The knowledge of air flow in the engine room has become increasingly important in recent car design. In the current research, an experimental study as well as a numerical study has been conducted regarding the flow field in engine room. Investigation has also been made upon the flow rate and the uniformity of the axial mean velocity of the flow entering the radiator, by varying the front-opening area. Both factors are thought to be directly affecting the cooling performance of the radiator. As it has been expected, the result shows that there exist a high degree of non-uniformity in the mean flow velocity at the front of the radiator.