Do lights have any effect on energy used?

I know it's already been mentioned, but I'm feeling kinda mathish.

Miles Per Gallon (MPG) is a fuel -vs- distance ratio.
Gallons Per Hour (GPH) is a fuel -vs- time ratio.

Any parasitic load, AC, headlights, MFD screen (yes I'm serious) will increase your your fuel use -vs- time. Higher GPH which is bad.

Now "how bad" the parasitic draw all has to do with how big of a piece of the GPH pie it's taking. To find GPH from MPG all you need is average Miles Per Hour (MPH). So MPH / MPG gives you GPH.

So if your netting 44 MPG at 75 MPH that's 1.70 GPH (75/44). If you also notice notice that turning off all your accessories bumps you up to 45 MPG at 75 MPH, then you have found that your parasitic load from your accessories is 0.0379 GPH (75/44 - 75/45). Now that seems insignifigant when your "normal" GPH consumption is 1.70. It only nets you a 2% boost in MPG (45/44 - 1), what most would call "insignifigant". Now watch what happens when you get off the highway.

So now lets look at city driving. If your netting 55 mpg around the city averaging 30 mph that would put your GPH at 0.545 GPH (55/30). Well your parasitic load isn't gonna change. It's still going to be 0.0379. So now at 30 mph if you turn off your accessories, your MPG would jump from 55 MPG to 59 MPG (30 / [0.545 - 0.0379]) . That's a 9% boost (59/55 - 1). Well outside the "insignifigant" range.

So parasitic loads have a MUCH higher *RELATIVE* impact at lower speeds than in a conventional car. This is because hybrids are unique in the fact that their MPG goes UP as their speed goes DOWN. So the old "insignifigant" argument used by the car "gurus" for 30 years doesn't really hold water in this case any more.

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From a public policy point of view, I wonder if anyone in the Canadian government did the calculation on how much more fuel the country as a whole is using because we all have daytime running lights. Is it outweighed by the energy and other costs reduced by the supposed reduction in accidents?

 

well i am tracking mileage with and without lights on and there is a difference. BUT, in the morning with the lights on, its colder, the car is colder, etc. so have to use another metric. will probably have to track mileage per minute or something.

another issue that complicates matters is there is nearly no traffic in the morning, bumper to bumper in the afternoon. average speed in the morning 31-34 mph. in the afternoon, 18-22.

so...not gonna be as easy as i thought. i kinda screwed up since i drive to work at 5.30 AM with no lights on for 2 months a year... oh well. remind me next year