I've been using my old HTC Design 4G as a dash cam with "AutoGuard Blackbox - Dash Cam" and "Autosleeper Auto power ON-OFF" which are both free apps in the play store. It does a great job, but the issue I'm running into is Heat! I live in Florida, had no problem in the winter, it's now summer! The autosleeper only puts it into a sleep mode where it is still very slowly draining the battery, and when the car is started and it starts recording video it instantly overheats. Powering the device off/on completely works but takes forever! A custom rom is definitely needed here, one that turns your old somewhat junky phone, which is still 720p or better, into a sweet dash cam. Keeping the GPS features and camera features enabled is all that's needed. Just have it power on/off with the power connection and autostart/stop recording. Many more features could be cranked into it, but I can't believe nobody's made one of these already. Someone please step up!