Comment: Re:consistency more important (Score 1) 374
I think that over a certain speed, fuel economy goes way down.
This is because:
For high velocities drag will vary as the square of velocity. Thus, the resultant power needed to overcome this drag will vary as the cube of velocity. The standard equation for drag is one half the coefficient of drag multiplied by the fluid mass density, the cross sectional area of the specified item, and the square of the velocity.
http://en.wikipedia.org/wiki/Drag_(physics)