cut into the mpg, I got one that came on my 2009 sport fit.

 

Most likely would since its seems slightly less aerodynamic than just the body would be.

I read on a Prius forum about people getting better MPG by doing some grill mod with cardboard to deflect more air over the hood and not through the grill. It wasnt just one post. There were a lot of people experimenting with it.

The point Im tryng to make is that it doesnt take much to change airflow over the vehicle and any areas of the bra that are not flat, including those little raised sections that some bras have could change the aerodynamics.

You could always do a test with it on and off for a tank and post the results

 

I need that too...

 

A grille block is a pretty standard modification for increasing mileage. It cleans up the airflow at the front and helps the engine warm up faster. It's on my List of Things To Do.

 

also makes your car over heat if you aren't running a cai grill modd on a fit would be minimal increase in mpg if any