Originally Posted by elp_jc
It's main role is give front bumper and inner fender rigidity at the bottom, and prevent bumper from pushing and cracking the plastic parts in the lower ducts at high speeds, plus possibly bending the tranny cooler. And yes, they also play an aerodynamic role, but other than the above, you'd be just wasting more fuel and flapping connectors and such around inside the fender
. The middle one is also important, since it sends hot air from the oil cooler under the car.
But forget about all that; the car looks awful without them, the bumper moves like an old car under way, and they're cheap to replace, so no reason why not fix them, especially on an expensive sports car like the M3. Take care.
I am fixing them, that's the point.