You car already records your speed. It's not stored forever, but in the event of a crash your last X seconds of speed, throttle, brakes, steering, and more are

You car already records your speed. It's not stored forever, but in the event of a crash your last X seconds of speed, throttle, brakes, steering, and more are being stored in a rolling buffer https://www.govtech.com/fs/in-car-devices-records-information-in-the-event-of-an-accident.html https://www.govtech.com/fs/in-car-devices-records-informatio... http://techinfo.honda.com/rjanisis/pubs/OM/AH/AT202222IOM/enu/details/guide02.html http://techinfo.honda.com/rjanisis/pubs/OM/AH/AT202222IOM/en...