Problem. Today, there is a problem associated with the need to increase the efficiency of railway transport. Recently developed methods for determining the parameters of energy-saving operational work in stable and transient modes, as well as sets of corresponding technical means from various manufacturers allow us to speak of an integrated energy-saving technology. This development relies on the use of electronic controls. It is very effective both when used on new locomotive diesel generators and when retrofitted during a major overhaul. The integrated indicators existing in railway transport were developed without taking into account the capabilities of modern control systems in the formation of both stable and transient modes. Therefore, it is difficult to obtain estimates on their basis that make it possible to compare the efficiency of energy saving of control systems of various manufacturers and the actual payback period under operating conditions. Goal. The purpose of this work is to develop a methodology for assessing the impact of technical controls on improving the operating efficiency of diesel-generators in a relative form, which allows, even at the stage of preparation for the introduction of energy-saving measures, such as modern frequency and power control systems for a diesel-generator, to determine the efficiency of diesel generators in steady state, transient and idling conditions expected during the operation of the vehicle. Methodology. The paper uses methods based on obtaining relative estimates based on well-known ratios for fuel consumption in stable and transient modes. Results. The simple expressions obtained in the work make it possible to evaluate in a relative form the degree of influence of electronic technical systems on improving the operational efficiency of mainline and shunting diesel locomotives without carrying out a time-consuming and material-resources experimental study. Originality. In the case of a mainline locomotive, the expected efficiency from the use of only frequency and power control systems (electronic regulator) is estimated, and in the case of a shunting locomotive, relative estimates allow us to estimate the expected efficiency from the simultaneous use of two control systems: a start-stop system and an electronic regulator. Practical value. The proposed method of relative estimates can be applied to analyze the potential increase in the operational efficiency of diesel generators of shunting diesel locomotives, the fleet of which is a significant consumer of diesel fuel in railway enterprises, mining and metallurgical industries in almost all countries.