Im going to start looking for a diesel car to save on fuel. What kind of MPG does something like an 85 300SD. Also what are the best yaers? looks arent relly big in my book. I have the 98 for that i just need somthing that gets me there cheap. starting in the fall my Girls going to MSSU about 80 miles away. so this is going to be more of an interstate cruiser than anything else.

 

The 80"s of the Mercedes are suppoose to be the best for Bio also ,, I have seen a few and they were lots of $$

 

there was an 85 on craigslist here in town for 1200.00

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it sold

 

They're pretty cheap. I believe 30-35mpg highway is pretty typical with them IIRC.

 

The 300D non turbo, 300D turbo, and 300SD all seem to run about the same for economy, the SD being slightly lower due to being a few pounds heavier if you do alot of driving around town. If you don't mind the "not having a turbo" I'd suggest a 240D (2.4 4cyl) as economy is greatly improved (at cost of power, of course).

From about '79 to '85 were good years, though all mercedes diesels were exceptionally long lived motors. Stay away from 6-cyl diesels though, not that you will find one that still has a strait head on it.

They have 190D as well, if you can find one of those I highly suggest you get it, we have a few customers with them and they all see 45-50mpg regularly. They come with suspension squeaks though, you can't shut them up, but it's a trade off between paying at the pump, or turning up the radio.

 

I have a 450SL(gas) and I know that when I was with the Mercedes Club the guys couldn't give a mercedes diesel away and that was about 7 years ago....Now I checked and the prices are sky rocketing here...The guys said they could make between 32 to 38 MPG...The early 80's diesels,I heard are tough engines...

 

I had a 1981 240d with 4spd manual 40mpg was worse ever got, I'm now putting that motor in a suzuki samurai

 

the old 5cyl OM617 turbo and non turbo engines are known for over 400k miles with regular oil changes and valve adjustments.

 

If you treat them right over a million miles is not impossible.

 

I have seen a lot of inflated MPG claims over the years. Remember that to get accurate MPG numbers you need to fill the tank, drive until the reserve light comes on, then fill the tank again. Divide miles driven by gallons used. Now repeat that over several tanks. Any other method will NOT provide accurate data. I track every tank on all my cars in a spreadsheet, so I know precisely what my min, max, and average MPG is for every one of them. For a 1987 300D (3.0L), average is 26-28mpg, peak is approx 32. For a 1990-1993 300D (2.5L), average is 28-30mpg, peak is approx 34.


Anyway: The W126 S-class diesel through 1985 will get mid-20's for MPG, maybe near 30mpg if it's in flawless condition with a tailwind. No way they will get over 30 unless it's going downhill for 400 miles. The 86-87 300SDL got a newer, more efficient engine... those can get high 20's, possibly 30mpg. You need to get an E-class (W124 or W210 chassis) if you want 30-35mpg, or get a 190D (W201) with manual transmission if you want 35-40mpg. The old 240D only gets 25-30mpg (even with a manual trans) due to the 3.69 gears, and the pre-1986 300D with the old iron engine also gets 25-30mpg at best.


Also, fuel quality affects MPG significantly. If you're lucky enough to live in an area with "good" diesel, you'll get better MPG numbers. Some places have low-BTU diesel fuel, which I suspect may be oxygenated. California has had this for years, I think starting in the late 90's. Sadly, Idaho has phased in the crap fuel starting somewhere around 2006. The difference is about 10%... all four of my diesel cars got about 10% better economy when fed the "good" fuel. On a recent trip to Utah, my '87 once again shot up by 10% over three full tanks, and went back down after it was fed Boise fuel. Grrrrr!