37 miles per gallon, is it possible? - Page 2 - PeachParts Mercedes-Benz Forum

Biodiesel300TD · #16 02-23-2012, 12:36 PM

There is a lot that affect mileage. Tire inflation, condition, size, brand, tread patterns, alignment, fuel and air filters, dragging brakes, length of time driving in one sitting, speed of travel, engine temp, wind conditions, hills, differential gear ratios, AC, fuel quality and type, condition of your injectors, valve clearances.

That said your 200D should be getting more, the 240D's usually get in the upper 20's to low 30's so I'd suspect your 200 should be closer to that range I'd be surprised if you can get it into the 40s. I'd start looking through all the things above to make sure everything is in tip top shape. Start with the basic stuff and work into the more complicated stuff.

Raptelan · #17 02-23-2012, 12:59 PM

Quote:

Originally Posted by Biodiesel300TD

There is a lot that affect mileage. Tire inflation, condition, size, brand, tread patterns, alignment, fuel and air filters, dragging brakes, length of time driving in one sitting, speed of travel, engine temp, wind conditions, hills, differential gear ratios, AC, fuel quality and type, condition of your injectors, valve clearances.

That said your 200D should be getting more, the 240D's usually get in the upper 20's to low 30's so I'd suspect your 200 should be closer to that range I'd be surprised if you can get it into the 40s. I'd start looking through all the things above to make sure everything is in tip top shape. Start with the basic stuff and work into the more complicated stuff.

Why do you say the 240's get so low?? I thought even 300's should generally get above 30. My 240 got much higher. I also lived in an area which was quite hilly at the time, which isn't the case now. The 240 sucked on hills, but mileage was good. I have new fuel and air filters, brakes don't drag, I recently checked/adjusted valve clearances (they weren't much off to start). Don't know how good the tires are for efficiency but they're Bridgestones and less slippery in rain than some of my other cars' tires though not as good as the set of Michelin Weatherwise's I have (I suppose better traction means worse mileage). A/C has a broken line in the 200, so it's never running, however if I switch it on it bogs down the engine so I don't think the belt being attached is an issue in general. Could it be that because I didn't do much maintenance on the 240 that it's fuel injectors ended up more clogged thus getting better mileage or something? Or maybe a previous owner had tuned it somehow? The 200 has a 3.92 differential - I've been thinking of putting one from a 240 on it which is a bit lower. How do you differentiate fuel quality/type? There's never more than one option for diesel at stations...

Bio300TDTdriver · #18 02-23-2012, 01:44 PM

Quote:

Originally Posted by rscurtis

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

OM602 in a 201 or 124 I believe. OM603 not so much.

Biodiesel300TD · #19 02-23-2012, 02:03 PM

Quote:

Originally Posted by Raptelan

Why do you say the 240's get so low?? I thought even 300's should generally get above 30. My 240 got much higher. I also lived in an area which was quite hilly at the time, which isn't the case now. The 240 sucked on hills, but mileage was good. I have new fuel and air filters, brakes don't drag, I recently checked/adjusted valve clearances (they weren't much off to start). Don't know how good the tires are for efficiency but they're Bridgestones and less slippery in rain than some of my other cars' tires though not as good as the set of Michelin Weatherwise's I have (I suppose better traction means worse mileage). A/C has a broken line in the 200, so it's never running, however if I switch it on it bogs down the engine so I don't think the belt being attached is an issue in general. Could it be that because I didn't do much maintenance on the 240 that it's fuel injectors ended up more clogged thus getting better mileage or something? Or maybe a previous owner had tuned it somehow? The 200 has a 3.92 differential - I've been thinking of putting one from a 240 on it which is a bit lower. How do you differentiate fuel quality/type? There's never more than one option for diesel at stations...

In my 240, folks I've talked to, and all the numbers I've seen here show 240s getting the numbers I posted. I'm usually pretty skeptical of folks touting much more than low 30s in any 123 diesel Benz, and I know I not the only skeptic. That's not to say it can't happen it's just not the norm.

As for fuel, you're getting different fuel types weather you know it or not. Winter diesel is different than diesel sold during the rest of the year. Winter diesel yields lower mileage due to the additive put in for winterizing the fuel. Fuel quality has also changed over the years, and also differs from one stations to another as well as one state to another depending on state mandated required fuel additives. I can't really speak to how these affect mileage, but they surely do just like gasoline. Biodiesel is also something to think about. It has less BTU's/gallon which causes a loss of fuel mileage from 7-10% if you're running 100% bio. Straight veg oil follows suit. Some states have also mandated that small amounts of biodiesel to be put into all diesel. Though small amounts 2 or 5% probably doesn't affect mileage.

1987 300D · #20 02-24-2012, 11:08 PM

hi guys... My 75 miles trip was all hi-way... no stop lights and cruising at around 70 MPH.. 65MPH if you're a cop and reading this.
I know surface street it will reduce my GPM significantly. I think I consistanly get around 23 MPG for surface street.

satyr · #21 02-25-2012, 04:52 AM

I've driven the same 525 mile commute per week for nearly a year. I've noticed that winter blend D2 gets lousier mpg than summer blend for some reason. In the summer, with recent oil change, tires properly inflated, no weird wind conditions, running B5 I can get up 45-46 mpg at 60mph in the 190. In the winter- same filling station, same weekly route and I'm getting 41-42 mpg. So the fuel you're burning may make a difference too.

t walgamuth · #22 02-25-2012, 06:00 AM

Quote:

Originally Posted by Raptelan

Why do you say the 240's get so low?? I thought even 300's should generally get above 30. My 240 got much higher. I also lived in an area which was quite hilly at the time, which isn't the case now. The 240 sucked on hills, but mileage was good. I have new fuel and air filters, brakes don't drag, I recently checked/adjusted valve clearances (they weren't much off to start). Don't know how good the tires are for efficiency but they're Bridgestones and less slippery in rain than some of my other cars' tires though not as good as the set of Michelin Weatherwise's I have (I suppose better traction means worse mileage). A/C has a broken line in the 200, so it's never running, however if I switch it on it bogs down the engine so I don't think the belt being attached is an issue in general. Could it be that because I didn't do much maintenance on the 240 that it's fuel injectors ended up more clogged thus getting better mileage or something? Or maybe a previous owner had tuned it somehow? The 200 has a 3.92 differential - I've been thinking of putting one from a 240 on it which is a bit lower. How do you differentiate fuel quality/type? There's never more than one option for diesel at stations...

I hate to say anything is impossible but an automatic 240d 115 chassis should only be capable of low 20's highway.

I had one which I rebuilt the motor and did all the right stuff with fresh injectors and timing.

Your mileage of over 40 would lead me to believe your odometer is off.

Mid 20's for a 123 with an automatic is very normal.

Putting in a taller 369 or 358 diff would probably increase your mileage a bit in the 200. Gearing is about the only way to increase mileage in them significantly, in my experience. I've had about 20 123 chassis diesels.

nutsnbolts · #23 02-25-2012, 09:36 AM

Just to back up the info from other members here...

I have a '75 300D that I purchased this summer, and I drove it on several weekend trips over the Green Mountains in Vermont, ranging from 65-75MPH, depending if I was uphill or down. During those trips, I recorded 23-24MPG every time, with fresh injectors, which for an auto trans, high-revving 3.0 in a 3500lb+ sedan is probably pretty good.

I was a bit disappointed though, since my '85 4WD 3/4 ton Suburban with a 6.2 l diesel, an auto trans, and 3.73 gears gets 22-23MPG at 70.

But, that's the real-world numbers...

-Rich

Crazy_Nate · #24 02-25-2012, 09:53 AM

I don't think 37 is realistic for the W124 with the OM603. Maybe with a OM602 and a really light foot, or with the W201 chassis (602, 601). But, take some data over a longer period of time and remain hopeful

The best that I've done was 33 mpg and I just did 32.2 mpg on a 470 mile tank (all highway 55-70 mph). City is consistently around 24 mpg. When I do mixed driving for my commute (70% highway / 30% city), I'm about 28 mpg.

Actually, I think my mileage for the '87 is very similar to the '82 240D (auto)... As much as I love the W123, the '87 is so much more fun to drive

Grdenko · #25 02-27-2012, 01:05 PM

Quote:

Originally Posted by Crazy_Nate

Maybe with a OM602 and a really light foot,

Maybe at 55mph. I once got a little over 34mpg with the turbo disabled and the cruise set at 75 the whole way, no overtaking.

cho · #26 02-27-2012, 02:11 PM

Quote:

Originally Posted by Desert Panther

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!!!!

thrown from the cliff..... maybe

sethza · #27 02-27-2012, 08:50 PM

Mpg for a diesel benz seems like fingerprints on a homo-sapien, they are all different from individual to individual and seem to stay relatively the same from birth to death. My 240d got around 28mpg, wasn't affected by tires, alignment, ride height, injectors, load, weight of my nikes, oil type, fuel type, etc. The worst I figured was 27 mpg with bad injectors, clogged fuel filters, bad alignment, discount tires' cheapest rubbers with a busted outer tie rod, and four full grown men and all of their musical instruments. The best was a hair under 29 with just me and ALL of the above fixed. I haven't figured any numbers with my transplanted engine, but I have a feeling they will be different. It's almost as if some where made on a monday after a full nights rest and a cup of coffee, and had mpg in the 30s. And others where made by workers with a hangover or the flu, or maybe someone sneezed while they were making your injection pump.

Bio300TDTdriver · #28 02-27-2012, 08:57 PM

That or not everyone on this forum was a math major.

Raptelan · #29 02-27-2012, 09:05 PM

I wish I'd held on to my first '76 240D. I am not pulling legs when I say it regularly got 42-45mpg - I used to write down the mileage and gallons every time I'd buy gas and kept a log book for a long time, and the odometer counted miles accurately too. Every MB diesel I've had since then gets less than 30 I think, though I'm not as anal about keeping track as I used to be.

There's a certain satisfaction that comes from driving a 61x diesel regardless though. The V-8's are fun now and again but are massively overkill for everyday driving. And I can tell you that 12mpg's as I get in my 1974 450SE regardless of driving style is quite depressing!

Bio300TDTdriver · #30 02-27-2012, 09:19 PM

[QUOTE=Raptelan;2892377 it regularly got 42-45mpg - I used to write down the mileage and gallons every time I'd buy gas [/QUOTE]

Well there's your problem right there, you are trying to burn gas in a diesel.