Flimsy bumpers fail

Even when bumpers engage in collisions without under- and overriding each other, the components may fail. Bumper bars may not be strong enough. Energy-absorbing materials (foam or something similar) may not be up to the job.

        The Audi A4 was the best performer among the luxury cars in both front and rear full-width tests. Equipped with components that work like shock absorbers to dissipate crash energy before it can damage the car body, the A4 sustained less than $1,000 damage in each test.

        “It isn’t coincidental that the A4 is the only luxury car among the 11 we tested with this kind of absorbers, which usually outperform other methods of managing the energy of crashes. If the A4 had longer bumpers for protection in corner impacts, it probably would have been the best performer among this lot of cars instead of second to the Saab 9-3,” Nolan says. A bonus of stroking energy absorbers is that they don’t have to be replaced after every impact. They can absorb energy again in subsequent collisions.

Gap in regulations

Federal rules don’t cover bumpers on minivans, pickups, or SUVs. The barrier the Institute uses to test bumpers is set 16 to 18 inches off the ground, in keeping with a federal rule that specifies a zone for car bumpers 16 to 20 inches from the ground. The idea is to ensure that car bumpers line up reasonably well so they engage each other in collisions, allowing them to absorb crash energy.

        But there’s a problem in collisions with other vehicles because the rule that applies to cars doesn’t cover minivans, pickup trucks, or SUVs. The bumpers on these vehicles often are much higher off the ground, failing to line up with those on cars at all.

        For example, the bumper on the Infiniti G35 luxury car is much lower than the one on the Infiniti FX35. An Institute test involving these vehicles indicates that in a collision into the back of the SUV, the G35 would slide right under the bumper system, especially if the driver were braking hard, which would cause the front end of the car to dip.

        “Infiniti equipped this car with a bumper that wouldn’t prevent damage in a minor collision with the same company’s SUV,” Nolan points out. “This makes no sense, and it won’t be solved by tinkering with the bumpers on cars alone. The federal rules have to be applied to minivans, pickups, and SUVs too. Only then will we start to see good bumper match-up in collisions at low speeds.”

Sky-high parts prices

Even when bumper systems perform adequately to minimize damage in low-speed collisions, the damage that does occur still can empty a consumer’s wallet because of the price of the parts needed to restore the vehicle. In the rear full-width test, for example, damage to the A4 was confined to the bumper cover. However, the cost of the cover alone approaches $600. Then it has to be attached to the car body and painted to match.

        Headlights were damaged in 15 of the 22 frontal tests the Institute conducted, 8 corner impacts and 7 full-width ones. It cost $847 for the G35's replacement headlight and $1,046 for the one on the Lexus ES, not counting installation charges.

        “If an automaker is going to charge this much for a headlight, it ought to do a better job of shielding such an expensive part from damage in a minor bump,” Nolan suggested.

Put luxury in bumpers also

It wouldn’t take much for automakers to reduce the cost of repairing the damage that occurs in low-speed collisions. Nolan pointed to three main things automakers already know how to do and could be doing:

        1. Make the bumper bars longer so they protect headlights and other critical and costly equipment at the corners of vehicles. The bars all could be as wide as those on the Volvo S60, which was the only car that limited damage in the front corner test to the bumper cover alone. The rest of the luxury cars sustained damage to fenders and other body parts.

        2. Make bumpers taller so they engage the bumpers on higher riding SUVs and pickup trucks instead of underriding them, even during emergency braking.

        3. Don’t sacrifice function for style by mounting bumpers too close to the car body. This makes for a sleek look, but it doesn’t leave much room for absorbing crash energy. Mount bumper bars farther out and use the available space under a bumper cover for energy absorption.

        Without these design changes, “we can’t say anything good about the bumpers on these luxury cars,” Nolan concluded. “There’s nothing exemplary about even the best performer, the Saab 9-3. It simply avoided racking up the most damage in any single test and ended up coming out the best of a mediocre lot.”