Mike,

As GM demonstrated with their Diesel car experiments conducted by the public, there is nothing about running on Diesel fuel that makes the engine last longer. However, if you examine the markets where Diesels dominate, such as heavy trucking, train locomotives, marine transportation, etc., you see singificant numbers of machines that last, in very severe service, many hundreds of thousands of miles. While this is not an unachievable goal for gas engines, as there are notable examples with the ability to last for similar, unusually high numbers of hours of use, it is rare to combine this feature with exceptional economy.

Heavy trucking use pits much more highly stressed, using your perspective on stressing an engine, engines against much more rigorous use than any 240D or 300D will see. The horsepower per pound ratio for trucks and their usage factors are much higher than a 240D or the typical car.

Diesels designed for these industrial markets are engineered to have long lives, more so than the typical gasoline automobile engine. Mercedes-Benz brought the Diesel to the automotive industry and practically owned the taxi cab market around the world, except the US and UK. So, they were optimized for economy and longevity. They missed out on a few things people like about gas engines though, like low weight, high output, etc.

There is nothing that says gasoline engines could not follow the same path, they just have not for various reasons. The most probable being the added cost for something a lot of people would not keep long enough to see the economic payback on, so it has no value. Hope this helps, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)