Riley, if this whole post is about the tiny 1" wide vertical face of the L bumper, its likely that vertical section was a design feature by Tom Tjaarda to prevent the bumper from either climbing or submarining when impacting other car's bumpers in minor collisions. Or it was a DOT or Ford design mandate for the same reason. Compared to the surface area of the rest of the car's nose, that small vertical section will have a negligable effect on aerodynamic lift or dive but in the event of a collision, a slope could slightly increase the damage..
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