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.