Watch this video to get a better understanding of how drag coefficient works.
"Drag coefficient describes a car's shape — not its size. Think of it as a coupon code that reduces or increases a car's effective frontal area, the measure of how big the air sees it.

A low Cd can make a huge difference in a vehicle's overall aerodynamic drag. A Tesla Model X has 1.6 times the frontal area of a Lotus Elise SC, and yet its overall drag is lower. Meaning: to the air, the tiny Lotus is actually the bigger car."