Drag experienced by a vehicle travelling through an environmental media, such as air, is actively modulated by an energy beam which may either increase or decrease the drag. The energy beam may provide either a chemical, acoustic, or electromagnetic energy at a transition region between turbulent and laminar flow or at the leading edge of a laminar flow, or in the direction of a crosswind, in order to facilitate the respective increase or decrease in drag. An energy beam may be directed in a rearwards direction, relative to a direction of travel.