probally nothing having the ram effect - in general vents are used especially in cherokee's where the underhood temps are high in the smaller engine bay to release heat at idle and on the trail at slow speeds - unless you are conjuring some type of cold air intake or relocating the air intake to a higher place on the jeep it is best to keep the vents facing the winshield - in fact i think somewhere around here i read that having the air being sucked in can actually hinder cooling - this was in relation to intake cowls and having small vents on the front/ grill of the hood or fascia like the isuzu rodeo's have and some smaller nissan pathfinders