With my 1992 300D 2.5 Turbo, I typically get 24 mpg city, 30 mpg highway. However, I have seen several on this board with my car (1990-1993 300D) getting upwards of 37 mpg highway and a solid 30 mpg city.

My question: is my experience within "acceptable limits" (so many factors affect mileage) or is my mileage enough on the low side as to suggest that there's something that needs to be addressed/fixed?

Thanks.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I got 33 MPG the other day, thats fill up to fill up

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2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

My 91 typically returns 33 MPG in a mixed mode environment - I have gotten over 40 MPG on rare occasions. Typical highway mileage is 36-38 @ 65-70 MPH with no air.

I think your stated mileage is low enough that I'd have somebody take a look at it - but realize that you are going to spend far more $$$ in diagnostic/repair costs than you are ever going to get back in a 4-5 MPG improvement.

Tim

Driving style and climate makes a big difference. The AC compressor can demand 5-7 hp. Then there's fuel. With most fuel (including most major brands - not just generics) it's rare to get better than 28-30 mpg from my 190D 2.5 turbo (same 602.96x engine as in your car) but BP/Amoco usually delivers 32-35 mpg under the same conditions (summer driving - AC functioning). In spring and fall I usually get a little better mileage.

When fuel supplies get tight (as they have been during the last 5-6 months) it is usual for the engergy content of most diesel blends to drop to the absolute lowest tolerable limit - and the lower the energy content, the more fuel it takes to go the distance at whatever speed. BP/Amoco has maintaained their energy content better than the other majors in recent years (although a few years ago, even they dropped the ball for several months). Itb is NOT unusual for the fuel mileage to dro[p by 20% when fuel supplies get tight just like it does in the winter when D #1 with it's lower energy content is mixed with #2 to prevent gelling.

Marshall

I do alote of mountain driving, 7000ft above sea level, I would second every point Dr. Booth makes, my car gets 32.5 MPG day in and day out, driving at speeds well in excess of those posted 75-85, the one time I drove at 60mph the car returned 38mpg. very difficult to do, this car is much more at home in 80mph range.
Fuel quality as mentioned earlier can easily make a 10% difference in MPG.
Day in day out, this in my opinion is the best diesel MB has made.

Ron

I get 30 to 33 mpg on CA fuel. Lots of A/C.

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'91 300D 2.5 Turbo 330K
'00 VW TDI Golf, 190K
'67 BMW R50/2
'73 Norton Commando Interstate

i get about 32mpg highway at about 80-85 mph. 24-26mpg city with lots of a/c and i drive very fast.

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1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350

I get 25-27 80% city, and 29-31 80% highway tanks. I think my car is smoking more then it's supposed to be, so it could be on the low side. I ran a purge, but think I need to do it again and I noticed a little fuel on the injectors this morning, so need some attention there.

I would GUESS that 28-30 should be city and 32-35 should be freeway on average grade fuel.

Good luck!

-m

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Now:
2018 Tesla Model X
1999 S500 Grand Edition 164k
1992 300D 2.5 Turbo 287k
2005 E320 4MATIC wagon
1991 Alfa Romeo 164L 99k (sleeping for a while)

Then: 96 Lincoln TC, 93 Lincoln TC, 87 560 SEL, 87 300 SDL, 80 300D, 89 560 SEC

Your numbers are decent for an OM603 turbo, but definitely on the low side for a 602. I'd first make sure you don't have a "stop & go" odometer, which is all too common with the VDO units used in these cars...

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Dave
Boise, ID
Check out my website photos, documents, and movies!

25-27 80% city, and 29-31 80% highway

Those numbers are about typical or just a tad low with generic #2 fuel, but with Amoco/BP #2 or equivalent mileage 10-15% higher should be possible.

Marshall

For 4 years I have consistently got about 38 mpg in my '91 300d 2.5 turbo when driving smoothly at about 60-65 on pretty-flat, mainly Interstate driving. I drive from Atlanta to Rome, Georgia and back a few times a week against the rush-hour traffic, and I only notice significant mpg decrease when dodging maniac cowboys driving 18-wheelers in convoys at 75+ mph as I approach Atlanta...
-sg

LOL. Drive at 60-65 on interstates out West and you'll have six-guns blazing through your trunk. Thirty-eight mpg is fantastic; whatever you're doing, don't change a thing. I got 36+ mpg tops on a trip to the midwest this summer.

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'91 300D 2.5 Turbo 330K
'00 VW TDI Golf, 190K
'67 BMW R50/2
'73 Norton Commando Interstate

Remember that MPG varies greatly with different fuel. Try a few tanks each from different stations near you and measure the difference. Also remember that winterized fuel (usually from mid-October through mid-April) will provide lower MPG numbers, depending on the exact blend - it tends to get worse in the middle of winter as they change the blend and the BTU content drops.

My last 5 tanks in my '87 (with the 6-cyl OM603 engine) have been 31-32mpg using the "premium" diesel from a local Sinclair truck stop. That's mostly with a 16-mile, one way, commute with a half-dozen stop lights, mostly 45-55mph. That's the best the car has ever gotten in seven years!!! I expect it to drop back to high 20's with winter fuel. The smaller 602 motor should be capable of 34-38mpg with a light foot and GOOD fuel.

YMMV - literally.

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Dave
Boise, ID
Check out my website photos, documents, and movies!