Federal regulators said yesterday that DaimlerChrysler Corp. minivans have not experienced an unacceptably high number of deaths from their passenger-side air bags, the second time the agency has declined to further investigate the performance of the safety devices.

Instead, the National Highway Traffic Safety Administration opened a formal investigation into deaths caused by passenger-side air bags in Hyundai Motor Co.'s Accent, a small passenger car.

The agency's decision stunned auto safety advocates who had been pressing the government to look closely at deaths caused by the minivans' passenger-side air bags. They have contended that DaimlerChrysler's air bags are too forceful and are defective in their design.

DaimlerChrysler minivans, which include Dodge Caravans and Plymouth Voyagers, have experienced 17 deaths from passenger-side air bags since 1994, the highest number of any vehicle, while the Accent has had seven.

But the Accent ranked first in the number of deaths caused by passenger-side air bags, according to an agency analysis that compared 80 makes and models manufactured since 1994, factoring in the number of vehicles on the road and the likelihood of a child riding in the right-front seat.

So, because there have been so many DaimlerChrysler minivans on the road during that period, and because of the higher likelihood of children riding in them, the minivans' fatality rate compared better than expected with the rates of other vehicles.

All seven air bag-related fatalities in the Accents involved children under the age of 5. Hyundai noted in a statement yesterday that in each case it examined, without saying how many, the children were either unbelted or improperly belted.

Of the 17 deaths from passenger-side air bags in the minivans, four were not fully analyzed by NHTSA and are considered unconfirmed, 12 involved children and one involved a 98-year-old woman.

DaimlerChrysler officials were anxiously awaiting NHTSA's decision, one that could have had a major impact on sales if the agency had decided to pursue a formal investigation that could have led to a recall. The company's minivans are its best-selling product line, and the company touts them widely for their safety.

Chrysler had extensive discussions with regulators and defended minivans based on its methods of statistical analysis, which the agency largely adopted.

"We're encouraged the facts are driving the decision," said Sue Cischke, vice president of vehicle safety for DaimlerChrysler. Cischke said she hoped the work done on this project would reinforce the message to parents that children should ride in the back seat.

Hyundai said that it will cooperate with the NHTSA investigation.

NHTSA officials said they did not pursue a formal investigation of the minivans because "when you factor in all vehicles and their exposure, they [Chrysler] don't stand out. We will open an investigation into [the] Hyundai. That one clearly stands out."

NHTSA did not include in its analysis the results of its own tests on crash dummies. The results showed that the minivans' passenger-side air bags caused severe neck injuries to dummies representing small-statured women and children. One official said the results of those tests "shocked us." Nonetheless, the agency said the crash tests were not a "predictor or a soothsayer."

"The test doesn't reflect what is happening in the real world," said one NHTSA official, speaking on condition of not being named. She said the agency doesn't want to "stifle manufacturers in their willingness to be creative in their technology and design things in a way they haven't before."

Safety advocates, who asked the agency in 1996 and again last May to investigate Chrysler's air bags, criticized the agency for relying on statistical analysis rather than the number of deaths in making its decision.

"NHTSA has made a terrible mistake in not opening an investigation and pursuing this vigorously," said Joan Claybrook, president of Public Citizen and a former administrator of NHTSA.

Robert Sanders, director of Parents for Safer Air Bags, said 12 lawsuits have been filed against DaimlerChrysler for air bag-related fatalities. Sanders's 7-year-old daughter was killed by an air bag in a Dodge Caravan in 1995, and Sanders has filed suit against the company.

Sanders said the agency's analysis "ignores reality."

DaimlerChrysler would not confirm the number of lawsuits pending against the company, but acknowledged it had been held liable for $750,000 in damages in one case in New York.

The NHTSA study also revealed for the first time that there were other minivans with deaths from passenger-side air bags. According to the agency, Nissan North America has had one death, Ford Motor Co. has had one and General Motors Corp. has had two.

Overall, to determine DaimlerChrysler's safety record, NHTSA looked at 216 cases of serious injury and deaths from air bags to passengers and drivers in 80 makes and models of vehicles. It found that two-thirds of those deaths involved passengers, rather than drivers, and 90 percent of the victims were children, most of them unbelted.

CAPTION: NHTSA will investigate deaths caused by air bags in Hyundai's Accent.