Fuel mileage and diesel Benzs... - Page 2 - PeachParts Mercedes-Benz Forum

#16 04-23-2002, 04:09 PM

I keep complete records, and my 85 300CD has gotten 27.3 mpg over the last 30K miles. My 240D has gotten 27.6, but only over about 5K miles, so probably not so accurate.

If you want better mileage, you'll have to get a 190D manny tranny.

Surprisingly, the 300 SD seems to get better mileage than the 300D. Don't know why, but it's commonly reported.

The Warden · #17 04-23-2002, 04:55 PM

One other thing...how many people use fuel additives, and what types?

I put some form of fuel additive in any diesel I drive, religiously. I've been putting ATF in the van's tanks, solely 'cause that's what the previous owner got the van used to and I don't wanna break the routine...the truck, I've used Marvel Mystery Oil, Red Line, STP Diesel Lube, and last time I got some other stuff...don't remember the name of it, but it seemed to work nicely; gave the truck more power...it'll take a few more fuelings to tell if it's really making a difference, though.

I'm sure that some form of additive will positively help with mileage some, and it helps to keep parts clean...

And, again, 25's a bit low, but I'll be happy with that...so I think my fuel mileage fears about about quelled (BTW, I also stick to the speed limit; no 90mph freeway runs

)...

p.s. Sorry for any spelling errors in the last few posts; I'm at school right now and the keyboard for this computer sucks...

One other question, on auto trannies...for both the 300D turbo and the 300SD, what trannies were used? I'm guessing a 3sp early on, and a 4sp with an overdrive gear later...I'm sure having an OD gear will help with mileage.

In what years were any tranny changes made? BTW, I'm looking for '85 and older...again, turbo'ed if at all possible. Thanks!

Ridge · #18 04-23-2002, 05:54 PM

The Warden,

How much mileage that you get depends on a number of things. One, you've got to know your injectors are good. Two, the rear end ratio makes a lot of difference. Normally the 300D and 240D have a 3.47 which gives them good acceleration even with the automatic. But if you go with the turbo 3.07 rear end ratio and a manual transmission, you can get as much as 27-28.8 around town and 32.8 on the highway and that's at highway speeds of 82MPH. Mine seems to really quite down at 82.

So you can always buy the car of your choice and then modofy it as you desire.

Ben

The Warden · #19 04-23-2002, 06:15 PM

Ben, I see what you mean...

BTW, I haven't forgotten about you; I've just been busy over the last couple weeks or so...I'll give you a call when I get a chance.

GregS · #20 04-23-2002, 07:12 PM

I have an '84 300D which consistently gets 23 mpg, although sometimes it might get 24! If you want fuel economy, don't buy this diesel. I believe the people on this board who say they get 29mpg in their SD's, but if the seller of the car you are looking at tells you that, chances are he is full of it. Expect 23mpg.

Greg
'84 300D

diesel don · #21 04-23-2002, 08:01 PM

300D-T 25.8
300TD 22.0
240D 23.5 (but just adjusted IP so hoping for more)
Volvo 27.8

I used to hear that the MB's delivered near 30 but no so with all the guys around here (about 12 different cars)

Don

#22 04-23-2002, 09:02 PM

on one trip down to LA from SF on Highway 5 in California, I averaged 25 mpg in my 300D turbo. This was with cruzing at a constant 85 mph and in about 95-100 degree heat. The car didn't heat up past 95degrees and only just touched the bottom of the 100 degree mark once. Going up the Grapevine. Coming back I got caught up in a high speed pack. We were averaging between 95-105mph. I know, I know. I was practically at the redline a couple of times. But, the car seemed to like it. Very stable at that kind of speed. We did this for about an hour and a half. I stoped to fill up and calculated that I got about 23mpg. Not bad. I always reset my trip odometer and calculate my mileage after every fillup. I average about 25mpg if I keep it under 85mph.

#23 04-23-2002, 09:06 PM

Oh, and I've been using Rotella for years and don't use any addidives. I tried that E.R. stuff once. I heard about it at the race track from on of the engineers. It actually did make a difference. The car got about 1-2 mpg better. But, at about $25 per 12 ounce bottle it can get a little expensive. Oil changes already cost about $40. And I do them every 3000 miles too. Religiously.

#24 04-23-2002, 09:09 PM

I've got something...I see that a lot of people used additives in their diesel fuel and adds a few mpg, I don't use any additives and my mileage varies from summer to winter...I get about 26-28 mpg highway in the summer and 21-23 mpg in the winter when ambient temps are below 40 degrees F.

Do the fuel additives help in the cold, I never noticed a difference, I used to use Power service in the winter, but I stopped becuase I seemed to be getting less performace....

190D22 · #25 04-23-2002, 09:13 PM

I get about 30, and I do all city driving. I have a little bit of the lead foot syndrome, since I also have a grand cherokee (don't get me started on that gas mileage!!!!) and I always want that quick jump off the get go. I always try to be nice and easy on acceleration, since I want to keep the wear and tear as low as possible on this baby.

I've always wondered... what's a fully loaded semi get mileage wise? or a school bus? Seems like these school bus drivers today floor them all the time...

#26 04-23-2002, 09:14 PM

i always get about 22-23 mpg in the winter with temps in the 30s and 40s. No additives either. Can't get hot enough for good combustion I guess.

#27 04-23-2002, 09:16 PM

With my dads old business we had couple of big rigs. The Freightliners got about 6-8mpg loaded with about 30000lbs of produce. All they did was go back and forth to the produce wholesale market.

190D22 · #28 04-23-2002, 09:18 PM

That's gotta be way higher than what a gasoline truck loaded like that would get!

#29 04-23-2002, 09:28 PM

definitly. We had one old 10 wheeler with a gas motor. A Ford F750 I believe. It had a 460 in it. I think when fully loaded with about 18000lbs of produce it got around 3-5 mpg. It was a slug too. The 18 wheeler would blow it away on the hills. By the way, those things are extreamly fun to drive, as long as no one cuts you off.

gsxr · #30 04-23-2002, 10:51 PM

Ummm, guys, I think a lot of you are comparing apples to oranges. I don't think anyone else has pointed this out that THERE ARE TWO VERY DIFFERENT TYPES OF ENGINES used between ~1980-1998. There are the iron-head OM617's used up to 1985, and then the aluminum head OM60x from 1984-up. The aluminum headed versions are more efficient by ~20%, with both increased power AND higher MPG.

The OM617 generally gets 20-30MPG, depending on chassis (123 or 126), transmission, and other various factors. Some very few lucky folks get a tad over 30 but that's not very common. I've also read about some that get low 20's even though they run perfectly otherwise, and won't get anywhere close to 30 no matter what you do to it. I've never heard a solution to that one either (my '84 has this problem and gets 19-24, unfortunately.)

Now, the OM601 and OM602 in the 201 chassis do routinely get 30-45mpg (higher numbers with OM601 and/or manual trans). It would be hard to get one of these cars UNDER 30mpg I think! I got 40+ with my 1985 190D 5-spd.

The OM603 used in the 124, 126, and 140 chassis usually gets 24-32mpg. A few get a little higher but not often (steady 55 on level ground for hours, maybe, but I don't consider that "normal" driving!) Mine typically get 22-26 but I have a seriously lead foot. I get 26-30 on extended freeway trips (got 31 or 32 a few times).

Next, the OM602 used in the 1990-up 124 gets high 20's to mid 30's. I have never heard of one reaching 40 though. Low to mid 30's is pretty common for these.

The newest diesel, the OM606 used from 1995-1999 is still more efficient with it's 24-valve head. These get high 20's to high 30's, usually mid 30's on average. The STAR reported getting 40+ on an extended highway trip but I think that's pretty rare. The 201 is about the only MB I know of that can routinely achieve 40+MPG.

So in summary, the engine technology (617 vs. 60x) and chassis type (small [201], med[123, 124], large [126, 140]) all have a BIG impact on mileage figures. You simply can't make a simple statement that "5 cylinder Benz diesels averaged around 30mpg".

My personal favorites:

For max MPG, a 190D with a 5-speed (or a 1995-up E-class, ~double the power and not much loss in MPG)
For max power, a 1987 300D (for under $7k) or a 1997/98 E300 (under $16k).

[edited Sep-2002 to adjust market prices on above cars...]

HTH,