But, you probably don't know that something similar may be in your own car. Car makers have equipped millions of automobiles with "event recorders" -- mini-black boxes tucked under the seat or inside the dashboard.
The event recorder is really part of the air bag system. It constantly monitors information - like speed and braking - and when it senses a serious crash, it sends a signal to fire the air bags.
In the General Motors version, the black box also records the last five seconds before a crash, and that information can be downloaded.
The black boxes can tell whether and when the brakes have been applied and whether the driver was wearing a seat belt. That kind of precise information about what happens in a crash can lead to safer designs.
"A black box allows us to understand what happens and so get away from guessing. And when you know, you can do a better job of creating safety performance," said auto safety expert Ricardo Martinez.
Black boxes in cars is not a completely new idea.
In London, they are on police cars. And event recorders have been used for years on the racing circuit to enhance safety and fine tune performance.
But do you want a black box on your car?
"I would not buy a car that had this kind of capability," said Evan Hendricks, the editor of Privacy Times.
"The problem with all the information that's collected about us is it's only one subpoena away from a law enforcer, a district attorney or your spouse's divorce lawyer," Hendricks said.
It's already happened. Former NFL football player Jerome Brown was killed when his Corvette slammed into a tree. Brown's family sued General Motors, claiming the car's air bag went off prematurely and caused the crash. But GM, using information from that car's black box, proved otherwise and won the case.
But carmakers argue that's not really what black boxes are for. GM points to its own recall of nearly 700,000 cars after the boxes revealed air bags were going off when they shouldn't.
Phil Haseltine heads a safety group funded by the auto companies.
"Here's a case where event data recorder information directly served consumers by ensuring that they had an air bag system that worked exactly as it was intended to," Haseltine said.
The car companies are skittish about privacy concerns and don't like to talk about black boxes. But the safety potential makes the technology appealing, even if it's installed without fanfare, and perhaps even without you knowing about it.
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