Daytime running lights: UK vs US vs Germany

DRLs are permitted rather than required in all three markets, so the rules are about how they behave rather than whether you may have them. Two requirements recur everywhere: white or amber at the front within an intensity limit, and yielding to the dipped beam by dimming or switching off when the headlights come on. That second one is what most retrofits get wrong, because an LED strip wired to a permanent live never dims and therefore never complies. Germany is alone in fixing the mounting geometry numerically, specifying height, distance from the edge of the vehicle and spacing between the lamps, and it explicitly rejects decorative strips sold as DRLs without approval. The UK and US regulate the same outcome without the tape measure.