NEW YORK (CNNMoney.com) -- The National Highway Traffic Safety Administration has passed a regulation requiring car makers to inform customers when their car has been equipped with an Event Data Recorder, the agency said Monday.

EDRs, similar to "black boxes" used in commercial airliners, record data about what a car is doing in the moments just before and after a crash. They do not record the voices of occupants but they do record things like speed, steering wheel movement, how hard the brakes are being pressed and the actual movement of the car itself.

About 64 percent of model year 2005 cars were equipped with EDRs, according to NHTSA. Some manufacturers already include information about the EDR in the owners manual, but not all, said Rae Tyson, a spokesman for NHTSA.

"If you have a new vehicle, chances are it's got one," he said.

Data from the recorders is used by law enforcement and attorneys to recreate events directly leading up to an accident. Data is also used by car companies to research how cars and drivers perform in actual crashes.

Some privacy advocates have expressed concern that the data, which can be used as evidence in court cases, is being collected without the knowledge of vehicle owners and drivers.

The devices are virtually impossible to disable because their functioning is so tightly integrated with vehicle safety systems such as airbags and anti-lock brakes.

Several states have already passed laws that restrict how the data can be used.

Car companies must comply with the new regulation beginning in the 2011 model year. Information about the EDR, if one is installed, will have to be included in the vehicle's owner's manual.

The new rule also requires EDRs to collect a uniform set of data. Having access to uniform data will help investigators to recreate crashes and determine causes, the agency said.

More-uniform data will also make it easier to develop systems so that, in cars equipped with automatic 911 emergency notification, data about the crash can also be passed along to paramedics and ambulance crews.

The data can also be used to research better road designs and ways to better protect young and old drivers, said Robert Sinclair, a spokesman for the New York chapter of AAA.

AAA had previously expressed concern to NHTSA about privacy issues that might hamper public acceptance of the systems. Those concerns seem to be addressed by the new rule, Sinclair said.

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