Fuel economy for our 4Matic-equipped model is estimated at 19 city mpg, 24 highway mpg, and 21 mpg combined. Skip the all-wheel drive in favor of a rear-driven model and you can add 1 mpg to the highway estimate. Those efficiency estimates aren’t particularly heinous, but the middle-of-the-pack averages aren’t much to get excited over either. Also factor in that Mercedes-Benz recommends that the GLK350’s 17.4 gallon tank be filled with premium gasoline, which very slightly increases operating costs.
Around town, the GLK350 handles like the vertically stretched C-platformed vehicle that it is. Differences in suspension tune give the crossover a smooth ride that dulls the worst bumps. However, it’s still firm enough that you don’t forget that the bumps are there. A bit of that firmness is probably due to the optional 20-inch wheels (though I can’t imagine that the stock 19-inchers are significantly smoother), but most of the thanks and blame should fall on the stiffly damped suspension system. The tradeoff for a slightly bumpy ride is that GLK does offer good responsiveness when dodging potholes and minimal squat and dive when accelerating or braking at intersections.
This is all assuming that you’re driving like a sensible person (or at least being smooth with your inputs). Get too lead-footed with jackrabbit starts and panicked stops or saw away at the steering wheel and the GLK350’s elevated center of gravity and the laws of physics will gang up on you.
The tall seating position of a crossover is a godsend for seeing over and around parked cars when easing out of blind alleys into traffic and 360-degree visibility is good thanks to the airy greenhouse and large windows. However, despite its parkable footprint, I found it difficult to spot the GLK’s corners during parallel parking maneuvers. Erring on the side of caution, I’d often end up further from the curb than intended, but it would be just as easy to scuff those shiny 20-inch wheels on a high curb.