[Big Dave]

NeilBlanchard posted:

“It is the square of the speed, IIANM.”


Dave says:

Aero drag FORCE is proportional to the square of the speed. Power is force times speed, therefore aero drag HP is proportional to the cube of speed.

Normally people begin to consider aero drag HP at the point it generally begins to exceed rolling resistance HP – for most vehicles around 40 MPH – but it is always there, even a 5 MPH. It is just not as important at very low speed.

Fuel burn is a function of power required.

Because of all this when someone tells me that fuel burn rate is lower at 35 than 55, my skepticism meter goes into the red.