TODAY 6 FEB Exclusive Jaguar News

...of different engines - not just Jaguars - and equipment to tinker with the recordings. They played with wavelengths and tones, then tested the results on buyers. Naively, I was amazed so much effort went into fine-tuning the music made by a car - so much that an entire building was devoted to it. I had assumed that if you designed a desirable engine, then desirable sounds would come out. Obviously not. A tour of Ford's sound laboratories in Detroit last month showed how far the pursuit has moved on. The entire cacophonous signature of a car, from firing up the cylinders through every phase of driving, is subject to intense scrutiny. Instead of just playing a recording to prospective customers, they drive virtual cars in a video game to decide what they like. Errant noises can be tracked down by special equipment that can reveal sound sources in the same way one of those heat-sensitive cameras shows up temperature.

It's an industry-wide effort that results in quieter cabins - freer from wind noise and rattles - except for the sounds we actually want. And here, the engineers have a lot in common with the makers of brass musical instruments. They are fixated by valves and resonances. These days, at least some of the plumbing under bonnets has nothing to do with the functioning of the vehicle. It's there to make it sing.

That's especially important in sports cars and Jaguar's revised large coupe, the XK, is a case in point. It has a new 5.0-litre V8, replacing the previous 4.2, supercharged in the XKR driven here. It's a state-of-the-art unit with the latest in direct fuel injection and clever variable camshafts. Whether supercharged or not, this V8 develops substantially more power and torque than before, at much lower revs. It's also more efficient and generates less carbon dioxide.

While performance was crucial almost as much effort, you feel, went into how it sounds. This can be a special problem for forced-induction engines - those with a supercharger or turbocharger - which can end up sounding industrial and devoid of character. For a Jaguar, that just won't do.

"In addition to the fully active exhaust system in which valves open to provide a more rewarding note, the new XKR has been engineered to provide an intake feedback system to enhance the V8 sound character," Jaguar says.

"Intake manifold pressure pulsations are fed into an acoustic filter at the rear of the engine that is tuned to provide an edgy sports car crescendo at high revs."

Bravo!

The previous supercharged 4.2 whined as the air pumps got going in a way that made it sound fierce and determined. A little unorthodox for a gentleman's sporting tourer, but it had a certain charm.

The new engine takes no such risks. The very epitome of a classy V8, it makes all the right noises from go to whoa. It's quiet when cruising but delivers a carefully calibrated amount of aural feedback when pressing on. It's both mellow and crisp. And if I'm not careful I'll start sounding like a wine writer.

This engine has already appeared in the XFR, the performance version of Jaguar's hit mid-size sedan, and top-specced Range Rovers. The fastest of the XK variants gains 69kW more power. It propels the XKR to 100km/h in 4.8 seconds - slightly quicker than before - and to a limited top speed of 250km/h. There's a 6500rpm redline, just above peak power, and you'll seldom use all that on the right side of the law.

At legal limits, it cruises just below 2000rpm, with peak torque just a foot flex away. There's very little throttle lag and it devours hills or overtaking manoeuvres with plenty in reserve.

The stated fuel economy looks realistic too. Appalling NSW summer weather last week over the Great Dividing Range, which included thick fog, rain, lightning and hailstones the size of marbles, dictated cautious driving. Nevertheless, I was still surprised when the XKR delivered better than the official figure of 12.3 litres per 100km. This is despite a weight gain of about 90kg.

The engine works extremely well with the six-speed automatic, which never changes abruptly and works seamlessly in auto or manual modes, when it blips on downchanges. German makers are moving to eight-speed boxes, but you can't help wondering whether they're really necessary.

With these revisions, the XKR gets the latest continuously variable dampers, which analyse driver inputs to predict what will be required to keep the car's body under control. The result is an accomplished chassis that has the sensitivity and delicacy of a much lighter car. It gives a compliant and sophisticated quality to the ride, too, although it's as detailed as the road itself and the system can get confused sometimes, making everything a bit too jiggly.

Light but accurate steering is a good match for the chassis while the brakes feel strong, although the pedal lacks the intimacy of Porsche stoppers.

The cabin has most of the comforts you should expect at this price, including seats that are comfortable all day, a leather-covered dash and alcantara headlining. The XK adopts the centre console cluster from the XF, which includes its unusual circular gearshifter selector and blinking starter button. Seat adjustment is by Mercedes-style switches in the door, there's a virtual "analog" clock between appealing white-on-black dials, and an audio system by Bowers & Wilkins.

Letdowns are few, although the steering wheel boss feels a bit down-market compared with the rest of the interior and the gearshift paddles are obviously plastic, when it would be better if they weren't.

Despite the low-slung shape, visibility is pretty good although the large rear window does get dirty quickly and there's no wiper. Wind and tyre noise stays within acceptable levels. Clearly, not all the time in sound labs was spent on the engine.

With this makeover, the price of an XKR coupe rises almost $15,000 and just overlaps Aston Martin territory. The cheapest Aston two-plus-two - the DB9 - has a V12 and another $90,000 on the price tag, but the seats in the XK are virtually useless for passengers so you might opt for a V8 Vantage, which is strictly a two-seater, for similar money.

A Porsche 911 Carrera S is about the same price and has part-time rear seats, but only six cylinders. The BMW 650i, which has just been freshened up, comes in at $227,300 but the Jaguar is much better to look at, and drive. Other options are more expensive: the Mercedes SL 500, a two-seat metal-roof convertible, is $327,000, while the most affordable Maserati Granturismo nudges $300,000 and a Bentley Continental GT is $384,400.

Which to my mind, makes the Jaguar a sound proposition.

NEED TO KNOW

Vehicle: Luxury coupe or convertible

Engine: 5.0-litre supercharged V8

Outputs: 375kW at 6000rpm, 625Nm at 2500rpm

Transmission: Six-speed automatic, rear-wheel drive

Price: From $255,000 plus on-road costs

On sale: Now