With cars becoming ever more complex and almost totally reliant on computers to function, the idea that cars can be hacked into electronically has long been a concern for motorists and automakers alike.
Early attempts at vehicular hacking were primitive, and centered around tricking keyless entry systems into unlocking cars.
Then researchers figured out how to gain access to a car's control systems via the Bluetooth connection intended for telephony and media players. Phone-based entrypoints like GM's OnStar and Ford Sync also provide other methods of entry, as does the car's own onboard diagnostic port.
To illustrate exactly what a hacker can do to the average modern car, Forbes journalist Andy Greenberg rode along with professional hacker Chris Valasek and Twitter engineer Charlie Miller in a Toyota Prius and a Ford Escape.
Neither Valasek or Miller disclose exactly how they accessed the cars's various ECUs, but the range of things they can do range from the annoying (forcing the horn to remain on, activating the seatbelt pre-tensioner) to the deceptive (altering the fuel guage to display a full tank) to the downright malicious (triggering the auto-park system at speed, disabling the brakes).
Almost every new passenger car has a computer-controlled throttle, and some cars now feature brake pedals and steering wheels that no longer have any mechanical link to the wheels either.
Miller and Valasek have been hired by the US Government's Defense Advanced Research Projects Agency to investigate the electronic vulnerabilities of cars, and determine just how "hackable" a modern car is, with a strong emphasis on braking and steering.
As the video shows, virtually any computer-controlled function can be hacked into, although just how much effort is required to do so remains a (justifiably) well-guarded secret.
The pair will present their findings at the Defcon hacker conference in Las Vegas next month.