Hi guys,

I've posted once before about the 300D I bought (84, one owner, 305000km). Hopefully you vaguely recall!

I drive almost exclusively in the city, and have noticed that I've got about a half tank (so, 40 litres or so) and have gotten about 350 Km out of it. That seems a little poorer than I'd expected - about 8.75L/km or roughly 21mpg? Is that what I should expect in the city? I'd assumed I should be getting more like 25mpg or so.

If it's within the realm of reasonableness (which it might be, because there have been a few occasions when I have driven it hard and fast on the freeway on this tank) then that is fine... but if not, what should I start looking at?

I'll also check around on the forum but figured I'd post here. If I take any action I'll update and pass on whatever I learn!

Best,

Josh

I average about 23mpg in my 85 300dt and I have a very heavy foot.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

My 83 gets around 25 when i use it for commuting and around town. Should be a direct comparision to your 84, same differential and trans spec. And around 27-28 on the road.

Using the A/c a lot will reduce the number slightly.

Since the 300D is not a fast machine, I tend to drive it in a manner that ekes out the highest mileage..... different game, still fun.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

24 around town. Don't exclude the possibility of a sticky odometer.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I get about 24 also (mostly town, some highway) running b100. I've read that bio doesn't produce as much power or get as good milage --- I once ran a tank of ULS diesel just to see. Besides lots more engine noise, my milage dropped about 10%.

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John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln

We drive these cars not mainly for the mileage but for the respect of engineering, the safety,the class, the style of them ...

For their time the W123 diesels were achieving MPG figures that others would dream about. Look at the 560SEL's and such of the time.. 15-17 mpg the 300SD's 24-25 mpg ish

right now they are still doing good for what they are, 40 year old technology on par with current standards... I would realllly like 40 mpg.. but I Reallly like driving my 300D

I calculated that my 300TD is getting about 25mpg. That's after two tanks of fuel with mostly city driving. I'm anxious to check it out for purely highway driving.

I was looking for something that would do better than my Linclon which only gets about 18-19mpg.

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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

I got 19.7mpg with my leadfoot and 100% city driving last week. So you're doing better than I!

It was also about 25 degrees colder outside when I filled up that time than the previous, so it may have partly been denser fuel led to more fitting in the tank....Either way, I only got about 20-21 tops.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I haven't done a full tank of city driving in the 300D to tell, but based on limited observations from partial tanks, the city mileage seems to be in the low 20's. Highway depends mostly on speed, with nearly 30 mpg at 70-75 on down to 26 at 80-85. Then there was the time I ran through a whole tank doing 85-110 most of the way-averaged 22 mpg and probably 95 mph.

Cold weather and short trips where the engine is doing more miles without being warmed up will affect mileage.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Compare apples to apples in regards to fuel economy.

What was the average mpg for the same chassis, same displacement gasser version Mercedes.

The actual mileage figures are very good. Mercedes in general, are gas hogs. The older ones are big, stodgy cars that have a lot of weight to throw around, and a lot of drag to overcome at high speeds. That's just the price one pays for driving an old German tank. Tanks are not known for efficiency. Their strengths, however, are much more obvious.

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1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

I get about 30 mpg in Atlanta. If I'm sitting in traffic a lot and inching along, with the a/c on, then I only get about 25-26. But mostly, on the dot every refill, I get 500 miles per refill (I probably still have 2 gallons left by the time I refill; the low fuel light comes on with 2.5 gallons still in it, or so), which is 30 mpg, almost every time. I get about 35-36 on the hwy.

Try some Diesel Kleen in the tank, might help clean out some injectors. Even without it, I get 30 mpg, I've never checked with it, but it does make my car run quieter, and they say gives up to 5% better mileage due to its ability to increase cetane levels. Check your pre-filter, make sure it's clear and not dirty. Empty all your lead weights out of the trunk so you're not carrying excess weight.

Good luck.

jeff 1991 300d, 114k

If you're driving an MB it's either Premium or Diesel (any Benzes use regular?)
Out side of that, the comparison is between marques.

With the MPG difference, diesel would have to be 25% higher
than premium just for "break even" compared to fuel costs vs a gasser.

I'm getting 24-26 city (Chicago) and just got 31 hwy on a trip from
Chi to Pittsburgh. It was on 17" wheels at an averaging 70-75 mph.
(Indiana speed limit is 70. Ohio 65). On the stock 15s I get 2 more mpg.

25/30 is what the new energy conservation legislation is targeting
over the next 8 (i think) years. That will catch everyone up
with these 20+ yr. old masterpieces.

Remember... we're weighing in like SUVs.
And a BluTec at 52,000 ?? If I'm buying new, I'd be all over that!

Right now I'm just trying to get 20 more years out of the 300D

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k. darkman
1987 300D Turbo 200k

After 4 year of driving two different w123 300TDs (85 and 84) and keeping track of every ounce of fuel, I can conclusively say that my cars get better mileage in the summer (24-25 mpg) than in the winter (20.5-22 mpg).

Whether that is because of external temps or fuel quality is up for debate.

City vs highway seems to have less to do with fuel economy for me.

Very informative stuff in here - thanks everyone! Yes - I think there are some mitigating factors at play here. Typically my drive roundtrip is ~ 6km, so there's hardly much time to warm up the motor at all. Not to mention it's getting cold outside -- only about 4 or 5 degrees C out. I think those two things alone might account for my slightly lower than expected fuel economy. Probably the most important thing I can do is check my tire pressures, in this situation.

On a different note - I have lately heard some "new" noises under the hood. It sounds almost like increased valvetrain / exhaust noise, and it only manifests itself in a small range of rpm's - only between about 900 - 1000 rpm. I am not sure at all how best to describe it... almost like a resonating exhaust noise that I can her over the usual (totally normal) engine noise. Upon investigation, I noticed that the fitting and hose leading from my valve cover to the air intake / cyclonic oil separator was totally loose and disconnected. Putting it back together (to the best of my ability) seems to have greatly diminished the noise. I presume this is probably the logical source of what I'm hearing - and I presume the parts are equally trivial to replace, since the flexible rubber hose on the air cleaner itself seems good, but the hose from that to the valve cover fitting seems shot (no matter how much I fiddle, it just doesn't make a good positive connection anymore).

Believe it or not I was actually scouring my factory engine manual to try and find a part number for that, but came up empty

Only recently have I begun to review the mileage in our SD and will soon track the TD. Reason being, I am doing repairs and maintenance and want to understand what repair or maintenance item did what.

I add 5 gallons at 1/4 of a tank and then track the 5 gallons until it is dead center with the 1/4 mark. I am doing that to gather more data points, more quickly.

With mostly rural road highway driving with speeds at 60 to 65 it is getting between 28 to 30, depending on the overall length of trip. I notice my greatest fuel consumption getting started in the morning or in the smaller trips with shutdowns and re-starts.

The window sticker (I have it) had an EPA of 27. Amazing how accurate it is.

If you take the weight..near 4000lbs and compare it to a Lexus of the 400 series which is similar in weight, you will find that the MB will get at least 5 mpg better. That is comparing it against one of the most technologically advanced cars made. I realize that isn't the best comparison as it can be argued the Lexus was/is a higher performance car. If you want to step into the pedal of a Lexus to experience that performance, you will pay for it at the pump a lot more than 5mpg difference if your careful.

It isn't reasonable to compare the MB diesel mileage to a Toyota Camry nor compare it to a Bentley. However if we want to talk mileage... I had a 70ish VESPA and .......

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1980 300TD-T (82 Turbo and Trans) 159,000 Miles "Jackie-O"
1983 300SD 272,000 Miles "Aristotle"
1987 Jeep Wagoneer Limited - keeps the MB's off the ice and out of the snow
1994 BMW 530it