City Car Drag Reduction by Means of Shape Optimization and Add-On Devices

In recent years, the automotive industry has moved its attention to green technologies, investing in high efficiency engines, lightweight materials, and low-rolling-resistance tires. Under these circumstances car body styling and aerodynamics play an important role in reducing vehicle drag force, permitting an improvement in fuel and energy efficiency. The objective of this study is the reduction of a city-car prototype’s aerodynamic resistance by means of standard aerodynamic devices (i.e. spoiler, finlets, rear underbody, front bumper, rear dam and wheel cover). This work starts with a CFD analysis performed on the baseline configuration of the XAM 2.0 (eXtreme Automotive Mobility) vehicle, whose critical areas are then considered for the aerodynamic improvement. A CFD analysis of vehicle aerodynamics is performed in order to design different add-on features to be manufactured and tested in Pininfarina Wind tunnel. A final correlation between virtual and experimental results is carried out, validating the drag reduction, demonstrating the predictive capabilities of CFD analysis.