Believe it or not, the local M.B. serice advisor recommends that at least once a week you should do a high speed driving segment (and he means HIGH speed 70 to 90 m.p.h.) for at least 20 minutes to half an hour.
Also, to cure all kind of erratic behavior (rough idle, weird electric gremlims, etc.) there is nothing like a high speed run on your M.B.
The worst you could do is always drive your M.B. only very short distances and at town speeds.
CL 500, 1998
S 500 L, 1998
E 320 T, 1995