This paper studies the effect of the electrically-driven pump on improving the efficiency of internal combustion engine cooling systems. Numerical one-dimensional simulation of the system operation was performed according to the European transient cycle (ETC). The paper compares the cooling system with a belt-driven pump and electrically-driven pump. It was found that the electrically-driven cooling system not only could maintain a more stable coolant temperature, and also provided energy savings for the pump drive. It can be noted that the mechanically-driven cooling system has disproportionately high energy costs, unstable coolant temperature, so in case of sudden changes in operating modes, the built-in thermostat cannot keep it within two degrees Celsius. At high engine speeds and low load, the drive consumes too much power, and when thermostat is faulty and the coolant is overcooled, at low speeds and high load, the coolant is overheating. The paper also considers options with electric-driven pump with and without an enabled thermostat. With a working thermostat and electrically driven pump, the system consumes a little more energy, because the thermostat does not open fully and as a result, the pump speed is 8.2% higher than in a cooling system without a thermostat.