An adjustable assembly of a first structural part and a second structural part, in particular for automobiles having a flap and a pivotable arm for the flap, is such that the first structural part is displaceable along two orthogonal axis with respect to the second structural part and is fixed against movement along a third axis extending perpendicular to the first and second axis. A first adjusting element is moveably supported on the second structural part. Actuation of this first adjustable element moves the first structural part along the first axis. A second adjustable element is movably supported on the second structural part. Actuation of the second adjustable element moves the first structural part along the second axis. Devices are associated with the first and second adjustable elements for releasable fixation thereof in selected positions.