DES MOINES, Iowa (AP) — The federal government has taken another step toward wide distribution of gasoline mixed with 15 percent ethanol by allowing manufacturers to register as suppliers. While the EPA is moving the process forward by allowing the registration, E15 still has to clear another set of federal tests and become a registered fuel in individual states. Ethanol makers then must convince petroleum marketers to sell it at gas stations. Most ethanol fuel sold for passenger cars and pickups today is 10 percent ethanol and 90 percent gas. The new blend boosts ethanol to 15 percent. It would only be used in 2001 and newer vehicles. Twenty ethanol makers that have registered to sell E15 are based in Colorado, Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, South Dakota, Texas, and Wisconsin.