I took a GLK320CDI 4-Matic out for a spin the other day and here are some of my opinions of the car:
It felt smaller and a lot bulkier in the body shape all over than I thought from seeing it on images.
Inside it was roomier and sight was good, except for the rear window that will be a problem on rain and dirty roads if the viper is not on all the time, its a big time dirt collector. About the sight is that the B pillar on the right side is too wide, when I was looking out to the right side it was taking up to much space.
Gearbox was lovely smooth and effective.
Engine had a nice growl when accelerating and the 4-Matic works like a charm (I guess as supposed to).
Had not that much time on my hands so I never got to try climbing any steep slippery hills but some climbing in snow was experienced and the car behaved as running on rail.
In my conclusion the GLK320CDI feels very sturdy and robust and overall high quality just as expected from A Mercedes-Benz. Even the correct door thump sound when closed was present. If you are looking to buy a car in this segment (small SUV) I would recommend it.