[aerohead]

Had the designers of the vent had to design for houses that move at 100-km/h they would have discovered that their creation had about the highest aerodynamic resistance of any form they could have conceived of.The most basic fluids book would illustrate the extreme vena-contrata entry losses associated with a design like the one depicted.Better it remain on a home rather than a car. If you want to defeat the whole purpose of a grille-block,this would be the one to do.