Не мога да го търся на АДАК, но ето ти драсканици за и против.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14618358&dopt=Abstract

А това е за ЮС граждани-превод от немското законодателство. Забележи че има изрично упоменаване кога могат да се ползват фарове през деня:

Lighting.

(1) Vehicle headlights must be used at night, at dawn, and at dusk. Low-beam headlights must be used during the day when visibility is limited because of inclement weather (for example, fog, snow, rain).

(2) Using only parking lights when driving is prohibited.

(3) Fog lights may be used only with low-beam headlights when visibility is less than 50 meters.

(4) High-beam headlights must be dimmed for oncoming vehicles and when approaching a vehicle from behind.

(5) Drivers who park in an area that is not lit well enough for the vehicle to be seen (for example, where streetlights do not remain on all night) must use front and rear parking lights. Traffic sign 394 is posted in areas where parking lights are necessary. Drivers of POVs with U.S. specifications should try to avoid parking in these areas, because their vehicles are not designed so that the lights can be left on without weakening the battery.