Ford Motor Company has signed an agreement with the Environmental Protection Agency (EPA) to develop a new diesel engine that meets tough new emissions standards to be phased in over the next few years in the United States.Ford and EPA announced the agreement last Friday at EPA's National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Michigan. On display was a Ford Galaxy minivan that demonstrated 'Clean Diesel Combustion' (CDC) technology, developed by EPA.The diesel minivan gets 30-40 percent better mileage than a gasoline minivan, while meeting EPA's emission standards for nitrogen oxide, EPA researchers claimed in news reports.Diesel fuel has given off far higher levels of harmful smog-forming pollutants than gasoline, but the difference has narrowed considerably as technology has improved in recent years. Tough new federal regulations will soon require diesel and gasoline-powered cars to reach the same emissions levels, making it harder for automakers to bring diesel vehicles to the United States. The chief hurdle is reaching a low level of emissions for one pollutant, nitrogen oxide. Most companies say that filtration or treatment technologies to remove nitrogen oxide will be costly and complex. The diesel engine developed by the E.P.A. does not require filtration because it uses a combustion temperature that is far lower than usual, preventing the creation of nitrogen oxide.