This is a really cool project, and I'm always thinking about doing something similar with RPi or other small computer. In the past, I had built my own x86-based

This is a really cool project, and I'm always thinking about doing something similar with RPi or other small computer. In the past, I had built my own x86-based CarPC for music/media/GPS/automation/etc. However, the rise of dash cams are better solution for video as they are much cheaper, easier to install and run, and video is much higher quality. The cheap $45 dashcam has 1080p with 30fps, no need to buy 12v relay timer and deal with other power issues. Also the video on dashcams outperform the webcam attached to the RPi due to RPi's slow USB2 (we're talking 15fps at best). For more complete and capable product, I'd suggest using something with USB 3.0 port, or possibly a used laptop, which provides enough processing power to record multiple videos at higher quality, and at the same time, has built-in battery, provide power management (using serial port/other hack to handle automatic shutdown and WOL for reboot). Note: A lot of the functionality of CarPC has been deprecated due to mobile device/phone/tablets, but it's still fun to have a PC running in a car.