The wing shape crosssection on this piece is far clearer on Schumacher's FIAT. When the inside wheel goes over a curb on a bend that you want to shorten and short-cut across the apex, the messing about on that inside wheel will cause it to loose some grip and centrifugal effects could cause the car to drift outwards. With V shaped wings, as well as pulling down, the wings pull out. When the car leans (for example due to taking a curb) the inner wing will become steeper, pulling the car into the bend and partly countering centrifugal effects. The outer wing will become flatter as the car rolls and give more downforce to the outer tyre, the one firmly planted on the ground, and give it more grip.
Today's GP showed a couple of slow-mo's of cars taking a curb on a right hand bend, and the inner side of the FIAT bounced about a lot more than the Renault.
Are curbs and centrifugal effects the reason for the angle on these wings, or is it just legislation, one end has to be attached to the car, and they have raised the other end to a height where they get the airflow they want?