The Series 60, able to deliver the best fuel economy in the market, resulted in a two-decade-plus period of market domination among large fleets for its manufacturer. It was the first heavy-duty diesel using an overhead camshaft to operate electronic unit injectors directly (no use of pushrods) with rocker levers. Its cylinder head was the first that had a true crossflow design, with both intake valves on one side and both exhausts on the other, driven by odd U-shaped rocker levers.

The Series 60 was the first heavy-duty engine to abandon aluminum pistons in a four-stroke design by substituting cast iron, which established the use of more heat-resistant metals. It also featured a smaller 12.7-liter size, but was built as heavily as its competitors, resulting in maximum longevity for a design that used smaller cylinders to save fuel.