It’s part of an "early warning reporting” program Congress set up to prevent a repeat of the Firestone tire-failure scandal.

General Motors, Ford, Chrysler and some German and Japanese manufacturers have argued that this information should be kept strictly confidential. And officials at the National Highway Traffic Safety Administration have agreed, despite protests and court challenges from public safety groups.

Late last month, the highway-safety administration proposed the latest in a string of rules over the confidentiality of those millions of documents. It did so on the orders of a federal judge, who accused the agency earlier this year of pulling a "switcheroo” by deleting from an earlier draft a presumption that the data would be available to the public.

The tug of war over disclosure is intense because millions of dollars – and many lives – may be at stake. In the Firestone debacle, the tire company said it would recall 10 million tires because of tread separations and other failures that were linked to at least 271 deaths.

Many of the accidents came after rollovers by Firestone-equipped Ford Explorers, and Ford ended up doing a substantial redesign of the popular sport-utility vehicle. Both companies faced massive legal bills from resulting lawsuits, and their reputations took a beating.

"What manufacturers are afraid of is not cases already filed, but people mining for trends to file class-action suits” if the data are made public, said Sean Kane, president of Safety Research & Strategies in Rehoboth, Mass., which has worked for plaintiffs’ lawyers.

Automakers have campaigned through their trade group in Washington, the Alliance of Automobile Manufacturers, to keep the quarterly reports classified as "confidential business information.”

"This is all information that is unsubstantiated and submitted to the manufacturer,” said Robert Strassburger, vice president of vehicle safety for the alliance. He argued that the data are "competitively sensitive.”

The alliance told NHTSA in 2002 that it would cost auto manufacturers $52.5 million to set up the early warning system and $10 million a year to maintain it.

The traffic-safety agency says the new information is worth collecting, even if only its investigators see it.

"It is serving the purpose Congress intended ­­– putting vital information in the hands of our defects investigators,” said Rae Tyson, an NHTSA spokesman.

Still, the agency said it has opened about the same number of defect investigations in the five years since Congress passed the early warning system than it did in the five previous years. That suggests that the new data haven’t had an extraordinary impact.

Businesses filing information with public safety agencies often ask for exemptions from disclosure under terms of the Freedom of Information Act, and agencies have different policies on granting them. In the case of the traffic-safety administration, some of this sensitive information would become public when the agency reaches a certain stage in a defect investigation.

In originally agreeing in 2003 to keep the data secret, the agency said it worried that if it were made public, companies might stop collecting the information or avoid making repairs to keep claim numbers down. In other words, the agency said it weighed the importance of public disclosure against the agency’s need for the information in conducting investigations and serving consumers.

That conclusion caused an uproar among auto-safety advocates, who said public access to the database would result in problems being spotted earlier and less dependence on the traffic-safety administration.

Public Citizen sued in 2004. The Washington-based public-interest group, headed by former NHTSA director Joan Claybrook, complained that the agency didn’t allow enough time for proper notice and comment on the rule deciding that the data be kept from the public.

The group also claimed that the final rule was markedly different from the earlier proposal. It said the draft led Public Citizen to believe that the information would be presumed to be public unless the traffic-safety agency kept it secret. Instead, the agency granted whole classes of information confidentiality.

In March, U.S. District Judge Richard Leon ruled that the agency would have to try again because there was no "logical outgrowth” between its proposal and what it finally decided to do.

"The final rule was not only the direct opposite of the proposed rule, but the agency pulled a ‘switcheroo’ in completely removing the presumption label as to early warning reporting data,” the court’s opinion said.

The latest version, proposed Oct. 31, is essentially a repeat of its initial final rule. In addition, it said the agency had tentatively concluded that the last six digits of a 17-digit vehicle identification number on death and injury reports should be withheld to protect the privacy of consumers.

The agency repeated its argument that public release of the four classes of information "will cause substantial competitive harm and will impair the government’s ability to obtain this information in the future.”

"This secrecy makes no sense,” said Claybrook, who added that Congress intended that the information be made public. "NHTSA has dragged this out for years. It may take a hearing in the Democratic Congress to probe the delays and force some disclosure.”

In the meantime, the Rubber Manufacturers Association, a trade group that represents Goodyear; Michelin; Bridgestone, the successor to Firestone; and other major tiremakers, is taking an even more absolute position on disclosure in another court case.

The group argues that even reports of deaths and injuries and property damage, all now in the public domain, should be kept confidential.

By Cindy Skrzycki, regulatory columnist for Bloomberg News