As is bound to happen, government regulations are getting in each others way. Almost all states prohibit the use of "running lights" (why, I'm not quite sure). Motor vehicle manufacturers and insurance companies are now campaigning to legalize daytime running lights. Next they'll be petitioning NHTSA to mandate universal use of daytime running lights.
Motor vehicle manufacturers will benefit from such a mandate because it will reduce per unit costs and increase maintenance costs for vehicle owners. The insurance industry generally supports any mandate that combines the virtues of increased operator costs, increased irritant quotients and decreased driving pleasure. Daytime driving lights are a natural.
Increased fuel consumption and vehicle maintenance costs have the potential for far exceeding the savings resulting from increased conspicuity. The increased conspicuity may also be transient and more the result of novelty. Burning headlights on 170 million automobiles will become just so much background clutter.
Be prepared for glowing testimonials from Sven Bargerneuter, President of the Sweden Auto Safety and Reindeer Preservation Society and the Canadian Council on Alcohol, Tobacco, Dirty Windshields and Other Sinful Things. Both groups will claim daytime running lights are directly responsible for a 50% reduction in some category of accident. (All safety initiatives reduce accidents, injuries and fatalities by 50% according to their proponents.)
If you have an opinion on this subject, you can address it to the Administrator at NHTSA, 400 Seventh Street, S.W., Washington, D.C. 20590.