Detail pictures of the roll hoop on the McLaren MP4-28 have revealed that the team has largely retained the cooling layout of the 27. Just as on any other current F1 car, the main, somewhat triangular inlet feeds air to the engine required for burning fuel in the cylinders. Contrary to popular belief though, air is not pushed into this inlet, but the engine is sucking air in, reducing the drag penalty a normal cooling inlet would generate.
Underneath this main inlet is a smaller one, positioned more or less behind the driver's helmet and a little backward of the airbox inlet. As the picture shows, a small cooling radiator is positioned in the engine cover, underneath the channel that feeds air to the engine. Already since the MP4-26 of 2011, McLaren have positioned the KERS cooler here in an attempt to free up some space inside the sidepods. It's a change originally fuelled by the U-shaped sidepods on the McLaren MP4-26, a car where McLaren pushed for low, small sidepods to clean up airflow to the back of the car. As it gives packaging benefits, the team retained this solution, albeit that a radiator positioned this high up in the car, no matter how small, will have a negative impact on the car's centre of gravity.