I know this is an old thread, but I just got 34 mpg on two fill-ups in my 87 TD which I am happy to report. The driving was virtually all freeway miles through southern CA, no A/C, and I kept my speeds at 65-ish (when possible). For one of those tankfuls, I was stuck in traffic for a while, but I did my best to drive smoothly. When I first bought the car 6 months ago, I got 29 mpg doing the same drives. Since then bought new tires which are low rolling resistance Michelins (Energy Saver A/S). I used the same diesel fuel pumps and tried to refill the tank consistently. Also, I have checked my odometer against highway mile markers. On the old tires, it read quite high (so I corrected for that). On the new tires, my odometer reads just slightly low (so a correction is hardly needed). I also add 12 oz of Diesel Kleen per fill up (and I included that volume in my calcs). I honestly doubt that low rolling resistance tires got me 5 mpg at highway speeds, but I am glad that they seem to have helped.


I probably won't ever achieve this again because 65 mph feels very slow on a day-long drive, but I just wanted to run a little experiment this weekend and share the results.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

After discovering my 1987 300TD Wagon had a dragging caliper, my mpg went from 22ish to 25-27 all around. This with no AC and tried with all sorts if variations of highway only, City only, mixed, etc. I've never hit the 28 mark and I cannot remember the last time I went under 25.

The car has 240,000 miles or so and despite the failing head, it runs quite well.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

Use fuelly. Its quite handy for tracking mileage and cost over the long term and you can compare your results to other cars in the real world.
Mercedes-Benz 300D MPG Reports | Fuelly

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CENSORED due to not family friendly words

My w126 300sd would get slightly above 30mpg highway. Highest was about 33.5.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

'83 300CD, 94 miles/days commute, 303,600 miles on the clock, normally run 65-68 mph at 7-8psi, 12-13 psi on hills, 195/75/14 Unicure A/S retreads on all 4 corners at 35psi, no a/c, windows down, no cruise control, 90-110 degrees outside, avg 23-24 mpg consistently. For the last month and a half, I've been siphoning fuel from my '87 KW cabover and '85 Cummins F350, but I'll fuel once in awhile at Quiktrip to check my mileage.

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'83 Mercedes 300 CD, auto, 301,000 mi,
'85 Ford F350 crew cab, Cummins, 5spd 426,000 mi
'88 Ford F250 reg cab, 351, auto, 124,000 mi
'07 Honda Civic ex, auto 62,000 mi

1983 300SD with 146K miles has averaged 24.78 mpg over 24,000 documented highway & city miles.

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flymehomenow

1983 300 SD

When I started driving it w 315K I was getting 29, mostly because I was diving it easier. Last few were 26-27 combined mostly hiway!

In town driving 19mpg. On the road at a steady 75mph, 22-23 mpg. This is a CA car with their stupid SMOG controls. Car has plenty of power and no other issues so engine appears to be in good shape.

Anyone removed the SMOG equipment on one of these CA cars?

I have been tracking my mileage precisely from Dec 2012-June 2013. My driving is a mix of street and highway and I burn about a tank a month (2696 miles over 6 months). Over the past 6 months my average mileage has been 21.5 mpg (stdev 0.9) running B20 from Pearson fuels (New Leaf brand biodiesel) in San Diego. My Mercedez-Benz is a 1983 300CD with everything original (I have all service records the car was purchased new) and just over 300,000 milies on the odometer. Any ideas on how to improve my gas mileage would be appreciated! The first thing I will try is a Lubri Moly purge and see if I see a difference!

Just drove my 83 300SD From CA to TN. Along I-40 and through hills/ mountains...loaded moderately...75 mph, I got 28 and change. It has 285,000 miles on it.

My 07 ML320 CDI got 29.5 driving 75 mph, it probably had 70,000 miles on it at the time.

I have to say, the 300SD was built better than the ML320CDI was. More durable...lots more plastic under the hood of the ML...also just a tad more complicated to work on.

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dmcginn2
2014 E250 Bluetec
2015 Golf Sportwagen TDI

I get 29 mpg on my 83 300Cdt. Present mileage 253000 .

1978 300SD 14.7 lbs boost & 2.47:1 axle - 25-28 mpg @ 80 mpg cruise with A/C on...

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

my 1985 300TD with 60,000 miles gets 25 mpg mixed highway and city (measured between 2007 and 2011 when it went from 34000 to 55000 miles)

1983 300td turbo 350,000mi at 25 - 27 mostly B100
1986 190d 2.5 NA 300,000mi 33 - 38 mpg on B100 and plenty of power

Hi all,
I have 1991 2.5 300D with 230K miles and it give city 30 MPG and Highways around 35 MPG. 1984 euro model 300d with 185K miles daily driver (non turbo) give around 26 local and 28-29 (very rarely go on highways).