Electricity consumption for traction depends on a number of operational parameters, including the use of power of electric rolling stock. On Russian Railways there are flat areas of great extent, which operated the locomotives inefficient use of power and work modes with low energy performance. The aim of this work is to examine ways to improve the energy efficiency of passenger locomotives, such as the operation of electric rolling stock with rational values of power and number of axes for the modern passenger transport on the flat sections of the road long-haul and assess their energy performance. To achieve this goal was determined by the rational value of the power required for driving trains on this stretch of track with maximum speeds of 160 km/h, the calculations of the asynchronous traction motors obtained traction and power characteristics of electric locomotives with asynchronous traction drive, and a proposed comparison methodology, allowing to evaluate the difference of power consumption for traction of electric locomotives with asynchronous traction drive (with rational values of power and number of axes) currently operating a DC electric locomotive EP2K. On the basis of the conducted research it was concluded that there are reserves for improvement of energy efficiency of passenger locomotives on the flat sections of the road long-haul, such as operation of electric rolling stock with rational values of power and number of axes corresponding to the train weight, speed and track profile, which will significantly reduce the cost of electricity for traction of trains.