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Door mirrors have a small but measurable contribution to the overall aerodynamic drag of a road vehicle. Typically for passenger cars and SUVs this is in the range 2.5–5%. It can be difficult to refine the shape of door mirrors as the improvements are, sometimes, too small to measure with any accuracy. A test rig has been developed which allows a full size door mirror to be tested in a model wind tunnel facility, which has better balance resolution, where the mirror is mounted to a partial vehicle body. This also results in a faster and cheaper method to develop shapes for door mirrors. The rig is described and the initial correlation tests presented. The limitations of the rig and some further applications are discussed.

Various techniques to reduce the aerodynamic drag of bluff bodies through the mechanism of base pressure recovery have been investigated. These include, for example, boat-tailing, base cavities and base bleed. In this study a simple body representing a car shape is modified to include tapering of the rear upper body on both roof and sides. The effects of taper angle and taper length on drag and lift characteristics are investigated. It is shown that a significant drag reduction can be obtained with moderate taper angles. An unexpected feature is a drag rise at a particular taper length. Pressure data obtained on the rear surfaces and some wake flow visualisation using PIV are presented.