Read this and answer the question. If the question is unanswerable, say "unanswerable".

If access is gained to a car's internal controller area network, it is possible to disable the brakes and turn the steering wheel. Computerized engine timing, cruise control, anti-lock brakes, seat belt tensioners, door locks, airbags and advanced driver assistance systems make these disruptions possible, and self-driving cars go even further. Connected cars may use wifi and bluetooth to communicate with onboard consumer devices, and the cell phone network to contact concierge and emergency assistance services or get navigational or entertainment information; each of these networks is a potential entry point for malware or an attacker. Researchers in 2011 were even able to use a malicious compact disc in a car's stereo system as a successful attack vector, and cars with built-in voice recognition or remote assistance features have onboard microphones which could be used for eavesdropping.

When were self-driving cars built?
unanswerable