We all have this FULL Belly pan under our engine bay. One direction of thought is that it allows air to pass under car and may prove to be more aero dynamic that way. - At the same time, cooler air is NOT entering the engine bay area - therefore trapping the warm engine air. (supplemental sources are needed) / another thought ; since only warm air is there, could that be a reason why many of us experience warm air flow into the cabin when we have our A/C off? - overall the hood, the engine cover and the belly pan all trap and recirculate warm not COLD air! does this make sense to you ? Would it be wise to slice off the rear half of the Belly pan?