The growing demand of lightweight construction concepts in the automotive sector has led to an increased usage of light metals. In the area of the exterior body panels, hardenable aluminum alloys of the 6xxx family are used. After joining the so-called „body in white“ (BIW) and before the paint-bake process, it is often necessary to grind the surface of the sheet metal. In case of a damaged coating, progression of corrosion beneath the protective layer may occur, especially in aggressive atmospheres. In the present work, results from electrochemical measurements, filiform corrosion tests and transmission electron microscopic (TEM) investigations on 6xxx alloys – with different copper contents – are presented. Various surface and heat treatment states of these alloys are characterized and compared with each other regarding their corrosion potential, their microstructure and their susceptibility to filiform corrosion. Based on the presented results, an electrochemical "rapid test" is recommended, by means of which ground sheets of high-strength aluminum 6xxx alloys can be classified with respect to their susceptibility to filiform corrosion. Thus, a time-intensive filiform corrosion test is obsolete.