Mine is the same way. I think its just the nature of the car, for whatever reasons. The ride is ok at high speeds, though.

My 123 car is a better riding car around town, by far. My old 116 car felt the best, by far.

the 124 car with the 5 link rear was a huge step forward in all aspects. A 140 car with the 5 link rear makes the 126 feel like a jalopy.

My 126 car has always disappointed me a far as suspension goes- it rides harsh, but rolls like a boat in turns. Bad wheel hop over bumps, too.

This is after new shocks and a front end rebuild.

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'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E