With the increasing demand for smaller automobiles that will conserve natural resources and save energy, and the need to systematize the development of such vehicles by shortening their developmental period and by reducing the number of required experimental vehicles, the analysis of automotive collisions has become increasingly important for us. The analysis of automotive collisions was first conducted by a lumped-mass method, although it has some shortcomings, e.g., it is difficult to make models and it is inappropriate for three-dimensional analysis. Consequently, a finite element method is also presently in use. From the finite element method currently in use, for the purpose, however, a practical level of analysis duration and deformation analysis cannot be expected. Therefore, we have developed a hybrid program called “FEMASS”, which is a combination of the lumped-mass method and the finite element method programs. Some vehicle hybrid models made by this program have been utilized in the analysis of rear-end collisions. The resultant simulations reveal that the acceleration-time characteristics and deformation-time characteristics, as well as the deformation modes of the respective parts involved, agree quite well with the test results.