My dad has a 1994 sl600. apparently the suspension as far as I have been told is hydraulic.
His car had problems with it sitting too low. He had to have it repaired. I am not sure what happened, but his car drives great and drove great even before.
I'll do the test you have done and let you know what I find on his car. I'll also try to find out what they did to the hydraulic system. IT could be hydraulic pressure is building up too much?
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.