i'm not sure if it uses the same sensor, because sometimes my headlights will come on when it overcast, but the gauges do not illuminate. it may still use the same sensor with different sensitivities, but I do know my head lights have turned on without the gauges changing.
I know on mine, the Gauges change color when the auto lamps come on.
This is actually the first car that I have used them on, and only because it lets the fog lights come on also.
And what is it with People wanting Daytime running lights, to me they take away from the overall appearance of the car. If you want them turn on the headlights or get something like this Automotive Electronic Accessories - Quality Accessories for Your Car