I wrote about his issue for the Capitol Journal back in January of 2004.
Vehicle "Black Box" evolution - safety benefits and privacy challenges, published in Capitol Journal, January 2004. (PDF 1.95M) Download Cp_black_box
"No one wants a stranger invading their privacy, looking over their shoulder watching every move. Yet, every time the driver of a late model car turns the key, they could be inviting an unknown observer. An observer who can report indicator light status, seat belts on or off, motor speed, vehicle speed, brake activation, crash forces, and event times; should the driver be involved in an accident. All valuable information to reconstruct an accident, determine accident responsibility, check for insurance fraud, or to make critical medical decisions at the accident site."
The Volokh Conspiracy has details: Court Holds that Data About Car Speed and Brake Usage Stored in Car’s Computer Protected by Fourth Amendment
A California appellate court has handed down a fascinating opinion today in State v. Xinos on whether and how the Fourth Amendment regulates government access to data stored in a car’s internal computer that controls the airbags and seatbelts. After a fatal car accident, the police downloaded the data from the impounded car and used it to help reconstruct the accident and convict the driver of vehicular manslaughter. The information from the computer “showed information captured during the five seconds before defendant’s vehicle experienced a change in velocity. It disclosed the vehicle’s speed during the five seconds before the incident” and showed that the brakes had been activated at that time. Held: The data was protected by the Fourth Amendment, the retrieval of the data was unconstitutional, and the conviction had to be overturned.