Here is an interesting article from Auto Week about new and improved (?) electronic data recorders.
EDRs currently obtain data from airbags, yaw and stability sensors, antilock brakes, traction controllers, throttle controls and engine monitors. They initiate only when sensors indicate that a crash is imminent or has occurred. Some also keep data such as secondary impacts and vehicle roll angle for as much as five seconds after a crash.
However, the new version of the "black boxes," called vehicle status data recorders (VSDRs), run constantly and collect additional data such as wheel and engine speed. Used by Nissan, VSDRs gathers and stores vehicle operating data. Some fear that the information can be used for voiding warranties. Others have privacy concerns.
The data captured by these devices will play an increasing role in motor vehicle litigation.