35,000 miles on mine; and I've never seen any white puffs. Maybe they didn't include that technology in mine.So the one surprise you wouldn't have seen yet is the puff of white smoke lasting 10-20 seconds. I hear it happens sometime after 10,000 miles, depending on your driving style, conditions, etc. It's a self-cleaning exhaust system. Another slick Mercedes idea.
I'm thrilled with the technology in these vehicles!
I do, however, do regular pedal to the metal accelerations on freeway on ramps to help clean out the particle filter. (PS - If you don't do this once in a while, I've been told that you will "coke" up and restrict the flow in that filter.)