Almost four years have passed since the Citroën C4 was launched, the third generation of the brand's bold and unique car, which mixes the codes of sedans and SUVs. However, in addition to its groundbreaking design and comfort, the Citroën C4 contains many innovations that have unfortunately gone relatively unnoticed, although they represent all the audacity and innovation that characterise Citroën. In this first part, we will focus on the C4's aerodynamics, which have been particularly well thought out.
A Citroën tradition
Aerodynamics has always been at the heart of the brand's cars, which have always been characterised by a line shaped by air. From the CX to the AX, from the SM to the The fuel consumption of the AX and BX diesel is enough to demonstrate the importance of aerodynamics at Citroën.
It is in this tradition that the third generation of the C4 is part of a line sculpted by air that allows very low consumption for the category. This importance of aerodynamics is dictated by the 100% electric version, which manages to control its consumption and therefore its autonomy thanks to this careful aerodynamics.
An aerodynamic saloon with large wheels
With the C4, Citroën offers a different car in the compact saloon category, with a unique concept of an aerodynamic saloon with large wheels. The choice of this concept was made by the customers during the clinical tests carried out before the launch, as Audrey Amar, the C4 project manager at the time, confirms: "This concept was defined by working with and interviewing many customers who loved the concept of an aerodynamic saloon car with large wheels.
The initial specifications simply asked for a compact saloon to meet the expectations of this segment. And at first we worked on very aerodynamic concepts, because that is also the history of Citroën, we had made very aerodynamic concepts, very low, very tapered, but that did not work with the big wheels. Then one day something happened. We did a test with a concept on 640 mm wheels and, exactly the same, on 690 mm wheels, which we highlighted in black to emphasise this slightly raised side. And it was obvious, obvious, that we had to offer this concept in series production."
To compensate for these large wheels, which are not ideal from an aerodynamic point of view, the brand had to work on a number of areas to make up for this loss. This is particularly true of the underbody, which is fully faired - still a rarity in this category - and allows the C4 to let the air escape without trapping it. But the brand has also worked on the lowered rocker panels that channel the airflow under the car and has innovated in the size of the wheels, which are 195 mm wide instead of the 235 mm that took a lot of effort to achieve. accessible to everyone and not too heavy, while offering a size of 18 inches.
Naturally, the rear of the C4 required the most work because it had to be narrower than the front, like many of the brand's models such as the legendary DS. In particular, the C4 features a rear spoiler, which is crucial because, according to Denis Cauwet, technical manager of the C4 programme, it "ensures good braking quality of the vehicle at high speed". The design of this spoiler was a real challenge for the brand's teams, who had to deal with a number of sometimes contradictory elements. According to Denis Cauwet, "the spoiler had to be as thin as possible so as not to obstruct the rear view. So the spoiler had to be as thin as possible so that the rear view was perfect and not obstructed by the spoiler. Similarly, air must not be able to pass between the window and the spoiler in order for the spoiler to be as effective as possible. The spoiler also had to be easy to fit, and you have to think about it so that the assembly is simple and effortless. In the end you will see something surprising. When you are outside, you mainly see the part above the spoiler. But when you are behind the wheel of the C4, the part under the spoiler is at least as important as the one above. You will also notice that the C4's spoiler is positioned at a certain height so that it does not obstruct the view of the driver of the car behind, while at the same time masking the headlights of the same car very well.
The large, narrower wheels, the raised ride height caused by these large wheels, the fully-aired underbody and the spoiler are therefore a set of elements that required a lot of work to make this C4 an aerodynamic car. neat. Since its presentation, a number of cars have adopted the sloping rear and integrated spoiler concept, such as the Audi Q4 Sportback or the Volkswagen ID5. And the C4 is particularly efficient, having the greatest electric range (420 km) of these sisters based on the same CMP platform, while being bigger and taller, which is what the brand's teams say they have managed to do. Yes, the basic concept was to offer a compact saloon that was aerodynamic, as the latter was part of Citroën's history, and the brand has managed to offer not only a concept of a raised saloon that is completely unique in its segment, but also the most aerodynamically efficient. This required a great deal of effort and work from the teams and, unfortunately, this aspect is not as well known as some of the other innovations that this successful third generation of the C4 has to offer and that I will return to in this series of articles. .