Ideas for GPS speedometer HUD

Another option for the display would be to use a VFD (vacuum fluorescent display) - they tend to be much brighter than most 7-segment LEDs, and you can generally find ones that are HD44780 compatible (which means they should be workable with the Arduino LCD libraries).

I am not sure, but you may be able to find a KS0108-compatible VFD; I am not sure they make graphical VFDs, but they might! Actually - found this:

http://www.futaba.com/products/display_modules/module_products/graphic/index.asp

I also found this interesting device - something called a PLED display? Seems bright:

http://www.lcdstudio.com/forum/viewtopic.php?t=9315