a lot of new[er] vehicles turn off the DLR's when using the halo lights for turn signals.
it seems at night, the halo's [or whatever decorative shape is used] are brighter than the headlights.
i'm not sure if this is a factor that is controlled by the BCM [or whatever computer that controls the lights] or the lights have a double "filament" function.
i have been playing around with LED strip lighting for a custom installation, and that will be using strips of two different candle power. i know this is not pertinent to the discussion, but may be similar to how the new[er] stuff works.