Google has revealed it stopped developing features of its self-driving car that required drivers to take control in dangerous situations because running in autopilot meant they fell asleep or fiddled with their phones.

According to Reuters today, the decision followed experiments of the technology showing test users napping, putting on makeup and fiddling with their phones with the vehicle travelling up to 56 mph.

"John Krafcik, the head of Waymo , told reporters that about five years ago the company envisioned technology that could autonomously drive cars on highways as a quick way to get on the market,” reports Reuters.

Drivers were required to take control of the car in potentially dangerous situations.

Krafcik said a system that asked drivers to take control at the sound of an alert was unsafe after seeing videos from inside self-driving cars during tests.

The filmed tests were conducted in 2013, with Google employees behind the wheel.

The company decided to focus solely on technology that didn’t require human intervention.

Watch: introduction to Waymo's self-driving car