In this paper a potential use of the tangential coefficient of restitution has been analyzed on the basis of a computer simulation of a side oblique collision between two motor vehicles. The simulation was carried out in PC-Crash 8.0. The results obtained for a side impact collision have been considered along with the tangential phenomena occurring between the colliding vehicles. The simulation was repeated three times for the adopted values of the coefficient of restitution. Then the coefficient of restitution was divided into two components (normal and tangential) which has been described in further parts of the paper. The obtained results were compared with the certain analytical calculations basing on the vehicle crash model for a vehicles performing a planar motion but with the phenomena between their bodies included. Also a theory of collision between the rough surfaces was used. The aim of this analysis was to examine whether the coefficient of restitution divided into two perpendicular components will alter the results obtained from the analytical calculations and if it is worthy considering such division in analyzing the real accidents in road traffic. Also it has been considered whether such complication of a vehicle crash model is useful and necessary.