While not quite up to the level of interactivity that Hollywood dreamed up for the Knight Industries Two Thousand, Fiquett's TL will remotely start itself and turn off the ignition on his command. The system works by relaying the Siri command to a proxy server, which sends the instructions to a Viper car automation and security system. About the only thing missing here is William Daniels doing the voice of KITT – and that awesome black Trans Am itself.
Fiquett has put his source code up for download, so if you're interested in trying it yourself and you've got some coding skills, have at it on his website. Otherwise, just click through the jump to watch the video.