The notion that a lot of "around town" driving and lack of highway driving is harmful to a diesel is an interesting paradox. I've ridden in MANY diesel taxis in southeast Asia - some MB, some not. Many of them see heavy city duty - and that includes long periods of idleing, lots of stop and go traffic in the city, and rare highway jaunts. Yet so many of these taxis have well over 400,000 kilometers (250,000 miles) on the clock and run amazingly well.

I was in a W124 250D taxi with approximately 500,000KM on the original motor and transmission - no rebuilds. The driver said that the car sees the highway maybe once a week, and is mostly putting around the city, running for 10 hours a day or more. Yet it idled and ran so smoothly and quietly, and did not smoke - no black film on the rear of the car either. Overall it appeared that the car was in excellent running condition.