Dear Car Talk:

I look forward to reading your column each week! My question for you is this: If a car has automatic headlights, do I still need to turn my lights to the "On" setting at dusk? If the answer is "no," then what is the purpose of having both "On" and "Automatic" settings on the headlight switch?

-- Rachel

Well, the "automatic" setting is a nice convenience. It uses a photocell to sense when it gets dark out, and it turns on your lights automatically. It'll even turn on the lights when you drive through a dark tunnel, or into an underground parking garage. It's a great feature, because you never forget to turn your headlights on, or -- just as importantly -- off!

But there are situations in which you may want to override the automatic setting. For instance, in some parts of the country, daytime headlight use is required on certain sections of road.

Where there have been lots of accidents that seem to be related to visibility, local departments of transportation sometimes mandate headlight use at all times of day.

Some state laws also require that your headlights be on whenever your windshield wipers are in use, to improve visibility in rainy or snowy conditions.

Then there are funeral processions, where you might want to have your lights on during the day.

And, of course, you'll want to be able to override the automatic setting when you're visiting one of the four drive-in movie theaters that still exist, right?