Drag Area
Drag area, commonly written as CdA, is the product of a vehicle’s drag coefficient (Cd) and frontal area (A).
Why the product matters
Aerodynamic drag force can be written as one half of air density multiplied by speed squared, drag coefficient, and frontal area. Combining the last two terms as CdA shows how the vehicle’s shape and size work together. Drag area has units of area, commonly square metres.
A low drag coefficient does not necessarily mean a low drag area. A large vehicle can have a low Cd but still present a substantial frontal area. A smaller vehicle with a slightly higher Cd can have the lower CdA. Comparisons need compatible definitions and measurement methods for both coefficient and frontal area.
At a given air density and road speed, lower CdA means less aerodynamic force. The propulsion power needed to overcome that force rises approximately with the cube of air speed, so CdA becomes especially important at sustained high speed and in headwinds. It does not describe rolling resistance, drivetrain losses, auxiliary loads, or battery energy, which also affect consumption and range.
For the complete range model and the role of aerodynamic drag, see Understanding EV Range.