The Drag Coefficient – a little-known indicator

The drag coefficient, often denoted by Cx, is a keyfactor in automotive aerodynamics. While it is essential for engineers, it remains relatively unknown to the public. 

This coefficient measures the resistance a car encounters from air as it moves. The lower the Cx, the less resistance the car faces, which improves both energy efficiency and performance. 

Understanding the Drag Coefficient 

The Cx is a dimensionless value that generally varies between 0.20 and 0.40 for production cars. It is determined by the shape of the vehicle, the exposed frontal area and the driving speed. A low Cx means that the car is well designed to minimise air resistance, which is crucial for reducing fuel consumption and increasing the range of electric vehicles. 

Examples of cars with a good drag coefficient 

Some vehicles stand out for their excellent drag coefficients. For instance, the Tesla Model S has a Cx of 0.208, making it one of the most aerodynamic cars o the market. The Porsche Taycan follows closely with a Cx of 0,20. Th DS N°, an electric SUV coupé, has a Cx of 0,24, allowing it to reach an impressive 750 km range according to the WLTP cycle. Back in 1982, made history with a Cx of 0,30, earning the title of “aerodynamics world champion”. More recently, the Audi A6 Avant e-tron boasts a drag coefficient of just 0,24 – or even 0,21 for the Sportback version 

Benefits of a low drag coefficient 

A low drag coefficient brings several advantages. It reduces fuel consumption for combustion vehicles, benefiting both the environment and the driver’s wallet. For electric cars, a low Cx is even more critical as it increases driving range – a key factor for users. Lower air resistance allows electric vehicles to travel further on a single charge.

The relationship between Cx and range is significant: a 100% reduction in Cx can increase an Ev’s range by 5 to 8%. Even small aerodynamic improvements (such as integrated door handles) can have a notable impact. 

Additionally, a lower Cx enhances overall vehicle performance: better acceleration, higher top speed, and improved stability and quietness due to reduced wind turbulence at high speeds. 

Conclusion 

The drag coefficient is a crucial indicator for assessing a car’s aerodynamic efficiency. Though often overlooked, it plays a vital role in reducing fuel consumption and increasing the range of electric vehicles. Models like the Tesla Model S. Porsche Taycan, Mercedes EQS, DS N°8, and Audi 100 show that optimizing Cx leads to more efficient and high-performing vehicles. It’s time this metric received more attention from consumers when choosing their next car.