Quote:
Originally Posted by Phase
Well today I got 78 miles per gallon cruising at 80 miles per hour with a tail wind in eastern oregon
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I ran the numbers on your car ( I'll waive the $110 fee ), and it looks like it tops out at 40.05-mpg @ 80-MPH, thermally-equilibrated, with 'Standard Air, on a straight, level, smooth, dry highway, at sea level, on a calm day.
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In order to achieve 78-mpg would require a drag coefficient of Cd 0.0438, which cannot exist within our universe.
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* By itself, you would need a 33.4-MPH tailwind to achieve 78-mpg.
* Or the density-altitude coinciding with an air density of (rho)= 0.001360124538- slugs/ ft-cubed ( 0.6977461- kg/meter-sq. )[ There exist no highways on Earth high enough to experience an air density as low as required ].
* Or, some combination of tailwind, plus lower air density.
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In order to reduce the aerodynamic drag down to the Cd 0.0.0438 magnitude would require that you drive no more than 44.6-MPH.
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These are the cold hard facts of the matter.