A mud flap configured for installation in a mounted position on a vehicle adjacent a tire/wheel assembly to intercept and deflect matter being projected by the tire/wheel assembly from an outer circumference (OC 50) of the tire/wheel assembly and along any of a plurality of linear trajectory paths tangent to the outer circumference (OC 50) of the tire when the tire/wheel assembly is in rotation during vehicle operation and to permit the passage of air flow through the mud flap during vehicle operation to prevent the generation of elevated aerodynamic drag, the mud flap comprising: a height (H 10), a width (W 10), and a thickness (t 10), where in the mounted position the height (H 10) extends primarily in a vertical direction, the width (W 10) extending perpendicular to the height (H 10), the thickness (t 10) of the mud flap being defined by a front side (F 10) and a rear side (R 10) of the mud flap, the front side (F 10) facing the tire/wheel assembly and configured to engage the matter being projected by the rotating tire/wheel assembly and the rear side (R 10) forming an outlet for the passage of air flow through the mud flap; a barrier section configured to intercept and deflect matter projected from an outer circumference (OC 50) of the tire when rotating during vehicle operation, the barrier section including a plurality of horizontal louvers, each horizontal louver forming an elongate member having a length (L 32) extending primarily in a direction of the mud flap width (W 10), where the plurality of horizontal louvers are spaced apart in the direction of the mud flap height (H 10) in the form of an array (A 32), the spacing (S 32) between adjacent horizontal louvers within the plurality of horizontal louvers increasing with increasing height (H 10) of the mud flap, where each horizontal louver has a width (W 32) and a thickness (t 32), the horizontal louver width (W 32) extending perpendicular to the horizontal louver thickness (t 32) and being greater than the horizontal louver thickness (t 32), both the horizontal louver width (W 32) and the horizontal louver thickness (t 32) extending perpendicular to a horizontal louver length (L 32), where the plurality of horizontal louvers are configured to intercept and deflect matter of a minimum size traveling along any linear trajectory path from the outer circumference (OC 50) of the tire/wheel assembly towards the front side (F 10) of the mud flap while substantially maximizing the spacing (S 32) between adjacent louvers to minimize aerodynamic drag, characterized in that a centerline (CL 32) of the horizontal louver thickness (t 32) extends longitudinally at an inclination angle (α) relative to a direction of the mud flap thickness (t 10), such that a bottom of the horizontal louver partially faces downward and partially faces the front side (F 10) of the mud flap. a height (H 10), a width (W 10), and a thickness (t 10), where in the mounted position the height (H 10) extends primarily in a vertical direction, the width (W 10) extending perpendicular to the height (H 10), the thickness (t 10) of the mud flap being defined by a front side (F 10) and a rear side (R 10) of the mud flap, the front side (F 10) facing the tire/wheel assembly and configured to engage the matter being projected by the rotating tire/wheel assembly and the rear side (R 10) forming an outlet for the passage of air flow through the mud flap; a barrier section configured to intercept and deflect matter projected from an outer circumference (OC 50) of the tire when rotating during vehicle operation, the barrier section including a plurality of horizontal louvers, each horizontal louver forming an elongate member having a length (L 32) extending primarily in a direction of the mud flap width (W 10), where the plurality of horizontal louvers are spaced apart in the direction of the mud flap height (H 10) in the form of an array (A 32), the spacing (S 32) between adjacent horizontal louvers within the plurality of horizontal louvers increasing with increasing height (H 10) of the mud flap, where each horizontal louver has a width (W 32) and a thickness (t 32), the horizontal louver width (W 32) extending perpendicular to the horizontal louver thickness (t 32) and being greater than the horizontal louver thickness (t 32), both the horizontal louver width (W 32) and the horizontal louver thickness (t 32) extending perpendicular to a horizontal louver length (L 32), where the plurality of horizontal louvers are configured to intercept and deflect matter of a minimum size traveling along any linear trajectory path from the outer circumference (OC 50) of the tire/wheel assembly towards the front side (F 10) of the mud flap while substantially maximizing the spacing (S 32) between adjacent louvers to minimize aerodynamic drag, characterized in that a centerline (CL 32) of the horizontal louver thickness (t 32) extends longitudinally at an inclination angle (α) relative to a direction of the mud flap thickness (t 10), such that a bottom of the horizontal louver partially faces downward and partially faces the front side (F 10) of the mud flap.