Car companies concede convincing the public to let go of the wheel a challenge

Japanese car manufacturers will have to convince the public that letting go of the wheel in a self-driving car is safe, while also dealing with the biggest threat to the cars' security: the humans using them.

Toyota, Nissan and Honda are intent on putting autonomous cars on highways - and also city roads for Nissan - by 2020, and the triumvirate of Japan's auto industry were keen to stress the advances made so far at the recent Tokyo Motor Show.