Auto Service World
Feature   April 1, 2007   by Auto Service World

Moulded Bumpers Smooth, Stylish, and Ineffective, says Insurance Body

Moulded bumpers have received a failing grade in repair costs from the U.S.-based Insurance Institute for Highway Safety, which points squarely at the lack of standard bumper height as a major shortcoming.

In testing, only three midsize cars among 17–namely the Mitsubishi Galant, Toyota Camry, and Mazda 6–withstood four bumper tests with $1,500 U.S. damage or less in each test. Some cars sustained more than $4,500 in damage in just one of the four tests, and two cars rang up more than $9,000 total damage.

“Our tests measure how well bumpers protect cars from damage in everyday bumps,” says institute president Adrian Lund. “The whole purpose of bumpers is to keep damage away from headlights, hoods, and other parts that are expensive to repair, but this purpose was accomplished in only two of the 68 tests we conducted. In the rest, what we found is that bumpers aren’t up to the job.”

The new tests reflect the kinds of front and rear impacts that are common in the real world. Insurance claims in the U.S. of $4,500 or less for damage in these crashes total more than $6 billion each year.

The institute began conducting low-speed crash tests at 5 mph into a flat barrier in 1969. These tests led to the first federal bumper rules for cars, which required the bumpers to resist damage in impacts up to 5 mph. These requirements eventually were rolled back by the Reagan Administration in 1982, but recent research shows that some of the most costly low-speed crash damage occurs when vehicle bumpers slide under or over each other. This happens because the bumpers on colliding vehicles don’t line up, and braking before the impact can lower the front end of a striking vehicle just before it hits the other vehicle. Under- and override often result in damage to vehicle grilles, headlights, hoods, and fenders.

The Institute’s old flat-barrier tests were good indicators of bumper strength, but they didn’t assess over- or under-ride. Vehicles with comparatively good performances in these tests still sustained costly damage in real collisions. The Institute’s new series of tests comes closer to matching the damage that occurs in real-world impacts. Each car is run into a barrier designed to mimic the design of a car bumper. The steel barrier’s plastic absorber and flexible cover simulate typical cars’ energy absorbers and plastic bumper covers.

“We don’t want the automakers to change bumper heights just to get good performance in our tests,” Lund explains. “We want car bumpers to resist damage in real crashes with other cars as well as with higher-riding SUVs and pickups, so we revamped our tests to reflect such crashes.”

Many bumpers aren’t high enough or tall enough to take the hit in crashes between cars and SUVs or pickups. Even when bumpers line up with those on other vehicles reasonably well, many don’t stay engaged with the other bumpers in collisions or can’t absorb the energy of even a minor bump. This means expensive car body parts sustain most of the damage.

The full-front test represents a common situation where a car hits the rear of another vehicle that has stopped in traffic. In this test, the bumpers on only four cars–the Galant, Camry, Mazda 6, and Saturn Aura–stayed engaged with the test barrier instead of going under or over it. The result was lower damage totals than other cars in the same test. Damage to three of these four cars totalled less than $1,000, and the Aura was the only car among the 17 tested to limit damage to the bumper itself in the full-front test without getting into the car body.

“This test should be easy if cars had well-designed bumpers, because the energy of the crash can be spread across the whole front of the car. Instead, some cars sustained more damage in this test than the other three,” Lund points out. The Nissan Maxima, Pontiac G6, and Volkswagen Passat each sustained more than $4,500 damage in the full-front test. Costly repairs were required to the cars’ hoods, fenders, and headlights as well as air conditioning condensers.

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