keymastr wrote:
The air sticking to the flat rear of the vent is what creates drag/wind resistance. A model A ford is much more aerodynamic in reverse than going forward.
Although I like the aerodynamic "look" of the Aero-Flo vent covers more than some others, I'm not worried about wind resistance; let's be honest, nothing I could do on the roof on my class A would change the aerodynamics in any meaningful way (mpg, etc). I installed them to allow me to leave the vents open in inclement weather, nothing more.