Nearly 1,300 fatal accidents occur in Michigan each year. With large numbers nationwide, the National Transportation Safety Board says all cars should have an "event data recorder," or EDR.
The EDR records what happens seconds before a car accident. It includes how fast drivers were going, if they accelerated or braked, as well as the engine speed. Police and crash site investigators can then use that information to piece together what happened in the accident, and they can also use it in the courtroom as evidence.
The EDRs also record whether or not the driver was wearing a seatbelt. Some critics see the mandatory use of EDRs as an invasion of privacy. But law enforcement and crash site investigators agree with the NTSB, and believe all vehicles should have EDRs.
Most new models, and any cars with airbags, have an EDR. The EDR is the component responsible for telling the vehicle when to deploy the air bag.