I thought a handy circuit to tell it to start recording every time the car was placed in drive (or started, like Valet mode does) would be nice; seems like all you'd need to know is the PID that is broadcast for gear changes and the PID to broadcast to tell the camera to start, unless that's a multi-step process for some reason.
Before I break out VehicleSpy and waste a day, has anyone looked into it at all before? I'd rather stand on the shoulders of giants, as they say, than reinvent the wheel.