The government's top auto-safety official toned down his criticism of sport-utility vehicles during a Senate committee hearing yesterday and said he trusts carmakers to find ways to improve the vehicles' safety.

Jeffrey W. Runge, head of the National Highway Traffic Safety Administration, said that government experts will continue to study how to keep SUVs from rolling over and from demolishing smaller vehicles in crashes but that industry has a better chance of bringing about changes quickly. He said he will closely monitor the industry's efforts to improve safety.

"I bet you they get there before we get there," Runge said after testifying before the Senate Commerce, Science and Transportation Committee. Government regulations can take four years to go into effect, while a group of automakers has formed study groups and promised quick action to improve SUV safety.

Runge created a stir last month when he made unusually critical comments about SUV safety. But yesterday he said he did not intend to disparage all SUVs. Some are safer than others but no SUV is so unsafe that its sale should be banned, he told the committee.

"If we thought there was an unsafe vehicle out there, we would take it off the road," Runge said.

Runge said last month that he wouldn't let his daughter buy a vehicle with a high rollover risk "if it was the last one on earth."

The comment energized consumer groups working to force changes in SUV design, some of whom urged senators yesterday to require results from the carmakers.

"This doesn't feel to me like the place to rely on voluntary action," said R. David Pittle of Consumers Union. He urged the senators to press NHTSA for regulatory action.

"We believe this is the time that Dr. Runge should reach into his statute and pull out the authority you gave him and use it," Pittle said.

Committee Chairman John McCain (R-Ariz.), who called the hearing after Runge's earlier comments, credited carmakers for taking the issue seriously but urged them to provide a role in their study for consumer advocates.

After the hearing, Runge said his concern for SUV safety is no less urgent and he seemed pleased that his earlier comments had sparked an SUV debate. "Everybody's interested in this right now, and that's great, that's just great," he said.

While praising the auto industry for improving overall vehicle safety in the past two decades, Runge cited a number of new statistics about SUVs. For instance, light trucks -- including SUVs -- weighed an average of 1,130 pounds more than cars in 2001, up from an 830-pound difference in 1990.

That increasing weight disparity poses a greater risk for occupants of cars that are hit by SUVs. New NHTSA figures show that when SUVs crash into the sides of cars, 22 car occupants die for every one SUV occupant. Until recently, the ratio was reported as 16-to-1.

Representatives of Ford Motor Co., General Motors Corp. and Toyota Motor Corp. testified yesterday that their engineers are working hard to make SUVs safer both for their occupants and for other drivers who share the road with them.

"We have a bond with our customers. They buy our vehicles based on faith in our products," said Christopher J. Tinto, director of technical and regulatory affairs for Toyota Motor North America.

The carmakers and the Insurance Institute for Highway Safety have formed working groups to come up with plans for improving SUV safety. Runge said that NHTSA will continue its own studies but that the industry is better able to make concrete changes because its engineers understand how to change manufacturing techniques.

"Vehicles will get safer and NHTSA will happily watch," Runge said. "It's probably happening as fast as it can right now."