Thinking that perhaps the time has come to move over to the darkside - serial Mercedes buyer who has never owned a BMW,
Typically buy a 2-year (max 3) E Class V6 diesel saloon and rack up 25K miles per year for next 4 years, dispose of the car, "rinse and repeat".
The E400D is on the shopping list but so is the Alpina D5.
Have no immediate need to buy (as a Green D5S with gold decals and light coloured interior (sorry) has never come to my attention) ie can wait until 2023 but I think that am seeing the D5S values slowly but surely moving southwards - or is it wishful thinking.