Abstract: An aerodynamic accessory, such as a front and/or a rear spoiler, is adjustable by a deployed working position and a retracted rest position, and its positioning can be controlled automatically in accordance with vehicle conditions reflecting the need for road/tire traction. These vehicle conditions may include vehicle speed, crosswinds, road surface roughness or wetness, and/or road grade, these factors taken singly or in combination. The aerodynamic accessory may be a rear spoiler retractable to lie flush with the trunk lid and/or a front spoiler capable of selectably reducing the air-flow clearance between the road surface and the front end of the vehicle. Specific vehicle condition detection devices and techniques are also disclosed.