Abstract: The shape of a car body influences strongly the stability and moving resistance, which affects the gasoline wastage of a car.The paper simulates the 3-dimentional airflow around automobiles with front window angles of 20°, 30° and 45° respectively.The coefficients of flow resistance and of uprising force are defined. The streamline around the car is distributed in detail.Analyzing the result, it can be concluded that optimal front window angle is 30°, because the coefficients of flow resistance and of uprising force are lowest among three front window angles in the study.It means that the coefficient of flow resistance does not increase with increasing the front window angle.