The
R8 has no means of separating the air coming out of the wheel well from
that coming from the diffuser section. Audi adds front end downforce
via dive planes. Here in Sebring trim we can see two per side. 
In
this shot we can see the splitter that starts at the beginning of the flat
bottom. From there the air is diverted either side of the tub, merging
with the airflow from out of the wheel well. 