Throttle response is instantaneous from the standard XJ8's 290-horsepower V8 engine. On dry pavement, with the traction control turned off, the XJ8 will light its rear tires and deliver startling acceleration performance. Jaguar says the XJ8 can accelerate from 0 to 60 mph in 6.9 seconds, an impressive feat given its size and weight. Under the bonnet is Jaguar's 4.0-liter V8 with double overhead-cams and four valves per cylinder. Called the AJ-V8, it produces 290 horsepower at 6100 rpm and 290 pounds-feet of torque at 4250 rpm.

Likewise, the big Vanden Plas is fast traffic. Punch it at highway speeds and you're past all those lesser automobiles. We were surprised how well this longer wheelbase model handled on narrow, crowned roads in Virginia's Albemarle County. Handling is crisp and well controlled, even in vigorous transient maneuvers. Shocks automatically get firmer as the car is pushed through the corners. The Vanden Plas comes with Jaguar's Computer Active Technology Suspension, or CATS. It sounds like something from a James Bond movie, but it works great. Essentially, CATS is a two-stage adaptive ride control system that automatically adjusts the shock absorbers for road conditions and the driver's demands. Handling of the Vanden Plas is very impressive for such a big, heavy sedan. It comes with a choice of 16- and 17-inch tires on special alloy wheels.

Jaguar's five-speed automatic transmission is silky smooth, even at full throttle. You can almost feel the transmission signaling the engine to reduce power slightly because a shift is coming. There's a nearly imperceptible pause as the gear is changed, then the surge ahead continues. The five-speed automatic adapts electronically to varying driving conditions. It senses whether the driver is cruising the Interstate, hotfooting down a back road, or climbing a long grade, and it varies shift points accordingly for optimum power and efficiency. The driver may select Standard or Sport modes: The standard PRNDL pattern can be used, or shifts can be made manually by moving the stick to a separate gate on the left. This can be entertaining at times, but almost seems superfluous with a transmission that does such a great job of shifting on its own. The manual operation is electronically controlled to prevent downshifting at an inappropriate speed. The Jaguar transmission even compensates for aging by adjusting shift quality based on any slippage it detects.

Automatic Stability Control is standard on all Jaguars. ASC operates at all speeds, easing back on engine power to reduce wheel spin on slippery roads. If a rear wheel starts to spin, the anti-lock brake (ABS) sensor signals a computer, which then reduces the throttle opening, retards the ignition timing or cuts fuel to the cylinders. Jaguar's traction control system includes all ASC functions plus brake intervention. Both types of traction control can be switched off. The brakes work well on the XJ models and are easy to modulate.

The front suspension on the XJ Series is independent, with unequal-length upper and lower wishbones, coil springs, shocks and an anti-roll bar. Lower wishbones are used at the rear with the drive shafts acting as upper links, a setup Jaguar has favored since 1961. These components are arranged to discourage lift while braking and squat while accelerating. Variable-ratio rack-and-pinion power steering is speed-sensitive.

XJR, XJR100, and Super 8 models are transformed by the supercharged engine, and make the XJ8 seem sedate by comparison. The belt-driven blower is nestled between the 90-degree cylinder banks, forcefully pumping air to the intake system. Intercoolers chill the air to increase its density and, thus, its oxygen content: Call it O2 concentrate. The upshot is powerful and immediate throttle response, and the setup inflates the XJR's torque all the way up to 387 foot-pounds at 3600 rpm. At a mere 1600 rpm, the XJR produces as much torque as the normally aspirated XJ8 does at its peak. Zero-to-60 time is 5.4 seconds, and the quarter-mile arrives in the high 13s. That's quick by anyone's stopwatch, and amazingly quick for a big luxury sedan.

The supercharger whines when you're working it, a hot-rod sound that comes as a bonus with the XJR's hot-rod performance. Our test model was black, and it's the only color we can imagine for the XJR. In one package, you have elegance, brawn and, when you stand on the gas, outlaw aura. It may sound schizophrenic, but it all comes together in wonderful, symbiotic harmony.

For 2002, all XJRs ride on CATS. The XJR's suspension is tuned for its role. But this isn't a car you flick, it's a car you bend. And when you bend it into the corners with respect, it responds with dignity. The Pirelli 255/40 ZR18 tires certainly contribute to its impressive grip, which other testers have proven on a skid pad. But those same tires also deliver an ever-so-smooth ride. It takes an extreme road surface or an overly aggressive driver to upset the XJR. The ride and the engine could almost lull you to sleep, if you could possibly imagine falling asleep in such an exciting automobile.

The five-speed automatic transmission is perfectly suited to the Jaguar's personality. It's the same transmission used in the AMG Mercedes-Benz E55, and a heavier-duty unit than the five-speed automatic used in the XJ8, XJ Sport, and Vanden Plas. Punch sport mode and you can shift it manually, once you've slid the shift liver into the short end of Jaguar's trademark J-gate shift pattern.

The XJR also carries bigger brakes than the XJ8. The front rotors are 12.8 inches in diameter, up from the XJ8's 12.1, and the rear rotors are 8.0 inches vs. 7.2, yielding 16 percent more swept area. They'll certainly stop you quickly enough, but the pedal feel and travel is on the luxury side of sporty.

So despite its hot-rod demeanor, the XJR is really the ultimate grownup's cruiser. It's hard not to compare it to the far less compromising BMW M5, but they're totally different beasts, forcing one to admit that "high-performance sedan" is a broad description. The XJR may not be as quick as the M5 or AMG E55 on a twisting road circuit, but the Jaguar would hold its own on a banked oval like Michigan International Speedway or, better yet, the flatter Indianapolis brickyard. At those faster circuits you might back off the throttle and feel that fantastically smooth engine roll up and down. Top speed is rated at 155 mph.

Super V8 models offer the roominess and luxury of the Vanden Plas, but benefit from the much more powerful supercharged V8 and the XJR suspension.

Ford now owns Jaguar, and the XJ has greatly benefited from Dearborn's financial support and modern technology. Jaguar's traditional problems with electrical systems and electronics have been eliminated since Ford became involved.