NEW YORK (CNN/Money) - The U.S. Department of Transportation's National Highway Safety Administration released rollover ratings for 2004 sport utility vehicles today.

These are the first ratings incorporating results from the agency's new dynamic track test in which the vehicles are actually put through a turning maneuver to gauge their stability.

None of the vehicles tested so far received the highest possible rating on the five-point scale. The worst-rated vehicle, which received a two-star rating of, actually tipped up on two wheels during the test, according to NHTSA. Most of the vehicles tested so far so far received a rating of either three or four.

A four-star rating of indicates a 10 to 20 percent chance of rolling over during a single-vehicle crash. A three-star rating indicates a 20 t0 30 percent chance of a rollover and a two-star rating a 30 to 40 percent chance.

NHTSA has given vehicle rollover ratings in the past, but those ratings were based on a mathematical comparison of the vehicle's width to its center of gravity, or where its weight is centered. Generally, a taller vehicle will have a higher center of gravity.

Correction The text of an earlier version of this story incorrectly referred to the Ford Explorer as the vehicle that received a 2-star roll-over rating from NHTSA. The vehicle is actually the Ford Explorer Sport Trac, as the table correctly stated.

Narrower vehicles with higher centers of gravity were given lower rollover ratings, based on the idea on the idea that those vehicles should tip over most easily. New technologies that can help keep vehicles from tipping over during turns, such as electronic stability control, were not taken into account by that rating system. That "static stabilty factor" still accounts for most of the new rating.

In the dynamic tests, vehicle were put through a so-called fishhook maneuver, a series of abrupt turns at varying speeds. The vehicles are controlled by computer to ensure that every vehicle is put through precisely the same maneuvers.

The new ratings take into account both the "static stability factor" and performance in the fishhook maneuver tests.

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The lowest rating earned by any vehicle rated so far, a two-star rating, was garnered by the four-door two-wheel drive Ford Explorer Sport Trac. The Explorer Sport Trac, and extended cab pick-up, tipped onto two wheels during the test, according to NHTSA.

The four-wheel-drive Toyota Tacoma Xtracab, which earned a three-star rating, also tipped during testing.

Kristen Kinley, a spokesperson for Ford Motor Company, said that NHTSA's test does not accurately reflect real-world driver behavior based on Ford's research. Ford uses a J-turn test, which is a single turn rather than a series of turns. That simpler maneuver more accurately reflects how drivers really react to emergencies, she said, while noting that the Explorer has done well in that test.

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Several vehicles earned four-star ratings, including the Chevrolet Trailblazer and Subaru Outback wagon, the best of any vehicle rated so far. A four-star rating indicates a 10 to 20 percent chance of rolling over during a single-vehicle crash.

While single-vehicle rollover accidents are relatively rare, accounting for just three percent of all U.S. auto accidents in 2001, they are frequently deadly. In 2001, rollovers accounted for nearly a third of all vehicle-occupant fatalities.

According to data from the Insurance Institute for Highway safety for the year 2000, just over half of all occupant deaths in SUVs involved the SUV, by itself, rolling over with no other vehicles involved. Such accidents accounted for just 19 percent of deaths in regular passenger cars.

In 2001, according to data from NHTSA, SUVs had the highest rollover rates of all vehicle types: 35.2 percent in fatal wrecks, 10.8 percent in crashes involving at least one injury.