To the several gentleman who replied to my inquiry:
Thank you all for your quick and courterous reply. I will accept the fact that the pads are composed of a soft compount and must be replaced at a shorter interval that I would have ever expected. I remain disappointed as this extra annual expense is not one I would have anticipated.
Another question to anyone who drives an ML320: I drive about half my time on the freeway and half in the city. I've calculated every tank of gas (for the past 17,700 miles)and I average about 16 mpg. Is this what one should expect? Thanks and best regards, H.G.