A time cost effective methodology has been developed for the prediction of the A-pillar vortex formation and the side and the rear window flow separation for the purpose of wind noise assessment.This methodology combines a simplified Computational Fluid Dynamics (CFD) model and wind tunnel test data by CFD post-processing tools. The solution of the simplified CFD model provides background data for the whole flow field, but it lacks detail features such as mirror, sealing groove and glass in-set, which are locally important but difficult to mesh and require a very fine mesh resolution. The wind tunnel test data was taken in the specific areas of interest at the A-pillar, side window, rear window area, and roof from a real automotive. Then the wind tunnel test data was superposed upon the simplified CFD model to correct the numerical error due to geometry simplification and insufficient mesh resolution.The CFD result shows that solutions based on the simplified model already match well with wind tunnel test results. Phenomenon of A-pillar vortex formation and side/rear window flow separation were captured quite sufficiently. This makes the CFD results a good background for the test data superposition. The result - test data superposed CFD model will be used for the wind noise assessment. It has the advantage of using CFD post-processing tool for the test data manipulation. In the end, a high accurate data with easy post-processing capability is achieved.