Economic Analysis of the use of CNG Vehicles as means of Public Transportation in Nigeria using CNG-P, a Newly Developed Software is presented in this work. Port Harcourt ? Onitsha expressway is taken as case. This involves analysis on collection of gas from the sales point which is taken as a treatment plant about 10km off the route, through the pipelines to the sites of the CNG refueling stations which would be installed along the route to refill the vehicles. CNG-P was developed and used to conduct economic analysis of the project. The economic parameters determined with CNG-P are: capital costs; operating costs; gross revenue; net revenue; net present value; and profit per Naira invested. From the analysis, the project is found to be very economically viable as it generates high net present value of $829million and profit per Naira invested of 0.72. When compared with the results got by doing the analysis manually, the results got using CNG-P were found to correlate to a very high degree with the results got by performing the calculations manually. This new software is an excellent contribution to knowledge as it would make it much simpler for gas operators who wish to invest in CNG vehicles project to take well-balanced economic decisions.