Googling on ("event data recorders" automobiles) will give a lot of hits. For example: http://wpoplin.com/EventDataRecordersAutomotiveBlackBoxes.pdf These devices are a byproduct of the introduction of airbags - the airbag processor stores the data which led it to deploy the bag. This can include delta v vehicle speed engine speed brake use throttle position driver seatbelt use The cited report claims they only store the most recent 5 seconds of data, snapshotted at 1 second intervals. It notes that the data can thus be confusing - for example, if a wheel leaves the ground the speed reported can be way off, and if the driver pumps the brakes, the 'brake use' data is ambiguous. It's not clear whether they store data continuously, or just when the airbag deploys. OTOH, I seem to remember reports of drivers of high-end cars (Audis? BMWs?) getting their warranties invalidated because the main car computer noted that they had exceeded certain speeds during the break-in period. Its not just the airbag computer that can narc you out.... Peter