BYD surprised at the Annual Academic Conference of the Automotive Aerodynamics Committee in China by announcing that its future YangWang U6, which has not yet been officially presented, will be the most aerodynamic car in the world, with a Cx of only 0.195. In his presentation, he showed a graph with the ten most aerodynamic cars on the current market. The list was headed by the Mercedes Benz EQS, with a Cx of 0.200, although the Lucid men claim a Cx of 0.197 for their Lucid Air instead of the 0.215 they were awarded. And the Dutch Lightyear claim 0.175 for their '0' model, while the Mercedes EQXX concept announces 0.17.
Aerodynamics is a key factor in today's cars. Consumption and dynamic qualities depend on it. We can play with the air to reduce drag or to achieve more grip. Finding the optimal balance based on the use of the vehicle is key. And in electric vehicles, aerodynamics becomes even more important to reduce consumption and increase autonomy, an aspect that is very important for consumers.
The G.M. engineers understood this very well. When they designed the first modern electric car, the GM EV1, a car that was ahead of its time and had a Cx of 0.19, a figure that VW improved slightly, although they were not electric, with their XL1 and L1 concepts, they improved it.
Most electric brands seek to have an aerodynamic coefficient that does not greatly exceed 0.2 to offer the least possible resistance to progress. It is the complete opposite of Formula 1, where it is essential to achieve greater grip, even at the cost of increasing drag; Therefore, its Cx is “painful”, of the order of 1.1 and even more.
In reality, the Cx is a shape coefficient. Aerodynamic drag is the product of Cx times the front section of the vehicle, and grows with the square of the speed. Thus, the air resistance of a vehicle with a smaller frontal section may be equal to or lower than that of another with better Cx, but with a larger section.
Already in the 1920s, that is, a century ago, the importance of reducing drag was known. In those times, however, what was sought was to increase the top speed of cars in some cases and in others to be able to offer a reasonable speed with a small engine. Today, the objective is not so much to achieve greater performance as to reduce energy consumption.
The reduction of energy consumption began in the 1970s as a result of the oil crisis, and at the end of the last century and the beginning of this one it continued along the same path to limit emissions from cars with thermal engines. Now it is transferred to electric ones to improve autonomy.
Although much progress has been made in this field, the most aerodynamic car ever built was the 1939 Schörlwagen; That is, a car from almost 85 years ago. He could boast of his Cx of 0.15. The model, they say, gave a Cx of 0.118, but the rolling car increased the figure.
Its shape is quite close to the most aerodynamic shape known, that of the drop of water, "trypone" in front, and tapering towards the back. It was a curious car: it had the engine in the rear overhang, a central driving position and could seat 7 people. It was very wide (2.1 meters) to be able to have the wheels inside the body.
Only one car has lowered this figure. We are referring to the 1985 Ford Probe V Concept, with a Cx of 0.137. Possibly, it has been the most aerodynamic tourism prototype in history.
However, the advantages of a shape inspired by the 'drop of water' had been known for a long time. The best proof was the Alfa Romeo 40 HP Aerodinámica which, made by Carrozzeria Castagna, already established these principles in 1914.
In 1921 the Rumpler Tropfenwagen was born in Germany: with only 36 HP it reached a top speed of 110 km/h. It was a car long before the Tatra T77 of the mid-1930s, the work of engineer Paul Jaray, considered one of the first great automobile aerodynamicists. Even then it offered a Cx of 0.212, which would be the envy of many modern passenger cars. It was the first 'aerodynamic' to be marketed.
Slightly later, the Streamline Burney Car (1929), the Dymaxion concept (1939) or the Scout Scarab (1932) followed the same pattern. The idea is that the air 'sticks' to the bodywork, without offering turbulence, so that everything flows.
Even Ferdinand Porsche's prototypes to develop an economical car - which would later give birth to the Volkswagen - sought to approximate these shapes with the aim of offering interesting speed with a small engine.
This interest in aerodynamics was widely used in the 1930s by luxury builders. Some of the engineers and brand founders had had a lot of contact with aviation and knew the importance of knowing how to play with the air. But in this case, what they were looking for was for the cars to be faster.
