poor gas mileage???? - PeachParts Mercedes-Benz Forum

vwbuge · #1 08-30-2002, 01:20 PM

My last Benz was a butterscotch '79 300D. (Colnel Mustard affectionately) Anyway I remember getting around 30 mpg with that car. My '85 300SD gets almost 24mpg. Is this normal? I drive about 45 miles one way to work and I climb a decent size mountain. I know it will not get as good mileage as the non-turbo but I feel as though I should be near 30. Am I nuts?
the car runs great.

#2 08-30-2002, 06:39 PM

Normal as far as I am concerned, I have checked every fillup for the 7900 miles I have owned the car and my 81 300SD consistently gets 24-25 MPG. I drive 39 miles to work, mostly on highways. Best mileage of any car I own...and the cheapest fuel too.

P.E.Haiges · #3 08-30-2002, 07:07 PM

I think the turbos should get better mileage than the nonturbos. But the 300SD is heavier than the 300D, so you aren't comparing apples to apples.

I have a '74 240D that at beat gets 26 MPG. In contrast both of my 300SDs average 28 MPG and have gotten as high as 31 MPG.

MY '68 220D gets 34 MPG at best and I had a '74 190D that got 40 MPG on a trip.

P E H

ATLD · #4 08-30-2002, 09:13 PM

I never calculated the effective effeciencies of turbo between non-turbo, but it makes sense to me that a non-turbo should get better mileage as the turbo has an ALDA to boost the fuel injection beyond that of a NA diesel, giving more power and acceleration, but at the cost of consuming more fuel (mpg). But when it comes to terms of relative volumetric efficiency, turbos are more efficient in power generation (hp/liter) which is I think what P E H meant.

Hence the idea of a E320 being more efficient that an e430.

But that's only the way I see it.

Remember that fuel consumption is a good indication of the opperating condition of your engine too. If you notice a significant drop, you know there is something wrong. But, also the SD is much heavier too. Has it consistently been getting that economy, or is that recent?

My NA 300D on average gets low 30s around town/ hilly out here; sometines as low as 25 depending on weather and other conditions. Never take it on HW long enough to get an exact figure from a full tank, but have seen beyond 35mpg with mixed driving.

ATLD

190D22 · #5 08-31-2002, 12:15 AM

I've been a little concerned lately... I've been consistantly getting 28/29 mpg. I do mostly city driving. I get the impression that the 190D 2.2s get more closer to 35 range in the city and 40 on up on the highway.

Is this low? If yes what are possibilities of what needs done? I'm thinking of dumping pretty much a whole bottle of Diesel Kleen in next fill up (I don't let it get lower than a half tank and the needle is close the 1/2 w/ 210 miles on the trip).

Thoughts?