Ok, so its just the one pump with 2 stages controlled by the ECU. Seems like this must be contributing to the high failure rate in some way because VDO make some pretty decent stuff. What isn't so smart is not having a carpet cutout for the frequent servicing that seems to be required. It seems that no matter what the brand, engineers get it wrong quite often. I have a bit of a background with Benz diesel models and they did some pretty dumb things, quite often as well. There are some things we just have to learn to live with
https://www.aulro.com/afvb/images/icons/icon12.png.
PS. The old Merc pump diesels (pre common rail era) could easily get you down the road at 180km/hr with a failed fuel pump :)