Your EV’s Frunk Can Be Dangerous, But Only If You’re Very Silly With It

Now that there are more EVs on the market, a lot more cars have frunks. That got us thinking—do frunks pose a safety risk that we haven’t seen before? In the event of a front-on crash, what happens? Does a frunk’s cargo effect crash safety?

Frunks are more common in the EV era, but they’re not a new invention. Historically, most cars had an engine under the hood, and that was it. Rear-engine cars with under-hood front storage have been around almost as long as modern cars have been on roads, but even when rear-engine models were at their peak number, they were the rare exceptions to the front-engine rule. Now that EVs have made the frunk virtually mainstream, it’s worth looking at it in more detail.

I decided to hit up a couple of industry agencies and a professional engineer for their opinions on the matter. I learned that, while frunks aren’t a major safety risk, you can still do some harm if you’re particularly reckless or stupid.

What’s the Difference?

The front of the vehicle is a critical piece of crash structure for protecting the occupants. The thing about frunks is that they’re a large volume inside the front of the vehicle that is effectively uncontrolled. In traditional front-engined vehicles, this isn’t the case. Even though these cars have a big heavy engine up front, the vehicle is engineered to deal with this in a crash. Often, engine mounts and surrounding structures are designed to allow the engine to break free and move in such a way that it doesn’t present a risk to the people inside the vehicle.

In a frunk, though, the automaker has no idea what you’ve put in there or how it’s going to behave in an accident. Adding to the risk is that the frunk is generally directly in front of the driver and passenger. Thus, you might think that in a front-end accident, anything in the frunk could have an effect on the crash safety of the vehicle.

It’s easy to imagine a head-on collision turning fiery if you stored a big can of gas in the frunk, for example. But what would happen if you put a big heavy metal anvil in your frunk? Or a toolbox, or lots of lengths of steel rebar? These were just a few scenarios I gamed out in my head. An anvil or rods of rebar would surely pose a serious penetration risk to the cabin, right? And yet nobody seems to be talking about this!

My first port of call was the Insurance Institute for Highway Safety (IIHS). This independent organization investigates crash safety with the aim of reducing deaths, injuries, and property damage from motor vehicle accidents. The agency was first founded by three major insurance associations. As you might imagine, reducing negative outcomes from car crashes would have serious benefits for insurers. So, if anyone was concerned about this, surely it would be the IIHS, right?

The response from the IIHS ultimately suggested that it doesn’t see frunk safety as a big deal. “Carrying cargo in the frunk doesn’t raise any specific safety concerns,” said Joe Young, director of media relations for IIHS. Young did note, however, that it’s still not wise to put just anything upfront. “That said, placing something that is explosive or flammable in that space could present unique risks, as it would in a trunk during a severe rear impact,” he continued. Young noted that at this time, the IIHS does not place any objects in a frunk during crash tests.

Next, I wrote to the NHTSA. At the time of writing, the agency was yet to provide a specific response on the matter. However, they later came through with an update.

Electric vehicles currently undergo the same Federal Motor Vehicle Safety Standard crash tests as internal combustion engine vehicles. No passenger vehicle test requires placing cargo in the front or rear trunks expressly to test how that cargo would affect frontal or rear crash test results. NHTSA’s frontal crash tests of EVs thus far have been conducted with empty frunks.

Thankfully, though, at The Autopian, we’re well connected. I was able to reach out to an engineer who has worked on crash safety for decades. They were able to explain a lot about frunks and crash safety, and give me an insight into general industry thinking around this matter.

The Engineer’s View

Engineers routinely use a method called Design Failure Mode and Effect Analysis. This helps classify risks in terms of their likelihood of occurrence and the consequences if they occur. Naturally, it makes sense that crash safety engineers focus on highly likely scenarios with highly dangerous outcomes first, before they look at edge cases. For example, it’s important to make sure that passengers can safely survive common front-end or side-overlap crashes. That’s relevant every time an owner gets in their vehicle to go for a drive. We have real-world data that tell us what kind of crashes are most common and most dangerous, and automakers look to sort those out first.

Crashes where cargo in the trunk played a role simply aren’t popping up in the datasets.  That means our hypothetical frunk danger scenarios just aren’t as relevant, statistically speaking. Frunk utilization isn’t anywhere near 100%, for a start. In many cases, it’s pretty low. On some vehicles, some owners never even use their frunk, because it’s too small or inconvenient.

Even on vehicles with big frunks, like the F-150 Lightning, owners probably don’t use them every single time they drive. And, when they are using the trunk, it’s an even smaller percentage of the time that they’d even consider putting something potentially dangerous in there. And for a lot of frunks, their very design can inherently limit the potential danger. If you’ve got an EV with a tiny, cramped frunk, what are you going to put in there that’s so dangerous, anyway?

Fundamentally, in regular use, it seems that we aren’t seeing a lot of dangerous crashes where frunk cargo was involved. If we were, crash reports would have filtered through to agencies like the IIHS, and crash safety engineers would be working on mitigating these risks.

That’s not to say there’s zero risk in how you use a frunk. It’s entirely possible to put something dangerous in your frunk that could cause you great harm in the event of a crash.

For example, if you put a ton of jerry cans in your frunk, or a bunch of propane tanks, they’re probably going to cause an issue in the event of a bad accident. Of course, this is no different than if you had them in the trunk of your car, and your vehicle was hit from behind.

It’s also possible to interfere with the front crumple zones of your vehicle, but this is a very unlikely scenario. My contact explained that if you’re putting something in the frunk that is rigidly transferring loads into the vehicle structure, you’re going to have a problem. Otherwise, you’re probably going to be fine. For example, if you put a small toolbox in your frunk, that’s okay.

However, if you build a super-tough, super-rigid toolbox into your frunk that’s directly in contact with structural members, or bolted in, that could cause issues. It could add a lot of rigidity to the vehicle’s front structure, changing how it behaves in a crash. The front end of a vehicle is designed to dynamically crush to absorb energy in a crash. Often, at least over 2.5 feet (0.8 m) of dynamic crush space is desirable. If your toolbox or other cargo is rigidly interacting with the vehicle structure, it could prevent this happening. If that energy isn’t dissipated properly in a crash, outcomes for the vehicle occupants could be far worse.

Intrusion is also a risk, but perhaps an unlikely one. I wouldn’t go stacking lots of steel rebar in my frunk, for example. At least, not in a front-to-back orientation where it might skewer through the cabin in a crash. Any rigid item that can focus a great deal of load on a point could pierce through to the passenger cabin in a crash, and this would be highly dangerous to the occupants.

Hard, heavy objects can be dangerous cargo in general, but that’s not really specific to frunks. You wouldn’t want a small solid anvil bouncing around freely in your trunk, and it’s no different up front. Either way, it’s still preferable to having it in the passenger cabin, where it could become a missile that gives you a permanent brain injury. A larger, heavier anvil that fills the frunk space would likely be dangerous, given it could cause cabin intrusion in a crash. If you really had to move one, you’d be better off sticking it in a truck bed instead.

Ultimately, frunk safety isn’t that hard. Don’t chuck a bunch of flammable liquids or gas tanks in there. Don’t transport heavy, rigid building materials up there. And finally, don’t do anything that’s going to change the way the crash structure behaves. If you’re really having to shove in a big heavy toolbox to get it to fit, or you’re wedging in some steel beams right up against the frunk walls, you’re probably headed for trouble.

Don’t be silly out there, and you’ll be fine. Fill your frunk with prawns, not propane, and you’ll be safe out on the road. Stay milky out there, friends. Stay milky.

Image credits: Ford, BMW
Top graphic bomb image: Martin Bergsma/stock.adobe.com