IIHS Worried About Rear Seat Passengers After Lackluster Small Car Testing

Matt Posky
by Matt Posky

Following the introduction of an updated version of its moderate overlap crash test, the Insurance Institute for Highway Safety (IIHS) has reported that five of the most popular small cars sold in the United States had failed to receive a “Good” rating due to simulated injuries sustained among rear passengers.

This is something the group pointed out last December, noting that it would be upgrading testing protocols to address its own mounting concerns that rearward safety had not kept pace. The IIHS had already issued a study in 2019 noting disparities in chest injuries sustained by children and adults situated in the back seat. However, even this came from earlier data that had been compiled in 2014.

While the IIHS noted that all passengers had seen additional safety measures implemented over the years and that structural intrusions were less of an issue for those in the back, it suggested that forward-facing airbags and seat-belt force limiters could further mitigate injuries.

This year, the group noted that midsize SUVs had fallen short in terms of backseat safety and has followed up by saying the same is true of small cars.

From the IIHS:

To encourage manufacturers to improve rear-seat protection, the updated test adds a dummy in the back seat behind the driver. The driver dummy is the size of an average adult man. The rear dummy represents a small woman or 12-year-old child. IIHS researchers also developed new metrics that focus on the injuries most frequently seen in back-seat passengers.
For a vehicle to earn a good rating, there can’t be an excessive risk of injury to the head, neck, chest, abdomen or thigh, as recorded by the second-row dummy. The dummy should remain correctly positioned during the crash without sliding forward beneath the lap belt, and the head should remain a safe distance from the front seatback and the rest of the vehicle interior. A pressure sensor on the rear dummy’s torso is used to check whether the shoulder belt is too high, which can make the restraint system less effective.
As in the original test, the structure of the occupant compartment must maintain adequate survival space for the driver, and measurements taken from the driver dummy shouldn’t show an excessive risk of injuries.

All five vehicles (MY 2022-2023) tested showcased “Good” levels of protection for the simulated driver. But none managed to achieve the same for the dummy seated in the back.

The Kia Forte, Nissan Sentra, and Subaru Crosstrek showcased “moderate or high risk of head, neck or chest injuries” and received a “Poor” rating overall as a result. Though all vehicles tested saw the smaller dummy slipping beneath the safety restraints and forcing the belt to slide up onto soft tissue.

That fact meant that the comparably better test performance seen from the Honda Civic and Toyota Corolla still yielded an “Acceptable” rating overall, with rear-occupant safety dinging what could have been higher marks. Still, none of the vehicles ended up with anything other than a “Poor” assessment for rear passenger restraints and kinematics.

“These results highlight one of the key reasons that we updated our moderate overlap front crash test,” said IIHS President David Harkey. “In all the small cars we tested, the rear dummy ‘submarined’ under the seat belt, causing the lap belt to ride up onto the abdomen and increasing the risk of internal injuries.”

While vehicular safety has improved immensely over the years, and we’re certainly interested in seeing that trend continue, there have been consequences of adding equipment. If you haven’t driven a compact vehicle from a couple of decades ago, there’s a noteworthy difference in size. Your author’s resident backup beater is a seemingly unkillable 2000 Toyota Corolla. It’s a science experiment, kept around just to see how long an old car can survive with only the most basic home maintenance. But it also serves as a lesson in automotive history.

Parking my 2,500-pound Toyota next to its modern equivalent shows just how bloated today’s vehicles have become. A brand-new Corolla weighs roughly 3,000 pounds and one doesn't need to break out the measuring tape to see it's appreciably larger in every single dimension.

The older model would likely fare worse in any collision, however, and lacks numerous amenities that are now considered mandatory by the industry. Chucking on more standard equipment has real potential to yield a better vehicle than what came before. But it also adds weight and helps manufacturers rationalize higher price tags — neither of which are ideal when consumers are being lambasted by the economy, roads seem more chewed up than ever before, and governments remain obsessive about maximizing fuel economy figures.

Eternally shifting the goalpost likewise helps the IIHS rationalize its continued existence. Though that’s the whole point of safety entities. There will never be a day when the IIHS decides vehicles have achieved perfection and opts to disband. Whether funded by insurance agencies or the government, safety regulation is always about addressing changes made by manufacturers and trying to achieve higher standards. New targets are always made when the old goals are met.

Ultimately, some improvement to the seat belt probably won’t be forcing total redesigns. But adding frontal airbags for occupants situated in the back might, especially in smaller vehicles with tight back seats. That could prove costly in the long run and make these lower-priced options less financially feasible. Of course, nobody wants to be subjecting their own children to unnecessary risks.

It’s a delicate balance. But, with fatal accidents having risen over the last few years, I’m constantly of the mind that many safety advocates and government regulators are looking in the wrong place. When the IIHS started addressing how modern headlights were blinding oncoming traffic, it seemed they hit the nail on the head. Though the group has failed to showcase the same amount of concern in regard to distracting infotainment systems, lackluster outward visibility, and advanced driving aids that can lull motorists into complacency. These are issues that, if addressed properly, might help avoid accidents altogether and bring down the number of annual wrecks.

But that’s not to suggest physical restraints couldn’t use some additional polish. Two things can be true simultaneously and we just want to ensure that drivers are given the best chance possible to make it to their destination unscathed.

[Images: IIHS]

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Matt Posky
Matt Posky

A staunch consumer advocate tracking industry trends and regulation. Before joining TTAC, Matt spent a decade working for marketing and research firms based in NYC. Clients included several of the world’s largest automakers, global tire brands, and aftermarket part suppliers. Dissatisfied with the corporate world and resentful of having to wear suits everyday, he pivoted to writing about cars. Since then, that man has become an ardent supporter of the right-to-repair movement, been interviewed on the auto industry by national radio broadcasts, driven more rental cars than anyone ever should, participated in amateur rallying events, and received the requisite minimum training as sanctioned by the SCCA. Handy with a wrench, Matt grew up surrounded by Detroit auto workers and managed to get a pizza delivery job before he was legally eligible. He later found himself driving box trucks through Manhattan, guaranteeing future sympathy for actual truckers. He continues to conduct research pertaining to the automotive sector as an independent contractor and has since moved back to his native Michigan, closer to where the cars are born. A contrarian, Matt claims to prefer understeer — stating that front and all-wheel drive vehicles cater best to his driving style.

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  • SPPPP SPPPP on May 15, 2023

    Frontal airbags for rear seat passengers would be a huge, massive engineering challenge. Every front seat would have to be redesigned to include an explosive charge right behind the driver's spine, and the armor to protect the driver from the resulting explosion. In addition, all seat reclining mechanisms and sliding mechanisms would have to be reinforced to withstand both the explosive force of the airbag and the impact of the rear seat passenger. (In fact, front seats probably already should be stronger than they are, according to a different IIHS study. https://www.montlick.com/montlick-blog/auto-accidents/3503-unbuckled-rear-seat-passengers-may-kill-front-seat-passengers)

    • See 2 previous
    • SPPPP SPPPP on May 15, 2023

      They might be able to inflate from the roof, but I don't think they would be effective without the structure of the front seats being involved. FWIW, I don't think side airbags work too well with windows open. I mean, if front-facing airbags can deploy from the roof, why not do it for the driver and front passenger as well? As for the fate of glass roofs, well, now you're impacting people's quality of life. Like making your kid wear a helmet every time they go for a walk ... do you want to make every trip worse just in case of the few bad things that *could* happen?

  • ToolGuy ToolGuy on May 16, 2023

    "Small Cars Suck"

    Source: Big 3, 1973

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  • Leonard Ostrander Plants don't unionize. People do, and yes, of course the workers should organize.
  • Jalop1991 Here's something EVangelists don't want to talk about, and why range is important: battery warranties, by industry standard, specify that nothing's wrong with the battery, and they won't replace it, as long as it is able to carry 70% or more of its specified capacity.So you need a lot of day 1 capacity so that down the road, when you're at 70% capacity with a "fully functioning, no problem" car, you're not stuck in used Nissan Leaf territory."Nothing to see here, move along."There's also the question of whether any factory battery warranty survives past the original new car owner. So it's prudent of any second owner to ask that question specifically, and absent any direct written warranty, assume that the second and subsequent owners own any battery problems that may arise.And given that the batteries are a HUGE expense, much more so than an ICE, such exposure is equally huge."Nothing to see here, move along."
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