The
Audi's diffuser is relatively simple. It consists of three
planes,
one main section in the middle, and one each side of the main
section.
The diffuser sections all appear planar, that is perfectly flat with no
radius. Also, they are relatively shallow. 
There
are six strakes in the diffuser section, three either side of the
centerline.
The two closest to the centerline lie in the main section, the ones
furthest
out are in the outer diffuser sections. 