Conventional aerodynamic simulations have been carried out by using Supercomputer and over a hundred thousand grid points. It takes a long CPU time to get a result. So this method has been mainly used as a research and demonstration tool.In this paper a practical aerodynamic simulation for early phases of the automobile design is presented. This new method basically uses the conventional (wall function used) k-ε turbulent model which is regarded as the most promising in engineering and industrial fields.Firstly, the third-order upwind scheme is introduced to the convective term to improve flow field and pressure distribution. Secondly, the modified turbulent energy production method (M.P.Method) which was proposed by B.E. Launder in 1993, is introduced to the k-ε turbulent model to reduce the excessive generation of turbulent kinetic energy.It takes 20 hours to generate a computational mesh from design CAD data by a new semi-automatic mesh generator and 10 hours to get the steady flow result by using EWS (IRIS Indigo2 R4400, 1CPU).It takes only 4 days to get an aerodynamic solution within an error of 5% for CD (Drag Coefficient) and CL (Lift Coefficient). This new method has been applied to the aerodynamic simulation system, a designer has been able to carry out the practical simulation on early designing phase of an automobile.We also present a CYM (Yawing Moment Coefficient) simulation between 0 and 45 degree and the influence of a outside rear view door mirror on Two-Box automobile.