Spoiler for motor vehicles

The invention is concerned for a spoiler for motor vehicles, having a rear window, in particular for estate cars, integrated into a rear door, which window is formed by an aerofoil-shaped baffle profile which is supported on both sides and can be swivelled alternately between a swivelled-in position in which it extends approximately as a continuation of the contour of the roof and a swivelled-out position in which it partially projects beyond the contour of the roof, both limit positions of the baffle profile being lockable. In order to further improve the slipstream conditions, there is provision for the baffle profile to be arranged on the rear door, for the rear door to form a rear roof section, for an attack edge of the baffle profile to rest, in the swivelled-in position, on the rear roof section and for the baffle profile to define, in the swivelled-out position, a nozzle-shaped channel together with the external contour of the rear door lying opposite it, the said channel having a minimum entry height of 85 mm and a maximum outlet height of 65 mm.