Think all bumpers are created equal? Think again.

Tests conducted by the Insurance Institute for Highway Safety (IIHS) show that the difference in bumper height between cars and sport utility vehicles leads to costly accident repairs after even low-speed crashes.

Car bumpers are required by a federal standard to match up reasonably well. However, no such requirements apply to SUVs, and some of these vehicles don't even have bumpers. So mismatches in crashes are increasing, and the resulting repair costs from low-speed collisions are escalating. The Institute's new series of 10 mph front-into-rear crash tests demonstrates this mismatch problem.

Test Methods
The tests involved five pairs of vehicles, each composed of a car and a midsize SUV from the same manufacturer. The pairs included a Ford Taurus and Explorer, a Chevrolet Malibu and TrailBlazer, a Dodge Stratus and Jeep Grand Cherokee (both DaimlerChrysler products), a Nissan Altima and Murano, and a Volvo S40 and XC90.

In the tests, a car going 10 mph struck the back of its paired SUV, which was stopped. Then the configuration was reversed, with the SUV striking the back of its paired car. Results of these low-speed impacts varied widely, from a total of about $1,250 damage in one test to more than $6,000 damage to the paired vehicles in two other tests.

In some cases, the low-speed crash damage included major leaks from broken radiators. In real-world collisions like these, the motorists couldn't even drive away. If they did, their vehicles could overheat and the engines could be permanently damaged. So in addition to paying for costly repairs, the drivers would face the aggravation of having to get their vehicles towed.

Fords Do Better
In both car-into-SUV and SUV-into-car tests, the vehicles with the lowest repair costs, by far, were the Fords. This is almost entirely because the bumpers on the two Fords match up better than the bumpers on the other vehicles. Virtually none of the damage from the Explorer-into-Taurus impact was apparent during a cursory inspection after the crash. The damage was hidden underneath the plastic bumper covers.

The other pairs of vehicles sustained much more damage than the Fords, mostly because their bumpers don't line up. The bumpers on some vehicle pairs completely bypassed each other in the tests.

Adrian Lund, the Institute's Chief Operating Officer, says this was a pattern, explaining that, "when there was underride and override between the car and SUV bumpers, that's when we saw a lot more expensive-to-repair damage than most people would associate with a 10 mph impact. Bumps at this speed involving Volvos and DaimlerChryslers produced more than $6,000 damage to the two vehicles."

Most of the repair costs from these tests weren't because a heavy SUV inflicted damage on a lighter car. The SUVs also sustained expensive damage. Even when one SUV hit another SUV, the damage was costly.

Toyota RAV4 strikes RAV4
The Institute conducted another 10 mph crash test to show that the problem isn't confined to crashes between cars and SUVs. In this impact, the front of a Toyota RAV4, a small SUV, hit the back of another RAV4, producing more damage than in any of the car-into-SUV or SUV-into-car crashes.

"When one RAV4 struck the other, it didn't engage the rear bumper because this SUV doesn't have a rear bumper. Instead the striking RAV4 hit the spare tire mounted on the tailgate," Lund says. "This spare tire was the 'antibumper." It didn't absorb any energy. It didn't prevent any damage. In fact, it caused most of the damage to both vehicles. The spare damaged the hood and grille of the striking RAV4. It also crushed the tailgate on the struck RAV4."

Rules apply to cars only, not SUVs
A federal standard specifies a zone on cars for bumper protection extending from 16 to 20 inches off the ground. This means car bumpers line up reasonably well. When two cars collide at low speeds, the bumpers are more likely to engage. Then they have a chance to absorb energy and prevent damage. But no such bumper requirements apply to SUVs, pickup trucks, or minivans, so these vehicles often have flimsier bumpers than cars. The heights of their bumpers often are different from the mandated heights for car bumpers.

As SUVs have proliferated in recent years, so has bumper mismatch. Now SUVs account for about one of every four-passenger vehicles sold in the United States. Together pickups and SUVs account for almost half.

Federal bumper rule changes needed
Because SUVs don't have to meet the bumper requirements established for cars, automakers are free to equip these vehicles with minimal bumpers or, like the rear of the RAV4, no bumper at all. If an SUV does have bumpers, they aren't required to line up with those on cars.

Lund believes the federal rules should be changed to make SUVs and cars more compatible. He says the manufacturers already are working on this for high-speed collisions, and they ought to be doing it for low-speed impacts like these tests. SUVs can have the same utility they do today and still be equipped with decent bumper systems that extend down to where they match up with those on cars.

"Until then, motorists who bump into mismatched vehicles, even at very low speeds, will have no choice but to open their wallets," Lund said.

Referred from: (http://www.consumeraffairs.com)