Felix Sabates'

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Driving Impressions

We had the opportunity to drive one of the first production versions of the GLK350 in Dusseldorf, Germany, and came away very pleased with the GLK and bullish about its future.

The GLK350 is powered by a 3.5-liter V6 engine, coupled to a seven-speed automatic overdrive transmission called the 7G-Tronic 7. The GLK350 V6 engine will be rated at 268 horsepower at 6000 rpm, with 258 foot-pounds of torque available from 2400 to 4500 rpm, and 87 percent of that maximum number available as low as 1500 rpm, useful for crawling off-road.

The GLK350 can accelerate from 0-60 mph in just 6.5 seconds, says Mercedes, with a top speed of 143 mph and expected highway fuel economy of 22 miles per gallon. This is one of the most efficient and sophisticated engines that Mercedes-Benz has ever built, including lightweight casting techniques, forged connecting rods, variable valve timing on both intake and exhaust valves, variable intake tuning, and advanced combustion techniques for cleaner emissions and greater power.

The seven-speed transmission, as with most recent Mercedes-Benz automatics, will gradually adapt to the driver's own driving style and change shifting patterns accordingly. By analyzing speed versus throttle opening comparisons, the transmission will know whether the GLK is going uphill or downhill and will either delay upshifts or hasten downshifts accordingly. And, unlike most SUV automatics, the 7G-Tronic in the GLK will come with a TouchShift feature for side-to-side manual control and a choice of Comfort or Sport shifting modes for the driver's choice of higher rpm shifting and harder shifts or lower rpm shifting and softer shifts.

All-wheel drive is available and, called 4MATIC, it is the latest development of this technology. The new, lightweight 4MATIC computer-controlled all-wheel-drive system uses a 45/55 front/rear torque bias and uses a dual-disc clutch that acts as a locking center differential in difficult traction situations.

The front suspension combines two separate lower links with coil spring struts, twin-tube gas shocks and a stabilizer bar. Rather than one large control arm like a conventional MacPherson strut, the two forged-aluminum lower links provide better impact absorption in case of an impact. The low mass also contributes to better wheel control and damping. The top of the strut is connected to the body by a triple-path bearing, in which spring forces are transmitted directly to the body, but damping forces go through a rubber bushing that turns with the bearing during steering. Forces that exceed the suspension's travel, like a pothole or a curb, pass through a bump stop, then go directly into the body. The front suspension links are mounted to a high-strength steel subframe that also carries the engine, transmission and rack-and-pinion steering, which is mounted in front of the wheel center. The Mercedes-Benz five-link independent rear suspension has been updated for the GLK. Mercedes engineers have redesigned it to minimize unsprung weight and optimize strength. A new rear high-strength steel subframe holds the final drive and suspension links.

Agility Control technology provides the benefits of both soft and stiff shock absorbers. Each shock absorber in the GLK is fitted with a hydraulic by-pass piston that acts like a very soft shock absorber to dampen road noise and tire vibration. The by-pass piston is inactive during normal shock absorber operation, to maintain the steering and handling response of a stiffer shock absorber.

The new GLK features four-wheel disc brakes with a standard anti-lock braking system (ABS). The brake pedal operates an aluminum master cylinder, and a tandem brake booster uses two eight-inch diaphragms to amplify the pedal power. Floating calipers, twin-piston up front and single-piston in the rear, squeeze the brake pads against vented brake discs, 13 inches in front and 11.8 inches at the rear.

The GLK rides on 19-inch, ten-spoke alloy wheels shod with 235/50HR-19 all-season tires. Optional 20-inch seven-spoke wheels, 8.5 inches front and 9.5 inches in the rear, wear 235/40R-20 tires in front and 255/40R-20 at the rear.

In our drive from Dusseldorf to the Schloss Ehreshoven and back, traveling on the autobahns, winding country roads, and village streets, we pushed the GLK as hard as we dared, trying to find flaws in its driving manners, and we came up empty.

The GLK behaves more like an E-Class sedan than a truck, quietly soaking up bumps and potholes and other imperfections, and it cruises easily at 115 mph with the 3.5-liter engine when traffic and space permit. Acceleration is very good for a vehicle of this weight, and in seventh-gear overdrive, it just purrs along at about 1800 rpm at 75 mph.

On the truly rugged and challenging off-road course at Schloss Ehreshoven, with a 35-percent grade and a 35-degree side slope on one section, the GLK performed brilliantly. Through deep water, over logs, through narrow gaps in the trees, it took the entire course in stride, without having to back up or back down once to negotiate a very tough course. The combination of the new 4MATIC system, traction control and ESP kept the GLK going through mud, over rocks, and through the water. In several situations where only one tire was touching Mother Earth, the system pulled through.

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