I’ve been working on a small Arduino project to datalog my commute. I’m using an Arduino Uno with SK Pang’s CAN Bus Shield. I also have added the optional GPS and LCD to the mix. There is an micro-SD card slot for storage. The aim of the project is just to collect data. As much as I can put into the SD card. I plan on calculating driving efficiency using somewhat arbitrary measures like throttle modulation, temperature, etc.