Sometimes you just have to start all over again. That’s a lesson Jaguar learned after the launch of its “all-new” XJ sedan for 2004. The flagship saloon car boasted plenty of positive attributes, including a lightweight aluminum chassis, but it looked almost identical to the model it replaced and fell flat in the competitive premium luxury segment. The British marque isn’t making that mistake again, not with the upcoming launch of the 2010 Jaguar XJ.

Sometimes you just have to start all over again.

That’s a lesson Jaguar learned after the launch of its “all-new” XJ sedan for 2004. The flagship saloon car boasted plenty of positive attributes, including a lightweight aluminum chassis, but it looked almost identical to the model it replaced and fell flat in the competitive premium luxury segment.

The British marque isn’t making that mistake again, not with the upcoming launch of the 2010 Jaguar XJ. The new car is more than a flagship for Jaguar; it is an industry icon that could determine the success of a brand that has gone through some radical changes in recent years.

The new “saloon” car, as the British prefer to call it, has a decidedly more coupe-like shape, especially with the flowing roofline. The elongated teardrop-shaped windows are the most striking feature in silhouette. The nose, if it brings anything to mind, shares some of the basic design DNA of the smaller Jaguar XF. From the rear, the LED taillights, highlighted by three vertical red stripes, flow into the rear fenders.

“Sultry” and “sculpted” are two words you hear in a conversation with Jaguar’s managing director Mike O’Driscoll. He’s also quick to point out the nearly all-glass panoramic roof.

On a more practical line of conversation, there will be both a short- and long-wheelbase version of the four-door, the latter delivering an additional 5 inches of rear legroom.

Under that sculpted skin, the 2010 Jaguar XJ features an aluminum and magnesium chassis, making the overall car 300 to 400 pounds lighter than more conventional entries into the premium luxury segment. There are several benefits, including better mileage, reduced emissions and improved performance.

All three versions of the new sedan feature a 5.0-liter V-8. In the “base” car, it is naturally aspirated, which makes for 385 horsepower and 380 pound-feet of torque. A mid-level version bolts on a supercharger and brings the output up to 470 horsepower and 424 pound-feet. The top-line supersport, also supercharged, gives chase to some of the most powerful competitors in the segment, turning out 510 horsepower and 461 pound-feet.

Like just about every new, high-line offering, Jaguar has put a premium on electronics, whether for performance, safety or “infotainment” applications. Rather than traditional gauges, there’s a 12.3-inch high-definition virtual instruments display that provides an adaptable alternative to traditional analog instrumentation. It is complemented by an 8-inch touch-screen display that handles tasks such as audio and video, navigation and climate control.

For those looking for a premium audio experience, Jaguar is offering the optional, 1200-watt Bowers and Wilkins system, which features 20 speakers.

The new 2010 Jaguar XJ will reach dealers in early 2010, with prices running from $72,500 to $115,000 for the top-line supersport.

If past is prologue, the striking looks of the new 2010 Jaguar XJ will have premium luxury buyers enthralled and standing in line when the new sedan reaches U.S. showrooms.

Paul A. Eisenstein is an award-winning journalist who has spent more than 30 years covering the global auto industry. His work appears in a wide range of publications worldwide, and he is a frequent broadcast commentator on subjects automotive.

2010 Jaguar XJ

Miles per gallon: Estimated 16 city/25 highway for 5.0-liter naturally aspirated V-8.

Engine options: 5.0-liter naturally aspirated V-8, 385 horsepower, 380 pound-feet torque; supercharged 5.0-liter V-8, 470 horsepower, 424 pound-feet; supercharged supersport 5.0-liter V-8, 510 horsepower, 461 pound-feet.

Manufacturer’s suggested retail price: $72,500 to $115,000, plus destination, depending upon model.

Cost fully loaded: $125,000 (est.).