In the article are presented studies regarding the cooling efficiency of a finned housing that is common to servo-machines. The studies are performed considering three-dimensional model of the housing. Under the hood of an electric vehicle the motor can be mounted in various positions. Moreover, the electric vehicle travels at various velocities. Therefore, the study considers two parameters: the mounting position of the electric motor and the velocity of fluid surrounding the electric motor. Based on the results, a dependence between the two parameters and the housing cooling efficiency is derived. A comparison with analytical expressions for usual cylinder cross-sections is also provided.