What is a good coefficient of drag for a car?

In practical terms, a good drag coefficient (Cd) for a car is typically around 0.20–0.25 for the most efficient designs; most mainstream vehicles sit in the roughly 0.27–0.32 range. Lower Cd generally means better highway efficiency and longer electric range, but the ideal target depends on the car’s size, purpose, and speed range.

Understanding the coefficient of drag and its role

The coefficient of drag, Cd, is a dimensionless number used in the drag equation Fd = 0.5 × ρ × v² × Cd × A, where ρ is air density, v is speed, and A is the vehicle’s frontal area. A smaller Cd reduces aerodynamic drag at a given speed, but real-world drag also depends on frontal area and other factors such as tires, ride height, and underbody design. In other words, a large vehicle with a modest Cd can still experience substantial drag if its frontal area is large, while a small, boxy car with a very low Cd may be more efficient overall thanks to its smaller CdA (Cd multiplied by A).

Where “good” Cd sits by vehicle type

The following ranges summarize typical values seen in modern production cars. They reflect the broad reality that efficiency targets vary with size, use case, and design philosophy.

• Ultra-efficient EVs and aero-focused hybrids: roughly 0.20–0.25 Cd


• Modern mainstream sedans and compact cars: roughly 0.27–0.32 Cd


• Hatchbacks and small crossovers: roughly 0.28–0.32 Cd


• SUVs and larger crossovers: roughly 0.32–0.40 Cd


• Light trucks and heavy-duty vehicles: roughly 0.35–0.45 Cd

Conclusion: Cd is a valuable benchmark, but it’s not the whole story. The same Cd with a much bigger frontal area can yield more drag than a smaller car with a slightly higher Cd. Real-world fuel economy or range depends on both Cd and CdA plus how the vehicle is driven and maintained.

How Cd is measured and tested

Cd values are determined under standardized conditions, typically in wind tunnels or with validated computational methods, using a defined frontal area. Automakers publish Cd values for comparison, but the effective drag in real driving also depends on wheel size, tire choice, mirrors, ride height, and accessories. Precision testing is essential, as small changes in wheels or aero enhancements can shift Cd by a few hundredths.

Strategies that reduce drag in production cars

Manufacturers employ a suite of design choices to lower Cd and the overall drag area. The goal is to squeeze efficiency without compromising usability, cooling, or safety.

• Underbody panels and a smooth undercarriage to reduce wake and turbulence


• Active grille shutters that close when cooling isn’t needed to reduce flow resistance


• Aerodynamic wheel designs and low rolling-resistance tires


• Flush door handles and streamlined side mirrors to minimize frontal disturbance


• Rear-end tuning, spoilers, and diffusers designed to reduce wake at speed


• Lower ride height and optimized chassis geometry, sometimes aided by adjustable suspension

Conclusion: These techniques collectively lower Cd and the overall drag area, contributing to better highway efficiency and extended range. Manufacturers must balance aero gains with cooling requirements, practicality, cost, and ride quality.

Real-world caveats and practical takeaways for buyers

When evaluating a car, Cd should be considered alongside CdA and real-world performance data. A very low Cd is not a universal guarantee of excellent fuel economy if the vehicle is large or heavy, or if it uses aggressive tires or a high ride height. Conversely, a modest Cd on a compact, lightweight car can translate into meaningful gains at highway speeds. For electric vehicles, reducing drag has a direct impact on range on long trips and overall efficiency in typical driving conditions.

Summary

A good drag coefficient for a car sits around 0.20–0.25 for top efficiency, with most mainstream vehicles in the 0.27–0.32 range. Cd must be interpreted in the context of vehicle size (CdA), ride height, wheels, tires, and cooling needs. Aerodynamic design—underbody panels, active shutters, aero wheels, flush handles, and careful rear-end shaping—helps bring Cd down, but practicality and price also shape what’s achievable. For buyers, comparing Cd and CdA, along with real-world highway performance data, provides the best sense of a car’s efficiency potential.

What is a normal coefficient of drag?

A "normal drag coefficient" is a dimensionless number that represents the resistance of an object moving through a fluid, and its value depends on the object's shape. Typical drag coefficients are approximately 0.290.290.29 for a common car, 0.0310.0310.031 for a Boeing 747, and 1.121.121.12 for a flat circular plate. These values indicate that shape is a major factor, with streamlined objects like cars and aircraft having much lower drag coefficients than blunt or flat objects. 
Examples of drag coefficients

• Automobiles: A streamlined modern car can have a drag coefficient around 0.2−0.30.2 minus 0.30.2−0.3. 
• Aircraft: Subsonic aircraft have very low drag coefficients, such as 0.0120.0120.012 for a subsonic transport aircraft or 0.0310.0310.031 for a Boeing 747. 
• Geometric Shapes:
  • Flat circular plate: Approximately 1.121.121.12 
  • Sphere: Varies from about 0.070.070.07 to 0.50.50.5, depending on conditions 
  • Hollow semi-sphere: 0.380.380.38 when facing the flow 
  • Airfoil: Around 0.0450.0450.045 for a typical airfoil 
• Other objects:
  • Skydiver (horizontal): Around 1.01.01.0 
  • Dodge Ram pickup truck: 0.430.430.43 
  • Buildings: Typically have a drag coefficient around one or greater. 

What is the drag coefficient of a F1 car?

The drag coefficient (Cdcap C sub d𝐶𝑑) of an F1 car is typically between 0.7 and 1.1, which is significantly higher than modern road cars (Cdcap C sub d𝐶𝑑 of about 0.25−0.30.25 minus 0.30.25−0.3). This is because F1 cars are designed to prioritize downforce for cornering over top speed on straights, and the aero devices that create this downforce also create a large amount of drag.
 
This video explains why F1 cars have high drag coefficients: 19sPremier AerodynamicsYouTube · Dec 29, 2023

• High drag is a trade-off for performance: To achieve high cornering speeds, F1 cars generate massive amounts of downforce, which pushes the car into the track. This downforce-generating design inevitably creates substantial drag. 
• Design prioritizes cornering: The priority for an F1 car is lap time, which is improved more by high downforce for cornering than by raw top speed. 
• Regulation changes: The drag coefficient used to be even higher, but regulations now restrict the size and complexity of aerodynamic devices, which has helped to reduce it slightly over time. 

This video explains the basics of aerodynamics in Formula 1: 58sF1 AerodynamicistYouTube · Jul 6, 2023

What is a good drag coefficient for a car?

The average modern automobile achieves a drag coefficient of between 0.25 and 0.3. Sport utility vehicles (SUVs), with their typically boxy shapes, typically achieve a Cd=0.35–0.45. The drag coefficient of a vehicle is affected by the shape of body of the vehicle.

What is the best drag coefficient car?

• Tesla Model 3 (2017-present)
• Porsche Taycan (2019-present)
• Mercedes A-Class Saloon (2018-present)
• BMW 5 Series Efficient Dynamics (2011-13)
• Tatra T77A (1935-38)
• Tesla Model S (2012-present) Drag coefficient: 0.208Cd.
• Mercedes-EQS (2021-present) Drag coefficient: 0.202Cd.
• Volkswagen XL1 (2015-16) Drag coefficient: 0.199Cd.