By July 1, 1992, the department shall develop, in cooperation with the departments of *general administration and transportation, and Washington State University, aggressive clean-fuel performance and clean-fuel vehicle emissions specifications including clean-fuel vehicle conversion equipment. To the extent possible, such specifications shall be equivalent for all fuel types. In developing such specifications the department shall consider the requirements of the clean air act and the findings of the environmental protection agency, other states, the American petroleum institute, the gas research institute, and the motor vehicles manufacturers association.