Mercedes-Benz has been caught road testing a prototype version of the all-new Mercedes-Benz GLK medium-sized SUV. The new car features discreet revisions over the existing GLK, a model which isn't sold in Australia.

The car is loosely based on the Mercedes-Benz C-Class medium sedan, featuring similar engine packages and interior layout. With the new model, only slight changes will be made.

It will get new front and rear bumpers incorporating LED daytime running lights in place of the old spot lights at the front. There's also going to be more chrome trimming highlights.

The back of the new GLK will showcase only slight revisions including a redesigned rear diffuser section and exhaust outlets, and new taillights, even though this test car appears to be wearing the old taillight assembly.

Under the bonnet, the new GLK is expected to feature the new Mercedes-Benz C-Class 3.5-litre direction injection V6 petrol engine, as well as a 1.8-litre turbocharged unit for the entry-level model.

The new Mercedes-Benz GLK will reportedly go on sale sometime in late 2012, providing some German competition to the BMW X3 and Audi Q5.