<<I also drive nearly 80 miles on my commute. Setting the cruise on 78 gets me two things: 1) frequently flipped off, and 2) 24MPG. Remembering I have a 300D, does that seem correct? At what speed have yous guys noted 300Ds getting their optimum MPGs? Does 24MPG at 78-80 MPH seem right? (FWIW...I usually dislike fuel economy threads but my curiosity is getting the best of me)>>
I think it should do a bit better. My '78 300D under about the same conditions could reach 28.5mpg although it had fewer miles at the time. However, on the trip quoted, there weren't too many grades to climb. And, I know for a fact that pump timing was spot on and the injectors were all adjusted properly with good spray patterns. RLE/28.5 Mercedes mpg nothing but a memory, now.
