The Jaguar XJ's performance has as much to do with its lighter-weight, jetlike construction as it does with its engines, transmission, and suspension. The body hasn't changed much for 2013--only where it needs to, to accommodate the big differences in drivetrains that expand the XJ's desirability.
For those who missed the big Jaguar story of the past decade, the XJ is one of three model lines (XK and F-Type are the others) that have airplane-style aluminum bodies. The panels are riveted and bonded together with aerospace glue, which keeps the overall weight down a few hundred pounds. In the 4,200-pound range in base form, the Jaguar XJ undercuts other big luxury sedans by at least a few hundred pounds, and it feels like it.
Since the 2004 model year, the all-aluminum XJs have been V-8-only vehicles. For 2013 the XJ adds a new base engine, a supercharged 3.0-liter V-6 with direct injection and stop/start. Output from the engine is down 45 horsepower from the still-offered, 385-hp, 5.0-liter V-8--but with a new eight-speed automatic, the super six is a few tenths less brisk to 60 mph, according to Jaguar estimates (5.7 seconds) but gas mileage is far better, at 18/27 mpg versus 16/25 mpg. The ZF-built, Jaguar-tuned transmission gets a lot of the credit, with its class-standard shift quality and responsiveness. The six-cylinder's mostly subdued, with a little whine that subliminally reminds us we're driving something British--not at all a bad thing.
The six-cylinder alone brings with it Jaguar's available all-wheel drive system, new in the XJ and in the XF sedan for 2013. Set up to preserve as much of the XJ's nimble feel as possible, it puts most of the torque through a transfer case to the rear wheels, with some torque pre-loaded to the front wheels from a stop. When the selectable Winter driving mode is chosen, a minimum of 30 percent of torque is sent to the front wheels, and up to 50 percent is possible--while the traction control still can modulate power to the rear wheels as grip fades.
Like most luxury AWD systems, that in the Jaguar is invisible until it's not. We experienced a rear-right tire failure on snowpack in the XJ AWD, and figured for a brief, shining moment, the combination of electronics and hardware and run-flat tire tread staying intact gave us the only front-drive XJ on the planet. For what it's worth, the weight penalty for the new system is low, in the 120-130 pound range, with just some stiffening braces required across the front end, in addition to the AWD hardware. Zero to 60 mph times drop to 6.1 seconds.
Above and beyond these new drivetrains, the XJ soldiers on with its marvelous V-8s, all derived from a 5.0-liter engine shared with the XF sedan and XK coupe. The standard version offered this year only in the long-wheelbase XJ sedan puts out 385 horsepower, and it's teamed now to (as are all XJ engines) to the ZF eight-speed automatic. With supercharging, the same engine makes either 470 hp or 510 hp, depending on the buyer's wallet size.
We've been amazed how American this engine can sound: its vintage V-8 noises aren't at all quiet or syrupy-smooth, and the classic eight-cylinder rumble injects a note of seriousness into any stoplight challenge. The 385-hp drivetrain can toss off 0-60 mph runs in 5.4 seconds; the supercharged 470-hp engine is capable of 4.9-second runs; the Supersport, Jaguar says, will hit 60 mph in 4.7 seconds. The XJ is limited to a top speed of 155 mph unless you specify one of the new Speed or Sport and Speed packs, which lift the electronic limiter to 174 mph.
In most every way, the XJ is a brisk, engaging performer, and its manageable set of electronic add-ons keeps ride and handling more pure than in some of the perpetually-adjustable competition. The XJ goes about its work more directly, with an independent suspension with coils up front and links in back, electronically adjustable air springs in back, and an electronically controlled rear differential on supercharged cars. "JaguarDrive Control," activated by a console-mounted switch, lets owners choose Normal, Dynamic and Winter settings for the throttle, steering, transmission and ride quality.
The XJ may have a slightly narrower range of user-selectable performance modes than German or Japanese luxury sedans, but we think it's better for it. Its reflexes are more pure, more predictable, and the overall driving feel is more unified. The modes are related more closely than, say, the settings programmed into Audi's improved Drive Select system.
Big ventilated disc brakes with anti-lock, brake drying and good pedal feel match the XJ's crisp new feel. And Z-rated tires on 19- or 20-inch wheels stick admirably--though you'll certainly notice the long, storied reputation of Jaguar ride has also been ditched for a taut, athletic feel. The air mattress is gone; long live the Tempur-Pedic precision.