1995 S350 W140 "rod bender" cruising rpm

[valicaddy]

The boost is back on this old lazy barge after removing EGR blocking plate and replacing some rubber boots for the vacuum pipes. I can run faster than a naturally aspirated 603.971 in a W140 chassis...
One question remains though: RPM when cruising seem to high. Why this assumption?

I have two cars:
1993 S350 turbodiesel (pre facelift)
1995 S350 turbodiesel (facelift)

The older one makes 2500rpm at 140-150km/h
The newer one - well, see the picture.

Question is why? Both cars have the same transmissions and final drives (checked) and the same wheels.

I think acceleration is close to specs for the facelift car since EDS is out of fault mode. Only the rpm thing bothers me.

https://www.youtube.com/watch?v=Updg6XuO53w

It was always like this, since I bought them.