And as far as fuel consumption is concerned - If you want to be technical and really, really correct , you have a higher fuel consumption when lights are on. The load on your alternator is higher, thus requiring more power to drive it, thus needing more fuel. Whether this is measurable at all, is another question....
Your premise is only valid under 2 scenarios: that you manually adjust the throttle to match the output of the alternator under its load, or;
You are operating an engine-driven generator that is equipped with engine management controls to alter the engine speed to produce more output for the alternator under a load.
As far as all SOHCs manufactured between 1969 and 1978 I’m unaware of any equipped from Honda with this electronic capability.
And based upon Delta’s statement,
“
At traffic lights in daylight you may select neutral and save gas .
Being in neutral versus being in gear with a headlight OFF is similiarily silly. (I think he later concedes this point).