especially among Ford's 6.0 Power Stroke engine owners. Introduced in 2003, this V8 powertrain was used in vehicles like the F-250, F-750, E-Series vans, and Ford Excursions through 2007.

Diesel engines, for all their rugged usefulness, can be tremendously polluting. They produce more NOx -- nitrogen oxides-based emissions -- than gasoline-fed cars, as well as more particulates ...