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  #1  
Old 07-17-2004, 08:00 PM
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2.5 Turbo Fuel Mileage Question

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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  #2  
Old 07-17-2004, 08:44 PM
2.5 TURBO
 
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MPG

I got 33 MPG the other day, thats fill up to fill up
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  #3  
Old 07-18-2004, 09:00 AM
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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
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  #4  
Old 07-18-2004, 01:27 PM
Marshall Booth
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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
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  #5  
Old 07-18-2004, 05:21 PM
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Location: colorado
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Fuel consumption 93 300D 2.5 turbo

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
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  #6  
Old 07-19-2004, 01:37 PM
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I get 30 to 33 mpg on CA fuel. Lots of A/C.
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  #7  
Old 07-23-2004, 11:19 AM
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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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  #8  
Old 09-01-2004, 12:41 AM
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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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  #9  
Old 09-01-2004, 12:52 AM
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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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  #10  
Old 09-01-2004, 01:04 AM
Marshall Booth
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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
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  #11  
Old 10-14-2004, 08:08 AM
sgrist
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1991 2.5 turbo, 38 MPG

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
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  #12  
Old 10-14-2004, 10:59 AM
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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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  #13  
Old 10-14-2004, 11:57 AM
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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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