First road trip - PeachParts Mercedes-Benz Forum

psaboic · #1 09-19-2010, 11:42 PM

First roadtrip with the new-to-me 83 300D. Ran 622 miles on approximately 21.75 gallons of diesel. That works out to about 28.59 MPG. That is going from sea level to 4103 feet, then back again at a sustained 65-70 MPH.

Sounds pretty good to me.... what do you think?? Normal mileage or??

BTW, "Col. Clatter" as we call the car ran great, was very comfortable, and got many looks on the road.

tbomachines · #2 09-20-2010, 12:49 AM

Great!! From what I've read on here, that is very good mileage. I drive like a granny so I see that pretty regularly in the SD, still good though.

vstech · #3 09-20-2010, 03:25 AM

sooo, you filled up before leaving, went 300ish miles, filled up again, and drove home? or you went the 300ish miles then drove back, and when you were out of fuel you filled up again, and figured how much fuel you used?
21.75 gallons is more than the tank holds, so I'm racking my brain how you did it math wise.

psaboic · #4 09-20-2010, 09:11 AM

Filled up before I left, went 300ish miles and filled up before I left for the 300ish trip back. Once back I filled again.

vstech · #5 09-20-2010, 09:27 AM

sweet. I'm guessing the return tank needed less fuel? that coasting down mountains is great on economy, but tricky on brakes! any issues with fade? an upgrade to SD rotors and front calipers can give you a bit more capacity before fade sets in on mountain braking. but our cars engine brake quite well.

psaboic · #6 09-20-2010, 09:57 AM

No problems with brake fade. Like you said, these cars engine brake pretty well, and I took advantage of that. One thing I will say, these babies climb mountain grades like a champ. The diesel torque combined with the turbo enabled me to climb past many "high-end" cars and SUV's like they were going backwards! The looks from some of the drivers was priceless!!

kerry · #7 09-20-2010, 10:25 AM

MPG seems unusually high to me. I'd check the odometer with a GPS.

Stevo · #8 09-20-2010, 10:50 AM

I've found that most of these spedos do read high as Kerry said. My TD the spedo would read 55 MPH when I was actually doing 51 by the GPS. The tires were 195/70 and by going to 195/75 the spedo is right on now.

Biodiesel300TD · #9 09-20-2010, 11:31 AM

I don't think 28 is incorrect. I got 27 in my wagon once, but usually hung around 24mpg. If he was coasting down a mountain grade for many miles, the engine will get great milage. And probably still pulled 23ish up the mountain. psaboic, what was the milage on each tank?

You should have come down and visited me. I'm less than 600 miles away!

tbomachines · #10 09-20-2010, 12:27 PM

I've gotten a high of 32 mpg with my 300SD, odoemeter/GPS verified. No reason to doubt 28 - it all comes down to driving style. That is why I prefaced my first post "with what I have read on here"...meaning, the maximum that most normal members are capable of.

Skid Row Joe · #11 09-20-2010, 02:23 PM

Quote:

Originally Posted by psaboic

First roadtrip with the new-to-me 83 300D. Ran 622 miles on approximately 21.75 gallons of diesel. That works out to about 28.59 MPG. That is going from sea level to 4103 feet, then back again at a sustained 65-70 MPH.

Sounds pretty good to me.... what do you think?? Normal mileage or??

BTW, "Col. Clatter" as we call the car ran great, was very comfortable, and got many looks on the road.

"28.59 MPG @ a sustained 65-70 MPH," for a non-turbo aspirated diesel is outstanding MPG.

Skid Row Joe · #12 09-20-2010, 02:27 PM

Quote:

Originally Posted by tbomachines

I've gotten a high of 32 mpg with my 300SD, odoemeter/GPS verified. No reason to doubt 28 - it all comes down to driving style. That is why I prefaced my first post "with what I have read on here"...meaning, the maximum that most normal members are capable of.

"32 mpg" in an SD is definitely "a high."

They are 30 mpg highway cars tops, with 28 or less mpg, for their combined usual mpg.

Skid Row Joe · #13 09-20-2010, 02:31 PM

Quote:

Originally Posted by psaboic

Filled up before I left, went 300ish miles and filled up before I left for the 300ish trip back. Once back I filled again.

A cumulative 5 to 10 fill-ups AVERAGED, are a much better way to determine usual MPG for any vehicle.

I have gotten up to 38 MPG, and as low as 18 MPG on my '99 E300. Do you think either number reflects it's cumulative average MPG? I think not.

tbomachines · #14 09-20-2010, 02:42 PM

Quote:

Originally Posted by Skid Row Joe

"32 mpg" in an SD is definitely "a high."

They are 30 mpg highway cars tops, with 28 mpg their combined usual mpg.

I've also been told that about my 300E...where I get over 30 routinely on the highway. The SD hovers right around 30mpg, but more above than below typically (talking 1/10s of a mpg here). A major contributing factor is probably traffic, most of my driving is on heavy interstates, so figure 60-70% of the time I am behind a truck, or perhaps an SUV that can have a slight slipstream effect. Perhaps in a lab, 30mpg may be extremely tough to achieve but in a real world scenario it is very doable. There are a number of forum members convinced it is completely physically impossible for either of my cars to get above 30mpg, which is simply not true. To the OP I say bravo - means the car/engine is probably in great shape to achieve that and it sounds like it was a good time and pleasant drive!!

That being said, my city MPGs are pretty dismal, but I live in a city on a steep hill (river valley) with lots of lights and lots of stop and go.

tbomachines · #15 09-20-2010, 02:44 PM

Quote:

Originally Posted by Skid Row Joe

"28.59 MPG @ a sustained 65-70 MPH," for a non-turbo aspirated diesel is outstanding MPG.

I do agree, the OP's car is a turbo though. IIRC the w123 has a significantly higher drag coeffieicnt and is heavier than the w126 as well--I don't completely discount it but a few tanks average would yield a more stable result.