A Weaponized Key
If all this sounds like another one of those paranoid security theories, this type of technology has already been proven to be of interest to security researchers. In fact, the concept has been put into a point-click application that allows a person to package any number of payloads into a similar device from http://www.prjc.com.
As can be seen from this post(http://www.secmaniac.com/august-2010/social-engineer-toolkit-v0-6-1-teensy-usb-hid-attack-vector/), security researchers have integrated the infamous Metaspoit penetration testing suite with a social-engineering toolkit designed to create a package that can be installed onto a USB microcontroller in a couple of minutes.
Once inserted into the target device, the controller uses the same technology as the Hyundai key to emulate a keyboard, launch Powershell, and dynamically build a program that phones home to a waiting serverall by sending keystrokes to the host OS. The end result is a backdoor on the target device.