At first glance, it might seem like adding dimples to cars—similar to the ones on golf balls—could improve their aerodynamics and fuel efficiency. After all, dimples help golf balls fly farther by reducing drag. So, why don’t we see this design on cars? The answer lies in the fundamental differences between the aerodynamics of small spheres and large vehicles.

How Dimples Work on Golf Balls

Golf balls have dimples because they create a thin layer of turbulent air around the ball as it flies through the air. This turbulent layer clings to the ball's surface longer than a smooth layer would, which reduces drag (the air resistance acting against the ball) and allows the ball to travel farther. The dimples essentially reduce the wake (the low-pressure area behind the object), which is the primary source of drag for a sphere​.

Why Dimples Don’t Work for Cars

1. Cars Are Too Large

The size and shape of a car differ significantly from a golf ball. Cars are larger and move much slower relative to their size compared to a golf ball. The aerodynamic principles that apply to small, fast-moving objects like golf balls don't translate well to large, slower-moving vehicles.

2. Different Types of Drag

• Golf Ball Drag: Golf balls experience pressure drag, which dimples help reduce.
• Car Drag: Cars experience both pressure drag and skin friction drag. Skin friction drag is caused by the air moving over the large surface area of the car. Unlike a golf ball, dimples on a car would increase surface area and lead to higher skin friction drag, negating any benefits from reduced pressure drag​.

3. Laminar vs. Turbulent Flow

Cars are designed to maintain laminar flow—a smooth, streamlined airflow—over their surface. Dimples create turbulent flow, which is useful for small, spherical objects but undesirable for large, flat surfaces like car panels. Turbulence around a car would increase drag and reduce fuel efficiency rather than improve it.

What Automakers Do Instead

Instead of dimples, automakers use other techniques to improve aerodynamics and fuel efficiency:

• Smooth, Streamlined Designs: Modern cars are shaped to minimize air resistance and maintain laminar flow.
• Underbody Covers: Many vehicles have flat underbodies to reduce turbulence underneath the car.
• Spoilers and Air Dams: These features manage airflow around the car, reducing drag and improving stability.
• Active Aero Features: Some high-performance cars use adjustable aerodynamic components that adapt to driving conditions for optimal efficiency.

When Dimples Do Work

Interestingly, dimples or similar textures are being explored in other industries:

• Aerospace: Some experimental aircraft and wind turbines use dimpled surfaces to reduce drag and increase efficiency.
• Sports Equipment: Beyond golf balls, dimples are used on certain swimwear and cycling helmets to reduce drag in competitive sports.

While dimples work wonders for golf balls, they aren’t suitable for cars due to the differences in size, speed, and aerodynamic needs. Instead, car manufacturers rely on smooth designs and other aerodynamic features to achieve fuel efficiency and performance. So, the next time you drive past a golf course, remember that what works for the fairway doesn’t always work for the freeway!