"The NASCAR cowl intake system serves two purposes. It gets a little higher pressure air into the engine (poor boy supercharging) and it relieves the pressure at the base of the windshield."

Not sure about the second point being a plus, or more then an opinion or how even much pressure is really "relieved" by engine consumption. This high pressure area might be actually an improvement in streaming the rest of the air over the roof less abruptly, maybe like the the advantage measured of having the tail gate up creating a high pressure area and smoothing air flow in the back of a pick up vs having tailgate down, and very turbulent. And I believe its high pressure because of the rebound of air from striking the front nose of the car at speed, and less so from slope of the windshield, which the latest HR posted link might also indicate