1. An apparatus comprising: an aerodynamic microstructure defining an external surface of a vehicle; a first pattern of sub-microstructures superimposed on the microstructure, the first pattern having a first reflective property; and a second pattern of sub-microstructures superimposed on the microstructure, the second pattern having a second reflective property different from the first reflective property, wherein sub-microstructures of the first pattern of sub-microstructures have at least one of a different size or a different orientation from sub-microstructures of the second pattern of sub-microstructures, the first and the second patterns superimposed on the microstructure to convey a representation of a graphic.