Jaguar is as serious as a heart attack about tackling Porsche territory-hence the transplant of its big, bawdy 5.0-liter V-8 into the 2010 XK and XKR.
The engine tosses off 385 horsepower and 380 pound-feet of torque. With the sole transmission offered, Jaguar says 0-60 mph times will fall to about 5.2 seconds. It's not quite a Jekyll-and-Hyde moment, but the added 75 horsepower are far more vocal and come with a muscular, NASCAR-ish exhaust noise that's addictive. Acceleration is beyond brisk, and throttle response is prompt; the base XK will overstep its 19-inch Dunlops if you apply too much pedal with cold tires.
The gearbox, a six-speed ZF automatic with manual shift control, paddle controls, and Sport and Snow shift modes, is a faultless combination of seamless, fast gearchanges smoothed over with rev-matching on downshifts. The XK's fuel economy is EPA-rated at 16/24 mpg (16/22 mpg for the convertible), and we've seen a decent 18-mpg average in mixed driving.
Ride and handling are superb. Steering is a responsive joy, and Jaguar's tuned the highway ride for good tracking, flat cornering, and great grand-touring comfort. In our test cars, the XK's brakes have been particularly full of feedback and easy to modulate. All XKs have the Adaptive Dynamics suspension, with continuously variable dampers; it does an amazing job of filtering out abrasive road surfaces and jarring road scabs, without much excess body motion.
Did we forget the XKR? How could we? It's essentially the XK formula, with a few thousand more BTUs applied. The V-8's supercharged, blown up to 510 hp and 461 lb-ft of torque. Jaguar says it's capable of 0-60 mph runs in just 4.6 seconds, but some buff books have dropped it in 4.0 seconds flat. This is one...hell...of a fast car. Flexible, too-it'll loaf all day around 2,500 rpm, where it's already churning out three-quarters of its maximum torque. The adaptive suspension's electronic screws are tightened a bit more and 20-inch wheels are fitted, but the XKR keeps most of the fine damping and immediate feel of the base coupe and convertible, with the same accurate, light steering.
Edmunds: "rip-roaring acceleration"
Motor Authority: "one hell of a fast car"
Cars.com: "convertible can leap from zero to 60 mph in 5.3 seconds"
Car and Driver: "smokes the Aston Martin DB9 in every regard for a lot less money"
Motor Trend: "When you step into the throttle, the XKR simply lurches forward and disposes of passed traffic quickly and confidently"
Cars.com: "manual-mode response is quicker than most"
Car and Driver: "ride is relatively civilized"
Motor Authority: "the XKR's limits are close to astonishing"
Car and Driver: "precise and communicative steering"
Edmunds: "will comfortably eat up hundreds of highway miles"