Being involved in a low-speed bumper-to-bumper accident can cost you big money depending on the car your drive. In fact, repairing a bumper on some cars costs as much as one-third of the vehicle's total value.

In a series of crash tests released in September 2008, the Insurance Institute for Highway Safety (IIHS) assessed how well the bumpers of 20 small car models protect your vehicle from damage in low-speed collisions. It found that many car bumpers are not designed to handle what should be a low-damage accident.

The worst performers were the Hyundai Elantra, Toyota Prius and Volkswagen Rabbit. These cars suffered anywhere from $1,000 to almost $5,000 in damages in low-speed accidents clocked at 6 miles per hour. The Elantra, which scored the worst of all, suffered roughly $4,954 in damages in a full-front bumper crash test. According to NADA Guides, the used car value of a 2007 Hyundai Elantra is $14,800. Therefore, the repair cost of this vehicle's bumper for a 2007 model could about 33 percent of its value (see chart below). On the opposite side of the spectrum, the Ford Focus performed the best. A full front-bumper crash test caused only $588 in damage.

"That's a huge range in performance," IIHS Senior Vice President Joe Nolan says. "We were a little surprised that there was such a disparity between the results for the Ford Focus compared to some of its peers — which were really bad."

Modern bumpers take a step backwards

To assess and compare bumper performance, IIHS conducted a series of four crash tests for each of the 20 vehicles. Those include full front and rear bumper crash tests at 6 miles per hour and front and rear corner impacts at 3 miles per hour. Results show that many modern front-end bumper designs often either slide under the bumpers of the vehicles they strike or don't have enough room to absorb the energy of a low-speed crash. Other bumpers were not big enough to provide much protection from damage (especially those that didn't extend to vehicle corners) or they proved be too flimsy to absorb much crash energy. Nolan says that car manufacturers know this but many have sacrificed function for style.

"They look nice and match the car," he says. "But I think Ford shows that you can have a modern look but still have good performance."

The front bumper of the Focus is tall enough to do a reasonably good job in the full-width front crash tests. Nolan says that the Focus shows that decent bumpers don't have to be costly. Other cars, like the Rabbit or Prius, suffered damage costs comparable to those of luxury cars in the same crash test. For example, the front bumpers of the Rabbit and Honda Civic each suffered more than $4,000 in damage to their grilles, hoods, fenders and air-conditioning condensers. Similarly, the Prius sustained nearly $4,000 damage in the rear full-width test because its bumper is mounted too low to protect the vehicle's tailgate, rear body panel and tail lights. By comparison, a 2007 Mercedes suffered almost $5,500 in damage to its front bumper in a similar crash test for luxury cars last year, Nolan says. Another factor driving up damage costs is the price of parts. For example, a tail light costs $205 to replace on the Prius compared to just $65 on the Focus.

IIHS officials recommend that manufacturers make bumpers wider and taller to effectively manage crash energy. To illustrate how small changes to bumper design can make a significant difference in repair costs, IIHS worked with Tech-Cor, the research division of Allstate Insurance, to modify the front bumper of a Prius. The reinforcement bar and foam absorber were extended another 10 inches on the passenger side under the headlight. When the Institute tested the Prius again, the headlight and fender were undamaged and the repair cost dropped from $1,200 to $254.

Nolan says that it wouldn't take much for automakers to fix these problems. But because they are motivated by style and aerodynamics, many don't want to change — and the law allows it. Presently, federal law allows automakers to build a bumper that, when tested, can suffer unlimited damage — although there are restrictions on lights and safety equipment. Federal legislation used to be much tougher. It required that all bumpers pass a crash test at 5 miles per hour and suffer no damage, Nolan says. The laws changed in the 1980s when automakers focused on building more energy efficient cars (without steel bumpers to weigh them down).

To show that its tests weren't too difficult, IIHS applied the same tests to a 1981 Ford Escort. In all four tests combined, it suffered less than $500 in damages. Its front and rear bumper suffered $0 in damages.

Today, "'bumpers' on most cars aren't worthy of the term," Nolan says. "Even the best bumper in this group still allowed more than a thousand dollars damage in one 3 mph crash test. Some simple changes could prevent a lot of damage to cars and expense and headaches for consumers."