I am replying to the April 7 letter from Norman Carter.
In my experience - which includes 20 years as a fleet manager of a 200-plus-vehicle mixed fleet - the long-held theory about gasoline vs. diesel engine durability no longer holds water.
Our fleet used diesel engines from Cummins, General Motors, Detroit Diesel and Navistar.
We used gasoline engines from Ford, and GM.
The gasoline engines routinely outlasted the diesels, generally lasting 200,000 to 300,000 miles vs. the diesels' 100,000 to 150,000 miles.
We utilized the factory service intervals, suggested lubricants and service parts; and the gasoline engines still returned better service life cycles and fewer nonscheduled maintenance hours.
In all fairness, the overall "average" of the diesel engine life cycles was dragged down by the early GM diesels.
If I were to take them out of the equation, the average life of the diesel would be closer to that of the gasoline engines but still below.
In my opinion, the life cycle costs of the diesels in our fleet were excessive.
Also, they smell and are noisy, and fuel is harder to find.
Even after taking into account the slight mpg increase they can provide, I would argue the value of putting them in passenger cars.