Jeep's available high-output 4.7-liter V8 is lively. Its 30-horsepower advantage over the standard 4.7-liter V8 is noticeable. This engine provides the Grand Cherokee with smooth acceleration performance, and it sounds refined. It produces 265 horsepower at 5100 rpm and 325 pound-feet of torque at 3600, compared with the standard 4.7-liter V8's 235 horsepower at 4800 rpm and 295 pounds-feet of torque at 3200 rpm. In other words, it produces more power, but revs higher to do it. Most of the power increase comes from a higher compression ratio (9.7:1 vs. 9.3), so the high-output engine requires premium fuel.

The five-speed automatic transmission that comes standard with the V8 engines shifts unobtrusively. It makes hurrying up a mountain or passing slow-moving trucks a breeze. It has two overdrive gears, so in fifth gear the engine is only turning 2000 revs while cruising at 70 mph. You could say this transmission is actually a six-speed automatic: There are two second-gear ratios, a low second gear ratio for up-shifting from first and a higher second gear ratio for downshifting from third. No more than five gears, however, are used in sequence. Sometimes, usually when lifting off the throttle while coasting under momentum up a steep hill, the transmission will upshift with a hard thump, as if to remind us that we're in a vehicle built for serious off-road duty.

The Grand Cherokee seems sluggish off the line at first, but this is partly due to the throttle's long pedal travel. Experienced off-road drivers prefer a longer pedal travel for precise manipulation of the throttle in tricky situations. Deliberate mashing of the throttle brings a quick launch, quicker than in most other SUVs in this class.

The quick acceleration is due in part to the relative light weight of the Grand Cherokee, whose figure is kept trim by its unit-body construction. This design results in a platform that is lighter and more rigid than traditional truck-based designs that are built on a frame. The Jeep feels faster and more responsive than most V8 SUVs, especially the huge Chevy Tahoe and Ford Expedition.

A surprisingly tight turning circle adds to the Jeep's spirited, nimble feel. The Grand Cherokee feels controlled and steady when driving down a bumpy, rutted rural lane or off road. There's no need to slow down for rough railroad crossings. But under many on-pavement conditions, the Grand Cherokee drives like a big, heavy truck, leaning noticeably in turns.

Steering is quick but isolated. The steering was recalibrated for lower effort for 2003. When you turn the wheel you can't feel how much the front tires are slipping on pavement. You don't really steer the Grand Cherokee so much as guide it. But that's the same for all of the top-selling sport-utilities. Like them, the Jeep is a truck, sitting tall, and leaning side-to-side in corners and high winds.

All Grand Cherokees stop with four-wheel-disc brakes and ABS. Jeep refined the brakes for 2003 with new brake calipers and a high-output master cylinder to reduce pedal effort. Our Overland stopped confidently, but with the telltale diving motion of a high-riding off-road vehicle. The Up-Country suspension package that comes on the Overland lifts the body an inch higher than the standard Grand Cherokee suspension.

The trend among competing sport-utilities is to use independent suspensions for better highway handling. The Jeep Liberty uses an independent front suspension, and the new Ford Explorer's suspension is independent at all four wheels. The Grand Cherokee, however, rides on live axles, front and rear. This is a drawback on washboard-rutted roads, where the Grand Cherokee will bounce itself sideways at speed.

For the most part, however, the Grand Cherokee stays pointed straight ahead on bumpy roads. A triangle link locates the rear axle, keeping it square with the body. Careful tuning of suspension and drivetrain mounts allows a lot of compliant movement, so that the Jeep's axles lift and pivot over large bumps and dirt holes where the independent suspensions of other SUVs reach their limits of travel. As a result, the Grand Cherokee rides tolerably.

The Grand Cherokee requires fewer try-and-fail attempts to conquer off-road challenges. It will instill trail-driving confidence you never had, particularly if you know a few off-road skills, such as lifting both feet off the pedals while the Jeep is engine-braking down a mud-slicked embankment, or keeping both feet on both pedals while creeping over a pile of wet logs. You'll learn to make use of the long throttle-pedal travel to finesse the accelerator over slick obstacles in your way. This is a superb off-road vehicle.

Four-wheel-drive systems vary by model. Four-wheel-drive Laredos come standard with Jeep's Selec-Trac system, whose planetary center differential sends a fixed proportion of torque to the front and rear axles. Manually selecting the low range locks the center differential for maximum traction. Limited-slip differentials are available for both front and rear axles.

Quadra-Trac II, standard on four-wheel-drive Limited and Special Edition models, optional on Laredo and Freedom Edition models, is an on-demand transfer case that incorporates a progressive, speed-sensing torque-transfer coupling that varies torque automatically between the front and rear axles depending upon which has more traction. Quadra-Trac II comes with a low range. Laredo offers a similar system without the low-range set of gears called Quadra-Trac I. Limited-slip axles are available.

Quadra-Drive comes on Overland models, optional on Limited ($550). Quadra-Drive combines the Quadra-Trac II transfer case with Vari-Lock axles, which use hydromechanical torque-transfer couplings between the wheels. Jeep claims the Quadra-Drive system can send nearly 100 percent of engine torque to a single wheel when necessary.

Also standard on Overland is the Up-Country Suspension Group ($435 on Laredo, $290 on Limited), which includes heavy-duty springs and gas-pressurized shock absorbers, skid plates and P235/65R17 all-terrain tires.