Windshield wipers stutter on windshield and malfunction. this jittering across the windshield impairs visibility. windshield is not kept clear, even with new blades. windshield cleaners also plug up continually making washing the windshield while driving in areas which create visibility problems due to dust, bugs, etc....impossible -- even if cleaner fluid tank is full. the entire system is an issue. mercedes knows this is a problem. the suv has been in for repair 4 times since purchasing last october. they have replaced it each time, say they know there is a problem, and say they will not replace it again. they say that non-mercedes windshield wiper fluid is a problem (but the first 3 times, the fluid was original mercedes fluid). they say putting the vehicle in a car wash is prohibited -- a ridiculous comment. who doesn't put their suv in a car wash? the mechanism is faulty and mercedes won't take responsability and it is a safety problem.