You might have already noticed that there are more and more cars designed with hidden door handles, whether you are a car enthusiast or not. There's the same anecdote to all the Model 3 owners of showing their first-ride friends how to open the door. And if you are in a better developed, or more environment-conscious area, you will even find that some big automobile companies are also trying to hide their wing mirrors. 2013 Volkswagen Xl1 was an early example, Audi e-tron,Lexus es, Honda E, Hyundai IONIQ 5 are all recently replaced their wing mirrors with camera (virtual mirror).
Why are these automobile giants working so hard on such tiny exterior parts? The short answer is to reduce air resistance, therefore the electric cars can run more miles and the gas cars can burn less energy, it’s for the environment!
Surprisingly those tiny parts might make a much bigger difference to the cars than people thought. Drop shape is the shape with the lowest air resistance, and this is the goal for all the automobile manufacturers. However, a car can never be a perfect drop shape, they are doing their best to make the car body as smooth and round as possible, the rear end as even as possible, and there is only one component that is always standing out: the exterior wing mirror.
The wing mirror must be a flat surface and it has to be big enough to provide a good view. And that is not a perfect shape in high-speed moving, it can cause a low air pressure behind and form a big drag effect. And what’s more is the sharp edge of the wing mirror can severely disturb the air, leaving the air flapping the car body irregularly. As a result, this small standing part has always been a big problem in the eyes of car designers who pursue perfection.
Various recent studies show that by removing the wing mirrors, the air resistance can be reduced by 2-7%. In the existing case, Audi claims that the virtual rear view mirror of the e-tron reduces the drag coefficient from 0.28 to 0.27, increasing the WLTP cruising range by 2.5 km. This seems to be ridiculously small, but note that WLTP is not dominated by high-speed working conditions. Audi once revealed that the endurance contribution of the virtual rear view mirror at high speed can be 4.8 km. In addition, e-tron, as an SUV, has a large natural windward area and a small proportion of rear view mirrors. The advantages of virtual rear view mirrors of smaller cars may be even bigger.
Elon Musk is also a big supporter of "eliminating the wing mirror". He believes that removing the rear view mirror can increase the durability by 5%. The second-generation Roadster does not have an exterior side rear view mirror as well. (although the display is a prototype car, the virtual rear view mirror is not installed). Unplugged Performance, a company for upgrade and customization of Tesla cars, used CFD simulations and found that if Model 3 removes the rear view mirror, the overall wind resistance will be reduced by 2.8%.
Roadster 2
You can still think that removing side rear view mirrors is not that beneficial to electric vehicles. After all, even at high-speed conditions, the increase is only about 5%; but its main value of removing side rear view mirrors is more visible in the durability of high-speed driving, which is actually exactly the weakness of electric vehicles.
However, the high requirements of the camera(virtual mirror), capable of rapid response, night visibility and the high cost, are still the obstacles of this technology being safely widely used. The increased possibility of being carsick is also another problem the designers need to worry about.
At the moment, the visual mirror is still at the stage that mainly serves for the fancy high-tech look. And same as the side rear view mirror, the hidden door handle is also a design that might have a little bigger impact than you expected, but also at the moment it;s mainly for the design and fancy-looking. However, hidden door handles do not pose a threat to vehicle safety and the cost is not huge so that is it more widely adopted by more electric vehicles. The contribution to driving durability, improvement of NVH, elimination of blind spots is still small, but potential. With people’s increasing awareness and concern about the environment, energy saving is the way to go and eliminating protrusions on the car surface seems to be helpful and promising! It might make a big positive influence on our life and our planet despite its small body!
