Tesla Autopilot works great as long as it isn't abused. In the USA California a drunk driver got behind the wheel, started driving and put the car on autopilot, and actually fell asleep. Police noticed a sleeping man behind the wheel, drove in front of the car and slowed down the car to a halt. 

"One of the officers basically ended up going in front of the vehicle and basically tried to slow it down," a CHP spokesman stated, and it took about seven minutes for an officer pursuing the vehicle to get it to pull over.  The officers said that it took a while for them to wake up the driver. Once they did, they drove him to a nearby gas station where he failed a sobriety test. California Highway Patrol Public Information Officer Art Montiel added:

“It’s great that we have this technology; however, we need to remind people that … even though this technology is available, they need to make sure they know they are responsible for maintaining control of the vehicle,”

When activating the Autopilot features, Tesla reminds drivers that they are responsible for the vehicle and they need to be ready to take control at all time.

Tesla on Autopilot Drove 7 Miles With Drunk Driver Sleeping