As I begin to look for a 300SD daily driver, I wonder if anyone might be willing to educate me as to the engine/drivetrain differences among these cars from '81 through '85? What year was the best?

They are all basically the same car, the engines are all basically the same, and the transmissions will all basically be the same. The California models and 1985 Federal Models have the trap Oxidizer. I think the later ones have different gearing. The 1984 and 1985 models had optional ABS and Airbag.

The best year is whatever car you drive and like the most. Some say that the W116 300SD's are better than the W126 ones, but these are getting hard to find in good shape.

The vacuum system was modified from 81 thru 85 on the 126 Diesels with 85 getting the final improvements on the transmissions, shifting, etc. I love my 85 but have driven in a 83 and an 81. I can't tell much difference between them. They all drove with the same classic ride of a 126 chassis Benz.

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Orland Park, IL
1985 300SD 215,000 miles

Try to look for an 84 or 85, as these were the last two years of the 300SD and MB got all of the minor kinks worked out of them. Some had ABS and/or driver airbag as well. Great cars, nearly indestructable.

Agreed with Turbodiesel....

Go for the latest car possible, but otherwise the earlier car is just fine, although I would recommend to avoid an '81 if possible. I have an '83 and love it to death, it's my daily driver. Kristen has an '84 and her's basically just has an LCD outside temp display and a factory alarm system (mine has neither). Nothing else is much different physically. And yes, if you find an '85, you might also get lucky and happen across one with ABS, Airbag and heated seats! All are VERY rare options on those cars.

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Regards,
Aaron