OK genius, provide me with the evidence of speed being related to gas mileage. After all your comment was nothing but insult that proved nothing but your arrogance minus reason for you to be that way.
Bud a if you want an engineering education - go to school. I don't have the time to explain the concepts of velocity, drag, work, and energy to you. Suffice it to say that moving an object through the air at 75 compared to 55 will require a larger force and an even larger use of energy.
energy consummed by an automobile at constant speed (such as on a trip on an interstate highway) is a combination of rolling resistance + aerodynamic drag. The rolling resistance component has to do with energy losses in the tires, plus frictional losses in the drivetrain. For the sake of a first order approximation, they can be treated as being essentially constant i.e., they don't go up very much with speed. Conversely, the aero drag is calulated using an equation that looks like:
where:
Faero is the retarding force produced by aerodynamic drag
A is the frontal area (of the car in this case)
Cd is the coefficent of drag (a unitless number that represents the relative aerodynmic "sleekness" compared to a flat plate)
rho is the air density
v is the vehicle velocity through the fluid medium, in this case air
Note that while the rolling resistance is a relatively constant value, the value of the areo drag component for a particular vehicle increases with the square of the vehicle's velocity. That means for most automobiles and trucks, the dominant component of drag at constant speeds above about 50 mph will be aerodynamic drag, and it's value is extremely dependent on velocity. EXAMPLE: a 10% increase in velocity will increase aero drag by 21%; an increase from 65 to 75 mph increases aero drag by almost a third!
In short, aero drag becomes the dominant source of drag on an automobile at constant highway speeds, and is extremely sensitive to changes in speed because it varies with the square of the vehicle's velocity