A recent crash in Chengdu involving a Xiaomi SU7 Ultra has reignited public debate over the safety of new energy vehicles (NEVs). According to an official report, the vehicle caught fire after veering across a central divider and colliding with a barrier.
Videos recorded by bystanders show several men attempting to rescue the occupants, pulling on the car’s door handles, but none were able to open the doors.
The incident remains under investigation, and many details are still unclear. Yet once again, questions about NEV safety have taken center stage for millions of consumers. Most notably, in an emergency, how can the doors of such vehicles be opened?
When should car doors automatically unlock?
A car’s door locking mechanism is a complex physical system composed of two main parts: the lock and the latch. When a driver uses a key, remote, smartphone app, or central console to secure or open the car, those actions control the locking portion. Pulling the handle, however, operates the latch that physically opens the door.
In short, opening a car door requires two steps: unlocking it, then releasing the latch.
Door locks are designed to prevent unauthorized access and protect passengers. Under normal conditions, drivers and passengers can choose to keep the doors locked.
However, in a collision, occupants may be unconscious. If only those inside can unlock the doors, rescuers may face serious difficulty, often resorting to cutting through the vehicle body. This process increases both risk and repair costs.
To address this, automakers developed a safety mechanism that links automatic door unlocking to airbag deployment.
Airbags form the top tier of a vehicle’s safety system. The collision sensor and airbag control circuit have the highest operational priority, built with precision wiring and fast data transmission. When a sensor detects a severe impact, the system decides whether to deploy the airbags. If the conditions are met, the airbags deploy, and at that instant, the car’s doors automatically lock.
This brief locking is deliberate. It coincides with the tightening of seat belts and lumbar supports, helping to stabilize passengers and minimize secondary injuries.
Once the vehicle comes to a complete stop, sensors trigger the system to unlock the doors, allowing rescue efforts to begin.
Whether by regulation or in practice, this automatic unlock only disengages the lock—it does not physically open the door. Someone still needs to pull the handle from inside or outside, as auto-opening could pose new dangers in unpredictable crash environments, an automotive engineer told 36Kr.
Airbags must be replaced after deployment. According to another engineer interviewed by 36Kr, replacing ten airbags in an economy car costs about RMB 10,000 (USD 1,400), since the entire system, including wiring, must be reinstalled and recalibrated.
Airbag activation itself is a delicate balance. If they fail to deploy in a major crash, passengers are left unprotected. If they deploy during a minor collision, they can obstruct the driver’s view or cause secondary injuries by ejecting loose items. As a result, automakers treat airbag calibration with extreme caution.
When a crash is not severe enough to trigger airbag deployment, the occupants are typically conscious and able to unlock the doors themselves. In such cases, the automatic unlocking sequence is unnecessary.
This system—linking automatic door unlocking to airbag activation—has been repeatedly validated across the global automotive sector. So why do some accidents still result in doors that cannot be opened? Based on both theory and practice, there are two main explanations.
Redundancy is crucial
The first scenario arises when the automatic lock-unlock mechanism fails to function properly. For the system to work, the vehicle’s power supply, control module, and wiring must all remain intact. In a severe collision, any of these components can be damaged, disabling the entire locking system.
To mitigate this risk, automakers design redundant systems. For example, door locks may draw power from both the main high-voltage battery and a smaller auxiliary battery, with separate wiring paths. If the front section of the vehicle is destroyed, the rear system can still function, and vice versa. However, redundancy also increases manufacturing costs.
Some vehicles add a third, independent circuit for the door locks. Each of the four doors connects to a dedicated power source, often located beneath the second-row seats. This setup provides an additional safeguard: even if both the main and auxiliary batteries fail, the independent power source may still operate.
Even with triple redundancy, no system is entirely fail-safe, one engineer explained. But if an impact is strong enough to deform the structure beneath the second-row seats, rescuers will likely face far greater challenges than a jammed door.
Some automakers also include mechanical emergency mechanisms. In these systems, a physical lever triggers the unlock when the collision sensor sends a signal. As another engineer noted, not every manufacturer fully trusts electronics alone—when cost allows, they often include a mechanical backup.
Mechanical systems remain indispensable
The second scenario occurs when the doors are unlocked but still cannot be opened.
Because unlocking is only half the process, releasing the latch requires a functional handle. Traditional mechanical handles connect to the latch via cables or rods, allowing rescuers to open the door by pulling.
Many modern vehicles, including the Xiaomi SU7, now use electronic handles. At the product launch, Xiaomi founder Lei Jun highlighted the car’s semi-concealed handle design, which features a touch button inside the recess that activates a motor to open the door. This setup eliminates the physical cable connection entirely.
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To open such a door, the button, wiring, and motor must all remain intact—any damage breaks the chain. The more electronic components involved, the greater the risk of failure during an emergency.
An engineer told 36Kr that most passenger vehicles can reach top speeds above 180 kilometers per hour. To ensure the doors remain sealed at high speeds, automakers design the latch and seals to be extremely tight.
With an electronic handle, if the motor fails, the latch will not release, no matter how hard rescuers pull, the engineer said. By contrast, external mechanical handles can often still open the door from outside as long as they remain physically attached.
For vehicles with electronic handles both inside and out, there is usually one final safeguard: a mechanical release for the driver’s interior handle.
In most models, this handle is not electronically controlled and opens the door directly when pulled. If trapped inside, occupants can use a window breaker to shatter the driver’s window, then pull the mechanical handle to escape.
If the door frame is only slightly deformed, a strong pull can still work, an engineer added. Mechanical handles remain the last line of safety.
Consumers can check whether a car has a mechanical handle by seeing if the handle can be pulled outward rather than just pressed or touched.
In late September, China’s Ministry of Industry and Information Technology released a draft of proposed national safety standards for automobile door handles for public comment. The draft stipulates that all vehicles must include both internal and external physical handle mechanisms. Once enacted, mechanical exterior handles will become mandatory across all models.
Still, if a crash is severe enough to deform the entire door structure, even the best design may not help. Ultimately, the foundation of safety remains simple: obey traffic laws and drive responsibly.
After years of prioritizing futuristic aesthetics and aerodynamic optimization, NEV makers appear to be refocusing on what matters most: safety. The evolution of the door handle may be just the beginning. Going forward, both automakers and consumers are likely to scrutinize every detail that affects vehicle safety.
KrASIA Connection features translated and adapted content that was originally published by 36Kr. This article was written by Xu Caiyu for 36Kr.