The Ford Explorer Sport Trac got the worst rating of 14 vehicles subjected to a new government safety test designed to predict the likelihood of a rollover during a sharp turn.
The federal auto safety agency, which announced the ratings Wednesday, used a scoring system in which five stars was the best and meant the likelihood of rollover was less than 10%.
The Sport Trac 4x2, a sport utility vehicle with rear-wheel drive, earned two stars, meaning the rollover risk in a one-vehicle crash was 30% to 40%.
Ford spokeswoman Kristen Kinley said the test used an extreme maneuver that does not necessarily reflect real-world driving. She said company tests indicated the Sport Trac was very safe, but added that Ford was considering adopting the test conducted by the National Highway Traffic Safety Administration.
The government's ratings are determined by a mathematical formula based on a vehicle's height and the width between its rear wheels, and a driving test added last fall that measures a vehicle's performance when it swerves sharply to the left and then to the right.
None of the vehicles got five stars. Earning four stars were two SUVs, the Volvo XC90 and the Chevrolet Trailblazer 4X4; two station wagons, the Ford Focus and the Subaru Outback; the Chevrolet Silverado 4X4 and 4X2 pickups; and the compact Toyota Echo. Four stars means the likelihood of rolling over in a one-vehicle crash is 10% to 20%.
Vehicles earning three stars were the Chevrolet Trailblazer 4x2, the Jeep Liberty and Toyota 4Runner sport utility vehicles and the Toyota Tacoma 4x4 pickup. The rating means the likelihood of rollover is 20% to 30%.
GM spokesman Jim Schell said automakers were pleased that the agency was no longer using only the mathematical test.
"What it didn't take into consideration were some of the characteristics of the vehicle that help in its stability," he said.