The conditions of use of the vehicle significantly affect the performance results. Traffic conditions in a specific city directly affect
the consumption of energy, fuel and emissions of harmful compounds in exhaust fumes. Conduction of the measurements of a vehicle’s performance parameters in operating conditions is very troublesome and is often not possible to realize. An alternative is
to use the simulation programs. Vehicle simulation programs offer options related to vehicle models or drive unit components and
allow development of new models. Based on the results of simulation testing, it is possible to analyse the level of fuel and energy
consumption as well as emissions of harmful compounds in exhaust gases and the operating effectiveness of the drive system in
the speed profile. The paper presents the evaluation of the effectiveness of using hybrid electric drive system in passenger cars in
medium-sized city traffic conditions using the Kielce example. The simulation tests were based on the speed profiles recorded during real-world test drives in various times of the day. The simulation results were used to conduct an analysis of fuel consumption
and pollutant emissions recorded by conventional and hybrid vehicles.