For those who would like to know more, last year, Charlie Miller and Chris Valasek demonstrated some hacks on a few cars including a Prius.
Long version (quite technical ):
Shorter video in Forbes:
These attacks were done locally, but with more and more communications stuff added to cars (GPS, 3G/LTE, Wireless remotes and sensors, etc), the potential for remote attacks is going up.
This year they presented a survey / stats on the possibilities of remote attacks:
https://www.blackhat.com/us-14/brief...ttack-surfaces