The invention relates to covers (11) for seats (10) used in transport vehicles, especially motor vehicles. Said covers (11) are manually finished whereby they are smoothed at least steam with the aid of steam. Said manual finishing treatment is not only expensive but also leads to much fluctuation in terms of quality. According to the invention, the covers (11) of the seats (10) are automatically finished as the manufactured seats (10) are transported by a conveyor (14) through at least one treating chamber (116, 17) of a tunnel finisher. All of the seats (10) are treated in the treating chamber (16, 17) at least with steam which smoothes the covers (11) thereof. The inventive finishing treatment results in an even smoothness of said covers (11), even in areas which are difficult to reach manually.