Hack Takes Over Your Car's Steering While You're Driving | Popular Science
Pop sci did it with both a Ford and Toyota. A longer article I read on the subject noted that the sync system on the Ford's is able to talk to the engine management computer and the traction control modules etc, allowing a direct path to shut down cylinders, brake individual wheels etc.
And as a side note, allows law enforcement to shut down your vehicle as required with the assistance of Ford.