Size or Speed? IIHS Study Examines Safety Between Models

Matt Posky
by Matt Posky

With the rate of fatal automotive accidents having spiked dramatically in recent years, just about everyone has been theorizing why. While there still seems to be a level of willful ignorance surrounding how modern infotainment systems and driving aids create more opportunities to be distracted behind the wheel, most outlets tracking safety seem to have come to the realization that size disparities between vehicles play an important factor in crash survivability.

The Insurance Institute for Highway Safety (IIHS) recently published a list of the models with the highest death rate per million vehicles registered. Its takeaway seems to be that the uptick in fatalities could be attributed to smaller vehicles and powerful models that encourage aggressive driving.

“Overall, newer vehicles are much safer than those of the past,” said Chuck Farmer, IIHS vice president of research and statistical services, who calculated the death rates. “But, unfortunately, there are still major differences in the levels of protection that various models provide. There was also a spike in speeding-related fatalities during the pandemic, which may help explain why we find so many muscle cars among the worst performers for this period.”

The vehicle that saw the most per capita deaths (2018-2021) was the Mitsubishi Mirage G4. The model had an unfortunate, commanding lead and was followed by the hatchback variant.

However, vehicle mass likely wasn’t the singular factor here. Because the little Mitsubishi was pursued by the Dodge Challenger. From there, it’s another batch of microscopic cars before we get into a mix of domestic performance vehicles, small commuters, and the occasional midsize sedan.

From the IIHS:

The average driver death rate for all 2020 and equivalent models increased to 38 deaths per million registered vehicle years, compared with 36 for 2017 models. That’s a further increase from a low of 28 for 2011 models following a steady decline since the 1970s. The rise is consistent with a larger number of U.S. traffic fatalities over the four-year period covered by this study, compared with the previous one. From 2018 to 2021 there were 155,136 fatalities, compared with 147,599 from 2015 to 2018.
Minicars had the highest driver death rates, averaging 153 deaths per million registered vehicle years. Very large luxury cars had the lowest, averaging only 4 deaths. In contrast, very large pickups had the highest other-driver death rates, averaging 121 deaths, while small sports cars had the fewest other-driver deaths, averaging only 11 per million registered vehicle years.
The average other-driver death rate for all 2020 and equivalent models was 53 deaths per million registered vehicle years. There are more other-driver fatalities than driver fatalities because these newer models are more crashworthy than many of their crash counterparts, which come from the wider U.S. fleet, made up of mostly older vehicles.

But, if size and speed are really the biggest factors, one might wonder why the Mazda MX-5 and Mini Cooper aren’t on the list. The Mirage may be the smallest vehicle presently available on our market but it’s only a couple inches shorter than they are and boasts none of their fun-loving attitude.

The IIHS faulted Dodge, Ford, and Chevrolet for marketing their vehicles in a manner that encourages aggressive driving. But they’re not the only performance models that exist on our market and don’t appear to have contributed to fatalities pertaining to other drivers at anywhere near the frequency of large pickups and SUVs. While we could assume domestic muscle simply has a tendency to slap into more guardrails than people, there could be another explanation. Overall size and powertrain zestiness may not be the only contributing factors to how much carnage a vehicle can create. The overall shape of an automobile remains relevant.

We already know that tall vehicles with a flat face result in lower survivability rates for struck pedestrians. Cars boasting a lower hood are more likely to see their victim rolling over the top, while the shape of larger pickups and SUVs has a tendency to pull a body beneath the wheels after the initial strike.

But that same phenomenon may also apply when automobiles crash into each other. Many of the vehicles that performed poorly in terms of per capita fatalities were comparatively lightweight with lower belt lines. It may also be worth noting that convertible sports cars tended to perform worse than their hardtop brethren. This sizing/shape disparity is a speculative theory. But one that’s supported by the laws of nature and something yours truly has long believed contributes to increases in fatal accidents. I would argue this dramatically impacts safety overall and helps explain why the IIHS noted that pickups had the highest instance of “other-driver death rates” and sporting vehicles boasted the lowest.

The concept was drilled into your author’s head as a youth while attending motorcycle safety courses. One of the first things they teach you is how much more vulnerable you are than a motorist surrounded by a steel cage. But the concept carries over to individuals driving smaller automobiles, as physics won’t be on their side should they go head-to-head with a much larger vehicle that’s tall enough for the grille to ride up during a wreck.

But there are outliers in the IIHS data. While the vehicles appearing to boast the highest levels of occupant safety tended to be pickups and larger SUVs, names like Subaru Outback, Lexus ES 350, and even Toyota C-HR also made the list.

Meanwhile, vehicles boasting the highest rate of “other-driver deaths” were all large pickups. But the rest of the field was varied and included a staggering amount of Stellantis products. There were also a few vehicles that carried over from the driver-death list — including the Kia Rio, Kia Optima, Kia Forte, Dodge Charger, and Nissan Altima.

This might indicate that there are a few models boasting lower-than-average safety or perhaps cater to a clientele that’s not terribly interested in safe driving.

The IIHS also speculated that crash avoidance systems and other advanced driving aids played a factor by noting they were standard equipment on most luxury vehicles that tended to perform better overall. It’s certainly a possibility. But the outlet seems to have a vested interest in shaping the insurance landscape and has long championed these systems without much criticism. We’d argue there’s a broad disparity in how they function between models and suggest that certain systems may actually do more harm than good while others (e.g. blind spot monitoring) seem to be a net positive.

Data also didn’t support that power and speed were enough to do a model in all by itself. The IIHS noted that the Audi A4 and Mercedes-Benz E-Class offered nearly as much horsepower as some of the worst performers on the list. But it claimed that the image of premium luxury vehicles differed from the American muscle cars and that it could make all the difference.

“The explanation may lie in the image of the vehicles. Luxury cars are associated with ease and comfort,” reads the report. “In contrast, the muscle cars on this list are associated with the early days of the drag strip, as illustrated by features like racing stripes, hood scoops and spoilers, and that seems to influence how they’re driven.”

“Marketing for the Dodge Charger HEMI, for example, focuses on its ‘ground-shaking’ power, its acceleration ‘bolting off the line’ and its ‘racing-inspired” high-performance brakes, while the Chevrolet Camaro promises buyers the ability to “dominate on the daily’ with an ‘extreme track performance package’ and the Ford Mustang offers ‘adrenaline chasers’ the power to ‘keep ahead of the pack.’”

“These two lists illustrate some of the intangibles of crash risk,” said IIHS President David Harkey. “We can measure horsepower and weight and test for crashworthiness. However, the deadly record of these muscle cars suggests that their history and marketing may be encouraging more aggressive driving.”

It’s plausible. But the premise feels over-hyped when the vehicles in question are mixed in with a slew of economy cars boasting the same level of risk to the occupants. Most muscle cars also failed to represent an elevated risk to other drivers vs large pickups and SUVs. That seems important, especially if the drivers' oversized vehicles represent a larger risk to their fellow motorists.

But you'll have to make up your own mind on the biggest contributing factors and are welcome to browse the full study to that end. While the IIHS is definitely keen to blame muscle cars, it doesn't seem quite that simple.

[Images: Mitsubishi; 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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6 of 29 comments
  • Theflyersfan Theflyersfan on Jul 19, 2023

    A coworker of mine just got a brand new Traverse. I was kidding around with her saying I'll park next to her so her car can keep mine in the shade! But that picture sums up the size differences out there. I like small cars. I don't want to lug around thousands of pounds of extra car that I don't need. But the roof of my car doesn't reach the bottom of her driver's side window. And this isn't as tall as the taller HD trucks, Suburbans, Tundras, etc. Am I putting myself in a potential death trap given many of the cars out there are over double the weight of the Mazda? Probably. I probably stand a better chance against a tree compared to a Ram or Suburban given a stationary object won't have higher bumpers that will override mine. But it's like a motorcycle - you take the chance every time you head out. Just wear a helmet (or buckle up in the car) and keep your head on a swivel because odds are, the person in the jacked-up truck doesn't see you down there and isn't paying attention.

    And the Kias on the list - in my part of the country here, Forte and Rio drivers are starting to morph into Altima drivers level of aggressive and awful. Second (or third) owner Fusion drivers as well. And their cars do match with at least one dead exterior light, tape somewhere on the car, blasted off clearcoat on the paint, and a stench from said Kia (or Nissan or Ford) that would have a drug dog at the airport miles away getting a little antsy.

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    • FreedMike FreedMike on Jul 19, 2023

      And we don't think of a Traverse as necessarily being all that big. Wow.

      Couple of weeks ago, I spotted a late-80s FWD DeVille in a parking lot - a huge car by the standards of the day - and it looked puny next to all the three row CUVs.

      BTW, concur on Rio drivers - and, unfortunately, that includes my kid, who drives like a maniac.

  • TheEndlessEnigma TheEndlessEnigma on Jul 19, 2023

    The problem isn't small cars, the problem is over-large and over-weight trucks and SUV's (which are essentially the same thing).

    • Colin Colin on Jul 19, 2023

      Its also people modify their trucks / suv's by lifting which aims their bumpers higher at the windshield of other cars. Then add 400lbs of armored bumpers and well, its punisher time. I think a lot of the problem is those stupid bumpers and illegal lifts. The lift has the added benefit of enhancing the headlights (or are they tactical lights?) ability to blind the driver while you move in for the kill.

  • Bob65688581 We bought zillions of German cars, despite knowing about WWII slave labor. Refusing to buy something for ideological reasons is foolish.Both the US and the EU have imposed tariffs, so the playing field is level. I'll buy the best price/quality, regardless of nationality.Another interesting question would be "Would you buy one of the many new European moderate-price EVs?" but of course they aren't sold here.Third interesting question: "Why won't Stellantis sell its best products in America?"
  • Freshblather No. Worried there will be malicious executable code built into the cars motherboard that could disable the Chinese cars in the event of hostilities between the west and China.
  • Bd2 Absolutely not - do not want to support a fascist, totalitarian regime.
  • SCE to AUX The original Capri was beautiful. The abomination from the 90s was no Capri, and neither is this.It looks good, but too similar to a Polestar. And what's with the whacked price?
  • Rover Sig Absolutely not. Ever.