I made one of these for a coworker. Here is how I made it.
I used an Arduino box which is heavily modified. Arduino with headers removed, A salvaged RJ11 phone jack from an old PCI soft modem, a standard LCD, and some small push button switches.
I think it turn out really good. I also added in the save data hack into the source code. In my opinion this makes the device much better.
If I had an older car ( I currently have a 2000 MT Insight and 2006 Prius ) I would love to build another one to play around with.
