From the beginnings of industrialization, man has ceased to be dependent on animal or his own power to move in the sphere of traffic, but has become dependent on the energy that drives the motor vehicle. Road traffic in Croatia and the EU countries is the dominant category of transport for which oil derivatives are used in general and the continuation of their use is also a continuation of energy dependence on oil and continuation of the environmental pollution. For this reason, the European Union has adopted directives on the promotion of clean and energy efficient vehicles in road transport and the establishment of infrastructure for alternative fuels that are appropriately incorporated in national legislation of the Republic of Croatia with the intent to gradually replace to vehicles without carbon dioxide emissions and pollutants. The interruption of European dependence on oil and the reduction of the adverse impacts of road transport on the environment is a long-term goal that requires a transitional solution whereby the use of compressed natural gas (CNG) is ideally suited to its ecological and economic advantages in relation to the existing state. By analyzing the network of roads and motorways and urban agglomerations in Croatia, it is possible to determine the number and locations of future CNG filling stations, but it is important that authorities of larger cities decide to procure CNG vehicles for public transport and utility vehicles and build at least one CNG filling station to stimulate the trend of significant increase share of vehicles driven by CNG. By comparing the buses of the same characteristics powered by diesel fuel and CNG, the cost saving using CNG is at the level of 15%, while the saving for utility vehicles is even higher. The economic and financial analysis of the investment in the city CNG filling station that would supply at CNG EU- average price public transport busses, utility vehicles and private CNG vehicles would lead to the conclusion that for the presumed fleet of vehicles construction of CNG filling station is cost-effective even without any financial incentives. In the existing economic and legal framework in the Republic of Croatia, there is possibility to build a sufficient number of CNG filling stations, to significantly increase the number of vehicles driven by the CNG and to achieve economic benefits and contribute to environmental protection. Concrete analysis of the hypothetical city CNG filling station proved the exceptionally high profitability of this kind of project, and the analysis in this paper has also shown wider benefits for the economy of cities and the entire national economy.