ARLINGTON, Va. - The Insurance Institute for Highway Safety (IIHS) announced results of a study conducted on bumper damage on mini and microcars. The IIHS reports none of the bumpers on seven mini and microcars earns the top rating of good, and just one, the Smart Fortwo, is acceptable. Five out of the seven earned poor ratings and one earned a marginal.

The Institute evaluated results according to a new ratings protocol for low-speed tests that better represents the damage insurance claims centers assess daily. The worst performer was the Kia Rio with $9,380 total damage in the four tests, two full-width and two corner impacts, to earn a poor rating. The Rio's repair bill was worse than those of most other small and midsize cars and minivans the IIHS tested. This minicar racked up about $3,700 in damage, or 30 percent of its purchase price, in the full-front test alone. The Toyota Yaris, Honda Fit, Hyundai Accent and Mini Cooper also earned poor ratings for bumper performance.

The Smart Fortwo was best overall, with $3,281 total damage in 4 tests. The IIHS says costs are relatively low for this microcar because its prepainted plastic body panels are dent-resistant, inexpensive and easy to replace. The Chevrolet Aveo, a minicar, is next best, with $4,490 total damage.

"You should be able to drive your car home after a low-speed crash, but too often vehicles are sidelined by only minor impacts," says IIHS senior vice president Joe Nolan. "Damage to sheet metal, air-conditioning condensers, and safety equipment like headlights should never happen when your car is bumped at just 3 to 6 miles an hour. Bad bumpers add up to one big headache for consumers."

Test results were released under a new IIHS ratings protocol that's based on repair costs averaged and weighted to reflect real-world damage patterns. These averaged and weighted repair costs determine each vehicle's overall rating of good, acceptable, marginal, or poor in 4 bumper tests representing full-width and corner crashes at low speeds. Weighted average repairs must be less than $500 for a good rating, less than $1,000 for acceptable, and less than $1,500 for marginal. Repairs of $1,500 or more earn bumpers a poor rating.

"Bumpers can be designed so there's no damage in these low-speed impacts. At a minimum, repairs should cost less than the typical insurance deductible for a collision, which is $500," Nolan explains. "This is why we set the benchmark for a good rating at less than $500. Damage at this level may be only cosmetic, so consumers may choose not to bother with repairs. Likewise, $1,000 is about the cost of a new bumper cover, reinforcement bar and paint, while $1,500 includes replacing vehicle parts like grilles and
headlights. When you reach $1,000 the bumper isn't doing its job, and anything $1,500 or higher is egregious."

No vehicle can earn a good or even an acceptable rating in the IIHS's bumper tests if it's unsafe to drive afterward or can't be driven at all. Inoperable headlights or taillights, severely buckled hoods, or a compromised engine cooling system would prevent any vehicle from achieving the top 2 ratings. For instance, the Accent's hood buckled and its radiator hose kinked in the full-front test.

The Smart Fortwo joins the Ford Focus and Scion xB as the only cars to earn acceptable ratings. The Aveo is 1 of 15 to rate marginal. Of the 61 cars the Institute has tested so far, 43 rate poor.

"Bumpers are doing their job if the only damage is to the bumper cover. Bumpers aren't doing their job when headlights get knocked out or sheet metal crumples after a low-speed impact," Nolan says.

The IIHS reports the Smart's plastic body parts easily can be replaced in sections, making repairs relatively affordable in comparison to other vehicles. For example, front and rear bumper covers come in 3 sections each (left, right, and center), so mechanics need to replace only the damaged parts instead of the entire plastic cover. Also keeping costs down is the fact that the bumper cover sections are prepainted. They cost roughly $160 for the center section and $180 each for the left or right fender sections.

This is the first car the Institute has tested that has prepainted body panels. In comparison, it costs $480, not including labor, to replace and paint a front bumper cover on the Aveo.

Nolan says, "Our new bumper ratings should help streamline the buying process so consumers can zero in on vehicles with good bumpers. At the same time, the ratings should
encourage automakers to make improvements that help move cars off their lots."

Better bumpers don't have to be complicated. Auto manufacturers already know how to make good ones. Longer and taller reinforcement bars and energy-absorbing material are key to reducing damage in low-speed collisions.