What are the different levels of driverless car technology? Autonomous vehicles explained

Confused about the different levels of autonomy in driverless cars from Level 0 up to the self-driving Level 5? Here's all you need to know.

Last updated: 3 February 2018 - 5.30pm

Self-driving car technology is moving forward at a remarkable level, with more and more autonomy expected in on-road vehicles over the next five to 10 years

There’s now a generally-accepted industry standard for the levels of autonomy that any individual car can provide, which runs from the ‘no autonomous features’ level 0 to the totally autonomous Level 5.

[Read more: All the latest developments in autonomous cars]

This standard for autonomy in cars was originally proposed in 2014 by the Society of Automotive Engineers (SAE), an international organisation of automotive engineers and tech experts. The industry body was keen to develop common terminology for developments in the field of autonomous driving.

Bring yourself up to speed on what each of the six levels indicate with our guide below.

Level 0: Car has no autonomous features

Put simply, this level indicates a ‘normal’ car in which the driver controls acceleration, braking and steering at all times - even if they're assisted by certain car systems. If your car has automated emergency braking, for example, it can still be viewed as Level 0.

Level 1: Driver assistance – some autonomous features

In certain situations, a car with level 1 automation can take control of the steering wheel or the pedals. Level 1 is fairly common in newer cars, taking in features such as cruise control and parking assist. The car’s automation is never in control of both steering and acceleration/braking, though, and the driver must be ready to retake full control at any time.

Level 2: Partial automation – ‘hands off wheel – sometimes’

In a vehicle with Level 2 automation, the car can take over accelerating, braking and steering, but only under certain conditions. Again, the driver must monitor systems and be prepared to immediately intervene at any time if the automated system fails to respond properly.

Level 3: Conditional automation – ‘hands off wheel, eyes off road - sometimes’

In a Level 3 vehicle, the car can fully take over the driving responsibilities under certain conditions, and the driver can have their attention on non-driving tasks – though they will be expected to retake control within a time limit specified by the manufacturer, when the car’s systems request it.

A Level 3 car can decide when to change lanes, brake in an emergency, and respond to incidents on the road. Audi announced Level 3 autonomy with its A8 saloon and its Traffic Jam Pilot last year, and became the first manufacturer to add laser scanners to cameras and ultrasonic sensors on commercially-available vehicles.

[Read more: Check out Audi’s hands-free autonomous driving tech]

Level 4: High-level automation - ‘Hands, off, eyes off, mind off – sometimes’

Level 4 autonomy on a vehicle is the same as Level 3, but the car can drive itself under specific circumstances, and a human driver is not required to take control at these times. A Level 4 car can ask for human help, but should be able to park itself and put its passengers in no danger if the help is not forthcoming. Google’s self-driving car is currently at this level, and in November 2017 Waymo announced that it had been running Level 4 autonomous cars in Arizona since mid-October.

Level Five: Full automation

No human attention, or indeed a human driver, is required with Level 5 autonomy, and a steering wheel is optional. 

Read more: The UK's infrastructure isn't ready for driverless cars

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