Design is not just a question of aesthetics, but also efficiency. About half of the fuel consumption is due to air resistance, but hardly anyone who buys a car considers or ignores aerodynamics per se. From a speed of 60 km/h, aerodynamics is the decisive factor, because then the air resistance exceeds the rolling resistance. With increasing speed, the air resistance increases by the square.
A teardrop-shaped car would be ideal
A drop of water, with its shape, represents the optimum with Cd values of up to 0.02. In the case of cars, on the other hand, manufacturers have to consider more than just a streamlined body shape, because customers usually prefer a practical car to one aerodynamic before. And a typical car with five seats and a large trunk no longer bears much resemblance to a drop. This causes the airflow to break and there is pressure loss or turbulence. A car first pushes the air in front of it and compresses it before it displaces it. At the rear end, on the other hand, a negative pressure or suction forms which drag the car backward. An aerodynamically good car achieves a Cd value of around 0.2. SUVs as a comparison 0.35 and more.
Laws on pedestrian protection, for example, which require steep radiator fronts, already influence the body shape. The most difficult thing, however, is to find the balance between efficient aerodynamics and good driving safety. Because a certain amount of downforce is indispensable for safe and dynamic driving, which improves handling and stabilizes driving behavior at higher speeds. To do this, the airflow is directed in such a way that it presses the car onto the asphalt or pulls it in the direction of the road through targeted negative pressure on the vehicle floor. From the aerodynamic point of view, however, downforce means to drag, so the drag coefficient deteriorates.
In many test cycles, the average speed is often below 50 km/h
At this city pace, aerodynamics are secondary, which explains the deviations from the customer´s consumption values. On the motorway at high speed, the drag coefficient and the so-called frontal area are decisive. And that has deteriorated with many new models, especially due to the SUV trend. Vehicles with a high seating position may be comfortable, but the massive fronts damage the aerodynamics. So that the bulky cars are not slower than their predecessors, the average engine power increases at the same time. No wonder that the fleet consumption of many manufacturers has stagnated or even increased for some time.
Car shape trends from the consumer side
No other body shape has such a high proportion of private customers as SUVs. Especially old people who often want to buy new cars get in comfortably, sit high, and enjoy plenty of arm and headroom. Sedans and station wagons, on the other hand, can only hold their market share as company cars. If you want to have some more detailed information about the problems SUVs cause click the following link: Sport Utility Vehicle (SUV). Climate killer, whether electric or with combustion engine. – Greater Ideas
Manufacturers do a great job, but it’s on the consumers to buy the right models
Most manufacturers have already optimized the aerodynamics of their car models. The car manufacturers only build the models that the customer wants. It is therefore up to the customer to buy the aerodynamically best models. Because everything else is a step backward at efficiency. Design, comfort, and a high seating position seem to be more important to many car buyers today than the lowest possible consumption and a streamlined body shape. Manufacturers, too, rarely advertise their latest aerodynamic achievements.
Ultimately, it can be said that the car buyer should make more conscious decisions. This saves fuel and helps the environment as well as your wallet.