Originally Posted By: ffracer
The whole premise of why DRLs are not useful is that you should be focused on the car's motion, not a focal point on the headlights, which creates target focus.
Totally agree.
That's why I'll sometimes turn on my secondary lights (so people can easier see the car's motion) in marginal viewing environments, but NOT the headlights. In such situations (overcast, for example), the secondary lights can aid others in seeing the vehicle's motion (by better seeing the vehicle's shape against the background) without causing glare. But the headlights (including all too many headlight style DRL designs out there) will just cause glare, and therefore make it HARDER for others to track your motion!
Originally Posted By: ffracer
Plus, they waste a small amount of gas that adds up across the vehicle pool.
True.
And the reason many DRLs waste gas (the exception is the DRL designs that use secondary LED modules, instead of the stupid headlight style DRL designs), is the same reason why headlights lower your fuel economy. i.e. the gas is "wasted" due to the extra drag the alternator puts in the engine to generate the needed electricity to run them! Because the less electricity you can (safely) use in a car, the less drag the alternator puts on the engine, and therefore the better fuel economy you will likely get. And headlights (and many of the DRL options out there) use a lot of electricity, which ultimately translates into more alternator drag on your engine (and therefore lower FE)!
Which is why I don't use my headlights except when I need them (either to see, or because the law says they have to be on in those conditions). When I don't need my headlights, I will leave them off. I will sometimes turn on my secondary lights to be seen by others, and that uses a little fuel (but IMHO is a good trade-off for the increased safety). However, even there I limit the amount of energy used for the lights, by swapping out a lot of my secondary lights for (bright but energy efficient) LED modules.
NOTE: If after-market LED headlight swaps were out there, I might consider getting them for our family cars (as headlights do use a fair amount of electricity, and LEDs are much more energy efficient). But at this point, while OEM LED headlights are just starting to come out, there aren't any good aftermarket LED swaps for headlights. So the best I can (currently) do, is to switch my secondary lights to LEDs (which does noticeably help FE in my car, btw), and just put up with the headlight energy use if/when I have to run the full headlights.
