That facts are: a W126 300SD will in fact easily get 32 ~ 36 MPG on open highway as long as you don't exceed 65 MPH and keep the engine properly tuned .
My big brother's '81 300SD does this all the time, we tour in it across America, using only petro - Diesel Fuels .
It has 300,000 + miles in it and is nice but no cherry .
I have various W-123's and they only get 24 ~ 25 MPG's no matter what, the W-126 is vastly more aerodynamic, that's where the highway fuel economy comes in .
Me, I'll keep my W-123's
FWIW, my other big brother in New England is one of those lying A-holes who never, EVER tunes his Mercedes Diesels nor does he change the oil but he brags about the wonderful 40 + MPG's he never acutally gets. Lotsa jerks lie like this, they're all pathetic.
I have had too many MBZ diesels beginning with my first, a 1961 190D/b in 1961 . .
Eleven in all counting my current W-211.
This latest one gets the best Fuel Economy save for my 1984 190 2.2L with a five-speed manual.
The SDs cannot and will not get even 32 MPG (actual tank mileage) on an all day trip no
matter what speed
you drive because they are heavy boats and do not have lock-up torque convertors.
You say that you drive it all day long at 65 mph or less and get actual tank mileages of 32 mpg or better?
I cannot believe that! Next time you are in that SD, watch what happens on the tack when you hit a slight
upgrade or are traveling into the wind. RPMs really climb, and you cannot get high F E with a slipping T/C.
because you are only heating tranny fluid. No locking T/C is the reason I got rid of both of my '99 E-300 DTs.
You're saying that an SD will get better fuel economy that the same year E-300
Turbodiesel (W-123) with the same powertrain? That can't happen.
Check out the entries on Fuelly, and not even those reporting the highest figures get such high fuel economy.
There is no way that one of these older SDs can begin to approach the Fuel Economy of my W-211.
Were I able to hold my speed down to only 65 mph or less all day long, I could get
38 mpg or better tank mileage, but who can go cross county at such speeds?
My most recent tank yielded 37.022 mpg and that was over a week and with several
cold starts covering 734 miles with some local city driving thrown in.