I know my SDL tops out at about 115. It does have alot of get up and go at 55 but once you get to about 100 and stop on it, not much will happen, its a slow climb to 115.

A 420SEL and definately a 560SEL will bury the 300SDL in just about anything (except fuel economy).

The 420SEL will do about 120 or 125 (I know mine would ) and im pretty damn sure the 560SEL will do 140 or 150 and the Euro 560SEL's would bury the speed at 160+ mph. I've always wanted one of those

BTW: I just remembered, If you are really curious, I made a couple of moves of my car acclerating 0-60 and from 80 to 100..

http://www.zemkowski.com/movies

This is in my 87 300SDL..