UPDATE (June 2013): This is the project that will never die. I have new car and a new idea. I'm going to use a ST7735 based graphics lcd and the adafruit libraries located here: http://learn.adafruit.com/adafruit-gfx-graphics-library/graphics-primitives

Unfortunately I could never get the liquidware screen to work correctly. I kept having issues connecting the arduino to the micro-controller on the screen. The new method seems much simpler.

UPDATE (March 2, 2011): I have another full setup of the touchscreen version (MKII) that is being set up and I have a friend who will be doing some development work on the project.

I had been working on a 3rd version that uses only 7 segment displays.

These are the displays: http://www.sparkfun.com/products/9766

Software serial allows you to use a number of these at the same time.

So far I've coded up a boost gauge. Here are videos of it using a counter instead of the pressure sensor:

http://www.youtube.com/watch?feature=player_embedded&v=x4el0VcbJW8' target='_blank'>http://img.youtube.com/vi/x4el0VcbJW8/0.jpg' width='425' height=344 />

http://www.youtube.com/watch?feature=player_embedded&v=-bqscDTiXdY' target='_blank'>http://img.youtube.com/vi/-bqscDTiXdY/0.jpg' width='425' height=344 />

The two older and unfinished version of this project I've dubbed the MKI, which uses a serial 16x2 LCD and the MKII which uses a liquidware touchscreen. The MKI works fine and is running in several cars at the moment. It has several features I'd like to add, but never got around to. The MKII has always had issues with communication between the arduino and the touchscreen (Note: these have now been solved). Anyone is welcome to join the code project and work on any of these items.

MKI http://www.youtube.com/watch?feature=player_embedded&v=vNwBDjoZ7mY' target='_blank'>http://img.youtube.com/vi/vNwBDjoZ7mY/0.jpg' width='425' height=344 /> MKII