[Piwoslaw]

When Poland switched to mandatory lights 24h/year round I saw newspapers usually citing 2% as the increase in fuel consumption. I decided to install LED DRLs (2 x 5.5W = 11W) since in order to drive with my lights I'd not only have the headlights (2 x 55W), but also position lights, registration plate lights, dashboard lights, etc., plus all the relays that power those lights, which I figured totalled to ~200W. When the engine is warmed up I see instant fuel consumption at idle go from 0.50-0.53 l/h to 0.56-0.64 l/h when I turn the lights on.

As for whether DRLs increase safety I can say that yes, they do. First of all, on a sunny day (when many people think that DRLs don't help) some cars tend to blend into the pavement and/or horizon when far away. I can spot them much sooner if they have lights.

Second, among the many dumb games teenagers like to play is driving at full speed on the highway. Against traffic. At night. Without lights. If their car has DRLs which can't be turned off, then that increases the chances of any innocent drivers that might be unlucky enough to be on that stretch of highway.