Two engines, three four-wheel-drive systems
The Grand Cherokee is the first vehicle to use Chrysler's new Pentastar V-6, an engine that is set to replace a total of seven different six-cylinders currently used in the company's cars, minivans, and trucks. The aluminum-block 3.6-liter boasts a substantial power increase with a modest fuel economy benefit over the Grand Cherokee's outgoing 3.7-liter unit. That outdated engine had just two valves per cylinder controlled by a single camshaft over each cylinder bank. The Pentastar uses a decidedly more modern design, with four valves per cylinder, two camshafts per bank, and dual cam phasing. City fuel economy is unchanged at 16 mpg, but highway climbs two ticks to 23 mpg on the highway (22 mpg for four-wheel-drive vehicles). The power gain is decidedly more impressive, climbing from 210 hp to 290 hp with a torque output of 260 lb-ft.
At more than one mile above sea level in the hills surrounding Moab, Utah, we needed every bit of power to hustle our 4850-pound test vehicle. The power is adequate for most situations, but we'd like more for the uphill sprints, highway merges, and inviting roads. Our V-6 Limited model was also burdened by inconsistent behavior from the standard five-speed automatic transmission. The lightest throttle application sometimes delivered aggressive downshifts. Other times, we would plant the gas pedal without response from the transmission, left to build revs from 3000 rpm. Despite those complaints, the 80-hp boost over the old 3.7-liter is worth celebrating and the engine is unobtrusive in relaxed driving.
The safe bet for passionate drivers is the familiar 5.7-liter Hemi V-8 that can be had in cars like the Dodge Challenger. It makes 360 hp and 390 lb-ft in the Grand Cherokee, and will quash any acceleration complaints. A five-speed automatic is again the only transmission, but it's an entirely different gearbox and the programming is better sorted out. Downshifts are predictable and upshifts are smooth. Early estimates put the fuel economy of four-wheel-drive V-8 trucks at 13/19 mpg.
Regardless of how often Grand Cherokees are or aren't taken off-road, the reputation for all-terrain competence is core to this Jeep's image. Three unique four-wheel drive systems are available, with varying degrees of complexity and capability, along with a rear-wheel-drive offering for those in southern states. The entry-level system is more for foul weather and a sense of security. Called Quadra-Trac I, it fixes the torque split at 48 percent to the front and 52 percent to the rear wheels.
Quadra-Trac II is the bare minimum for any serious off-roading with its two-speed active transfer case. The active part means that the torque distribution can be varied between the front and rear axles from 100 percent at the rear wheels to a 50/50 split. The two-speed portion indicates that there's a low-range gear for low-speed, high-torque crawling on dirt, in sand, or over rocks.
Both our V-8 and V-6 test vehicles were equipped with the top-end Quadra-Drive II. The all-wheel drive hardware is the same as Quadra-Trac II with the addition of an electronically controlled limited-slip differential on the rear axle that manages side-to-side power distribution.