48MPG in an 87 300d - and no... not the cars for sale on Craigslist! - Page 2 - PeachParts Mercedes-Benz Forum

777funk · #16 08-27-2008, 05:26 PM

Quote:

Originally Posted by babymog

True that the pedal position changes significantly, but the lower fuel flow rate / gallons per hour is also creating a lower miles per hour so it doesn't all go to MPG increase.

Of course, and you're 100% right... but what I noticed is that it doesn't feel like a linear relationship there. Just like above a certain speed point RPMs to MPH becomes less and less linear in 4th gear.

mpolli · #17 08-27-2008, 05:48 PM

If it was a 4 cylinder I would believe it. It seems a little high for a 6 cyl. However, if you had a tailwind that could give you the result you got. Ditto if your elevation decreased. Also did you do any drafting of trucks? That can add lots of MPG. There are ways to get super MPG. It sounds like all you are trying is: not speeding, not going fast up hills. Those are a couple of good ones but there are others. Is that car a stick or automatic?

JimFreeh · #18 08-27-2008, 05:58 PM

In thirteen years of driving an 87 300TD and 150K miles, I never got a sustained average of better than 30mpg.

Granted this was with a wagon, but I'm a cheapo kind of guy, and I'm aware of how to drive for mileage..... It's been a game I've played since the mid eighties when I was running a 64 Lincoln sedan as a commuter. Got 17mpg out of that car, with a 430 V-8 and over 5k lbs of fine Detroit steel.

Sounds like a fluke reading to me.

Jim

babymog · #19 08-27-2008, 08:16 PM

The '87 300TD hwy estimate is 3mpg lower than the sedan.

Hatterasguy · #20 08-27-2008, 08:31 PM

I'd be happy if I could just break 23. I have been driving 55-60 on the highway, 2k around town and getting 22.79xxxx. If I drive like a nut I get 21.

777funk · #21 08-27-2008, 09:13 PM

Quote:

Originally Posted by Hatterasguy

I'd be happy if I could just break 23. I have been driving 55-60 on the highway, 2k around town and getting 22.79xxxx. If I drive like a nut I get 21.

Wow! I don't know SDL's very well... but is that normal? Sounds a little low. Have you had the timing adjusted? I had the dealer adjust mine a while back (advance it 3 degrees from where it was) and it was much more responsive with less pedal action. I believe I've got mine a hair further advanced (reference the pump to the block) now than he had it and it's faster yet. I'm sure it's helping my MPG because I don't have to put my foot into it as much.

Hatterasguy · #22 08-27-2008, 09:57 PM

Done everything, thats all they get. My broker doesn't do any better with her's.

I think the people who get better either, drive very slow and steady on level straight roads for long distances, or simply lie. Most likely a little bit of both.

777funk · #23 08-27-2008, 10:06 PM

Quote:

Originally Posted by Hatterasguy

Done everything, thats all that they get. My broker gets the same out of her's.

I think the people who get better either, drive very slow and steady on level straight roads for long distances, or simply lie. Most likely a little bit of both.

Wow yep I guess I've done too much reading on here. I figured they did better because I'd read the SD gets around 24 to 27 MPG.

I still would like an SDL someday. Seem like great cars with lots of leg room. Can't say that about the 87 300d but I really enjoy it. Just wish it was a little bigger with kids and car seats.

derburger · #24 08-27-2008, 11:20 PM

I did a test for a few tankfulls this summer. I call it my "Drive like an ass" test. Prior to this test my 300cd non-turbo has consistently gotten no less than 21mpg in the city driven with economy in mind, steady acceleration, coasting to stoplights, etc. If it gets 21mpg normally while babying it, what will the mileage be if every stoplight is a drag race? Driven like an ass, mileage increased to a rounded-down 22 mpg in the city, average of three tanks. City speeds are less than 40mph with many stoplights. Maybe it was a fluke or me not using A/C (I didn't anyway, it was broken), or driving stupid got me better mileage than smart.

Highest mileage I've gotten out of my 300cd is 24mpg, 55-65 mph local interstates.

Hatterasguy · #25 08-27-2008, 11:27 PM

My 300SD never did any better than low 20's. The PO said the best he did was around 30 on the highway, but at the time the car was less than 10 years old.

You have to remember one thing about mileage claims, they are like fishing stories...

DslBnz · #26 08-27-2008, 11:47 PM

Quote:

Originally Posted by Hatterasguy

My 300SD never did any better than low 20's. The PO said the best he did was around 30 on the highway, but at the time the car was less than 10 years old.

You have to remember one thing about mileage claims, they are like fishing stories...

How slow is your commute? With me, I stop about 3 times to work over 15 miles. I accelerate pretty hard (shifting at ~ 4400 rpm minimum, sometimes stretching out to the full 6K), and coming out of corners, I hit it hard too.

I average 28 - 30 mpg, in the SDL. On the highway, it's about the same. I do have a straight pipe, though.

I averaged about 21 mpg in my old 1990 300SE. Again, highway mileage was equivalent.

pawoSD · #27 08-28-2008, 12:17 AM

Huh....I have been regularly getting 24-25mpg, and I go fast on the highway, and drive "normal" in the city (I'm not a slow driver)....yet again the good o'l 617 wins.

rcounts · #28 08-28-2008, 12:31 AM

I started that "slow is the way to go" thread. derberger, your mileage on that NA 300CD sounds seriously low. My 300CD Turbo gets better than 21 if I drive it like Mario Andretti! Normal mixed highway/city commuting I get 24-26, straight highway at 70 I get around 26-27, straight highway at 65 I get around 30-31 and on a long highway trip at 60, I got almost 33.

I know the newer (87+) engines tend get better mpg than my old all-iron 617 - mainly due to the cross-flow head, but 48 is so high as to sound too good to be true.

Keep working the experiment and driving at 60 for a while. I'll bet you end up with an average in the 36-40 range. I'm trying to keep the highway part of my commute down to around 55-60 as well - though it is a really hard thing to do when the average speed of traffic is 65-70...

Jetmugg · #29 08-28-2008, 08:21 AM

That car is not getting a consistent 48 mpg at 60 mph over any kind of significant distance.

Drive it from Columbia, MO to Denver, CO and back at 60 mph. Then measure your mileage. You should take a series of measurements and then do an overall average of total distance traveled and total gallons used to determine the mileage. If the number is over 45 mpg, I'll buy the fuel.

SteveM

nhdoc · #30 08-28-2008, 08:51 AM

These fuel economy threads are getting to be like oil threads. How many of them do we have to deal with? Here's the facts again, you CANNOT ACCURATELY MEASURE FUEL ECONOMY THE WAY YOU DID IT, PERIOD.

Can we be any clearer than that? You will not consistently get 48 MPG from a 300D so don't think it will happen again. Maybe low 30's, MAYBE if you are lucky.

At some point someone will post that they filled the tank to the brim, drove a mile and it was still full so they conclude their car doesn't burn any fuel and gets infinite MPGs.

Seriously, you just can't accurately measure MPGs by doing small trips and topping off the tank, almost everyone here knows this. Even one full tank is not significant statistically...you need to do several full tanks and average them to get anything that resembles an accurate measurement.