This paper will attempt to set forth a conceptual study of natural gas application as a vehicular fuel. In doing so it recognizes firstly, the critical importance of combustion and operational characteristics of the fuel in terms of fuelling, carburation, ignition parameters and etc. This is based on theoretical findings as well as experimental observation of different types of converted engines. Because of the strong mutual interactions involved, the value of any measure taken to optimize the engine performance should be conveniently judged within the framwork of a closed system.Then the paper examines the environmental and safety advantages of natural gas fuel, presenting a comparative emissions data with LPG and gasoline. Finally an analysis of the economics of natural gas -a direct substitute, along with data on estimated and proved reserves of the supply is given. This justifies economically also the shift to such a more decentralized, diffused and renewable energy resource.