This paper presents a Spalart-Allmaras based Detached-Eddy Simulation (DES) of the Ahmed reference car model with ¾ AE and ¿ AE slant angles using unstructured grids and the solver Cobalt. Comparisons are made to experimental laser doppler velocity measurements as well as total and surface pressure integrated drag. The Reynolds number based on body length was ¾ ¢ ½¼ , making the boundary layers approaching the slant fully turbulent. The flow over the base slant in the experiments is attached at

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... ¾ AE and separated at ¿ AE . This causes a large drop in the drag with the increased slant angle as the vortices on the side of the slant are weakened due to the separation. These cases stress turbulence models due to the need to accurately predict the boundary layer separation over the slant as well as predict the pressures in the massively separated base region accurately. The DES results are compared to the experiments as well as the Spalart-Allmaras RANS model. DES is seen to predict separation at ¾ AE slant angle, in contrast to the experiments. Drag is relatively close to the experiments, but the distribution of drag is more on the rear than on the slant due to the separation. At the ¿ AE slant angle, DES is in good agreement to the experimental drag, with the correct distribution, while RANS over-predicts the drag.