Ed Zarick has released details on his Arduino vehicular control system known as JEEPuter. Combining an Arduino UNO, shift registers, LCD display, pushbuttons and a relay board, Ed interfaced this controller to his Wrangler’s ignition, garage door opener, lighting systems (with light-sensitivity control), radios and more. The JEEPuter also includes a time and temperature display. Pretty much any vehicle system capable of being operated by a switch could be coded into in this system. (The overhead-mounted radio scanner earns this project extra geek points!)
The Arduino source code is available.