Nigel, thanks for posting. This is neat and would have missed it if you hadn't.
We have only half the mileage on my wife's 99 ML320 and am looking forward to the 500,000 mile goal ourselves, probably won't live long enough to get 800k. As a lifelong user of these vehicles, we tend to keep them forever, like my Leica camera.
I will send this link to Gary Anderson at the MBCA, as he is always looking for topics to put in the award-winning club magazine.😎