Automotive vehicle seat

The seat has a backrest (5) with a rigid framework (6) having sliding units (35a, 35b) disposed between two parallel posts (7a, 7b) and the framework. The units (35a, 35b) are formed by fixed parts (36a, 36b) carried by the posts and movable parts (37a, 37b) carried by the framework, respectively. The sliding units permit displacement of the backrest in a vertical direction between top and bottom positions with respect to a base (2). The base and backrest are simultaneously displaced by tilting units on a floor pan of a vehicle between a utilization position and a retracted position in which the base is placed horizontally in a housing (11) arranged below the floor pan.