Should I jump up and down for joys or do I need to take another math class?
This is on a 1987 300D Turbo. I just installed all new Monark injectors and decided to some test on the freeway with the new nozzles.
Here's what I did:
filled up the car at a gas station near the freeway (for others, it would be the interstate :-)), did a 75 mile round trip, came back to the same gas station, used the same pump to fill it up, it took 2 gallons.
75 miles divided by 2 is 37.5
Is it possible for a 1987 300D to achieve this kind of result?

I'd want to see consecutive results over about 100 gallons to call any mileage number reliable.

The only way you could get definitive results over a gallon or two is to unhook your feed and return lines and plumb in a container with a measured gallon of fuel, then run it until it reaches the bottom mark and note your mileage... preferably correlated to GPS numbers.

It's a lot of work for not a lot of information.

Better to just calibrate your speedo and drive for a couple of months and keep accurate fuel records.

You can get fairly dramatic fuel efficiency numbers by driving slow, employing hyper-mileing techniques, hoping for favorable winds and choosing your starting and ending points (beginning at Loveland pass outside Denver for example and ending at Dallas.)

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Once might be a fluke. If you get the same results a half dozen times you start to build credence. Further confirmation will come from going deeper into the tank. Drive until the reserve light comes on. Should be about 600 miles. If not for the uphill runs you should be able to make Provo before running dry. Pity you can't make Medford for some un-California-ized D2. Our Suburban 6.5t picks up about 2mpg on Oregon D2.

Sixto
87 300D

These cars do that and better every day on EBay.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

People seem to love measuring mpg this way, but it's not really a good way to do it. If you fill at the top of the mountain and drive down it for 75 miles and then fill up you'll get REALLY good mileage, but it's not an accurate measure of mpg. If you do the reverse, fill at the bottom then refill at the top you'll get really poor mileage. If you can get 37mpg for a whole tank and over many tanks then you're on to something. You did get 37 mpg, but it's a small portion of the driving you do and doesn't represent the whole picture.

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Hahahaha! So true! I saw a local Craigslist ad the other day where the guy was touting the "46 mpg" that his 1979 300d routinely gets!!!!

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2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4
1994 GMC S-15 pickup 4.3 5MT
1985 300 SD
1978 300 CD
1962 220-S Fintail - awaiting restoration

Friend of mine has one since new, and in the days of the 55MPH speed limit, that figure was not out of reach. I doubt it's too doable today with traffic moving at 70-80 MPH.

Wait, more importantly, where did you get Monarks? I thought they were no longer available for OM603s? And OM60x's??

And congrats on the mileage, keep driving her. Just got 35mpg on a 350 mile trip plus 50 miles of city...on 270k mile injectors, so I'd call it possible.

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05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD

OM602 or OM603?

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

Also interested in learning this.

Congrats on Mileage regardless of any naysayers.

(there are so many factors involved, think of someone legitimately breaking a world record and being told that if this or that was different it wouldnt have been possible.... )

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85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.

I usually fill up the tank until I see Diesel fuel ready to spill out of the filler neck, drive the car/truck until it is about to 1/8 tank, fill up the same way again and divide the miles driven by the gallons I just put in.

Truck is 14-16 MPG City 21 Hwy
Car - who knows, the odometer doesn't work.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Absolutely!

If the 75 miles is downhill both ways!

You're in the ballpark with 37. Depends on hills or lack thereof, tire pressure, etc., etc.

1991 300d, 168k

602. It's a 190D turbo. I misread the OP.

I'm really confused about fuel mileage. My first MB was a 1976 W115 240D, it consistently got 42-45mpg, which was awesome. I measured a few tankfuls driving very carefully, and other tankfuls flooring the pedal (it was an automatic 240, so that isn't saying much), and it really didn't make much difference at all. I never did much maintenance to the car, just got regular oil changes and fixed necessary problems. It even had working A/C (that I didn't use very often, but the compressor belt was never removed).

Now I've got a 1983 W123 200D, which I bought thinking there would be massively awesome fuel mileage. There's not. I got a pretty consistent 25mpg on all-highway driving when I drove it back from Texas. The injectors were absolute crap (when put on the tester they didn't pop at the appropriate PSI, rather they just started a steady stream at about 50-60% of the appropriate PSI), but I replaced them with ones that tested good (original Bosch, not Monarks yet) and it doesn't appear to have made any difference.

I would really like to know how to get my mpg's up to what I was able to get with the W115. In theory, shouldn't I be able to get even better since it's a 2.0L engine versus 2.4L? I think I get better mileage in my 3.0L's which is just bizarre.