Quote:
Originally Posted by Vekke
Audi A2 basic shape.
Rear spoiler is good for delta Cd -0,005
Diffusor is good for delta Cd -0,015
Total impact in Cd -0,02
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According to SAE Paper 2013-01-2414, from Graz University of Technology, a drag reduction from a modification in side elevation only ( top and bottom ) will produce only 65% of the aerodynamic benefit potential, compared to top/bottom/and sides, a 34.7% drag penalty.
Which is in the neighborhood of Wolf Heinrich Hucho's comment that, only 'non-ventilated cavities' ( boat-tails and box-cavities ) produced drag reductions.
Suggesting that the Mercedes-Benz IAA, fully-enclosed tail extension is more efficacious than the Mercedes-Benz EQXX's.