Heavy Hitters!

Almost all new cars come with an event data recorder, which is an electronic device connected to a variety of sensors around the vehicle both inside and outside. It can tell if a driver is wearing a seatbelt, or if the oil pressure is low, and in the event of a crash it will send a signal instructing the car's airbags to deploy. It also tracks the car's acceleration or deceleration and its speed in the seconds before a crash occurs. Such information is vital to crash investigators and commonly is used by insurance companies to determine who's at fault in a wreck.

But can it track a driver's every-day movements? GM spokesman Alan Adler explains that all GM vehicles produced since 1998 have event data recorders and that some models were fitted with the recorders from the late 1970s. The devices work by continuously collecting data, but the most recent data are continually overwriting previously stored information. In the event of a crash, the data cycle is "frozen," allowing a snapshot of the most recent data to be recorded. Insurance investigators or law enforcement officers can then retrieve that information electronically.

Drivers have little choice but to drive with the system intact. "To get rid of the system then you have to get rid of airbags, and it's illegal to drive without airbags."