Let me chime in here on this one. Best small to mid-size diesel engine in my opinion is the Izusu. I'm a professional fleet mechanic with a fleet of 25 delivery vehicles. Their road conditions range from in-town stop and go traffic to solid highway miles to mountain terrain. Number two is the Cummins 6.9T ISB engine. Number three is the Cummins 3.9BT. Mercedes 616 and 617 engines lag behind only because of the timining chain and auxillary vacuum pump issues.

I've run everything from, Perkins, Detroits, Cats, Dagenheims, Dorsetts (you old fishermen will recognize those last two), ALL Ford gas engines, GM's of all types, IH DT466's, Whites, Hercules and anything else you can stuff under the hood.

The ONLY diesel I'd ever have in an automobile is the Mercedes but then again I don't subject my cars to the daily abuse my trained monkeys, err I mean, my dedicated drivers do.