Truck Camper Magazine Blog

Trust the Dash or Do the Math?

In last week’s article, “2014 Ram 3500 Experience Update”, we revealed the fuel economy data for our 6.4L HEMI as reported by  On average, the hand-calculated miles per gallon is 11.5% lower than what our Ram dash displays.  How the onboard computer is that wrong is something I look forward to asking Ram Corporate next time I speak with them.

Several long time readers responded to our story to say that they too had been surprised by the results of hand-calculating their trucks fuel economy data.  This got us wondering about how many folks hand-calculate their trucks fuel milage, how they calculate and keep track of this data, and what mpg numbers they have discovered.

Are all dashboard fuel mileage displays wrong or misleading?  Are diesel trucks also off the mark?  Or are some manufacturers, and some truck configurations, more accurate than others?

This week’s Question of the Week is, “Do you hand-calculate your fuel mileage, or do you trust the dashboard fuel mileage data?”

If you hand-calculate your fuel mileage, tell us how you calculate the miles.  For example, you might do the math with pen and paper, or you might use a website or smartphone app like we do.  If you know, please also tell us how accurate your dashboard fuel milage data is.


By the way, getting 11.5% less mpg than we originally thought has been made easier to deal with by the fact that we’re also paying 17% less per gallon than we were in April.  Just look at this GasBuddy chart for 2014.  Alaska next year, anyone?

Here are 106 reader responses to this Question of the Week.

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