I've been working on something like this myself, pretty much have everything working that I want displayed. Just need to come up with a design for the output that looks nice.
http://freematics.com/store/index.ph...&product_id=30
This is the OBD-II to UART adapter I've been using.
https://en.wikipedia.org/wiki/OBD-II_PIDs
This page is also very helpful.
When the weather is nice I'm gonna be resuming the project.