The E420 is capable of 25-27mpg on the freeway if you have a LIGHT foot. A heavy foot drops that to low 20's freeway and teens in town. The M119 is a great engine. Better MPG than the M103, which IMO isn't all that efficient... I was never real thrilled with my old 300E.

I have had my 87 300D (124.133) to an indicated 120mph while the GPS was reading 125mph. That was with fat 17x8 wheels and 225/45/17 tires, which make the speedo read ~4% low, and also create some drag to reduce top speed a hair (factory spec is 129mph).