We have a winner in the longest brake pad life contest: P.E. Haiges!
Phenomenal! Never heard of a fellow Benz-lover getting 120K on MB pads. My brother did get that kind of mileage on his Lexus, despite a "lead foot," but MB, as I understand it, deliberately uses rather soft pads to maximize braking at the expense of the pads. Certainly, I (and others on the 'detailing' list) carp about the large volumes of brake dust on our front wheels!
Admittedly my 400E has a larger swept area that a 300E, for example, and may chew up pads quicker than some, but from what I've heard on this and other lists, about 20-25k on front pads seems to be about average.