System comprising an attachment element, which - has at least one fastening section with at least one through-opening, and a fastening system for fastening the attachment element to a carriage body structure having at least one through-opening, preferably to a carriage body structure of a rail vehicle, wherein the fastening system - comprises at least one fixing element which has a spreading section and a centric bore, and - at least one fixing screw, wherein in a pre-assembly state - the fixing element is arranged behind the fastening section as seen in a fixing direction and - the fixing screw is inserted into the bore through the through-opening of the fastening section, wherein the system is transferable from the pre-assembly state to an assembly state, in which assembly state the system is arranged in such a way with respect to the carriage body structure that - a first region of the spreading section is arranged inside the through-opening of the carriage body structure, and - a second region of the spreading section is arranged behind the through-opening of the carriage body structure, as seen in the fixing direction, and is spread due to a rotation of the fixing screw arranged at least in sections in the bore, whereby the attachment element is connected to the carriage body structure, wherein the system comprises at least one clamping element having at least one through-opening, wherein both in the pre-assembly state and in the assembly state - the fastening section is arranged at least in sections inside the clamping element, - the fixing element is arranged behind the clamping element as seen in the fixing direction, and - the fixing screw is guided through the through-opening of the clamping element, characterized in that the attachment element is a cladding element for covering inner surfaces of parts of a carriage body structure, and wherein the at least one clamping element and the at least one fixing element are designed in such a way that, in the pre-assembly state, they can be displaced in relation to the at least one through-opening of the carriage body structure as a function of a diameter of the at least one through-opening of the fastening section. - has at least one fastening section with at least one through-opening, and a fastening system for fastening the attachment element to a carriage body structure having at least one through-opening, preferably to a carriage body structure of a rail vehicle, wherein the fastening system and a fastening system for fastening the attachment element to a carriage body structure having at least one through-opening, preferably to a carriage body structure of a rail vehicle, wherein the fastening system - comprises at least one fixing element which has a spreading section and a centric bore, and - at least one fixing screw, wherein in a pre-assembly state - the fixing element is arranged behind the fastening section as seen in a fixing direction and - the fixing screw is inserted into the bore through the through-opening of the fastening section, wherein the system is transferable from the pre-assembly state to an assembly state, in which assembly state the system is arranged in such a way with respect to the carriage body structure that - a first region of the spreading section is arranged inside the through-opening of the carriage body structure, and - a second region of the spreading section is arranged behind the through-opening of the carriage body structure, as seen in the fixing direction, and is spread due to a rotation of the fixing screw arranged at least in sections in the bore, whereby the attachment element is connected to the carriage body structure, wherein the system comprises at least one clamping element having at least one through-opening, wherein both in the pre-assembly state and in the assembly state the system comprises at least one clamping element having at least one through-opening, wherein both in the pre-assembly state and in the assembly state - the fastening section is arranged at least in sections inside the clamping element, - the fixing element is arranged behind the clamping element as seen in the fixing direction, and - the fixing screw is guided through the through-opening of the clamping element,