Exchange device for data which is partly representative of at least one authorized user of an automotive vehicle

The assembly has a badge (14) movable from a longitudinal level in a tunnel (24) from a stable position towards an instable position for activating a start switch (40) and for stopping an engine. The switch is activated by the badge through a latch of the badge arranged in a fixed unit (12). The latch blocks the badge in the tunnel when the engine of the vehicle is started.