[aerohead]

From the photograph, the EQXX best fits Wolfgang Klemperer's Cd 0.15, 1922 half-body contour.
At about the rear 1/4-window, the roofline falls below the contour, deepening to perhaps a 35mm gap, then by the trailing edge, it's back onto the contour, creating a captured separation bubble ( in the Fachsenfeld schematic convention ).