Based on the C-Class platform, the GLK has a smooth 3.5-liter V6 that delivers quick acceleration and 18 mpg overall on premium fuel. Ride comfort is solid and tranquil when cruising, but the low-speed ride is a bit unsettled. The GLK handles fairly nimbly, but doesn't shine at its limits. The high, upright seating position affords a commanding view out through the big windows. The front seats are firm but well-shaped. Leg room in the rear is stingy at best and the wide doorsills impede access. The controls are better than in many Mercedes-Benz models, but some still aren't exactly logical. A 2013 freshening considerably improved the car, with a new V6 engine that increased fuel economy to 21 mpg overall and more luxurious interior materials. A four-cylinder diesel engine is also available.