Red Bull RB10 - rear floor duct 10 May 2014
It's all the small details that add up to give a Formula One car so much grip. Where the rear tyres meet the ground, the air that gets displaced has a tendency to get sucked under the car by the diffuser. If that is allowed to happen, it reduces the overall amount of downforce that the underfloor can create. With this small duct (red arrow) just in front of this area, the airflow that would normally spill over the edge of the floor and go underneath the car gets redirected and some of it will go around the outside of the tyre, allowing the underfloor to work more efficiently.