The plug-in hybrid electric powertrain is a new technology and a suitable option to reduce the volume of pollutants in the city. The batteries in these systems can be plugged into an external source in addition to recharging by the combustion engine and regenerative braking. These vehicles have larger full electric range because of their relatively large batteries. As a result, the fuel consumption of these vehicles is low. The aim of this research is the development of a smart sizing and simulation software for plug-in hybrid electric vehicles. The size of the combustion engine, electric motor and battery are calculated in the software according to the input based on the performance of components. Then fuel consumption and emissions of pollutants are estimated in a standard drive cycle using a predictive controller. To verify the result from the software, a produced plug-in hybrid electric vehicle has been used. The software outputs correspond to the determined values for the vehicle. The proposed software is a useful tool for the early phase of the plug-in hybrid electric vehicle development stage.