A device for transmitting data and/or signals between a first car body of a multi-member vehicle mechanically connected a second car body. The device includes an interface element having at least one optical fiber transmission medium for a line-connected communication system of the vehicle. The interface element displaceable in the longitudinal coupling direction relative to a coupling head of the first car body from a first position, wherein the interface element with the optical fiber is fully accommodated in the coupling head of the first car body, into a second position and vice versa, wherein in the second position of the interface element, at least the frontal end region of the interface element projects from the coupling head of the first car body to establish a data connection between the optical fiber and a contact terminal of a coupling head of the second car body.