Driverless cars do not exist yet. Try telling that to some Tesla owners. They apparently switch on the Autopilot function when they want to move to the back seat or take a nap. Judging from scary camera phone footage posted on the internet, they take little notice of Tesla’s in-car safety warnings.

Tesla’s Autopilot can steer, brake and accelerate. But it still requires human supervision. Real autonomy remains a work in progress. That was reflected in a tweet on Saturday from founder Elon Musk who said the US electric vehicle group was delaying the rollout of the latest version of its “Full Self-Driving” software.

Tesla hopes a small number of Tesla drivers with the highest safety scores will test the new software. But even this will not meet the top Level 5 scale of autonomy that means a car can go anywhere in any conditions. The head of the US National Transportation Safety Board is right to call Tesla’s use of the term “full self-driving” misleading.