I see that sort of fin on a lot of Hondas around here. (These cars also have the fart can exhaust as well as the chrome towing hook sticking from the bumper. usually driven by some douchy looking dude with a sideways baseball cap and breathing from his mouth.) I am sure it inspires a lot of racing. I know I try to quickly get out of his way to avoid the noise from the fart can.
And then there is the Subaru that came from the factory with the double-decker fin. That car must be very fast to need that level of air flow control to keep it on the ground.