The following terms, whenever used or referred to in this article, shall have the following meanings unless a different meaning clearly appears from the context:
(a) "Alternative fuels" include compressed natural gas, liquified natural gas, liquified petroleum gas, methanol, ethanol, fuel mixtures containing eighty-five percent or more by volume of methanol, ethanol and other alcohols with gasoline or other fuels, coal-derived liquid fuels and electricity (including electricity from solar energy).
(b) "Alternative fuel vehicle" means a motor vehicle that operates solely on one alternative fuel, a motor vehicle that is capable of operating on one or more alternative fuels or a motor vehicle that is capable of operating on an alternative fuel and is capable of operating on gasoline or diesel fuel.
(c) "Fleet" means fifteen or more motor vehicles that are centrally fueled or capable of being centrally fueled and are owned, operated, leased or otherwise controlled by or assigned to an agency of a political subdivision.
(d) "Political subdivision" means a county, municipality and any other unit of local government authorized by law to perform governmental functions, but does not include school boards or school districts.