Energy flow control and management in a vehicle is an essential aspect of the design process. These solutions are particularly important in the case of vehicles that do not have an external energy source, such as railway vehicles equipped with innovative energy storage technologies. The article presents analyzes of the theoretical energy consumption in a three-car passenger rail vehicle of Polish production, which was equipped with electric energy storage for the purposes of the simulation. An algorithm was developed in the Matlab program for research purposes, which was used to calculate the energy flow in a vehicle traveling along the test route between stations A and B, 73.5 km long, with 18 intermediate stations. During one simulation, the vehicle travels this route back and forth. The article presents the results of six theoretical test runs, which differed in the charging procedure of the vehicle energy storage systems during the travel along the test route. For the test drive simulations in the first variant, it was assumed that the vehicle does not consume energy from the overhead catenary, or from a stationary energy source, during stops at stations. In this situation, the train must have accumulated sufficient energy to cover the entire route back and forth before departing from station A. For the test drive simulations in the second variant, it was established that between stations A and B there are two sections with an overhead catenary, each about 10 km long, where the energy storage systems will be charged, i.e. four charging sections on the whole route. The drive simulations in the third variant are identical to the ones in the second variant, with the difference that the station B in the middle of the journey (30 minutes into the drive test) causes additional energy consumption during the vehicle stop. The simulations have shown that compared to the first variant tested a drive in the second variant could be carried out with an energy storage system of only half the original capacity, while in the third variant a storage system with only a quarter of the original capacity would be sufficient.