Along with the introduction of HID-headlamps and a luminous flux beyond 2000 lm the regulations concerning automatic levelling and headlamp cleaning systems were enacted. This reply regarding the position, HID-headlamps would produce a higher glare-illuminance, was only partly accepted. While levelling systems are well established, headlamp cleaning systems are challenged for economical and ecological reasons. The proposed paper will deal with the different aspects of soiling. Because standard dirt as defined in ECE R-1 is not representative for any dirt from the street, the efficacy of HCS on different kinds of dirt are analyzed. Initially 22 headlamps from H4 to HID have been systematically soiled with standard dirt, then the ECE-points and the luminance distribution have been measured. The maximum increase of the glare illuminances should highlight the moment where cleaning could have its most valuable benefit and what the minimal effects of cleaning should be. Furthermore standard-soiled headlamps have been system-cleaned at different degrees of soiling and the efficacy of the HCS is compared with the efficacy on street-dirt of comparable levels collected on the same headlamps. Since natural dirt consists of different components dependent on weather and street conditions, different degrees of efficacy are expected. This study merges and consolidates most of the previous researches regarding soiling and headlamp cleaning systems. Hence it could be a valuable contribution to the ongoing and upcoming discussions related to HCS.