There are two available engines in the 2014 Mercedes-Benz GLK–a direct-injected V-6, and the turbodiesel four-cylinder that it should've come with from day one. We've driven both, and the GLK's excellent road manners remain, even with the now-electric steering. As for the drivetrains, that's all going to be a matter of personal preferences–assuming smaller, boxy and German is your cup of tea.
With a big advantage in fuel economy, the diesel's the clear choice. The 2.1-liter turbocharged diesel four spins out only 190 horsepower, but typical of diesels, it's a torqueaholic at 369 pound-feet. With standard all-wheel drive and the paddle-shifted seven-speed automatic, the burbly four pushes the GLK to 60 mph in an estimated 8.0 seconds, with a moderate amount of the classic oil-burner vibration and noise. Top speed's also limited to 130 mph. With highway fuel economy of 30 mpg, the GLK is a leader in its class, along with the new Audi Q5 TDI.
The GLK looks like an SUV and is billed as a luxury compact SUV, but its performance leans much more toward large sedan—that is, it accelerates faster and turns better than its styling would lead you to expect. We liked the GLK's light but precise and well-weighted steering feel when it was hydraulically actuated; now that it's made the switch to efficient electric power steering, it's lighter and a little less precise, but reasonably dialed in to what's happening under the tire treads.
Adding 4MATIC all-wheel drive doesn't dampen the GLK's enthusiasm too much. The queasy body motions and pitchiness you find in some other comparable vehicles during abrupt maneuvers is remarkably absent here. If anything, the GLK has lots of lateral ride stiffness, which you'll feel as side-to-side head toss on rough pavement. Otherwise, Mercedes-Benz has tuned the GLK's suspension to be taut but well damped; it doesn't allow the GLK much body motion, but the suspension will soak up most roughness from the road and the cabin stays tight and quiet even over rough roads or in high-speed cruising.
Off-roading is not the GLK's forte. But its four-wheel-drive system adjusts as the various traction systems determine where torque is needed most. What the GLK does do well is get you home safety in foul weather; the 4MATIC system excels in distributing power smoothly on a snowy road and avoiding wheelspin.