The high-fidelity numerical simulation of unsteady flows around cars are a very challenging computational problem because of the huge computation caused by high Reynolds number and complex geometry. In this paper, we presented a scalable parallel Newton-Krylov-Schwarz based fully implicit algorithm for the full unsteady incompressible flows around cars and compared our results with results obtained from commercial CFD software. Our algorithm shows very good parallel scalability on a supercomputer with over two thousand processors.