I was looking at the rear of the car in this FlowVis pic and had a couple of thoughts:
There's a very deep recess on the top of the diffuser, directly below the crash structure. Are they using this to help remove heat from the engine compartment? It would also do a good job at catching oil from a blown turbo, but that can't be its real purpose. In addition, they have tons of room back here below the bodywork - as if they were playing it safe for the first test. I don't think that the car in Melbourne will resemble this one too much. Come to think of it, I have the feeling that Ferrari, Mercedes and Red Bull are using a negative pressure system to evacuate the heat from their cars. Basically using lower pressure at the exits to pull the air out of the body work. This would explain the smaller openings up front and the rear openings in the lower area around the floor. McLaren & TR seem to force feed their radiators (= positive pressure), which works great up front where the radiators are, but can lead to hot spots where the air flow under the engine cover isn't all too good. Or I need a beer....
“Strange women lying in ponds distributing swords is no basis for a system of government. Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony!” Monty Python and the Holy Grail