[j-c-c]

If the "L" is on the bottom of the side skirt and faced outward, it's thought the air flowing downward on car's side is now directed outward, helping to extract air already underneath car, a big plus for those seeking downforce and likely further reducing under carriage drag. I also believe any sized lower external wicker here on a side skirt helps promotes this advantage, but a larger wicker/ledge is more effective, obviously up to the point of diminishing returns.
I would think a better direction for street use would be, an inflatable/retractable side skirt design.