Assembly for uniting two bodywork pieces at their edges and bodywork thus united

The assembly of two motor vehicle body components (1, 2) with edges (5, 6) having interlocking tongues (11, 12) includes a support (20) that fits over the tongues and fixes them in place relative to one another so that the components are joined edge to edge. The tongues along the edge of one component are staggered so they fit between the tongues of the other, and the support is in the form of a rigid or elastic element with an open cavity to receive both sets of tongues. At least one of the joined components and the support can be made from a plastic, thermoplastic or thermo-setting material.