Volkswagen announced their Temporary Autopilot (TAP) system last month, and it's just shown up on video. If anything, it works better than advertised, and includes some innovative features that do their best to keep you safe, even if you completely zone out:
As you can see, this TAP system has been integrated into a production car, and uses production-level radar, camera, and ultrasonic sensors along with by a laser scanner and an electronic horizon to do everything that it does. In other words, there's no crazy custom electronics involved, and nothing that could keep a system like this from becoming (say) an optional extra in a production car relatively soon.
A big stumbling block for this kind of thing is the issue of liability and who is (or isn't) in control of the car, and Volkswagen very deliberately includes the following in their press release:
"The driver always retains driving responsibility and is always in control. The driver can override or deactivate the system at any time and must continually monitor it.” TAP always offers the driver an optimal degree of automation as a function of the driving situation, acquisition of the surroundings and driver and system states. It is intended to prevent accidents due to driving errors by an inattentive, distracted driver. ...Drivers must still continually focus their attention on the road, so that they can intervene in safety-critical situations at any time.
In other words, this is not (not) a substitute for a human driver. It's not even really an autonomous system, in the strictest sense. It's there in case you (the human) fail at driving for whatever reason, but it's not designed to enable you to not pay attention to the road. In fact, as the video shows, the TAP forces you to pay attention using audio alerts and what looks to be a rather aggressive tap on the brakes if it thinks you're ignoring it. Overall, this is a big step, but still just a step, towards the eventual goal of complete automotive autonomy.
More steps please.