I got the screen via special order from china. I believe the screens are designed for advertisements and subway car status screens.
I can get speed data via a mechanical speedo sender. It connects to the speedo cable (standard size). It sends 16 pulses per revolution. I can read them and using some math on a arduino can get the speed. Trip/Odo functions are when the arduino will write to an EPROM chip every 1/10th of a mile. This saves data when no power is in the system. I also will have the computer write to a log file every 10-15 mins or so as a backup.
Other data can be obtained by using aftermarket sensors
-Kevin