This guy posted his experience of when he took a ride in the Level 4 Autonomous Hyundai Ioniq. Seems like it works pretty well but there are certain everyday driver characteristics that it obviously will not follow because it's just not programmed to do it. For example the below:
Check it out the full thing here: Taking a ride in Hyundai's Ioniq autonomous car | PCWorldPerhaps the most interesting moments came when the car encountered the many minor law violations that occur on roads everyday. Hyundai has programmed it to obey the law -- it couldn't ethically do anything else -- but that meant the car stuck to a sedate and legal 25 miles per hour while most other road users cruised by at faster speeds.
At at one stage, when turning right at a junction, it encountered a pedestrian who wasn't waiting on the sidewalk but in the gutter. The car sensed him in the road and slowed to an almost halt. A human driver might have simply taken the curve a little wider.
The short drive only took about 10 minutes so it was impossible to really see the car working under a number of different conditions -- but then, the technology isn't production-ready yet.