Quote Originally Posted by TopSpeedInc
When racing you will have air trapped into the cabin. And it basically acts as a parachute to the vehicle somewhat. When you drill holes like that it can allow the air to escape without slowing you down too much.
also on some cars it allows you to reach certain things like a weight jacker, or some sort of shock or spring adjustment. sometimes it can be where the nitrogen line plugs in for airjacks. easy access to it means quick work/changes in the pits