Driving the V-6 Grand Cherokee reminded me that the laws of physics can't be changed. The SUV uses Chrysler's new Pentastar 3.6-liter V-6 rated at 290 horsepower and 260 pounds-feet of torque, but this is a heavy vehicle. The curb weight of the V-6 Limited 4x4 I drove was 4,850 pounds, and lugging all that weight around makes the V-6 labor; you can tell that it's working hard when you're accelerating. The V-6's performance is strong enough — which is good because Jeep expects 75 percent of Grand Cherokee buyers to opt for it — but it doesn't make the SUV feel quick. Once up to highway speeds, the V-6 cruises easily at 70 mph.

The V-6 teams with a five-speed automatic transmission, and it helps make the most of the V-6's available power. The transmission readily kicks down when you need more power to pass, and it shifts smoothly.

Choosing the optional 5.7-liter Hemi V-8 gives the Grand Cherokee more effortless acceleration; there's none of the laboring you feel when driving the V-6 on hilly terrain. However, considering the V-8 is rated at 360 hp and 390 pounds-feet of torque, it still doesn't feel as quick as you might expect. Again, the 5,210-pound curb weight of the V-8 Overland 4x4 I tested was like an anchor holding the engine back. Like the V-6, the V-8 drives a five-speed automatic.

Four-wheel disc brakes are standard, and the brake pedal has a very natural, linear progression.