The 4.2 liter V8 comes naturally aspirated or supercharged. Both engines are updated versions of those used in Jaguar's S-Type sedan (which the XF replaces), with reinforced engine blocks to reduce vibration and the latest control technology. The normally aspirated V8 is no slouch in output, delivering 300 horsepower and 310 pound-feet of torque. With its belt-driven, rotor-type blower, the supercharged 4.2, or SC, generates 420 hp and 408 lb-ft. It's easily the most powerful engine in this class, save those in limited-volume hotrod cars from BMW's M division, Mercedes AMG and the like, expensive cars with expensive engines.
Floor the gas pedal in the SC and you might be struck by what's missing. The supercharger whine is so subdued, compared to previous Jaguars, that it takes a couple of full bursts before the thrust convinces the driver that this is the upgrade. And thrust there is, in long, effusive swells that make you wish every road ran uninterrupted to the horizon. The supercharged V8 keeps pumping acceleration-producing torque from 2000 revs to its 6200-rpm redline, with no climax that suggests a peak. We'd estimate that the XF 4.2 SC will hit 60 mph from a stop in five seconds, or maybe a tenth more. It will go from 60 to 100 mph much faster than it takes a semi to enter two-lane in front of you. Top speed is electronically controlled at 155 mph.
Put another way, we'd guess that the XF SC is the quickest car in a group populated by some very quick sedans, except for the previously mentioned ultra-performance cars like the BMW M5 and Mercedes E63 AMG. The SC has, after all, the same mechanical package as the former S-Type R, which was Jaguar's version of the M or AMG cars. Yet nothing in XF suggests a hot-rod quality. Rather, it shoots ahead in a smooth, unruffled fashion befitting a $60,000 luxury sedan. The fuel mileage isn't bad, either, despite the power and acceleration advantage on the competition. Jaguar anticipates EPA fuel economy ratings 17 City, 23 Highway of the XF SC, which is better than any current V8-powered car in the class, and better than some six-cylinders.
The six-speed automatic contributes to the XF's sporting character, using adaptive gear-change strategies based on the type of road and the driver's application of the gas pedal. This transmission anticipates as well as any automatic, ever, generally shifting at precisely the point the driver would if he were doing so himself, and always, always, shifting smoothly. Manual shifting works nearly as well. The paddle shifts are impressively quick but never excessively harsh. In manual mode, the SC transmission stays in the driver's chosen gear at any engine speed to the redline, without shifting up on its own. Every automobile manufacturer should tune its automatic transmissions like the one in the XF.
JaguarDrive Control is a feature that lets the driver tailor various functions to taste with a single adjustment. This system, which comes standard, incorporates most electronic control programs, including: how early or late the transmission shifts; the throttle map, or how much the engine accelerates for a given dip of the gas pedal; and the Dynamic Stability Control, or skid-management electronics.
The driver can switch through three options: Winter is the most conservative; the transmission shifts up at low engine speeds, the throttle works lightly and the DSC intervenes quickly, all useful in slippery conditions. Dynamic is the most aggressive setting. There is also a set-and-forget Automatic mode. All of the electronics are state of the art. The DSC electronic stability control includes an Understeer Control Logic that helps manage sliding front tires or pushing, which is more likely for the typical driver on a dry road than a fishtail-type skid (called oversteer). The ABS (anti-lock brake system) features Cornering Brake Control, which balances brake application from side to side in a curve, allowing the inside and outside tires to brake with the same effective force.
Still, the slickest electronic systems ever aren't worth much if the underlying mechanical components aren't up to snuff. Our test drive suggests that the XF's are first-rate. It starts with a tight, flex-free unitized chassis and body, which lays the foundation for all of a car's dynamic behavior. The XF's suspension design is taken from Jaguar's XK sport coupe and roadster, with a sophisticated multilink arrangement in back and aluminum components to reduce weight and improve the suspension's response time. Normally aspirated XFs are equipped with conventional, passive shock absorbers, while the supercharged model has Jaguar's Computer Adaptive Technology Suspension. CATS uses electronically controlled shocks to vary the dampening rate, optimizing ride comfort or handling response depending on road conditions or the driver's preference.
If the engineering talk looks like gobbledygook, the bottom line is simple. The XF delivers a ride-handling balance and steering response that match its sporty looks nicely. Measured by overall, balanced performance, the Jaguar XF surpasses many other cars in a category populated by some of the best cars in the world. The XF glides over bumps that ruffle some luxury sedans more, yet it never leans excessively through fast curves. It stays nice and level front to rear under hard braking or hard acceleration, and it's as stable as granite at high speeds.
The steering uses variable-ratio technology, which was developed to reduce parking effort at low speeds while maintaining precision and feedback at higher speeds. Generally, the XF's steering leans toward the light side, but not toward airy, and it's quick for a fairly large sedan. Lane changes at interstate speeds are accomplished with a flick of the steering wheel. The XF turns neatly into bigger, slower curves, always where the driver aims it, and the SC's standard sport tires deliver sports car-style grip.
In its most sporting mode, CATS nearly eliminates squat, dive or lean. But even with the shocks doing their absolute best to keep the tires pressed to the pavement, ride quality never suffers much. Much of our test drive transpired in the rain, which demonstrated two things: First, that the XF is inherently balanced, meaning it's no more prone to slide on its front tires than it is to spin out in back, and second, that the Dynamic Stability Control does a great job.
In the Automatic mode, where most drivers will keep it, the DSC works early, throttling the engine back or tapping brakes before the driver anticipates that one end of the car or another might be sliding. Yet those who want to see a little more of what the XF can do can choose the Dynamic mode. This allows the XF to move a bit more laterally, and it allows the driver to slide the car a little, as enthusiast drivers are want to do, before the DSC clamps down. In a sense, the XF delivers the best of all worlds: comfortable ride, responsive, consistent handling, stress-free, secure skid-management in the rain or bit of latitude that allows capable drivers to express themselves. There's even a track mode for those who want to play race driver. This switches the DSC off completely and allows big fishtails and smoking tires, though we can't imaging the typical XF owner using it very often.
The 4.2 SC might be the XF for ruffians, but the Luxury and Premium Luxury models aren't exactly slouches. Their six-speed automatic works just as well in typical driving, even if it doesn't seem to hold first or second gear as diligently as the SC does when used in manual mode. The normally aspirated V8 delivers power in the same linear fashion, and it's even smoother, and the acceleration can still be exhilarating. We'd peg 0-60 mph times in the low six-second range, which is more than respectable by just about any standard. The normally aspirated XFs also deliver better mileage: 18 City, 26 Highway, according to the EPA.
The Luxury and Premium Luxury XF sit more toward the center of the ride-handling spectrum, with more emphasis on a traditional, plusher luxury ride. They're sprung more softly, not having CATS, so they respond to the driver's inputs a little less immediately than the SC. Yet they are no less balanced than the SC, and no less assured or consistent.
The brakes are outstanding in all cases. All XFs have large rotors and calipers, and the brake pedal has a nice solid feel. It's also progressive in application, meaning that a little bit of pedal delivers a little bit of deceleration, while a lot of pedal stops the XF right now.
Dynamically, we like most everything about the XF, but performance is only one requisite in this class. Luxury buyers expect extra smooth, quiet operation for the money and the XF holds up its end. It starts with that solid underlying structure, which is the first defense against vibration and harshness inside the car. From there Jaguar adds more measures, including a double bulkhead in the front of the cabin and rubber mounted subframes for the suspension, which minimizes the transfer of road vibration inside.
Cruising at 70 mph is generally a serene experience, with minimal wind noise and only an occasional slap of the tires on bumps to interrupt the solitude, or the assertive growl of the V8 if the driver decides to slam that gas pedal. Overall, the XF might be the smoothest, quietest Jaguar in memory. It's at least as smooth as Jaguar's larger XJ sedan, and quieter around town than any mid-size luxury sedan we've driven recently, even with the SC model's rubber-washer tires on 20-inch rims. It was so quiet that the slap of the wipers working at high speed seemed excessive and out of character, though Jaguar attributed this to sub-production tolerances on the pre-production pilot XF we tested. next page