INDIANAPOLIS, Indiana - Indianapolis wants to become the first major United States' city to replace its municipal fleet with battery and plug-in hybrid vehicles.Mayor Greg Ballard in Dec 12 2012 signed an executive order mandating the city to replace its current sedans with electric vehicles. FUTURE PLANSThe city will also work with the private sector to phase in snow ploughs, fire trucks and other heavy vehicles that run on compressed natural gas and it will ask automakers to develop a plug-in hybrid police car as one doesn't yet exist.Indianapolis, the 12th-largest city in the US with a population of 825 000 hopes to complete the switch by 2025.Ballard, a retired Marine officer, hopes that in making the switch Indianapolis will help the country to reduce its dependence on foreign oil. City spokesman Marc Lotter said the mayor considered it an issue of national security.The mayor added: "The United States' current transport energy model, driven by oil, exacts an enormous cost financially and in terms of strategic leverage. Our oil dependence in some cases places the fruits of our labour into the hands of dictators united against the people of the United States."The city fleet includes 500 non-police vehicles and the police-car switch alone has the potential to save taxpayers the equivalent of R86-million a year in fuel.Lotter did not provide an estimate on the cost of the change. The new vehicles will be bought as others are retired. He said the city bought about 50 non-police vehicles a year.