In most rear engined cars you absolutley need to suck fresh air in from everywhere you can get a vent. The rear wing is often chosen and some cars have vents low down around the door. This car has gone with a top mounted vent which no doubt feeds the engine with air, and may even assist brake cooling. The fox head shape of vent is probably the most visually pleasing and this also helps with aerodynamically grabbing as much air as it can.