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Driverless and self-driving cars – complete guide

What are self-driving cars?

Self-driving cars are vehicles able to drive themselves with little-to-no input from a human driver. Some are able to follow traffic on the motorway while others claim to be fully self-driving. Different types are defined according to their level of autonomy.

How do self-driving cars work?

Self-driving cars use powerful computers and an array of sensors to build a digital picture of the world around them and plot a safe course through it. This includes being able to respond to unexpected hazards or unclear road markings. Sensors used tend to include conventional video cameras, radar, laser or mixed lidar sensors. You can spot these on modern cars either nestled in the front grille or sat in a pod just in front of the rear-view mirror.

Production models you can actually buy currently only offer part-autonomous driving so will occasionally need a human to take over for more complicated driving environments such as in the city. When this is the case, the car will use a combination of audio and visual warnings to let you know you’ll need to take the wheel. The Society of Automotive Engineers defines six levels of autonomy to categorise the different types of self-driving tech available:

Level 0 self-driving cars – no autonomy

There might be monitoring systems on board, but they have no control over the car. Only the driver can control the car.

Level 1 self-driving cars – assisted driving

The car can control some driving functions itself, but must do so in cooperation with a human driver. This covers self-parking systems that require you to operate the pedals or adaptive cruise controls that can automatically follow the car in front.

Level 2 self-driving cars – partial autonomy

The car is able to control driving functions but a human driver must be present at all times, paying attention and able to intervene with no notice. Models including the Mercedes E-Class and the Tesla Model S are capable of driving down the motorway unassisted but the Mercedes requires you keep your hands on the wheel for the system to function.

Level 3 self-driving cars – conditional autonomy

Like level 2, the car controls the acceleration, braking and steering but, while the driver must be able to take over, they aren’t required to be ready at a moment’s notice. The system will alert the driver a short time before it needs them to take over meaning you can pay attention to something else while the car is driving.

Level 4 self-driving cars – high autonomy

Within a set area, the car fully takes control of the driving functions – the driver is not required to take over at any point and doesn’t need to pay any attention to what’s happening around them. Should the car stray outside an area it’s able to drive – often defined by geofencing – it must be able to safely park by itself.

Level 5 self-driving cars – full autonomy

This is the self-driving car we were promised by all those sci-fi films – able to drive itself in any scenario with no human intervention. In fact, the vehicle might not even be fitted with conventional controls to free up more passenger space. Experts in the industry predict we won’t see level 5 autonomous cars until around 2030.

Just want to drive yourself?

Of course, if you trust your own driving skills more than any computer, you can get a great car through carwow. Simply click ‘login’ on our homepage to sign up and configure a new car or see our range of new, nearly new, pre-reg and ex-demo stock cars available to drive away today.

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