I was watching this video (from the Yoshi link) when Yoshi mentioned the wind speed he would be using is 40 to 50 mph to simulate a full size car going 100 mph.
EDIT: I WAS WRONG , YOSHI ADDED THAT IT EQUALS 2MPH
It appears that you reduce speed to simulate a real car.
I had also thought I would need to increase the wind speed.. it just got easier to construct by a few fans at least and several mph.