"Driving with headlights on burns more fuel" That reminds me of an entertaining thread I get periodically that claims -apparently seriously - that solar panels are making the sun dimmer. :)

I too drive with headlights on- in Oregon they demonstrated fairly conclusively that human brains register the presence or proximity of a vehicle with lights on more quickly than those without. Also, as Joe O observed, many sections of a number of highways, especially those that have had more than their share of vehicular accidents are required by law to turn on their headlights. I can think of two sections right off the bat: in Oregon a 15 or 20 mile section of the Coast highway and in Alaska, the Old Seward highway out of Anchorage toward Alyeska.

One thing that does bug me though is when a vehicle has their lights on high beam in the daytime. It may make other drivers take particular notice of them but it hurts my eyes and irritates me.