What's normal MPG on '77 300D?

You should be getting between 24 to 28 miles per gallon. You might even get 30 if everything was working perfectly at 55 mph. The first thing I would look for is a fuel leak. Check the fuel hose coming out the bottom of your fuel tank. Make sure non of your fuel injector return lines are leakding. My manual Diesel Performance Tuning and Repair will also go over the many other reasons why your mileage could be so bad. Kent

I have both a '77 and '78 300D and on both I get low 20's (mpg). This may be due to the fact that I do mostly freeway driving (60+mph). I was hoping for more but I haven't checked the mpg while staying in the -55mph range. :-)

Is this the mileage for the 300D Turbo or the non turbo?

both my '77 and '78 are non-turbo. I don't think they made the turbo versions till later.

I am getting anywheres from 22-25 MPG depending on where I am driving. The engine is tuned/tweeked to the utmost......is there any hope of getting up in the low 30 range...if so what more can I do. Dave

Yes this one is Non-turbo.

Our '78 300D w/241K is averaging about 25mpg with a mix of freeway and secondary road driving as long as the maintenance is kept up to spec. It actually gets a little better mileage than our 240D.