The correct answer is: "Zero" MPH.

Park it and take a bicycle.

I just drove a whole lot this past week (2k miles) in my W124 E320 and averaged 26 mph. I usually drive about 10 MPH over the speed limit on the interstate and 5 mph over on all other roads. Except school zones. I don't mess with school zones. Oh yeah, I also slow down near police stations.

Botnst