I got the os loaded, java dependencies installed and installed the TunerStudio package. Was pretty easy. The screen is tiny! but I think it will work decent displaying just a few critical gauges; AFR, RPM, Boost...
The challenge will be powering it from the car. Actually that is the easy part, it will be gracefully powering it down when going key off or similar to not corrupt the os. I think this can be done over the GPIO pins.
Wow. That's cool. You have bad power (the lighting bolt). Those screens take some juice as does the pi. The power-supplies (plugged into the wall) have been the biggest challenge in using those screens. You might want to power a (fused) 12V to 5V regulator directly from a switched battery connection, that way you can turn it on an off independent of the ignition to avoid bad power-up/down. And (I think) you can power it directly using the GPIO, bypassing the on-board regulator -- I do that for Arduino all the time, but I'm not sure if I've ever done it with a Pi.)
HALT: I use the adafruit code for an 'off' button from one of the GPIO pins. (sudo git clone git://github.com/adafruit/Adafruit-GPIO-Halt). Easy as pi:-/
Are you planning to strip down the OS to run ONLY the necessary code?
Aside from the power-up down & boot-up complexity, the next issue you'll eventually run into is that those pi's don't last forever. Eventually it will probably fail. (I've probably owned at least 100 pi's, I teach kids linux as a hobby. Failures are not that uncommon.)
