There's only a small set of vehicles that have both good on-road and off-road performance, and among five-passenger vehicles, even fewer. The Grand Cherokee's the first one that comes to mind, from mud-loving Trailhawk models to the most powerful HEMI version of all, the SRT8.
The Grand Cherokee branches out from a single body style into three very different directions, offering reasonably frugal operation, luxurious power, or screaming thrust, all depending on which drivetrain you choose. There's also a variety of transmissions, four-wheel-drive systems, even a choice between air and conventional steel-coil suspensions, all part of the broad performance envelope that makes the Grand Cherokee a fit for so many uses--on par with vehicles like the BMW X5, Mercedes-Benz M-Class, VW Touareg, even the Porsche Cayenne, or something as prosaic as the Subaru Outback.
At the entry point into the lineup, the Grand Cherokee makes it work with a 290-horsepower, 3.6-liter V-6, a relatively new powerplant dubbed the Pentastar, now used across a wide swath of the Chrysler lineup. The new six incorporates a lot of technology that had been wanting from Chrysler's carryover and hanger-on engines for decades; the 3.6 can run on E85 ethanol blend, it has variable valve timing, and good midrange power. In each application since it's also felt more smooth and sounded less boomy, but we've noticed in the Grand Cherokee some resonant noise at freeway entrance speeds. Missing from the list of technology: direct injection, a big step forward for economy that's said to be coming within the current Cherokee's life cycle. Regardless, the engine's powerful and smooth enough to make it a viable choice, though we're eager to see its outdated five-speed automatic swapped out for Chrysler's new eight-speed unit, for fuel economy and drivability reasons.
The torquey optional engine is rated at 360 hp, and the 5.7-liter V-8 is more attuned to those who need its towing capacity on a regular basis. It's not badged a HEMI, but it's one in everything but name: it sounds like a HEMI, pulls like a HEMI, is identical to the HEMI-badged engines of just a couple of years ago, before fuel economy became such a selling point (and before Chrysler's parent company wore Italian loafers). It's aurally superior, but the HEMI's not such a huge improvement in everyday driving that it's worth the immense fuel-economy penalty. The V-6 version ekes out 17/23 mpg in rear-drive V-6 versions, or 16/23 mpg for the four-wheel-drive model; the V-8 musters only 13/20 mpg when coupled to four-wheel drive.
At the pinnacle of all things Grand Cherokee, there's the SRT8. As Chrysler tries to lift that SRT imprint into brand status, it's easy to see how this model could be one of its centerpieces. It's such a capable SUV, it bears comparison with Porsche's Cayenne--at sometimes half the price. The 6.4-liter V-8--a HEMI here too--tears around with 470 horsepower, channeling it to all four wheels through a five-speed automatic transmission with paddle shift controls. The claimed 0-60 mph time of 4.8 seconds isn't the only impressive number: the quarter-mile's pegged in the mid-13s, top speed hits 160 mph, and 60-0 mph braking cuts things short in just 116 feet. The downside, and there's always one, is the 12/18-mpg fuel economy, just 450 miles per big tank of gas. It's true performance art, and extravagant in ways you might never associate with the Jeep name.Further beneath its skin, the Mercedes contribution to the Grand Cherokee’s upbringing is more invisible. The Jeep's unibody architecture is stiffer and sounder than ever before, and that enables the steering and steel or electronic air suspensions to do their jobs more precisely than ever. No more live axle: the latest Cherokee's suspension is independent all around, and it gels with the steering to create crossover-like road manners. No more boundy ride or vague steering: the Grand Cherokee handles pavement about as well as a Honda Pilot, if not with the carlike ride motions of a Flex. With the Limited and Overland editions, there’s an available Quadra-Lift air suspension that can raise the Cherokee from 4.1 inches to 10.7 inches off the ground—great for off-roading, and even more settled on-road.
For the times you want to explore new territory, the Grand Cherokee can be ordered with one of three four-wheel-drive systems. The basic Quadra-Trac I is a standard locking differential in the middle, with power split 50:50 front to rear. Quadra-Trac II can split torque variably from front to rear, as traction disappears at either end; Quadra-Drive II adds on an electronic limited slip differential across the rear axle so that the Grand Cherokee can respond even more intelligently to slipping and sliding. You’d want the most extreme choice for the most extreme duties, but our favorite is the plain base setup—it’s lightweight, simpler, and more than enough traction control for casual drivers.
On top of all this, Jeep grafts a Selec-Terrain system to the torque-splitting systems. Selec-Terrain lets you choose one of five traction-control modes according to driving conditions: Auto, Sand/Mud, Sport, Snow, and Rock. In concept it’s a lot like the system in the Land Rover lineup; in practice, the Jeep version requires you to intervene more with the gas and brake. It’s useful stuff—if you don’t already know to take it slow and steady when conditions aren’t perfect. Lastly, with the rear-drive V-8 Grand Cherokee, Jeep claims a 7,400-pound towing capacity.
SRT8s, of course, get their own tuning, with adaptive air suspension and a "Selec-Trac" governing body that controls it and the stability control, transmission shift programming, transfer-case torque management, electronic limited-slip management, throttle and cylinder-deactivation controls, all split among five modes: automatic, Sport, Tow, Track and Snow. It's also working in concert with Quadra-Trac to ship torque around--all to one rear wheel if need be--to balance out traction on the SRT8's 20-inch, 45-series Pirelli all-season run-flats or optional P Zero summer tires. The sacrifice? SRT8s can tow only 5000 pounds while they turn in about 0.90g of grip. You'll never be able to compare an SUV driving experience to this one again unless you sample a Cayenne Turbo or an ML63 or an X5 M--it's flat, sharp, full of raucous engine noises, maybe a little agitated in its Track ride motions, fully tweaked for a great time.