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Old 03-13-2020, 08:47 PM   #4 (permalink)
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Little Red - retired - '05 Honda Civic EX
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Originally Posted by serialk11r View Post
For long freeway drives, probably 80% air resistance?
Not quite that much for the typical car, I suspect, but some bro-trucks might be more. In a Prius L Eco, at 70 mph you're using ~64% of the energy to overcome aerodynamic drag and the rest for rolling resistance. A 2020 Ram in its lowest drag trim, Cd = 0.36, is around 74% to aero drag at the same speed. At Cd = 0.45, the same truck is 78% to aero drag.

But the total resistive force acting on the last truck example, and therefore the work required to move it a given distance at a constant velocity, is two and a half times as much as the Prius. That puts things in perspective.


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