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The effect of pollutants emission on health and environment is a problem that has become even more important with time: WLTP represents the harmonization of test procedures that aims to characterize all vehicles predicting their emissions, depending on coast down road test results and new different driving cycles. UN GTR technical regulation allows the use of wind tunnel to perform a bench coast down with the use of dynamometer or flat belt to calculate the whole vehicle drag (aerodynamic, mechanic and rolling resistance). During 2013, FCA Italy made an upgrade to wind tunnel facility installing a new balance with 5 moving belts: one central belt and four wheels flat belts, each one connected to a specific balance. This upgrade is very important because wheel spinning unit balances allow the calculation of rolling resistance as required by UN GTR. Moreover UN GTR prescribes several criteria that must be respected from facility to allow wind tunnel to be used instead of road test.

Energy efficiency has become a major requirement and constraint in the automotive industry, playing a fundamental role on the product development. A relevant contribution to achieve lower fuel consumption and CO2 emission is given by the aerodynamic efficiency. Drag resistance reduction requires to develop and apply up to date analysis tools, to be able to rapidly evaluate and validate style shapes as a trade-off between drag performance and pure style requirements. Since the product development plans have highly stretched timings and several refinement loops may be required to achieve all the targets, the ability to analyse in detail the flow field characteristics in the most critical areas for a “bluff body” must be combined with the need to obtain the necessary information in a short time compatible with the vehicle planning. Therefore, both physical tests and virtual analysis simulations have to be applied and integrated throughout the development process.