The New Face of Vehicle Fires in an Era of Evolving Powertrains

William addressed the issue of electric retractable door handles as a serious concern at AEM’s Automotive Innovation Day 2024 Sequel last year. 
 

“We are now entering an era where what we don’t know far outweighs what we do.”
Are EV fires really less dangerous than internal-combustion fires? Many statistics suggest so - but William S. Lerner’s answer is unequivocal. When he first came to Korea shortly after the Incheon underground parking-lot fire, he carried early warnings. Now he returns with far more: new data, dozens of real-world incident investigations, the perspective gained from FBI infrastructure-protection work, and his prior involvement with ISO and SAE. And his conclusion is stark: the question is no longer whether a fire occurs. The real issue is how different powertrains, design choices, and modern “upgrades” amplify the danger when a fire does break out. This is not the old binary debate of “EVs are safe vs unsafe.”
Hidden 48-volt mild-hybrid batteries positioned beside gasoline engines, lithium-ion cells placed inside the cabin, manual door releases buried under carpeting, electric retractable handles, eVTOLs and helicopters, underground garages and airport hangars, heat that rises above 2,500°C, and invisible toxic vapor clouds - these unfamiliar combinations are accumulating every day, generating entirely new types of disaster scenarios. The term “vehicle fire” simply no longer means what it used to. Lerner shows this clearly, using actual vehicle models and real case studies.
In the interview, he walks through BMW’s X5 and X7, Jeep’s Wrangler 4xe, Lucid, Tesla, the new Mercedes-Benz E-Class, and even eVTOL aircraft - explaining how different machines and powertrains converge at the same incident scene to create “dual events.” A single lithium-ion cell becomes a 20-meter projectile, a hidden lever beneath the carpet determines whether a trapped occupant or a responder lives or dies, and the invisible residue left after a fire can cause secondary contamination that harms hospital staff, children, and building infrastructure long after the flames are gone. These are details the public rarely sees, but they define the new reality of vehicle-related emergencies.
And his proposed solutions are not about “thicker gear” or more equipment. They involve redesigning vehicles as information systems: morse-code-style emergency lights that remain invisible until the moment of an accident, tiny 3mm LEDs embedded in the shark fin, hidden QR codes inside the glass dot-matrix pattern, and a signaling framework that can warn responders, drivers, and bystanders within seconds.
This interview is a necessary - and at times uncomfortable - conversation about how evolving vehicle types, diverse powertrains, and design upgrades are reshaping risk in real incidents, and what we must understand and change to keep people safe at the moment when seconds decide everything.

by Sang Min Han_han@autoelectronics.co.kr
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Welcome back, William! Since we last saw each other in Korea, after the Mercedes apartment complex fire event in Incheon, what has changed? 
William        Almost everything has. It has been a remarkable time, concerning new data, events, automotive changes, and most importantly public health and safety. First responder’s gear no longer fully protects them, or those interacting with them.


You’ve been introduced many times before, but for our readers, could you briefly explain what you do today?
William        I educate first responders and police about the new challenges that EVs, Hybrids, and e-mobility bring. My work also covers land, sea, air and rail applications. I have developed technologies for immediate information for everyone at the scene, including passengers who have no protection from the initial highly toxic lithium-ion off gassing. The idea is to get everyone to a safe area as soon as possible. Information always leads to better results. My work now includes eVTOLs, which are electric vertical takeoff and landing aircraft. Many have electrically retractable handles. They take everything I have been studying and doing for the past fifteen years, and put the battery event over my head if I am airside, with no means to suppress the event. And, if the aircraft has a lithium-ion event, the pilot and passengers can’t get out, and no first responder can get in. I love aviation, especially electrified aviation, because it presents the most extreme challenges, and the most opportunities to learn, evolve and change my strategies and perspectives. And, you simply can’t smash the side glass of a helicopter in a hard landing like a vehicle. The ‘’windows and windshield” are not glass, and require specific tools to cut through them.


So please update us as we head into 2026.
William        Concerning the vehicles: The BMW X5 in 2024 introduced a mild hybrid battery next to the engine, unmarked, below a black plastic cover.  Below that, is another black cover with a small embossed area that is black. I was trying to understand where the placement of the mild hybrid, 48 Volt, 22 Kilowatt hour battery was. For the readers unfamiliar with battery specs, what that means in general terms, is that it is the same size and voltage as many e-bike batteries. Roughly one hundred and ten individual cells are located in the pack. The cells are called 18650s, and are found in rechargeable flashlights, power banks and many other battery products.
The vehicle has no badging changes, meaning that a first responder, or owner may be completely unaware that there is a battery in the engine compartment, close to the heat producing gasoline engine. So, why does this matter? It absolutely changes everything for passengers, first responders, those near the vehicle, and the infrastructure. Incheon unfortunately taught us very valuable lessons, and provided real world data. So, if the X5, X7 or X3 with this engine had an event, first responders would treat the vehicle as a gasoline / diesel fire event. That is a known event, since it has been all they knew prior to 2010 when the Nissan Leaf was introduced. Now, you may have a dual event. A gasoline event and a battery event. The event may start with the battery and spread to the gasoline engine components, or it may be a gasoline engine fire event that may spread to the battery. Concerning first responders, we now know that these cells can shoot sixty five feet, seven inches from the pack. How, and why? When these cells go into thermal runaway, and the first responders spray cold water on them for example, as a standard and typical response, it agitates the cells. Imagine a scorching hot pan on your cooktop. Now imagine throwing very cold water in it. It produces a violent reaction due to the extreme temperature difference. We have seen this time and time again. Now think of the force to shoot an individual cell sixty five feet. Now, understand that is like shooting hot bullets in unknown directions, which may bounce off the hood of the car, a wall for example, which can injure a first responder, or anyone in the area. First responder’s gear is not bullet proof, and those in the area do not have protective gear on, including facepieces to protect them. The BMW completely changed my training and understanding about how what seems to be the identical vehicle, is far from identical during an event. 



The 2024 BMW X5 houses its mild-hybrid battery right next to the engine. On the right is the Mercedes-Benz E-Class mild-hybrid lithium battery, which is essentially an e-bike - spec unit. 


  Why would the lithium-ion battery be near the gasoline engine? Why wouldn't they put it in a different location? 
William        Excellent question. Audi in 2017 released the A8  which was designed from the start to have a mild hybrid lithium-ion battery and a gasoline engine. Since this was an entirely new model, they chose the location, at the rear of the vehicle. Concerning the placement of the lithium-ion battery in the BMW, it is there because there was available space. They had to add the battery without redesigning the entire vehicle. It was a ''practical" and cost effective choice.
Two weeks ago, I went to a Mercedes dealership to understand where the mild hybrid lithium-ion battery was located in the all new E-Class. Mercedes chose to conceal their mild hybrid lithium battery in the engine compartment, as close to the front passenger area as possible, below the windshield, below two unmarked plastic covers. Why? I am truly perplexed by the choice.


So, what does this mean for the public, owners and first responders?
William        If there is a lithium-ion event, it could send the toxic emissions right into the cabin presenting potentially grave dangers for passengers and first responders alike. Remember, that is inches away from the fresh air intake to the passenger compartment. If the battery “event” occurs while the car is in motion, the toxic emissions can create a highly toxic situation for the passengers, and perhaps a confined vapor cloud explosion (CVCE) as we have seen multiple times with the Jeep Wrangler 4xe. What was a gasoline fire is now a dual event as discussed, but with the E-Class you have added a direct path of the vapor cloud and it’s unknown toxins into the passenger cabin during an event. We know that batteries inside the passenger cabin create unique dangers. As disclosed the 4xe has the battery in the cabin under the rear seat and the Lucid Air also has their individual cells inside the cabin area. During an event they have been witnessed to shoot though the glass roof upwards in a distance of forty feet.
 

What actually happens when incidents like this occur?
William        Now let’s discuss the event. We used to be concerned with the actual fire. Clearly it was the most obvious, and we learned quickly that it was not the average burn temperature of a gasoline vehicle, it was now a 4,000-5,000 degree fire. Once you change one thing, everything changes. So, the elevated temperatures do not match the first responders gear. Their bunker gear withstands roughly 1,550 F, their hood 780F and their facepiece 350F. So how do you deal with 5,000 degree heat, when at temperatures above 350 F? You can no longer see, or breathe non toxic air from your canister? You can’t. Science. The burning object, and the gear don’t match. A few months ago we finally got the data that I was waiting for. The first responder’s gear does not match the temperatures, nor the toxins produced by the lithium-ion fires.
How is this possible? What is burning during a lithium-ion event penetrates the semi-breathable gear. The mix of known toxins include formaldehyde, cyanide, and probably hundreds or thousands of other toxins, but what is currently most alarming is cobalt. These miniscule cobalt particles, breach the gear, and can enter the bloodstream. Once a metallic compound like cobalt enters the bloodstream it can not be removed. Compounding this, is that there is no diagnosis for lithium-ion vapor emissions exposure, no treatment, and no cure. The symptoms get treated, and treated and treated again as the patient's health unfortunately declines.
I recently did a training at a hospital, so first responders could get the information from emergency room personnel. Unfortunately, proof of what I knew was verified by Ulster University in the UK. They have a brilliant team of dedicated researchers, working tirelessly to understand and provide data. The burning lithium-ion batteries leave a residue of toxins post fire.
Common sense, right? Absolutely. Just like the residue from cigarette smoke. I have studied first responder gear and fire blankets, independently and with many departments, and there is no way to effectively clean them. That is known. So, what UK Ulster finally, and definitively tracked was secondary contamination. They tracked emergency room personnel who treated first responders post lithium-ion events. Four staff members became ill with the same symptoms as the affected first responders. So, how did this happen?
he remaining residue from their hands, gear, skin migrated to the emergency room staff. Many are still out on sick leave. A corollary I use is poison ivy. We all know how that can be transmitted from person to person, but what many do not know is that it can live on surfaces for months, and once touched produce the same symptoms. This holds true for infrastructure. Will a building ever be effectively decontaminated? Unclear. It did not happen in Incheon. Returning residents suffered from eye cloudiness issues to skin irritation issues. Many of the affected were children. So, once the lithium-ion residue from a vehicle fire enters the cabin, the residue will remain, in the areas that may not be possible to “clean”, like the air vents, under seat areas, roof headliner, etc. 
 


In October, a hybrid vehicle ‘exploded’ while charging in Izegem, Belgium. The entire rear wall of an apartment building was blown out, and six fire engines were deployed to extinguish the blaze. 


 
As EV fires increase and global powertrain options continue to diversify, how does this growing complexity affect real-world incident risk? 
William        We are in uncharted territory. Since more is unknown than known at this time, the latching on to “data” that has little merrit is the “EVs are X times less likely to catch fire.” True for pure EVs. However look around, most new vehicles have auxiliary lithium-ion batteries, mild hybrid batteries or are plug in hybrids. The ‘’data” used does not account for these variants. Remember a new 2010 Nissan Leaf which is a fully electric vehicle has a smaller battery than a gasoline powered large SUV with a mild hybrid or plug in hybrid battery. If the vehicle has any battery larger than a fully electric Nissan Leaf, it is put into my electric vehicle pool, based on the battery size. Why? It is a battery event, plus a gasoline event. The consequences at the scene are the same for the battery component, and are made worse by the gasoline components, and remember there may be 20 gallons of gasoline near a battery. That gasoline tank is no longer metal, but HDPE and will melt and spill all the contents of the tank on the ground at roughly 350 F, in a battery event that can produce heat up to 5,000F.


So, is it just the temperature of the fire that is the biggest problem now?
William        Sadly, no. I used to think it was the temperature, however data has proved that the most dangerous part of a lithium-ion event is the first seconds to minutes before the fire. That is the pre-ignition event that produces the vapor cloud that is the most injurious part to humans. We all know to get as far away from a fire as possible and as quickly as possible, but don’t understand what that white cloud of smoke is. We use the assumption concerning burning wood. You see the smoke then the fire, however the lithium-ion ‘’smoke” is the most deadly part of the event. 



The 2025 Armada (Patrol) is almost identical to the 2025 QX80. The key difference is that the QX80 has electric retractable door handles, while the Armada does not. 


 
That is very alarming to say the least. Are there new issues concerning passenger safety and first responder safety that are not lithium-ion based?
William        Unfortunately, yes. Electric retractable door handles. I discussed those at the event AEM held last year, but did not have the hard, real world data that I got last month. I feel like I am a detective, living in a snow globe of particles, following what I believe to be true, and waiting for the hard data based on research or documented incidents. Compounding that is when you change one thing, it often changes everything, and I mean everything. So, back to retractable electric door handles.
The 2025 Amada (Patrol) is virtually identical to the 2025 QX80 from the side, at night or during the day from a distance.The difference that changes everything as we are learning? The QX80 has electric retractable door handles while the Armada does not. A rescue or exit when there is no power in a moderate to severe accident changes it all, especially in EVs like Teslas as we have seen. However, what may seem like an EV issue, is not that simple. These handles are found on gasoline, hybrid and plug in hybrid vehicles. And, some may simply be a touch to open, some pop out, and there is absolutely no uniformity of design or functionality. Unfortunately as I was explaining my work, this happened on October 1st 2025. The driver of a Tesla in a low speed accident could not get out, because he did not know where the manual emergency release button was, and the first responders could not get in. They could not open the doors to rescue him as the car was engulfed in flames. The driver burned to death, while he was struggling to get out. Tragic, gruesome and numbingly sad. 
However, that was just one of three events. The second involved a father and three children. The exact same thing happened, but fortunately one child survived. Then an event involving a driver who hit a tree, also burned alive because they could not get the door open to rescue him, and he could not get out. This is not uncommon, and I can trace these events back to a closed NTSB investigation in Texas where two occupants died for the same reasons. That was about ten years ago. The event was not initially blamed on the inability to exit the vehicle, it was blamed on the driver using Autopilot and carelessly, and foolishly moving to the passenger seat. They found two bodies in the vehicle, neither in the driver’s seat. After years passed, the NTSB finally released the findings. The driver was in the driver’s seat, when the vehicle crashed, but he could not find the manual release, slid over to exit on the passenger’s side, where he could not find a manual release and burned alive in that seat.
Recently, the children of two Wisconsin families experienced a heartbreaking event. Neither the front passengers nor the rear seat passengers could exit the vehicle and burned alive. This event presented very unique findings. The rear doors lost power and the pull tabs to release the rear doors were located under the carpet. How could they know they were located in that position, when many of the owners are unaware of the location of the manual release in the front? That led me to realize that renters of vehicles with electric door handles probably do not know where the manual release is, nor do rear seat riders in Ubers or Grab vehicles. 
These electrically retractable door handles were introduced because they made the car look sleek and modern. The industry naturally has to constantly innovate to entice buyers to upgrade to new models. Theoretically I understand it. They are flush with the door, do not detract from the vehicle’s sleek beauty and do look modern, because traditional door handles have been around for many decades. But once you change from manual to electric, it affects every part of the user experience. 


That’s truly shocking and heartbreaking.
William        Let’s dissect an ‘’event.” If there was an accident with a potential fire (understand that an EV can go from inert to being fully engulfed in flames in four seconds) you want to get out as soon as possible, and if you are injured and can’t get out, you want the first responders to get in to help you as soon as possible. With some electric door handles, that adds time to the entry and exit and can end your life. Think of it this way: If there is a fire in a theatre, you see the emergency exits and run. When you get to the door, there is a manual push bar, and you are out of the building losing no time to figure out the door. Simple, and easy. Now make the theater door electrically controlled. If the power to the building is compromised due to the fire, the door won’t work unless you find the manual release. Does that make sense? We have seen nightclubs, with hundreds dead, because of locked or malfunctioning exit doors.
Tesla has one system, which is not the same as other manufacturers. The BMW 7 Series is designed to have its handles pop out during an event. They can only do that if there is power. The Mercedes E-Class has handles that can be manually opened from the outside if the doors are not locked. That is an odd plan, when in the USA they are designed to all automatically lock at a low speed as you start to drive, like most modern vehicles. So, let’s say that there is an event involving the Mercedes and there is no power to allow the door handles to extend out. They have designed a push / pull sequence.
What you have to do is push the left area inwards, which will tilt the flush door handle out on the other side, extending a small portion of the door handle, so you can now attempt to pull it open. Attempt? Yes. First responders wear gloves. This can not be done with them on. If the Mercedes is an EV, the flames will come from under the drivers door, passenger door, and rear doors. The flames are by their hands, and the temperatures can be as high as 5,000 F. So, can they take off their gloves? Absolutely not in an event involving any fire. If there is any damage from the accident that affected the sheet metal in a minor way, that can cause the flush door handles not to function. What has been done is potentially adding time, confusion and complexity to a rescue, when every nano-second counts.These handles affect the occupants and those trying to rescue them.
When I educate and train first responders and police officers (who have no protection at any scene) I always start by saying; “My role is to get you home at the end of your shift in the same physical and mental condition you left for work in.” First responders suffer from PTSD and these new events are taking a huge toll on their mental health. For the record, I do not, nor will I ever take a cent from any first responder. Trust is everything, and I am not selling my services or any product to them.


 
So what can be done to provide the vital information first responders, vehicle owners and the public need?
William        My work gives those in the area a Morse Code of bright lights, patterns or strobes, which are unseen during normal vehicle operations. My work covers unlimited applications. For example, the B Post may have an “invisible” QR code that back illuminates during an event. That shows the information using light, and they will know when they get to the vehicle it will have specific rescue information. Y
ou may assume that the emergency response guides are publicly available and instantly accessible to first responders at all times, right? Sadly no. In the USA for example, they are not required by law to be in a public, private or governmental repository. Mercedes and BMW do not make any emergency response guides available for their passenger cars in the USA available.
When I bought my new car in 2024, I went to the governmental portal and the emergency response guide was based on a model not sold in the USA. I have a gasoline vehicle but the response guide was for a plug in hybrid which is not sold in the USA. And, In the USA no side or front badging is required to show what the vehicle propulsion is. First responders are left without the immediate tools they need to understand what they are dealing with. That is why I developed and patented my technologies. I will soon be receiving my 21st patent. Many more are applications have been filed



The LED face of the Volkswagen Atlas.



Can you please explain how your work gives the public and first responders the vital information they need?
William        The work signifies what the car is, the propulsion, the battery size, is it being charged? state of charge (which matters), the number of occupants inside, high voltage disconnect, low voltage disconnect, electric retractable door handles (or not), battery size, charger location, mild hybrid battery size and location, location of auxiliary lithium ion battery, and other vital information. Including the battery pack architecture. All of this information is available instantly. Meaning, if an event is likely or just happened the visual indicators illuminate, show where the scannable QR code or codes are located, send a wireless message to the first responders, owners wearables, like a tablet or smart watch, and can send out an acoustical warning to tell those in the area to get as far away as possible. It can also alert the garage which the vehicle may be parked in. That would have helped in Incheon.
In the most extreme examples where an EV can go from inert to being fully engulfed in flames in four seconds, it still works. The visual Morse Code can relay the message in 3.99 seconds. Concerning aviation, and garages, it tells the team to evacuate the area and if possible move other lithium ion vehicles or helicopters. I am in the information business. Information always leads to better decisions and results. Remember it is one ambulance per patient, and you can have  a combination of passengers and first responders injured at the scene. The more you know the safer it is for all.
The lighting can be upward, to the side, on the ground, be path or general lighting. First responders need light to work in the dark, whether it is an underground parking facility or tunnel. 
These events require specific tactics, which are vehicle specific. Lucid cells shoot up through the glass roof, because they are in the cabin space, the Jeep has created many documented CVCEs (Confined Vapor Cloud Explosion) and the Tesla has shot hot cells fifty feet horizontally from the bottom of the vehicle, because many unmarked vehicles were designed to “assist first responders.” It is a natural path to explore and change the battery architecture. That is a given, and evolution. However, the changes which affect everyone must be known. What also must be known is if the vehicle is charging and connected to a charger and if it is a “do not drive it charge vehicle” under a manufacturer's discovery of an issue they are trying to remedy.


Modern vehicles now feature far more lighting - does this create any issues with identification?
William        Mid-range to luxury vehicles are introducing illuminated front grilles, decorative light strips across the rear of the vehicle and illuminated badges, which are even on lower range Volkswagens. On the inside you find driver adjustable 64 color decorative illuminated cabins. We all know how bright an iPhone's rear flashlight is, and what I am asking for is LEDs that are 3 millimeters in diameter (or 4/32nds of an inch) in diameter. These small, hidden LEDs are the same as drone anti-collision lights and can be seen for three statute miles by FAA regulations. They can be invisibility set in the sharks fin, the upper panels between the side doors, on top of the windshield and rear window, and repeat in the grille. The simplest and most cost-effective for them is the sharks fin. It has a 360 degree viewing area, is at the highest part of the vehicle and will most likely be intact unless there is a rollover event. The cost of these LEDs? For high quality Cree versions? Seven cents. The cost to embed a vehicle specific QR code where the sun dots are inside of the cabin by the rear view mirror? Nothing, just a call to the glass manufacturer, excluding my royalties for using my patented work, of course! 


 

AEM(오토모티브일렉트로닉스매거진)

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