I'm all in with the side elevation of skirts and tail, however, personally, I'd lose the rear flip-up spoiler. It would only add drag.
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In CD's rendering below your's there's a 'kink' in the contour, which is a no-no!
'... surfaces must be matched to prevent high pressure variation along the flow path... care must be taken that no kinks are present in the curvature.'
W-H Hucho, p.160, 2nd-Edition.
The upper 'tearing edge' at the rear is okay. And it's okay to use all of the length of the sides.
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The plan-view image shows no continuity of the taper of the boat-tails flanks, in relation to the HONDA's. This lack of evolving cross-section reduction could cost up to a 33% loss in drag reduction according to Mario & Hirz' research.
