If you’d like to monitor your driving habits, or perhaps keep them handy in the event of an accident, a “black box,” or more properly a “telematics” device is just what you’re looking for. 

Monitoring driving habits can be interesting, but what if you’d like to make a telematics box yourself, giving you total control over how data is collected and used?

That’s just what maker “TheForeignMan” did, using an Arduino Mega to take in data from his car’s OBD-II port, along with position information from a GPS module. Vehicle speed, engine RPM, and throttle depression are saved on an SD card, which can be removed and graphed on the driver’s computer.

DISCLAIMER: This custom-made black box may not always be valid evidence in a court of law. Some countries/states/local laws may not allow installation of custom monitoring units into moving vehicles unless authorized by an approved installation team. For these reasons, and any other associated to tampering with the OBD port, the author(s) of this article and website hold no responsibility over the outcome of your driving, your car, your car’s electronics (including on board computer), and any other incidents occurred with a custom-made monitoring unit fitted.

Instructions for this build are available here and code can found on GitHub.