Robocar – the preferred term here for a self-driving vehicle, capable of driving without human supervision.
Self-driving car – another popular term for the above.
Autonomous Vehicle – another common term.
Autonomous Ground Vehicle – military term for ground robots
Highly Automated Vehicle – term preferred by NHTSA and academics for a short period
Level 4 self-driving car – a more specific term by those who use the Levels.
Driverless car – a popular term, deprecated here, since the vehicles have a computer driving.
Autopilot – Tesla's term for their driver assist system combining ACC and Lanekeeping with other functions. It requires human supervision at all times. Sometimes also used in a generic way with lower case “a.”