I can look into it, but need to understand the intended audience better, so let me get some feedback here:
The first run as it stands would be:
The above schematic, zeners, big old capacitor power supply, atmega with a bootloader and the then current version of the code, header pin interface with the car with a small female plug you solder your wires too, LCD, IC socket so you can update the software, single sided PCB, etc.
Not included:
Exact instructions for your vehicle
fuses for power lines
fancy wiretaps, you strip and solder to your own wires or come up with something.
A chip programmer or header, use an existing DIP duino to update the software and swap in the updated chip, or come up with something.
Warranty, or any liability on my part.
Solder, tools, skill, nerve.
Rough guess would be $25ish +- 20% depending on quantity and using the current parts set. Might be a month before the software is really ready for pre-loading.
If you are interested let me know, I've not done this before so be forewarned
