Hey Guys,
Well, I am nearly at 40,000 miles on my 2013 Ford C-Max and I wanted to ask a question about my findings regarding some very simple aero mods.
First as you can see by the picture, I have blocked the lower and center grilles on my car as well as the fog lights (the right and left black covers visible in the picture). What you cannot see are the clear wheel covers.
Now, here is my question;
I have had the wheel covers for about 6 months now. I saw a slight improvement with them (maybe 1mpg or so). The center grille block gave me 1 to 1.5 mpg gain. The lower grill block gave me nothing what-so-ever. However, when I covered the fog light covers (I also covered the lower grille a bit better at the same time), I saw a roughly 2mpg improvement. This seems way over the top for such a tiny change. However, I have a theory that I want to share and get your opinion;
My guess is, the lower grille, fog lights, and wheels are at roughly the same level on the car. So, I am thinking that the deep fog light wells and the (not so well covered) lower grille were introducing turbulent air to the sides of the car partially spoiling the affect of the wheel covers. However, now the lower grille, and fog light covers are providing smooth airflow to the sides of the car and, with the wheel covers, providing good laminar airflow the length of the car, thus giving a steep boost in FE.
What are your thoughts? Do you think there is anything to my crack-pot theory, or am I totally off my rocker?
Whatever the cause, I am THRILLED with this improvement!
Matt