Not in this life time. Dropped from a crane "Mythbusters Style" maybe? Not to mention it is a wagon. Wagons get worse mileage by design aerodynamically. The person posting may have Dementia or something. My father has been diagnosed with that disease and it is funny some of the things he says sometimes regarding numbers.


This is a W123 thread... I remember clearly on the one I had. We were driving 600 to 900 miles per week at times (when I owned it). The amount of miles we were driving was part of the reason I sold it. It was just not holding up.

The 85 that I owned always returned 24 to 26 MPG. That was running a mix of B99 and #2. That is also interstate speeds around 75 MPH. I think it got 27 MPG one time? I just figured I calculated it wrong or something.

NOT an economy car to be sure...

Best- 29.4
Worst- 24.7
Average- 26.5

I love my Car Minder app.

OK. So let me get this straight... you have a diesel SL? That's pretty sick. All that stuff about the gear ratio is over my head though. Did you use the original turbo?

Yeah. I've had a half dozen of these cars and I've only seen numbers aproaching these coasting downhill in neutral.
That being said. If you all want to get better mileage the key would be to improve your aerodynamics by making several small mods that will gain you small MPG gains.
The easiest and lease obvious ones are the only ones I would do on a 123.
I've been reading alot about these aero eco-mods. Some of them are pretty over the top. But the best and easiest one I read about was from a guy who get about 30mpg from his volvo wagon: Cover the gaps between the gas tank and the rear bumper under the car. (uncovered it acts like a parachute)
Some other ones are to cover the entire underside of the car with hard plastic panels.
Have you ever looked at the underside of a 1987 300TD wagon.... panels. Block up the grill ( I wouldn't do that). Add little aero flaps in front of your wheels, these direct the airflow under your tires instead of up into yoour wheel wells where they will cause resistance.

Hi everyone!

The best mileage I've ever got out of my 240D was a consistant 36-38mpg, which baffles me because the only time I've achieved those numbers were driving round trip from Albuquerque, NM to Taos, NM. For those unfamiliar with New Mexico geography, Taos is on top of a Mountain. I used to make that drive every morning through blizzards and wind and really nice days too. Naturally, I coasted as much as I could on the way back down, but it just doesn't seem like that should make up for all the fuel burned on the way up.

On the flat, I get about 34mpg if I drive at 65, or about 30 if I'm running 75 to 80.
Cheers!
Chris

I forgot to mention. The 240 is turboed, four speed manual trans, and 3.07 gears. My only aero mod is taking off the side mirrors! :D

What year? Is that turbo and gearing stock?
Hows the pickup on the 240D?

I see 25-27mpg in my 240 4-speed. The wifes 300TD wagon gets about the same when she's driving, and worse whem I'm driving.

Gearing can do huge things to economy though. In my 89 van with an 80 240 motor, I see 27-29mpg very consistently. Its heavier and a worse aerodynamic shape by far, and It blows the doors off both 123s in the family because its got an overdrive 5th gear even though its using effectively the same engine as my DD 240

Search mach4's username, he has a fabulous thread on the conversion of his SL. Worth the read

Hi Chris!

The car is originally a 1983 240D non-turbo with an auto trans. I changed the gearing to a 3.07 diff out of a 300 turbo, which dropped my cruise rpm about 600rpm IIRC, so its turning about 3200rpm at 75mph. I'll re do the math if you would like. I also swapped in the four speed manual trans. I manufacuture an adapter plate that allows puttin a 5 cyl turbo manifold off a 617 on to the 4 cyl 616 which makes the conversion as easy as bolting together lots of junk yard parts, so thats how the turbo got on there! I have pics in my old posts. Since then a different air filter set up is used and I've improved the oil separator. I will post some new pics this weekend after the whole Thanksgiving family drama is over! :D
Cheers
chris

I forgot to mention the pickup is quite good! IP is also um......not stock. :cool:

That is pretty cool right there. I wonder why Mercedes never put a turbo on the 616.

What did you do to it? 617.95 elements?

This is gonna be kinda longwinded!
 

How I modifiy the IP:

The pump mod is dead simple. Take off the back cover of the pump. Once inside look at where the throttle shaft goes through the pump body. There is a tube that the throttle shaft goes through that I call the start/run lockout link. This link at one end engages some other parts that limit the rack travel, the other end links to the governer. How it works is that at cranking speed the rack is allowed to move to its Maximum fuel position for starting. As soon is the engine starts and the governer weights start to come out, this link limits rack travel, and the difference is Huge. The trick is to remove this link so that you can get Full Fuel all the time! Well at least till the governer pulls back due to RPM.

Removing the link is pretty easy. There is a little wedge with an 8mm nut on it that must be removed and of course the snap ring on the far side of the throttle shaft. Slide the throttle shaft out of the body untill you can remove the start/run lockout link, then slide the shaft back in. The little wedge will drive you crazy for a bit, but once everything is back together, you are set.

Stock fuel per squirt on a 240D is about 41.5 cubic mm. Stock fuel on a 617 turbo is about 51.5 cubic mm per squirt. Just this mod with stock pump elements make about 114 cubic mm per squirt! Thats nearly 3 times the fuel with one easy little mod and you don't mess up any of the governer spring balances or anything, and its easy to go back stock if you ever want to.

With this much fuel you absolutely Must have a turbo, or maybe a supercharger. I'm thinking of trying that! Sorry I dont have pics of all this. They were lost when my old computer died, but maybe this weekend I can take some more so you guys can see what the part I'm talking about looks like.

cheers
Chris

I think i need to do a little maintenance on the old girl but right now i am only getting right at 20mpg.

BJ3 i watched your videos and there is one that shows a 4cyl diesel in an astro van, what motor was used in that one? 4bt? the 4bt is not a cheap motor however finding a old Merc motor is not so tough even in you have to part out the donor car....