Front bumper valance

So it’s not protecting anything? If it was not there I would probably just get worse gas mileage right?

The mileage difference would be hard to measure.

Well yes and possible no. It depends in some cases the road or lack there of. For instance off-road or no-road plowing down small trees and small tree finds the extra few inches and goes toward the fan belt or radiator. Given that plastic is awful at stopping that anyway, a real metal guard/panels would be the answer to protect your underside, oil & trans pans from these issues, So I would chunk oem in favour of skid plates home-made or from after-market off-road stores.

The 4x4's typically come with skid plates. One with a off-road package definitely will.