Appearances really can be deceiving. From a distance-or even up close for that matter-the new Jaguar XJ8 L is a near dead ringer for its '97 counterpart. But just below the elegantly contoured sheetmetal of this long-wheelbase luxury sedan lies a whole raft of mechanical advances that make it a far more fetching feline for '98.
The most immediately discernible change is in the powertrain. The veteran AJ16 inline six has given way to the firm's highly touted AJ-V8, which first appeared in the '97 XK8. While the two engines share a common 4.0-liter displacement, all-aluminum construction, and chain-driven dual overhead camshafts operating four valves per cylinder, the high-winding V-8 is smoother and quieter and makes a welcome 45 more horsepower, giving it 290 at 4250 rpm against 245 at 4800. Torque rises, as well, but only by a modest 1 pound-foot (290 at 6100 revs versus 289 at 4000). Even so, a minimum 90 percent of that twist is fully accessible from 2500 to 5700 rpm, ensuring near immediate response to any throttle input.
An equally critical hardware upgrade is the new transmission. Also used on the XK8, this electronically controlled dual-mode (Normal/Sport) ZF five-speed replaces the previous GM four-cog unit. Motive force ultimately ships to the rear wheels via a new differential that houses a taller (3.06:1 versus 3.58:1) axle ratio. The most important change here is that the third member mounts on-centerline as opposed to the slightly offset position used in the past. Squaring up the driveshaft relative to the transmission and rearend results in diminished levels of noise and vibration.
Our test car also had the optional all-weather package, which supplements the standard Automatic Stability Control with a driver-defeatable traction control package. (The former works by regulating the throttle and ignition under low-grip conditions while the latter also integrates the ABS).
The net result of this comprehensive drivetrain transplant is a luxury sedan with legitimate performance-car overtones, able to streak 0-60 mph in a seriously quick 6.7 seconds. While 1.3 ticks slower, the factory claims, than its new V-8-powered XJR cousin will run, the latest XJ8 L is 0.1 second quicker than the old supercharged six-cylinder XJR. The XJ8 L's 15.0-second/94.2-mph best in the quarter mile also pips the previous XJR by 0.1 tick and 1.1 mph. Even more good news: EPA numbers of 17 mpg city/23 mpg highway indicate this added firepower exacts no penalty whatsoever on fuel economy.
Complementing the powertrain improvements are multiple chassis tweaks that also draw heavily on the XK8 for concept and, in some instances, components. Despite a longer wheelbase (117.9 inches versus 113.0 on an XJ8), the basic suspension design remains as before: double wishbones and coil springs at each wheel with Jag's signature use of the halfshafts as upper links on the rears. Up front, XK8 uprights and lower A-arms are paired with unique forged-steel upper wishbones fitted special ride-isolating rubber bushings. The entire assembly is iso-mounted to a steel subframe that further attenuates vibration and road noise.
Although fully retuned for XJ duty, the rear hardware is pretty much carryover XK8. Tying the XJ8 L to terra firma are 225/60ZR16 radials (Pirelli P4000s in this case) on 16x7.0-inch cast alloy wheels, while steering is via a new ZF Servotronic power rack-and-pinion unit that offers greater precision than before. A bit on the heavy side at lower velocities, it comes into its own as road speed escalates. The Jag's ABS-abetted four-wheel vented discs also deserve kudos. They hauled this 4044-pound sedan from 60 to 0 mph in just 128 feet.