supercharging works well with a high-performance gasoline engine because it boosts power low down. By contrast, turbochargers work best at higher speeds, and have a narrow range in which they are efficient. Mind you some of the latest turbochargers do overcome this problem with new technology.

Jaguar's new generation all-aluminum V-8 now develops 400 bhp at 6,100 rpm in supercharged form, against the 300 bhp of the normal engine. Torque is increased by about 30% as well, and is produced at 3,500 rpm, against 4,100 rpm for the standard engine. So not only do you get neck-jerking power, but you also get masses of oomph at lower speeds. To boost output, the valve timing is varied according to the engine speed, improving mid-range performance. On the Jag, the timing is varied by advancing or retarding the opening of the valves.

Six-speed automatic as standard

You're not likely to get caught out with a lack of power in this beaut, particularly as the engine drives through a six-speed automatic this replaces the earlier five-speed job. Of course, you can shift gear manually, or leave the auto to sort things out for you. That power comes at a price: the combination of a big, heavy car with a large supercharged engine and an automatic means that gas mileage is not brilliant.

Like Jags for many years, the XK series has advanced double wishbone suspension front and rear, with each drive-shaft acting as one link at the rear. Also following a Jaguar tradition copied by many others the suspension arms are mounted on sub-frames which are insulated from the body and this is one reason why Jaguars are so quiet even over rough surfaces. To cope with the greater power, large Brembo brakes with aluminum calipers are fitted.

Adaptive damping for the superb wishbone suspension

Although the XKR may not bristle with electronics as much as some of its rivals, it does have a number of systems designed to make driving safer and more fun. Of course, there's ABS, but more important are the adaptive suspension which adjusts the damping continuously to suit the conditions, and dynamic stability control which helps the driver remain in control if he gets into a corner too fast.

Not to be left behind, Jaguar now offers adaptive cruise control on the XKR at high speeds this keeps a constant distance behind the car in front, by slowing or accelerating as needed; all on auto-pilot.

Pretty refined, pretty powerful, definitely got all the gear has this Jag. The interior may look a bit more like a luxury sedan than a supercar, but it certainly has style. I can't help wondering what the next one will be like; hopefully smaller and lighter and just as powerful!