Q: What are clean diesels? When I think of diesels I think of black smoke.
A: Diesel powered cars only represent a small market share in the United States, but that may change. Automobile manufacturers have been working to make diesel engines burn much cleaner than their predecessors to meet the increasingly stringent emission standards. These engines run on ultra low sulfur diesel and use particulate filters, Nitrogen Oxide traps, and special catalytic converters to substantially reduce tailpipe emissions. DEF (Diesel Exhaust Fluid) is used to lower NOx emissions, converting NOx into water and nitrogen.