SANTA CLARITA, Calif. -- Enormous 20-inch Pirelli 295/45ZR20 Scorpions ply rubber to pavement on Sand Canyon Road coming down from the San Gabriel Mountains near Los Angeles as the throttle goes to the floorboard and the muscle of 470 stallions stampedes the world's fastest Jeep into a fast-lane frenzy.
We're talking too quick: This souped-up Grand Cherokee SUV, outfitted with a big-block HEMI V8 and the suspension dropped half an inch on sport-taut springs, zips from zero to 60 in less than five seconds, then passes the quarter-mile post in 13 seconds plus change.
A Jeep -- long-time synonym for go-anywhere four-wheel-drive traction in rugged mud-loving and trail-crawling off-road machines -- can muster fast-track times like a high-performance sports car?
New Grand Cherokee SRT8, swiftest and strongest vehicle ever to wear that chrome-coated J-E-E-P badge, performs like a raucous sports car but carries a boxy back bay under the thin disguise of a practical sport utility wagon.
This story begins with Jeep's flagship Grand Cherokee, which represents the original sport utility vehicle and traces for decades in Jeep history with innovations like the Quadra-Trac automatic full-time 4WD system in 1973, and a watershed design in 1984 for the first unibody SUV.
The nameplate of Grand Cherokee emerged in 1992 attached to a new wagon which demonstrated that a SUV could conquer rugged challenges of the off-road world and still transport riders in comfort due to cushy cabin appointments.
A larger version appeared in 1999 with a luxury-lined cabin plus mechanical systems aboard which raised the bar for SUV performance, while the 2005 Grand Cherokee with stronger structural systems and multiple engine options established even higher benchmarks.
But Jeep rolled out the Grand Cherokee of 2011 and everything about the redesign seemed fresh and better and bigger with a wagonload of new features.
Some gearhead gurus at the Street and Racing Technology (SRT) division of Chrysler requisitioned the latest iteration of Grand Cherokee and began to beef it up with their retinue of high-performance car tricks.
Result of these experiments becomes the street-legal 2012 Grand Cherokee SRT8.
The SRT initials mark high-performance vehicles for Chrysler and Dodge and Jeep, while the digit tacked at the tail indicates the number of cylinders in a big engine.
Grand Cherokee SRT8 of 2012 totes a larger and more powerful yet more fuel-efficient big-block HEMI engine, a new adaptive damping suspension with selectable suspension tuning for world-class ride and handling, a new SRT-badged heated steering wheel with paddle shifters for hands-on-the-wheel shifting, plus the option of a 825-watt Harman Kardon audio kit with 19 speakers.
The SRT8 treatment starts with that expanded big-block engine -- a 6.4-liter HEMI V8 which kicks out 470 hp at 6000 rpm plus 465 lb-ft of torque at 4300 rpm.
The V8 comes with standard Fuel Saver Technology (FST) technology which can switch seamlessly and transparently to a fuel-saving four-cylinder mode when all of that horsepower is not needed for romping.
Premium 91-octane fuel is recommended for the SRT Grand Cherokee and the estimated fuel economy figures come in at 12 mpg for city driving and 18 mpg on the highway.
All power from the big HEMI channels through a heavy-duty electronic automatic five-speed transmission (W5A580) teamed with the AutoStick manual shift controller.
Every Jeep comes with 4WD traction and the SRT8 is no exception, as it stocks Jeep's Quadra-Trac active on-demand four-wheel-drive transfer case and electronic limited slip differential (ELSD).
The device lets a driver dial in one of five settings (Auto, Sport, Tow, Track, Snow), then the system tailors the vehicle's traction performance to fit the type of terrain covered through modulation of powertrain response, transmission gear selections, and electronic controls.
SRT engineers worked on the Grand Cherokee SRT8 suspension. They lowered it by half an inch and tuned it tightly for performance with tailored spring rates and bushings, big anti-sway bars in place plus anti-skid controls via an electronic stability control (ESC) device.
To rein so many horses, the 20-inch wheels on Grand Cherokee SRT8 carry big disc brakes. Up front, the 15-inch rotors team with Brembo six-piston calipers painted red. Rear ones with 13.78-inch rotors get Brembo four-piston calipers. All four discs are linked and controlled through an anti-lock brake system (ABS) plus traction control system (TCS).
Special body modifications on the 2012 Grand Cherokee SRT8 are designed to enhance pavement performance. For instance, a new one-piece front fascia adds multi-function LED daytime running lamps plus special ducts that pull fresh air in to cool the front brakes, while the sculpted hood has dual black heat extractors to enhance engine cooling.
The five-seat passenger compartment skews to techno mode with trimwork in carbon fiber, Nappa leather and suede.
An optional Command View dual-pane sunroof measures twice the size of a standard sunroof and reaches from the windshield to the rear of the vehicle.
Jeep builds a more powerful and more sophisticated 2012 Grand Cherokee SRT8 with price points starting at $54,480.