Hidden door handles. Engineer: They can't save even 1 kWh per 100 kilometers.

Text | XU Caiyu; Editor | LI Qin

Consumers have long been frustrated with electric car door handles.

Nowadays, at least 4 out of every 10 new cars are new energy vehicles, and the number of new brands and models is gradually increasing. It's not even a rare thing to come across a car with an unfamiliar brand.

It doesn't matter if you don't recognize the car logo, but not being able to find the door handle or knowing how to open the car door has indeed become one of the biggest annoyances in the new energy era.

Most of today's car door handles are flat and strip - shaped, hidden handles that blend in with the car body.

To open the door of a Tesla Model 3, you need to press the right side while holding the left - side raised handle. Consumers encountering such doors for the first time often find themselves in the embarrassing situation of not knowing how to press and hold the handle at the same time.

Opening a Tesla door

The door handles of the NIO ET7 pop out automatically. When you approach to unlock or touch it, the handle will pop out automatically. However, many car owners say that the rear - door handles often cannot be opened by touch, which is indeed quite inconvenient to use.

NIO ET7 door handle

What's even scarier is that in the event of a car accident, these door - opening methods that "require exploration and learning" often become obstacles to rescue and escape.

Such a design that affects the user experience and even threatens safety has triggered a crackdown from the regulatory authorities.

On May 8th, the Ministry of Industry and Information Technology released a new notice soliciting opinions on the "Safety Technical Requirements for Automobile Door Handles", which will further clarify the requirements and test standards for hidden door handles in terms of installation, marking, anti - pinch, strength, and dynamic effects.

Through long - term communication with automobile R & D personnel, 36Kr has also found that in addition to the poor user experience, hidden door handles do not have obvious improvement effects in the product R & D and engineering fields, and their risks cannot be completely resolved.

The outcome of such a design that troubles users and headaches car manufacturers seems to be already doomed.

Interviewee: Q, engaged in functional safety development, with 7 years of work experience in a German luxury car company

36Kr: What is the biggest risk of hidden door handles?

Q: Hidden door handles can be classified. The ones on a Tesla are actually still mechanical, just with a hidden appearance. The ones with greater risks are actually the door handles with motors.

For example, the door handles of the NIO ET5 pop open automatically when you approach. This popping - open action is actually the result of the motor inside pushing it up. Another type is the Xiaomi SU7. Its door handle cannot be pulled; you need to press the switch inside, and then the motor opens the door.

Xiaomi SU7 door handle

With a motor, there are wiring harnesses and other electronic devices. Once these electronic devices malfunction or the whole car loses power and the motor stops working, the door may lock up.

36Kr: Is there a way to solve this?

Q: The solution is quite mature. For such safety - related components, as long as they are connected to the circuit, there are basically double redundancies. If the power battery fails, the small battery still has power. At worst, there is also a mechanical structure, and you can still open the door by pulling the handle. For core components like the door drive motor, a protective layer will be added to prevent short - circuits.

36Kr: Are these all the measures? Can it guarantee that the door can be opened at any time?

Q: To be honest, no car manufacturer can guarantee to solve the problem of hidden door handles not opening 100%.

Let me put it this way. Safety is built with money, especially when it comes to things related to electricity. Let me give you an example. In Northeast China, it's so cold in winter. Can the car door be opened?

Let's assume that the door handle isn't frozen. But due to the cold, the lubricating oil inside the motor will become very viscous, the resistance will increase, and the battery won't be as powerful.

If the motor's power is low, it may not run even if it isn't frozen because of the cold. If it's frozen, the low power will result in less force to push open the ice layer, and there's a risk that it won't be able to push it open.

The car door motor needs to be resistant to low temperatures, have high power, and be small in size so as not to take up much space in the door panel. Then the car manufacturer has to spend more money. Spending a few hundred more on a motor may increase the cost of a car by more than a thousand.

Moreover, the motor is just one component. Should the touch switch inside be replaced with a better one? It's all about economics.

36Kr: Can using better parts achieve zero failures?

Q: Our company uses relatively high - quality materials. Many parts on our 500,000 - yuan cars are imported. But even so, we can't guarantee 100%.

One of our colleagues encountered the problem of the door handle not popping out when testing a car recently. For industrial products, 100% perfection is impossible. We can only say that the probability of our products having failures is lower than others'.

Interviewee: H, R & D management, with dual experience in domestic car manufacturers and the supply chain

36Kr: Hidden door handles have electronic mechanisms. Shouldn't the R & D and BOM costs be higher?

H: Yes, that's right. The biggest cost of traditional door handles is mold - making. Curved molds are very expensive. However, when averaged out, the cost is only in the hundreds of yuan. But many new energy brands have small production volumes, so it's difficult to negotiate prices with suppliers, and the cost will be higher.

The cost of Tesla's door design is relatively low. The expensive ones are like those on Li Auto and NIO, which need to pop out.

For the pop - out type, there need to be a motor, a capacitive touch switch, a position signal switch, a wiring harness, and a bunch of other things inside. And power redundancy also needs to be set up. It definitely costs one or two thousand yuan to make a set. Moreover, once it has electronic components, testing is also required, which incurs additional costs.

36Kr: Since it can't save money, why do so many car manufacturers choose to make hidden door handles?

H: First, we need to understand the product development logic of car manufacturers. There aren't dedicated designers and engineers for door handles. How to handle this doesn't depend on the design department, nor does it depend on the aerodynamics people. Ultimately, it's up to the boss.

The answer is simple. The first reason is aerodynamic drag, and the second is design.

Most bosses nowadays think that their cars need to look high - tech, have long - range capabilities, and ultra - low aerodynamic drag for promotion. Under such requirements, they can only choose to make hidden door handles, right?

36Kr: Does the hidden door handle have a significant impact on aerodynamic drag?

H: Our colleagues have privately calculated that reducing the drag coefficient by 0.01cd only saves about 0.6 kWh of electricity per 100 kilometers.

If you charge at home, the money saved is almost negligible. The electricity price is too cheap. In fact, fuel - powered cars with high energy consumption need to reduce aerodynamic drag more.

Wei Jianjun also said that although the aerodynamic drag may be reduced a little, it's almost negligible.

36Kr: Then why do we have to reduce aerodynamic drag through the door handle?

H: The idea of hidden door handles originated from racing car R & D, like in Nissan's GTR, Mercedes - Benz, Lamborghini, etc.

It's normal for racing cars to focus on aerodynamic drag. Even a reduction of 0.01cd may mean one less pit - stop and ultimately a faster finish. In racing car R & D, there are many such technologies that focus on reducing aerodynamic drag bit by bit, and the accumulated effect can reduce the overall aerodynamic drag of the car.

Now, using hidden door handles to reduce aerodynamic drag is actually because car manufacturers have a high pursuit of cruising range.

To increase the cruising range of electric cars, you can either increase the battery capacity, reduce the vehicle weight, or reduce energy consumption. Battery technology breakthroughs basically don't depend on car manufacturers, so most car manufacturers are working on reducing vehicle weight and energy consumption.

Lightweighting is one of the most difficult automotive technologies, from racing cars to civilian cars, and from fuel - powered cars to electric cars.

The fastest way is to replace parts with lightweight ones, such as replacing steel with aluminum or even carbon fiber. But the problem with good materials is that they are expensive. With the current price war, it's already good if they don't replace aluminum with steel.

The second factor, energy consumption, is related to vehicle weight, but more related to aerodynamic drag. It's not easy to reduce the drag coefficient.

The more the whole car looks like a water drop or a bullet, the lower the aerodynamic drag, like the Li Auto MEGA. If you don't want to compromise on the overall shape, you need designs like spoilers and air ducts. The BOM cost of this approach isn't extremely high, but the difficulty is very great.

Li Auto MEGA

There isn't much racing car R & D in China, so there aren't many top - level aerodynamics experts. So the currently feasible way is to remove the protruding parts on the car. Electronic rear - view mirrors, hidden door handles, and enclosed wheels all follow this principle.

We can only say that this is the easiest and lowest - cost way to reduce aerodynamic drag at present. Every little bit helps.

36Kr: Well, since they want to make it, why can't they take good care of the user experience? It's not difficult to make a mark, right?

H: Nowadays, car manufacturers pay less attention to user research and durability and abuse testing than before.

Now, car manufacturers build cars based on what users are willing to pay for. If users say they want a cruising range of 800 kilometers, then achieving an 800 - kilometer cruising range becomes one of the top goals. Moreover, the product strength and development speed of competitors are so fast that those who take their time will be forced out of the market. So now, many manufacturers first meet the major requirements and deal with the small details later.

After speeding up, many testing processes are compressed. A well - known luxury car company among peers still conducts hundreds of violent door - opening and closing tests on each car. For automatically popping door handles, they also test the stability by repeatedly making the handle pop out and retract. And they not only test in the R & D center but also during winter testing.

In the eyes of some domestic car company leaders, these tests are ineffective. First, they may not necessarily detect problems. Second, even if problems are detected, can they definitely be solved? Engineers are honest and say they can't. Then the boss will say, "Don't waste money on these tests."

Think about it. Even companies with a complete verification and testing process can't guarantee 100% problem - free products. How can cars with less or no testing guarantee the smooth use of door handles?

36Kr: Now the Ministry of Industry and Information Technology has new requirements to clarify the requirements and test standards. Will this improve the risk problem of hidden door handles?

H: The national standard is just a minimum threshold. Cars that can't meet the national standard won't be sold to consumers. The safety levels of cars on the market also vary, right? There are always car manufacturers that invest more in safety.

After these technical requirements are released, some car manufacturers will definitely have to make up for their deficiencies and spend money on testing and verification.

Now it's easy to achieve a cruising range of five or six hundred kilometers. For the additional 20 - kilometer cruising range brought by the door handle, should they spend more money to keep the hidden door handle or simply switch back to the traditional door handle? There should be some changes.

The user experience and the safety of using the car are actually accumulated over time and with cost. Regarding the door handle issue, we can only say that the development of our new energy vehicles was too wild before, and now it's just gradually returning to the due rigor.

As front - line creators of automotive products, engineers are the people who know automotive products and technologies best. Whether the product is good, whether the technology is profound, and whether the materials are genuine. In the "Engineer's Letter" column of 36Kr, you can see a more real side.