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During the first decade of diesel particle filter development and deployment in cars, trucks, buses and underground sites, DPF regeneration methods were engineered that were compatible with the then prevalent high sulfur content in the fuel ≻ 2000 ppm. The mainly used methods were burners, electrical heaters, replaceable filters and non-precious metal fuel additives. Low sulfur diesel fuel became only available from 1996 in Sweden, 1998 in Switzerland, and after 2000 everywhere in Europe. Thus, the deployment of precious metal catalytic converters was feasible both as original equipment and retrofitting of in-use engines. The so-called CRT particle filters using PGM-catalysis for providing NO₂ for low temperature regeneration became very successful wherever ULSD was available.

Off-Highway diesel engines may benefit from exhaust emission control systems developed for on-highway vehicles. Both the diesel oxidation catalyst and the catalytic soot filter are being used to remove diesel smoke and odor. The advantages of both of these technologies are explained. NOx emissions control from diesel engines are now being addressed. Alternate fuels, such as methanol or natural gas, have been designed to replace diesel fuel as a measure to control NOx emissions. To avoid transfer to alternate fuels and permit continued use of diesel fuel in diesel engines, two approaches are being studied. These are the use of exhaust gas recirculation (EGR) and the development of a new technology called a lean NOx reduction catalyst. EGR, if successfully developed, probably will require the use of a catalytic soot filter. Lean NOx catalysts have been developed but still are not at a practical stage yet.