Bad bumpers are the norm. The Institute has been testing bumpers for 38 years, publishing comparative information about how well they resist damage in low-speed impacts. With few exceptions, the bumpers on most vehicles have allowed way too much damage in crashes at 5 mph or slower. Now the Institute has revamped the bumper test program, introducing a new series of impacts that more closely resemble the kinds of vehicle-to-vehicle collisions that occur in the real world.
The main finding is that bumpers still are bad. There are numerous problems. The bumpers on colliding vehicles often don't line up geometrically so they don't engage to begin with. Even if they do, they often don't stay engaged during impact so they don't absorb crash energy. Another problem is that the bumpers on many vehicles aren't wide enough to protect the corners. And once vehicle damage occurs in low-speed collisions, consumers pay sky high prices for many of the damaged parts that have to be replaced.
Only 3 midsize cars among 17 the Institute recently tested —the Mitsubishi Galant, Toyota Camry, and Mazda 6 — withstood 4 bumper tests with $1,500 damage or less in each test. Some cars sustained more than $4,500 damage in just 1 of the 4 tests, and 2 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 2 of the 68 tests we conducted. In the rest, what we found is that bumpers aren't up to the job."
The new bumper tests aren't like the ones the Institute used to conduct into a flat barrier. These led to the first federal bumper rules, which required damage resistance in impacts up to 5 mph. But the rules eventually were rolled back by the Reagan Administration in 1982.
New tests mimic vehicle-to-vehicle collisions
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 underride. Vehicles with comparatively good performances in these tests still sustained costly damage in real collisions. The Institute's new series of four bumper 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.
The four tests include front and rear full-width impacts at 6 mph and front and rear corner impacts at 3 mph. The test barrier is 18 inches off the ground in the full-width tests and 16 inches off the ground in the corner impacts. These different heights are designed to drive bumper improvements and lead to better protection from damage in a range of real-world crashes. In developmental tests, these configurations produced the kinds and amounts of damage that commonly result from actual low-speed collisions.
"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. In particular, we want to encourage automakers to use bumpers with energy-absorbing bars that extend farther into vehicle corners to reduce damage to headlights and other critical and costly equipment. We want car bumpers that are taller so they engage the bumpers on SUVs and pickups instead of underriding them."
Bumper performance in low-speed crash tests: vehicle repair costs
|1981 Ford Escort
Note: Sonata repair costs reflect reduced parts pricing, effective January 2007.
Bumpers still are poorly designed
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 cars with the lowest repair bills after our new bumper tests still sustained much more damage than they should have in some of the tests," Lund says. "We got crumpled grilles and headlights plus buckled fenders in impacts at speeds equivalent to an average person walking fast."
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 3 of these 4 cars totaled 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.
"A big problem is that the Maxima, G6, and Passat underrode the barrier," Lund says. "Our research shows that this is also what happens in many real-world crashes. The bumper bar on the Passat, which is supposed to take the hit and absorb the energy in the crash test, wasn't even damaged. The car's grille, hood, fenders, and headlights were damaged instead."
Results were similar in the rear tests. Reducing the damage required the bumpers to engage the barrier and absorb the energy of the impact, but this mostly didn't happen. A relatively good performer in the full-rear test was the Hyundai Sonata. Its bumper did engage the barrier, and most of the damage was limited to the bumper (minor repair of the rear body panel also was required). Total damage came to $739.
Good bumper performance requires not only engagement with the test barrier but also strength sufficient to absorb the energy of a low-speed crash. Hyundai engineers strengthened the Sonata's bumper after learning about the Institute's upcoming series of new tests.
In contrast to the Sonata, the bumpers on other cars did slide under the barrier, and damage was much worse. The Chrysler Sebring, Nissan Altima, Volkswagen Jetta, and AURA sustained more than $3,000 damage apiece in the full-rear test.
"The bumpers on the Altima and Sebring didn't stay engaged with the barrier at all. The bumper bars on these two cars escaped unscathed," Lund says, "which means they didn't do what they're supposed to do. They didn't absorb any of the crash energy. Making sure bumper bars line up better to engage other bumpers in crashes is the first step toward preventing damage in the kinds of low-speed collisions our tests represent."
All parts don't cost the same
The total cost to fix damage after a minor bump is influenced by more than the extent of the damage. Another issue is that the price of the same part — a fender, hood, or other part — varies from vehicle to vehicle. For example, the Toyota Camry needed a lot of repairs after the full-rear test, including repair of fenders and body panels. The trunk floor and unibody structure had to be straightened out. However, the total cost of these repairs was a relatively low $1,480, in part because Camry parts don't cost as much as those on some other cars.
What's your time worth?
Besides the cost of damage in low-speed collisions, there's the aggravation. Most people want to avoid having to get repair estimates, arrange for repairs, and then do without their cars while they're in the shop.
"Much of this could be avoided if car bumpers were better at doing their job of resisting damage," Lund says. "But instead we have to put up with so much damage that it can take days or weeks to fix."
Styling influences performance
The performances of three cars show how front-end styling can influence the amount and cost of damage that occurs in low-speed crashes. The AURA, G6, and Malibu are all General Motors cars built on the same platform. So they're similar cars, but the cost of repairing them isn't the same. The G6's front end slopes more, and its front bumper bar is lower than those on the other two cars. The result was that the G6's bumper didn't stay engaged with the barrier during the full-width test. Instead it slid down and under the barrier. Damage including a crumpled hood, buckled fenders, broken headlights, and a bent air conditioning condenser cost four times as much to fix as damage to the Malibu or AURA. On top of this, the G6's front unibody had to be straightened out. The bill for all of this topped $4,500.
Lund explains that automakers "don't have to sacrifice car style for function. There's empty space under the covers of the bumpers on all three of these cars that could be used to put in energy-absorbing materials. Engineers also could make bumper bars taller and extend them farther out to the corners of the car without changing the front-end styling."
Corners left unprotected
The bars that are part of most bumper systems often fail to extend far enough into vehicle corners. The result is a failure to protect vital and costly parts such as lights and fenders.
"Headlight assemblies on all 17 cars were damaged in the corner impacts," Lund points out. "The lights essentially served as the bumpers on these cars because the bumpers themselves didn't provide any protection. There's no excuse for this. Safety equipment like headlights shouldn't be damaged in impacts at a mere 3 mph."
The width of the bumper bars was a factor in rear-corner tests too. While the Honda Accord sustained about $600 in damage in this test, damage to the Mazda 6 totaled twice as much. The difference was that the Accord's bumper bar is nearly 80 percent as wide as the car, while the Mazda 6's is only 58 percent as wide.
Vintage Ford shows how
Bumpers used to do a better job of resisting damage in minor impacts. Under federal requirements that were in effect until 1982, car bumpers had to keep damage away from vehicle safety equipment and sheet metal parts in collisions at speeds up to 5 mph. Even damage to the bumpers themselves was limited. But since 1982 the test speed under the federal standard has been cut in half. It's now 2.5 mph, and unlimited damage is allowed to vehicles' bumper systems.
To demonstrate how this rollback has affected bumper performance, the Institute got a 1981 Ford Escort, which met the old requirements, and put it through a new battery of front and rear bumper tests. Comparison of this car's performance with those of new cars is dramatic.
For one thing, the bumpers on the Escort extend out from the car body to help keep the headlights, grille, and sheet metal away from the energy of impacts. Behind the bumper bar, the Escort has components that work like shock absorbers to dissipate the energy of an impact before it can damage the car body — and these components can absorb energy again in subsequent collisions, while the crushable energy absorbers that are components of most modern car bumpers can't. They have to be replaced after each minor impact.
"The Escort aced the 3 mph corner tests with zero damage," Lund says. "In the full-front test at 6 mph, the $86 worth of damage was limited to the bumper itself. There was more damage in the full-rear test but still only $383. This is much lower than for the 17 new cars we tested. The best performer among the new cars sustained 10 times as much damage as the Escort in the same 4 tests."
New series of bumper tests:
Test barrier mimics vehicle bumper
The Institute has revamped the bumper crash tests it has conducted since 1969 into a flat barrier or pole. The new series of tests do a better job of reflecting real vehicle-to-vehicle collisions and the kinds and amounts of damage they cause. Instead of a flat barrier, the Institute now uses a test barrier that's shaped like a bumper on a real vehicle and has a deformable surface. Vehicles strike this barrier in four tests — full-front and full-rear at 6 mph plus front and rear corner impacts at 3 mph. In the front and rear full-width crash tests the barrier is set 18 inches off the ground, and in the corner impacts the distance is 16 inches. These measurements are in keeping with federal rules that specify a zone for car bumpers 16 to 20 inches from the ground. The Institute's test barrier is 4 inches tall, or about the same as many real car bumpers. Results indicate not only the strength of car bumpers but also how well they engage, and then stay engaged with, the bumpers on other vehicles with which they collide.
Federal rules require car bumpers to match up reasonably well with the bumpers on other cars, but no such rules apply to pickup trucks or SUVs so the bumpers on these vehicles often don't match up with those on cars. They're higher off the ground. The result is mismatch in collisions so that one vehicle overrides the other (see "Huge cost of bumper mismatch: Cars and SUVs don't line up in crashes," Sept. 13, 2004). The energy of these collisions may go right past the bumpers and into the vehicle bodies, causing damage. Or the bumpers may engage but then slide off each other instead of staying engaged. Either way the result is expensive car body damage. Of the 17 cars the Institute recently tested, 13 underrode the barrier in full-front impacts. Six, including 5 of the same 13 cars, underrode the barrier in the rear impact. The 5 cars with underride in both front and rear tests were the Chevrolet Malibu, Chrysler Sebring, Honda Accord, Nissan Altima, and Volkswagen Jetta.
Best ever bumpers:
Ford's 1981 Escort sustains fraction of the damage to new cars
"Automakers could equip new cars with bumpers that are every bit as good as the 1981 Ford Escort's, but they choose not to," says Institute president Adrian Lund, referring to the best car the Institute ever tested in low-speed impacts. This car sustained no damage at all in 5 mph crash tests into a flat barrier and a pole (see "Same cars, earlier models: 1981 Ford Escort still best a 5 mph," Aug. 30, 1997). When the Institute recently subjected a similar 1981 Escort to a new series of tests into a barrier that mimics the bumper on another vehicle, the result was much the same — no damage in two tests and minimal damage in two others. In contrast the best performer among 17 new cars the Institute recently tested is the Mitsubishi Galant, which sustained almost 10 times as much damage as the Escort. The worst performers sustained almost 20 times as much damage as the Escort.
Style vs. function
The bumper covers on most modern cars, like the Nissan Maxima, fit snugly against the vehicle body. It's a stylish look, but it doesn't help when it comes to resisting damage in low-speed collisions because there's not much room for absorbing crash energy before it reaches the car body and damages it. Plus the emphasis on a sleek look encourages designers to shorten the width of the bumper bars that extend across the fronts and backs of vehicles to absorb crash energy. The results are bumpers that don't do a good job of resisting damage. For example, the Maxima sustained $1,732 damage in the Institute's front-corner test alone and more than $9,000 total damage in 4 bumper tests. The Pontiac G6 sustained $1,183 damage in the corner test and a whopping $4,588 in the full-front test (shown here). Total damage to the G6 in 4 front and rear bumper tests approached $9,000. In almost every test of all 17 cars, damage extended beyond the bumper. In many tests, safety equipment was destroyed.
It doesn't have to be this way. Automakers learned decades ago how to equip cars with bumpers that bump. For example, the 1981 Ford Escort sustained no damage at all in the front-corner test and $469 damage in the same 4 tests in which the Maxima and G6 sustained almost 20 times as much damage.
Parts prices drive up costs
The point of a bumper is to minimize damage, and some bumpers do a better job than others. However, the amount of damage from a crash isn't the only contributor to repair costs. Identical damage to two separate cars can result in different repair bills. The difference is the price of the parts. If the trunk lids on the Chrysler Sebring (shown) and Volkswagen Jetta sustain damage beyond repair, for example, it will cost more to fix the Sebring because its lid costs more than $800 compared with $250 for the Jetta's. On the other hand, the Sebring's headlight is relatively inexpensive at $169 compared with $571 for the same part on the Mazda 6.
Safety components may be damaged:
Repairing cosmetic parts is enough of an aggravation
without having to worry about vehicle safety too
A very bad outcome of a fender-bender is when you can't even drive your car afterward. First you have to arrange for a tow, maybe because a headlight was shattered in a late-night bump and it wouldn't be safe to drive without it. This happens too often because bumpers don't do a good job of protecting lights.
The headlights on all 17 cars the Institute tested sustained damage in front-corner tests. The headlights on 7 cars were damaged in the full-front tests too. So the aggravation associated with minor collisions isn't confined to paying high repair costs. There also may be the headache of finding your way home.