Headlights

[guesswest]

I'm not very science-minded at all and I know there's a lot of people on here who are - can someone help me resolve a discussion I was having with some friends today?

I mentioned that I'd read somewhere about an alarming practice in Taiwan of driving around at night without headlights on because of a widespread belief that it uses up more gas. The article I'd read also described this belief as 'erroneous'.

The people I mentioned this to immediately objected, saying that such a belief is correct, that using headlights does consume more fuel, albeit not much. I was arguing that, although obviously there's a finite amount of energy being produced, that since the battery is being sent charge by the engine anyway it's essentially 'free' energy because the battery would otherwise be incapable of receiving charge and that energy would be wasted (I assume it'd be lost as heat). Apologies if my understanding here is completely retarded, I hang out here for the philosophy and know nothing about this stuff, so I await correction.

So can someone clear this up for me? Assuming a modern car with a properly functioning electrical system / good battery etc, do you use more fuel by having your headlights turned on while driving? Obviously I know you can with a [censored] electrical system/bad battery etc (remember my 67 bug used to stall when I turned on the headlights!). Thanks in advance.