Roof spoiler of a motor vehicle, in particular of a passenger car, the roof spoiler comprising a body, wherein the body comprises: - an upper shell which, when the roof spoiler is mounted on the vehicle, is arranged or can be arranged in the extension of a vehicle roof surface and which is provided on the surface with a color coating, and - a lower shell which, in the mounting arrangement of the roof spoiler on the vehicle, faces the vehicle floor or can be arranged to face the vehicle floor, the roof spoiler having predetermined mounting regions for mounting the roof spoiler on the vehicle, the roof spoiler being designed as an elongated component with a longitudinal direction, which extends in the direction of or over the vehicle width in its fastening arrangement on the vehicle, the roof spoiler having a front side which can be arranged on the motor vehicle facing the front of the vehicle or is arranged in the fastening arrangement on the vehicle, and wherein the roof spoiler has a rear side which can be arranged facing the rear of the vehicle or forming the rear of the vehicle or is arranged in the fastening arrangement of the roof spoiler on the vehicle, wherein the predetermined mounting regions for mounting the roof spoiler to the vehicle are at least partially or completely integrally formed on the upper shell, wherein the upper shell and the lower shell are connected to one another in a tension-absorbing manner by latching means and/or form-fitting means, and wherein the at least one predetermined fastening region for fastening the roof spoiler to the vehicle, which is integrally formed on the upper shell, comprises a base which is integrally formed in one piece on the upper shell, characterized in that the upper shell of the roof spoiler is designed as an injection-compression molding part and that a base wall comprises at least one or more weakened areas which is/are separated from the fastener receiver on the base upper side by a preferably at least essentially dimensionally stable base area. - an upper shell which, when the roof spoiler is mounted on the vehicle, is arranged or can be arranged in the extension of a vehicle roof surface and which is provided on the surface with a color coating, and - a lower shell which, in the mounting arrangement of the roof spoiler on the vehicle, faces the vehicle floor or can be arranged to face the vehicle floor, the roof spoiler having predetermined mounting regions for mounting the roof spoiler on the vehicle, the roof spoiler being designed as an elongated component with a longitudinal direction, which extends in the direction of or over the vehicle width in its fastening arrangement on the vehicle, the roof spoiler having a front side which can be arranged on the motor vehicle facing the front of the vehicle or is arranged in the fastening arrangement on the vehicle, and wherein the roof spoiler has a rear side which can be arranged facing the rear of the vehicle or forming the rear of the vehicle or is arranged in the fastening arrangement of the roof spoiler on the vehicle, wherein the predetermined mounting regions for mounting the roof spoiler to the vehicle are at least partially or completely integrally formed on the upper shell, wherein the upper shell and the lower shell are connected to one another in a tension-absorbing manner by latching means and/or form-fitting means, and wherein the at least one predetermined fastening region for fastening the roof spoiler to the vehicle, which is integrally formed on the upper shell, comprises a base which is integrally formed in one piece on the upper shell, characterized in that the upper shell of the roof spoiler is designed as an injection-compression molding part and that a base wall comprises at least one or more weakened areas which is/are separated from the fastener receiver on the base upper side by a preferably at least essentially dimensionally stable base area.