The fuel consumption of a public transport bus depends on many factors. Various speeds, acceleration and deceleration modes, stopping times at bus stops and congestion, as well as the load depending on the number of transported passengers have a significant impact on the fuel consumption of the city bus. It is difficult to investigate the influence of these factors on fuel consumption using simple equations to determine the energy efficiency of vehicles. A very useful method in this case is the VSP (Vehicle Specific Power) method. The fuel consumption model based on this method uses a number of parameters. Taking into account the measurement data obtained from the actual mileage of city buses, the relevant parameters of the model were determined. The verified model was used in the process of computer simulation aimed at determining the fuel consumption of the bus in urban traffic. Particular attention was paid to the study of the impact of traffic during rush hours and congestion on fuel consumption. The impact and significance of the selected parameters on the fuel consumption of the city bus were also assessed using computer simulations.