If you drive a 300SE in a dignified manner, you'll easily get 24-25 hiway mpg. ( then again, MB's were never meant to be 'economy' cars, efficient-yes, but if you have to ask how much.....) If you want performance, it'll respond in kind...you just have to get used to that big body..need to think ahead a few seconds. Burning rubber is not what these are about. The real joy is driving an S class for the maintenance costs of a Corrola!
Bar none...this is the best dollar value on the road, IMHO.