NEW YORK (CNN/Money) - Of 13 midsized cars subjected to an insurance research agency's tough new side-impact crash test, only two protected occupants well enough to earn a "Good" rating.

Ten of the cars rated "Poor," including versions of the "Good" cars tested without optional side airbags installed.

The Toyota Camry and Honda Accord, when equipped with optional side airbags, were the only cars to receive the best possible rating of "Good." Still, neither one performed well enough to be rated a "Best pick," a designation given to exceptionally safe vehicles. When tested without side airbags, both vehicles were rated "Poor." In cars where side airbags are offered as an option, the Institute tested the cars without them. An additional test was done with side airbags only if the manufacturer requested the test and agreed to pay for the additional car.

Both the Accord and Camry offer torso and curtain airbags for front-seat occupants and torso airbags for rear-seat occuoants. Curtain airbags inflate to cover side windows and protect occupants' heads.

The tests, conducted by the Insurance Institute for Highway Safety, emulate a more deadly type of crash than that modeled in the U.S. government's side-impact crash tests. In the Insurance Institute tests, the car is struck in the side by 3,300 pound barrier designed to simulate the front of a pick-up truck or SUV. The barrier smashes into the car at a speed of 31 miles per hour.

In government crash tests, on the other hand, the barrier is designed to simulate a car. Cars are lower to the ground than trucks or SUVs, so there is much less chance the impacting barrier will directly strike the heads of crash dummies. In real-world side crashes with trucks or SUVs, car occupants' heads can be struck by the higher vehicle's front end as it punches through the car's doors and side windows, according to the Insurance Institute.

The crash test dummies used in the Insurance Institute's tests are relatively small, designed to simulate a small woman or older child. As with a shorter person, the shorter crash dummies' heads are more likely to be struck directly by the force of the moving truck-like barrier.

"This relatively new and very severe IIHS test procedure highlights the issue of compatibility between vehicles of different sizes and the role evolving technologies like side curtain airbags can play in raising the level of occupant protection," Honda said in a company statement.

Honda will offer side curtain airbags as standard equipment on all 2005 model-year Accords beginning this autumn, according to the statement.

Toyota said in a statement that the company was pleased with how the Camry performed in the crash tests.

"Basically, the test is designed so that only vehicles with side curtain airbags can do well," the company said in the statement.

Two of the cars that rated "Poor, " the Hyundai Sonota/Kia Optima and Saturn L Series, had standard side airbags installed. In the Saturn, the crash test dummy's head brushed past the car's side curtain airbag and was struck by the moving barrier. In the Hyundai/Kia car, the protection offered by the car's combined torso/head airbags was undermined by the failure of the car's body to resist crushing under the force of the impact.

The ability of a car's body to resist crushing in on occupants is an important factor in side crash protection, according to the Institute.

"In front end crashes, well-designed vehicles have front ends that crumple to absorb the energy and strong occupant compartments that resist intrusion," said Institute president Brian O'Neill. "This allows restrained occupants to be decelerated without injury. In contrast, there is virtually no crush space on the sides of vehicles. So in serious side crashes some intrusion is inevitable but it should be minimized."

Of the cars tested, only the Mitsubishi Galant, which was tested without optional side airbags installed, earned a "Good" rating for structural performance.

In the last couple of years, no cars have rated "Poor" in the Insurance Institute's 40 mile per hour front off-set crash tests. All vehicles sold in the United States now have standard front airbags, which help protect occupants in front end crashes and cars today are better engineered to deal with frontal crashes.

Car Tested with side airbags* Side impact protection rating Head protection (Driver/Rear Passenger) Structural integrity Frontal offset crash test rating Toyota Camry Yes Good G/G Acceptable Good (Best Pick) Honda Accord Yes Good G/G Marginal Good (Best Pick) Chevrolet Malibu Yes Acceptable G/G Marginal Good Mitsubishi Galant No Poor P/M Good Good Hyundai Sonata/Kia Optima Yes (Standard) Poor G/M Acceptable Acceptable Saturn L Series Yes (Standard) Poor P/G Acceptable Acceptable Nissan Altima No Poor P/A Good Good Honda Accord No Poor P/M Marginal Good (Best Pick) Toyota Camry No Poor P/M Acceptable Good (Best Pick) Dodge Stratus/Chrysler Sebring No Poor P/M Poor Acceptable Chevrolet Malibu No Poor P/M Marginal Good Mazda6 No Poor P/A Marginal Good (Best Pick) Suzuki Verona No (not available) Poor P/M Marginal Acceptable *Side airbags optional unless otherwise noted.

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