The two main types of trolleybuses running in Riga city are non-articulated or standard type Škoda 24Tr and articulated Škoda 27Tr. On its merits, 27Tr is devised to be applied when the demand for the carriage of passengers is higher. However, there might be situations when 27Tr runs at the route when the demand for transportation is low, i.e. 27Tr carries the amounts of passengers able to be carried by 24Tr. It becomes disadvantageous in electrical energy saving point of view. This paper compares the energy consumptions of both trolleybus types for various loads which are caused by passengers. Idealized trolleybus motion simulations were carried in Matlab/Simulink environment and in each case the same distance was travelled at the same time period. The percentage differences by which articulated 27Tr traction drive consumes and regenerates more energy, comparing to standard 24Tr carrying the same passenger amounts, are calculated.