No matter whether you opt for the big V-8 or skimp on fuel with the diesel, the Mercedes GL won't disappoint with firm, precise handling.
Our choice among the three GLs would be the version outfitted with Mercedes' turbodiesel six, the GL 350 BlueTEC. A "clean" diesel that uses low-sulfur fuel and treats its exhaust for cleaner emissions, the BlueTEC edition produces 210 horsepower and a very useful 400 pound-feet of torque from 3.0 liters of displacement. That level of torque gives the GL 350 a narrow powerband, but very brisk acceleration from a stop, with just a touch of diesel vibration and noise at very low engine speeds. Mercedes pegs its one-tank driving range at 600 miles, and the EPA rates it at 17/21 mpg, among the best of its kind.
The next step up the pricing and prestige ladder is the GL 450, powered by a 4.6-liter V-8 with 335 horsepower. It's relatively unstrained in any driving mode (though we haven't yet towed with the GL), but doesn't feel quicker than the diesel, while its gas mileage drops well off the BlueTEC mark at 13/18 mpg.
Before you get spendy with the 382-hp, 5.5-liter V-8-powered GL 550, make sure you can swing its gas mileage of 12/17 mpg. It's tempting, what with the rippling engine note and muscular acceleration to 60 of about 7.4 seconds.All versions shift power to all four wheels through a seven-speed automatic that's very well matched to the kind of driving most SUV drivers engage in. We've noticed some shift shudder in diesel-equipped models, but haven't been able to drive a 2012 model year to see if it's still the case.
The GL-Class doesn't earn all its kudos with strong acceleration. It's quite capable at corners, with balanced handling for its size. A standard air suspension is damped with a bias toward ride comfort, and steering is precise and has about the weight you'd expect from a large vehicle. The GL is fairly stiff in its resistance to body roll; softer settings might help produce a little less rocking motion side to side, but we'd also avoid the big 21-inch wheels if you can, since they tend to degrade the ride quality.
Mercedes' 4MATIC full-time four-wheel-drive system is standard across the board, along with Hill Start Assist, Hill Descent Control, and a load-leveling suspension. Whether it's crawling through challenging mud pits or just cutting through late-season snow, the GL is talented enough for the kind of medium-duty off-roading it would encounter on its way to a ski resort or a mountain hideaway. Of the three models, only the GL450 can be ordered with an Off-Road package for more hardcore use: it adds on a Class IV hitch, an adaptive-damping suspension system, underbody skid plates, and locking differentials.
Every GL-Class SUV can tow up to 7,500 pounds.