Bob
Funny you should mention this problem. I took a 500 km trip yesterday in the 230 SL and found that it had a similar feel on the highway, especially at speed. The car tracks quite well but I notice I'm correcting more than normal to keep it in a straight line. The suspension is quite tight althought there is a squeaking noise when you bounce the front end up and down by hand. It doesn't seem to be coming from the shocks and I don't hear it while driving. So, maybe I need to check the same things.
Mark
1965 230 SL light blue, auto, RHD