By on June 21, 2011

Earlier this year, the German safety nuts at DEKRA and AutoBild ran rear-end crash tests on a pair of five-star-rated (Euro-NCAP) vehicles, and found that back seat occupants were at risk of severe spinal, head and pelvic injuries. Now, the dour Deutschlanders are back at it, as the ADAC has run tests showing that rear-seat passengers are also at disproportionate risk in front impacts, a far more common cause of traffic fatalities. And again, no government crash test standard requires testing of the rear-seat effects of frontal impacts.

On one level, this isn’t wildly surprising: other than side-impact airbags, rear passengers are basically protected only by a simple shoulder belt. And though rear passengers are farther from the actual crumple zone, the ADAC says the simplicity of rear-belt systems mean rear passengers can often come off worse in a frontal crash, noting

While stress-absorbing belt force limiters are commonplace in the front, they are a rarity in rear seat belt tensioners. Also most cars rear seatbelts don’t offer active-pull-back…

Because of the combination of simple rear seatbelts and no airbags, the ADAC’s crash tests (40 MPH frontal) show that rear-seat passengers exhibit far more frontward movement, resulting in more chest injuries, as well as more backwards motion, causing dangerous head impacts and whiplash.

Another problem: rear-seat headrests are often too inflexible and are placed too far from the passenger’s head, exacerbating head injuries during snap-back and rear-impacts. In one rear-impact example shown in the video above, the dummy’s head hits the top of the head rest and actually bounces upwards, driving the forehead into the car’s roof. Luckily for the typical rear-seat passenger, the danger demonstrated in these tests is largely limited to adult passengers, while children are typically safest in the back seat.

Had front-seat passengers suffered similar stress forces, the car in question would have received extremely poor crash test ratings… but because NCAP doesn’t test rear-seat impacts, these results aren’t part of the comforting star-rating system.

The good news: the ADAC tests show more sophisticated belt force limiters can have a major impact on rear-seat safety, so there’s no need to start filling the backs of front seats with airbags. Between this relatively minor upgrade and improved rear headrest geometries, the ADAC implies that manufacturers can address these rear-seat dangers at a relatively low cost. But until rear-seat safety is measured model-by-model by either a government crash test standard or a non-governmental body like the IIHS, car buyers should be aware that those comforting, comprehensive-sounding safety star ratings are no guarantee of back seat safety.

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14 Comments on “More Bad News On The Back Seat Safety Front...”

  • avatar

    Good report. I’d like to see some safety correlation to rear legroom and headroom numbers, which range from inadequate to bad joke for most cars.

    At 6’6″, I pay first attention to interior dimensions, and strongly prefer a car in which I can ‘sit behind myself’ as a driver and rear seat passenger. I need make no apologies to the passengers in my xB1, but its thin construction wouldn’t help much in a crash.

    Glad to see that a simple safety belt upgrade can help these tests substantially, rather than going the expensive airbag route straightaway.

    • 0 avatar

      The Porsche Panamera rear passenger cabin shape and size was strongly driven by your concerns. We all know how most people feel about its consequent looks. To steal a line from a Billy Crystal character, “It is better to look marvelous than to be marvelously safer and more comfortable”.

    • 0 avatar

      Ditto in my xB1 (2006.5) as well. I’ve never seen a car of any size with better rear-seat legroom… It’s hugely tainted my car-buying, as I’m now stuck in a position where no car offers anything close to the interior space and economy that I’m used to. And with a stick, the xB1 has a far sportier drive than looks possible from the exterior.

      However, an increasing bent toward safety has me starting to look elsewhere…

      • 0 avatar

        @Thinkin… I’m in the same boat with my xb1. I’m basing most of my research on IIHS data. The top contenders are the FiveHundred and an 2005 Avalon. I’ll miss my toaster when I sell it though. I always laugh when my girlfriend will scoot up in the passenger seat to make room for people in the back, and end up giving them limo-sized legroom.

  • avatar

    Of course they “say” its relatively easy; just a change here, a tweak there – oh it’s no big deal. EVERY safety imitative they say that.

    Nothing a few hundred pounds per car and a couple of extra thousand dollars per unit can’t solve. Of course this will require another 20 HP under the hood to drag the weight around and make those government MPG standards even harder to achieve but hey – at least we’ll be safe.

    Globally, cars have never been safety, injuries and deaths in the United States (at least) have statistically never been lower.

    Now who is going to save us from our government overlords and the safety police???

  • avatar
    Sam P

    This just in. You can’t legislate all danger out of the world. Live with it.

  • avatar

    Wow, very surprising that the IIHS doesn’t test rear passenger crash data. You would think the insurance companies would have a vested interest in the info, they are the ones that have to foot the bill if that guys head really does hit the roof.

    So how are we to know if Ford’s cool new rear seat-belt airbags are actually worth a crap?

  • avatar

    can’t disagree about the belt tensioners but there is a bit of BS in that test – just look at where the front seat is in such a small car – almost ahead of B pillar, about a foot of space between the rear knees and the seatback. Typically in such cars there is hardly any space between the front seatback and the rear knees. My shoulder would typically be well overlapped with the B pillar.

  • avatar

    My guess is that they don’t regulate rear seat safety because the injury rate is so much lower then the front seat. Real world data trumps crash tests.

  • avatar

    Whew…I’ll breathe easier knowing that the air I haul in my unused rear seat – and the air in the unused rear seats of 80% or more of other cars on the road – is benefiting from the protection of seat belt tensioners and headrests.

    The problem here is that rear seats have to accommodate the huge child safety seats of today: It’s uncertain if belt tensioners would cause injury to a child in a safety seat, and there’s the potential for headrests getting in the way of proper installation.

  • avatar
    Secret Hi5

    Flip the back seats around. Rear-facing back seats for all!

  • avatar

    Too bad I don’t speak German, but I have to wonder how having no front structure as well as seemingly having the front seat moved about as far forward as possible affected these tests. Can anyone say if that’s addressed in the audio?

    • 0 avatar

      Don’t worry not speaking German. The video says nothing on the questions you had.
      As a precautionary measure I’d suggest to replace all your cars by either roadsters (bonus: you might enjoy it), by trucks (preferably 2-seaters) or articulated trailers, as long as those issues are not resolved, industry-wide.

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