The most likely reason Ford put it on was to improve air flow at higher speeds. It may have a slight improvement in fuel efficiency. U.S. and Canada 2011 Fiestas and perhaps addition years have a fuse box corrosion issues. I looked at mine when it was four years old, it was really bad. I was surprised I wasn't having electrical issues. Two week later I got a different car. So, it may protect components under the car. Why would Ford spend money on this part if it wasn't needed?