An interesting overview of marine diesel engines, also applies to car engines.
bq.. Before I get into this, let me first dispel some myths about diesels. These engines developed their reputation for reliability and very long engine life beginning over a hundred years ago, a reputation that, for the most part, no longer holds. That reputation was based up very unsophisticated, slow turning, low horsepower engines. Except for sailboat auxiliaries, you won’t find many such engines in existence today. Today we have a “need for speed,” and everyone wants to go fast. Going fast is what negates the virtues of those engines from a by-gone era.
The modern diesel is very sophisticated, complex, lighter weight and very powerful. Hence, their life span is often no more than that of a gas engine, often times even less. To say that they are delicate is not an overstatement. There is a very simple rule today that the more power you try to squeeze out of a given engine block, the less service life it will give. People can argue all they want to, but that is a fact.
Emphasis mine. Modern toyota diesel engines still last for a long time, but they definitly don’t remain at peak performance for too long. You could say common rail diesel engines are at leading the charge towards ever increasing power but decreasing life spans.
Still, back in the good old days diesel engines would start off heavy, inefficient and relatively underpowered, and stay that way for ages. That is not really something to strive for. Modern common rail diesels are 97-99% cleaner than their predecessors, and a lot more efficient.