Data recorders that collect information on speed, seat belt use, braking and other factors shouldn't be required in vehicles, US federal regulators reportedly said on Thursday.

According to the Associated Press (AP), Ricardo Martinez, former administrator of the National Highway Traffic Safety Administration (NHTSA), was among those pushing the agency to mandate the data recorders, saying they are essential for understanding what happens in a crash.

But NHTSA reportedly said carmakers are adding black boxes at a fast enough pace on their own - approximately 15% of vehicles now on the road have the data recorders, and the agency says between 65% and 90% of 2004 vehicles have some sort of recording ability.

AP said that, under a proposal released on Thursday, NHTSA said it wants recorders to collect a standard set of data to help crash investigators - by September 2008, the agency wants recorders to collect up to 42 specific elements, including the time it takes for air bags to deploy.

NHTSA reportedly said the systems that control air bags already capture a great deal of that information so the cost of standardising the data will be minimal - some carmakers already have the recorders installed in most vehicles: General Motors began installing them in 1994 while Ford started in 2001.

The proposal would also require manufacturers to include a statement in owners' manuals telling people the data recorders exist - nearly two-thirds of people surveyed by an insurance industry group didn't know their vehicles had black boxes, AP added.

The news agency said privacy advocates have urged NHTSA to clarify who owns the data from recorders, since data has been used against drivers in some court cases, but NHTSA sidestepped that issue.

"All that is for courts and legislation to decide," NHTSA spokesman Tim Hurd told the Associated Press.

Martinez, who petitioned the agency to require the recorders in 2001, reportedly said he is disappointed they won't be required - he is now the chairman of Safety Intelligence Systems Corp., which develops recording devices.

"The fact of the matter is that there's a crash every five seconds. Every crash that goes by is an opportunity to learn and to make cars better," Martinez told AP.

But Martinez also said the proposal is positive overall since it would require recorders to collect a standard set of data, AP added.

Alliance of Automobile Manufacturers spokesman Eron Shosteck reportedly said on Thursday the group was reviewing the proposal - the industry has supported the installation of recorders in the past, saying they collect valuable information on vehicle performance.

NHTSA will accept comments on the proposal for 60 days and will issue a final rule after that, the Associated Press noted.