Rarely does a luxury car transform itself as dramatically as the Jaguar XJ did in 2011. The previous-generation XJ hid modern mechanicals beneath a traditional design that recalled the classic XJ6 of the 1960s, and while this no doubt seemed like a good idea at the time, sales flopped. For its new XJ, Jaguar ditched convention and gave its iconic sedan a radical, strikingly modern design inside and out. A luxury sedan that once appealed only to those with fond memories of string-back leather gloves is now a fully competitive flagship.

Extensive use of aluminum in body panels and the underlying chassis delivers a relatively light curb weight -- about 4,000 pounds for the base model -- and gives the 2012 Jaguar XJ relatively nimble handling and maximum effect from the lineup of 5.0-liter V8s. Not that they really need that much help. Even the base XJ makes 385 horsepower, while the Supercharged and Supersport models crank out 470 and 510 horses, respectively, and produce stunning acceleration.

The XJ's cabin is another highlight. While all vehicles in this class are meticulously constructed, exquisite details and a dramatic design set the Jag apart. Better still, you get an awful lot of value for your money. The XJ stickers lower than its German rivals, yet generally gives you more standard features. And the higher you go, the better the deal. The XJL Supersport will match or surpass the performance of a BMW 760Li or Mercedes S63 AMG, yet costs $20,000 less.

Granted, choosing an absolute winner in a class that includes the 7 Series and S-Class as well as the Audi A8 and Porsche Panamera is near impossible. Each car has particular individual strengths. When it comes to the best combination of style, dynamic substance and value, however, it's hard to top the 2012 Jaguar XJ.

The 2012 Jaguar XJ is a full-size five-passenger sedan available in regular (XJ) and long-wheelbase (XJL) models.

The base XJ comes standard with 19-inch wheels, an adjustable and self-leveling suspension, adjustable drive settings, front and rear parking sensors, a rearview camera, automatic wipers, automatic bi-xenon headlights, auto-dimming and power-folding mirrors, a power trunk lid, a panoramic sunroof and keyless ignition/entry.

Inside, the XJ gets dual-zone automatic climate control, a heated and powered tilt-and-telescoping steering wheel, heated and ventilated power front seats (12-way driver, eight-way passenger, four-way lumbar for both), front seat memory functions, heated rear seats and extended leather upholstery. Standard electronic features include a fully digital LCD gauge cluster, a touchscreen interface, a navigation system, voice controls, Bluetooth phone and audio connectivity, and a 14-speaker sound system with a CD player, satellite radio, HD radio, digital music storage and an iPod interface. The Portfolio package adds four-zone automatic climate control, additional front seat adjustments with a massaging feature, heated and ventilated rear seats, additional leather trim, a faux-suede headliner and more color choices.

The XJL comes standard with the Portfolio package, and is thus known as the XJL Portfolio. Like all "L" models, it also gets additional rear seat legroom, rear vanity mirrors and manual rear side sunshades. The Executive Package adds a power rear sunshade, rear flip-down trays, a wood-trimmed steering wheel, chrome mirror covers and upgraded floor mats.

The XJ Supercharged gets a more powerful engine, different suspension tuning, 20-inch wheels, adaptive headlights, automatic high beams (optional on base XJ and XJL Portfolio), the power rear sunshade and a 20-speaker Bowers & Wilkins surround-sound audio system (a stand-alone option on the XJ and XJL Portfolio). The XJL Supercharged gets the usual "L" upgrades, but includes the rear business trays as standard.

The XJ Supersport gets an even more powerful supercharged engine, performance tires, upgraded leather upholstery, additional leather trim and a rear-seat entertainment system (optional on all other trims) that includes two headrest-mounted screens.

Optional on all XJ models are a heated windshield and an adaptive cruise control system, which includes a forward collision alert and advance emergency brake assist. A Sport package will be a late-availability option for the XJ Supercharged and XJ Supersport.

The 2012 Jaguar XJ and XJL Portfolio feature a 5.0-liter V8 that produces 385 hp and 380 pound-feet of torque. As in all XJ models, rear-wheel drive and a six-speed automatic are standard. In Edmunds performance testing, an XJL went from zero to 60 mph in a very quick 5.5 seconds. The lighter XJ should be a bit quicker. The EPA estimates fuel economy at 16 mpg city/23 mpg highway and 19 mpg combined for the XJ, while the XJL gets 1 mpg less all around.

The Supercharged model also gets the 5.0-liter V8, but it's supercharged to produce 470 hp and 424 lb-ft of torque. In Edmunds testing, an XJL Supercharged hit 60 mph in a rapid 4.5 seconds. The EPA estimates Supercharged models returning 15/17/21 regardless of body style.

The Supersport gets a more powerful supercharged V8, cranking out 510 hp and 461 lb-ft of torque. Jaguar estimates it'll hit 60 mph in 4.7 seconds, but given our time for the regular Supercharged, it's likely the more vigorous Supersport will do better. Fuel economy estimates echo the Supercharged.

Every 2012 Jaguar XJ comes standard with antilock brakes, stability and traction control, front side airbags, side curtain airbags, active head restraints and a blind spot warning system. A forward collision alert system and advanced emergency brake assist is included with the optional adaptive cruise control

In Edmunds brake testing, an XJL with the standard 19-inch wheels and all-season tires stopped from 60 mph in a rather pedestrian 125 feet. An XJL Supercharged with performance tires, however, stopped from 60 mph in an exceptional 106 feet.

Few cars strike such an excellent balance between ride comfort and sporty handling as the 2012 Jaguar XJ. It glides down the road with a sophisticated suppleness, though its big wheels may transmit more impact harshness over rough pavement than those of a Benz S-Class. More importantly, though, its lightweight aluminum chassis, adaptive suspension and communicative steering create a deceptively agile car. Choosing the car's "dynamic" driver setting engages sharper throttle response, firmer dampers and quicker downshifts, which make the XJ feel even livelier.

Your engine choice simply comes down to how quick you want to go. The base car offers less power than a BMW 750i, but the XJ's lightweight body helps it match the Bimmer's acceleration. The Supercharged and Supersport, meanwhile, truly surprise with their prodigious performance.

The Jaguar XJ's interior is exquisite. Not only is the design unique and appealing from an aesthetic standpoint, but the craftsmanship and materials are beyond reproach. Parallels to Bentley are not unwarranted. Supple leather covers the seats and most of the dash and doors as well. Rich wood trim wraps around the interior as though a structural element. Tasteful chrome, piano-black trim and ice-blue lighting further decorate a royal cabin.

A large touchscreen dominates the in-car electronics. It works OK, but doesn't operate as quickly as screen-and-knob systems like BMW's iDrive. Processing speed is also slow. The instrument panel is, in fact, a big LCD screen, and adapts to different driving scenarios and in-use vehicle functions (navigation, for instance).

As before, the regular-length XJ's backseat is on the small side. If you regularly have backseat passengers, consider an L model. The Jag's lower roof line provides enough headroom for most occupants, but competitors offer profiles that feel more like a limousine. Trunk volume is about average, with 15.2 cubic feet. A raised portion in its rearmost area may impede storage depending on what you're hoping to place in the trunk.