Every Car Powered By The Mercedes-Benz OM617 Turbo Diesel Engine

There are engines with reputations for being able to rack up over 500,000 miles with steady maintenance. Among those, Mercedes-Benz and its diesel engines are legendary. Here, we look at one of them in particular — the OM617A, which is the turbocharged version of the five-cylinder Mercedes-Benz OM617 engine. Mercedes-Benz drivers in the 2000s were reporting cars with up to 600,000 miles on them, with many stating that they could go even further by keeping up with routine maintenance.

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Fitting the turbocharged OM617 engine into a W116 platform for select markets outside of Europe created the world’s first turbo diesel sedan. There were three slightly different versions of the turbocharged OM617 engine produced, though a mid-life upgrade of the first version made the most difference in terms of performance. Mercedes-Benz had three different platforms that utilized this engine base: Namely the 1978-1980 W116, 1981-1985 W126 S-Class sedans, as well as some of the 1978-1986 W123-platform cars.

The first version of the turbo-charged OM617 engine was the OM617.950, built for the W116 platform, which made the resulting 300SD the world’s first passenger car with a turbo-diesel engine. While the turbo-diesel helped improve the brand’s overall fuel economy rating for its vehicle fleet, the W116 was also the first Mercedes-Benz to be officially called an S-Class — this was a flagship Mercedes-Benz model, and not an economy car by any means. Mercedes says that 28,634 300SD models were produced out of the 473,035 total W116 platform automobiles.

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Mercedes-Benz’s OM617 engine in the first 300SD models produced 111 horsepower — up from 80 horsepower for the naturally aspirated version in the 300D. In late 1979, this was bumped up to 121 horsepower, versus 88 horsepower for the non-turbo variant. That extra power was sorely needed, especially for cars with automatic transmissions. The same data show that early 300Ds ran 0-62mph in 20.8 seconds. Even after the 1979 upgrade, the 300D took 19.2 seconds. The 300SD turbodiesel? At first, 17.0 seconds — and after late 1979, 16.2 seconds.

The W126 platform was rolled out starting in 1979, but a version with the OM617 turbodiesel became available in the 1981 model year. Like its previous iteration, the 300SD Turbo sedan was built for the U.S. and Canadian markets, and up through 1985, there were 78,725 of them were built.

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The turbocharged W126 came out at a perfect moment for Mercedes-Benz. American manufacturers had begun attempts at improving gas mileage; at first by dropping both engine and body sizes. Cadillac, for example, dropped engines over 400 cubic inches after 1979, and introduced smaller cars such as the Cadillac Cimarron. However, in the early 1980s, Cadillac also experimented with a technology they called V8-6-4, which shut off some pistons at certain speeds. This failed to produce a long-lived engine for Cadillac because while the tech was novel, the onboard computer in Cadillac vehicles couldn’t keep up and caused some severe mechanical issues.

By contrast, with Mercedes-Benz taking an under-stressed engine and adding a turbo, its sedans were able to maintain reliability while improving performance and fuel economy. Mercedes-Benz claims that, at first, the OM617.951 produced the same output as its predecessor. That was then raised after the October 1982 revision to make 125 horsepower.

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Europeans who wanted the three-liter turbocharged diesel could not get one on the W126 platform. Instead, they came in the form of the W123 series station wagon, the 300TD Turbodiesel — or “kombi,” as they are known in Central Europe. In 1981, it briefly came with the OM617.951 engine. However, in 1982, the OM617.951 was reworked slightly to better fit the W123 platform. This engine — called the OM617.952 — made it into the 300TD Turbo models that were sold in Europe. Overall, 28,219 300TD Turbodiesels were made.

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The W123 also came in a coupe version for the North American market. This was the 300CD Turbodiesel, and 8,007 of them made it across the Atlantic. While it shared the same overall drivetrain as the other two vehicles, the coupe was up to 200 lbs lighter than the sedan, which affected acceleration significantly. According to Mercedes-Benz, the 300CD Turbo reached 62 mph in 14 seconds, versus 15.2 seconds for the full-sized four-door version.

In the mid-1980s, Mercedes-Benz updated its various platforms, providing a visual a refresh to several vehicles in its lineup. The engines, however, underwent an even greater overhaul. The success of the turbodiesel led to further developments, and the successor to the OM617:952 was called the OM602. The new engine was introduced in 1985, and it went into the new E-Class cars in 2.5 liter normally aspirated variants (from 1985) and turbocharged versions (from 1988).

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In case the OM617A bug has bit and you’re looking to snag your own classic S-Class, remember that the youngest cars with these engines are almost 40 years old now. Their positive reputation has never really declined, either. In 2018, Hemmings put it bluntly, writing that “both the coupes and the wagons are bona fide cult cars. Fewer than 200,000 wagons were built worldwide, and coupes are even rarer — not quite 100,000 were built over the decade.”

That said, the Mercedes-Benz 300SD is a different story. Even in 2024, a sedan with over 200,000 miles can still be picked up for under $10,000.