Since the introduction of daytime running lights to passenger vehicle the market penetration has been strongly increased even before becoming mandatory to ECE markets. The reduction of potential accidents due to daytime running lights is a function of their ability to attract attention and to enhance detectability. In depth analysis has proven that 50% of daytime crashes not seeing the other road user. For intersections even 80% has been analyzed involved and intersection crashes. Naturally the detectability decreases over distance between the lit object and eye of the observer and ambient light condition. Factors like ambient light, light output and distance/ angle of the observer's eye leads to reduced visibility or perceived glare. Among the safety effect of daytime running light some OEMs use dedicated daytime running lights as brand signature. Beside those positive items there are several effects affecting customer glare perception. The article describes the capabilities to adjust target luminous output to ambient light condition in order to reduce perceived glare under different ambient light conditions. Designing luminous output of daytime running lights is always a compromise between perceived glare and distance of visibility. A higher luminous output daytime running light will result in higher perceived glare values and vice versa. The spread in deBoer rating taking all ECE R87 legal lamps in to consideration is roughly 3 independent of distance of the lamp to the observer eye. It needs to be noted that this range is a theoretical one as the engineer can select only a single level of luminous output leading to a fixed bandwidth. The overall acceptable range of 4 ratings within the scale compared to the bandwidth of initial analysis shows the narrow band of acceptable design respecting perceived glare. Applicating the adaptive daytime running light system within todays legal candela limits as described in ECE-R87 enables the engineer to use the bandwidth calculated. Furthermore it has been proven that the rating spread is reduced by reduces from 3,5 down to 1. Conclusively the adaption of daytime running light within given luminous targets of today's R87 integrates the needs of reduced perceived glare and increased distance of visibility.