The Insurance Institute for Highway Safety (IIHS), a nonprofit organization supported by US auto insurers, has released results for a new crash test that more severely tests a car’s structure. Called the small overlap frontal crash test, 25 percent of a car’s front end on the driver’s side strikes a five-foot tall rigid barrier at 64 km/h. The test replicates the damage done in a collision with another vehicle or an object like a tree or utility pole. Shockingly, the Mercedes-Benz C-Class, Lexus IS 250/350, Audi A4, and Lexus ES350 all earned a poor rating. Acura TSX, BMW 3 Series, Lincoln MKZ and VW CC earned marginal ratings. Rated as the safest in this test: the Acura TL and Volvo S60. Volvo and Honda are the two carmakers that have facilities to do full-scale vehicle-to-vehicle crash tests, and this no doubt helped them develop the safer structures.
Here’s more from the IIHS: The key to protection in any crash is a strong safety cage that resists deformation to maintain survival space for occupants. Then vehicle restraint systems can do their jobs to cushion and protect people.
Most modern cars have safety cages built to withstand head-on collisions and moderate overlap frontal crashes with little deformation. At the same time, crush zones help manage crash energy to reduce forces on the occupant compartment. The main crush-zone structures are concentrated in the middle 50 percent of the front end. When a crash involves these structures, the occupant compartment is protected from intrusion, and front airbags and safety belts can effectively restrain and protect occupants.
Small overlap crashes are a different story. These crashes primarily affect a car’s outer edges, which aren’t well protected by the crush-zone structures. Crash forces go directly into the front wheel, suspension system and firewall. It is not uncommon for the wheel to be forced rearward into the footwell, contributing to even more intrusion in the occupant compartment and resulting in serious leg and foot injuries. To provide effective protection in small overlap crashes, the safety cage needs to resist crash forces that aren’t tempered by crush-zone structures. Widening these front-end structures also would help.
“These are severe crashes, and our new test reflects that,” Institute President Adrian Lund says. “Most automakers design their vehicles to ace our moderate overlap frontal test and NHTSA’s full-width frontal test, but the problem of small overlap crashes hasn’t been addressed. We hope our new rating program will change that.”
Luxury and near-luxury cars were first to the test because these models typically get advanced safety features sooner than other vehicles, Lund says.
Vehicle test performance varied widely in the three rating categories: structure, restraints and kinematics, and dummy injury measures. The majority of the cars had lots of occupant compartment intrusion, which contributed to their low overall rating. Occupant motion varied greatly as well, with the dummy missing the airbag in some cases. In others, safety belts allowed the dummy’s head and torso to move too far forward toward the A-pillar. Forces measured on the dummy indicated high risk of injury for the legs and feet in several vehicles.
Structurally, the Volvo S60 was best. With only a few inches of intrusion, the occupant compartment looked much the same as it did in a moderate overlap test. Reinforcement of the S60’s upper rails and a steel cross member below the instrument panel helped to keep the safety cage intact. Volvo has performed similar small overlap tests as part of its vehicle safety development process since the late 1980s, taking the results into account when designing new models.
The Lexus IS had up to 10 times as much occupant compartment intrusion as the Volvo. In the IS test, the car’s A-pillar bent and the footwell collapsed as the left front wheel and tire were forced rearward. The dummy’s left foot was entrapped by intruding structure, and its right foot was wedged beneath the brake pedal. Entrapment also was an issue with the Mercedes C-Class. The dummy’s right foot ended up wedged beneath the brake pedal as the left front wheel was forced rearward during the crash.
When the Volkswagen CC was put to the test, the driver door was sheared off its hinges. The CC is the first vehicle the Institute has ever evaluated to completely lose its door. An open door results in an automatic downgrade to poor for restraints and kinematics, as also was the case with the Audi A4, whose door opened but remained attached to the car. Doors should stay closed in a crash to keep people from being partially or completely ejected from vehicles.
Disclaimer: The comments uploaded on this site do not necessarily represent or reflect the views of management and owner of Cebudailynews. We reserve the right to exclude comments that we deem to be inconsistent with our editorial standards.
