Power vs velocity graph

Approximate horsepower required to overcome air resistance for a vehicle with Cd of 0.36 and frontal area of 2.318 square meters. Something like an Evo. ;)

In reality, additional factors such as rolling resistance, drivetrain losses, pitch angle, lift and so on should be considered before more detailed calculations to predict required horsepower vs velocity are attempted.

A change in Cd of 0.01 would yield about 2.78% difference in required horsepower.