Numerical simulation of two-dimensional and three-dimensional air flow in automobile passenger compartments is described. The flow can be expressed by means of an incompressible Navier-Stokes equation for a narrow temperature range. The results were represented visually using animation and a color graphics system. The two-dimensional simulation showed that heat ansfer takes place chiefly by convection in vortices, and that the effects of heat transfer are minimal. In the three-dimensional analysis, shading was used to show the shape inside the compartment, and instantaneous stream lines and temperature distribution were depicted. The three-dimensional stream lines swirl upward at the front seat, and do not reach the back seat. The results gained from this study show that present theoretical flow analysis methods are close to being perfected. Further advances will require additional refinement of supercomputers and graphic engineering workstations.