One-third of all new cars sold in Europe are diesel-powered, and analysts think the number will rise to at least 40 percent by 2005. Diesel engines can use 30 percent less fuel than gasoline ones, and they emit far less carbon dioxide and other greenhouse gases. In the U.S., meanwhile, less than 1 percent of new cars have diesel engines. A draft report to Congress by the U.S. National Academy of Sciences says diesel engines may be the quickest way to improve the fuel economy of America cars. But U.S. environmental groups remain opposed to the engines because of the sooty particulate emissions that come from them. Daniel Becker of the Sierra Club said, “As long as we have other technologies that are clean, I don’t see the point in producing carcinogenic soot.”