First change spotted on the F2012 at Hungary. Not sure if it means the exhaust is now pointing more inside or if the channel might have been angled more. But it is clear the gap highlighted is smaller now.
An educated guess that the bigger hole is just to increase cooling?
I've thought these are the current renditions of the Acer tubes, which I felt where designed to carry supplementary air from the radiators and around the exhausts to provide an alternate flow of gases to provide a different pressure point which would help shape the exhaust gas directional flow (particularly to help keep the exhaust plume lower at higher speeds). If you look at the curvature of the bottom part you can see that, in the German version, overlaps the cover, so, the opening may not be getting bigger, it may be the duct has moved closer to the centre. I'm pretty sure they introduced a sort of wedge shaped cut-out section around the rear tire in the floor in Germany.
There was some talk about that with the gearbox change here the engine angle would be changed. Not sure if it might be related, need to think about it a bit, let the old grey matter work up to speed

Cooling?...is this the exhaust or intake? Not sure what I'm looking at here. 
It's the exhaust outlet and surrounding bodywork. The section of the car is highlighted below, does that help?
