In the article, based on the analysis of the parameters of automobile engines during operation in the conditions of the Kabardino-Balkarian Republic, it is shown that the operating time of engines in unsteady modes, depending on the purpose of the power plant, can be up to 95% of their working time. It has been established that the magnitude of the torque developed by the engine in the transient mode is mainly influenced by the conditions for organizing the working process, which depend on the consumer of the engine power. The links between the influencing factors, operating modes and output indicators of the car, recommended speed modes during acceleration and relative fuel supply depending on driving conditions for trucks and buses are given. Studies have shown that with a short driving cycle path, fuel consumption increases sharply and, as a result, the efficiency of the car deteriorates. Therefore, every accidental stop contributes to the deterioration of the efficiency of the car. The research results indicate that there is a need for a differentiated consideration of these conditions in the design, testing and operation of vehicles, as well as an in-depth study of the speed and load modes of their operation in order to establish their qualitative and quantitative relationship with indicators of speed properties and fuel efficiency. For automobile rolling stock of the Kabardino-Balkarian Republic, it is recommended to supplement the standard operating route conditions with mountain-flat condition.