The invention relates to an air-guiding device (10) of a vehicle (1), comprising a spoiler (12) fastened to a spoiler base (14), and an adjusting device (20) for adjusting the spoiler base (14) between an inoperative position, in which the spoiler (12) is essentially situated within the vehicle contour (3), and at least one first operating position, in which the spoiler (12) is deployed beyond the vehicle contour (3) in order to provide a down force effect during the journey, the adjusting device (20) comprising a pivoting-link arrangement (22, 28) coupled to the spoiler base (14) and controllable driving means for pivoting the pivoting-link arrangement (22, 28) in order to adjust the spoiler base (14) between the inoperative position and the operating position. In order to permit a greater maximum deployment angle of the spoiler, according to the invention the adjusting device (20) is suitably designed in order to overstretch a joint (26) between a front region of the spoiler base (14) and an end of a front pivoting link (22) of the pivoting links (22, 28) during deployment of the spoiler (12).