I drove 2,502.70 miles for you to find out the mpg

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dexter

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So I drove 2,502.70 miles in 3 days to find out the mpg of my truck (see my signature line below for equipment) for you*.

Route - Atlanta, Ga to Pendleton, OR via Nebraska and Wyoming.

Tire pressure 62 front, 74 rear

Gas octane: 89

No air conditioning used

Load - 1 driver 200 LBS plus bed load of estimated 400 LBS

Temperature range 50 - 75 degrees

Average speed: 67.64 mpg

Computer MPG 17.00

Hand computed MPG 15.052



Time: 36.58.57

I was trying travel at about 75 MPH - what I think most here would drive.



*And to pick up a travel trailer, so I can figure out that MPG
 

drittal

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Margin of error. And it's much more accurate than the algorithm used by the EVIC




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Is there solid evidence either one is more accurate?

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drittal

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From Ward's http://m.wardsauto.com/blog/when-it-comes-mileage-cars-tell-truth

"Unless you want to spend millions of dollars on highly specialized measuring equipment, a vehicle’s trip computer is the most accurate way to judge its thirst.

“We need to know exactly how much fuel is being used by every stroke of every cylinder,” to meet emissions and fuel-economy standards, Roger Clark, senior manager of the General Motors Energy Center, told him. “We do a lot of precision measuring of the fuel injectors and exhaust treatment system.” The computer converts that data into fuel economy.

That kind of precision easily trumps Grandpa’s method, where temperature, sloping gas station parking lots and variations in the way gas pumps sense when a tank is full all can impact the outcome of fuel-economy measurements."

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drittal

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More from Clark at GM,

"Roger Clark, senior manager of GM's energy center, explains that the fuel economy gauge makes a calculation by counting the number and duration of pulses made by the fuel injectors as they squirt gasoline into the combustion chambers of the engine. The onboard computer system divides the distance the car travels by this estimated fuel consumption.

Clark says the gauge is "dead nuts accurate" — if you consider all the variables at work during driving, including temperature, driving conditions and driving style. The biggest fluctuation occurs because ethanol, which is blended with gasoline in varying amounts, contains less energy.

"When you fill up, you are paying for a gallon of gas, but the energy in that gas varies significantly," Clark says. This means that while the car's computer assumes the gasoline is providing energy to drive a certain distance, the fuel might have less energy and not propel the car as far."


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Iron Outlaw

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That's almost identical to what I got on a long trip. not that long though .

I actually got 11.7 pulling my dump trailer 200 miles. I was impressed
 
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dexter

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From Ward's When It Comes to Mileage, Cars Tell the Truth | Final Inspection

"Unless you want to spend millions of dollars on highly specialized measuring equipment, a vehicle’s trip computer is the most accurate way to judge its thirst.

From my observations the computer might be correct at A POINT IN TIME. The 17 mpg computer reading was a point in time at the end of my trip. The highest reading I saw was 17.5 mpg. To average 17mpg I would have had to seen many readings over 17 mpg because there were times when I saw 14 mpg.

But the hand calculations compute the mpg OVER A PERIOD OF TIME.
 

Danno

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and hand calculations have an error of margin.

Good enough for aviation to calculate a burn rate, there's no pulling off the road if you run out of fuel.

15 is what I would expect from flat highway, I don't know where the exaggerated MPG is possible.
 
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