fuel useage of head lights?

[Ryland]

Has anyone with a scangauge checked what the gallons per hour usage is with head lights on and with them off? it seem like this would be good info to have seeing as how head lights tend to be in the 110-130 watt range for the pair and with other running lights on can come up to nearly 200 watts.
I just want to get a feeling for the fuel usage of a 200 watt load.

[shovel]

I haven't looked into the fuel consumption, but given that headlights are a safety device I wouldn't consider deleting them.

There's a lot of talk here about "low hanging fruit" and I agree with it. Headlight omission is neither a significant load relative to other factors, nor a good idea to omit.

Projector-type HID's might save you 20 watts per bulb, and if you convert all your other lights to LED you might shed 100 total watts energy consumption at night ... or roughly 1/6th of a horsepower after generator/wire/etc losses are considered.

So, since the internet tells me a gasoline engine burns roughly 0.65 pounds of gasoline per horsepower per hour, you're looking at 0.1 pound of gasoline per hour at night that you would save by performing a thorough update of your entire vehicle's lighting system.

If we are to go with the weight of gasoline at 6.3 pounds per gallon at normal temperatures, that's 1/63rd of a gallon per hour you could save. In other words you would have to drive 60+ hours at night to save 1 gallon of fuel vs. the same night driving with your conventional headlights. At 60 mph that means you'd save 1 gallon every 3600 miles roughly. At $2 gallon, vs the $200+ it would cost you to update your lighting to high efficiency bulbs/diodes, you would have to drive a third of a million miles at night to recoup your costs.

[SVOboy]

I can't remember who tested, maybe it was basjoos? But it was something on the low order of a percent or two?

[jamesqf]

Still, it's something to think about, considering the number of people who like to drive around with their lights on in the middle of the day.

[Ryland]

My point was not to get people to drive around in the dark with their lights off, my point was to acquire a piece of information, if I want to get a stareo in my car with a big amp that is going to draw 200 watts, how much is that going to increase my fuel usage? head lights are a pretty standard number of watts 55 to 65 watts each, so if you sit in your fully warmed up car with the scangauge set to gallons used per hour, then flick the head lights on and you watch how much the number goes up, THEN you will find out how much of an electrical load it puts on the engine, and how much having a 500 watt dash board electric defroster might affect your mileage (altho that number on it's own would be nice as well) or how much savings switching to LED bulbs all around might get you, but if you don't have the information then you are just making stab in the dark.

[RH77]

Nevertheless, my driving takes me on hilly, 60 MPH, 2-lane roads. Visibility and split-second decisions on the part of other drivers are of utmost concern. Headlights are used 100%: day and night.

The solution of less consumption generally translates to either a lower voltage DRL setup, an LED adjunct, or OEM replacement bulb set. The problem then becomes usability, return on investment, and reduction in consumption in total.

From a "coolness" perspective, LEDs look pretty keen IMHO -- front and rear. It all depends on the budget and willingness to spend...

RH77

[Vwbeamer]

I have some raw data from my jetta TDi. The TDii has day time running lights, but I have the european switch, which allows me to turn them of, but it then turns on the parking lights. There is no switch setting where I can turn all the lights off.

Noticed the following while idling at a drive thru window.

headlights/tail lights/markers on =.08GPH
tail/lights/markers=.07 GPH
Daytime running lights/ no tail or markers=.07 GPH

As you can see, this was a highly scientific and controlled study....

[NeilBlanchard]

Hi,

I think every little bit helps: if you can, running without headlights and without the ventilation fan, I've noticed a slight improvement in FE. At dusk, I run with the marker lights, and when I see that the headlights really help me see better, I turn them on. And I now only turn on my fog lights when I need them -- in an actual fog, or when there are no street lights.

[basjoos]

Driving with the headlights on drops my mileage by 2-3 mpg.

[hummingbird]

It is not a question of how much it translates to gas alone....

For me, extreme P&G leaves my battery on a diet all through - it is never full and satisfied... If I could save on the consumption by the Lamps - the objective is not to delete, but economize on the drain there has to be - I can save on hair dye. I am perpetually worried about not being able to start for the next trip.

Even when I exaggerate, I consider this point to be important from this aspect.