Self-driving cars explained: how autonomous is my car?

The first self-driving cars could be on UK roads early in 2022. That's thanks to Government proposals to make it legal to use cars fitted with automatic lane-keeping systems (ALKS) on motorways without the driver having their hands on the steering wheel or their feet on the pedals. 

The new rules are expected to reduce driver fatigue in congested motorway traffic by letting the car take control. They should also cut the number of accidents because cars will be able to slow down and speed up automatically to keep them a safe distance from the traffic in front.

Although drivers won't have to be in control of the car's steering and acceleration, they will need to be ready to take back control at any time. The technology is expected to pave the way for the introduction of fully automated vehicles. In fact, by 2035 the market for self-driving cars could be worth £52 billion.  

Like semi-autonomous cars, fully self-driving vehicles should help to reduce congestion and improve road safety. They will be able to travel closer together and will be linked through the same data network, making them able to 'see' other road users and anticipate where other cars will go. 

Although some groups have voiced concern over the safety of highly automated vehicles, self-driving car trials have been running in the UK for a number of years in various locations, including Bedford, Milton Keynes and Greenwich in London. The trials have been closely monitored and controlled.

Thatcham Research – which conducts safety tests on behalf of Euro NCAP in the UK – and the Association of British Insurers have warned that the messaging around how autonomous cars are marketed needs to be consistent and clear.

They fear brand names including ProPilot, Pilot Assist and Autopilot could make drivers think their cars can effectively drive themselves in any situation. In reality, most current semi-autonomous systems act only as a safety back-up or assistance for motorway driving.

When will self-driving cars be available?

At the moment, no production car can be described as truly autonomous. The most advanced driver assistance systems are present in models such as the Mercedes C-Class, Polestar 2, and Tesla Model 3, where the car's software can control the car's steering, acceleration and braking, as well as changing lanes in certain situations.

Autonomous cars are divided into five levels, depending on how advanced they are and how much driving they can do for you. Below, we explain what those levels mean.

Autonomous cars – what do the different levels of autonomy mean?

Level 0

In Level 0 driving, the driver is completely in control of the car, for both speed and direction, with only warnings and alerts assisting them in extreme circumstances. Today, such cars are rare and almost invariably extreme, low-volume performance cars. The lack of driver assistance is said to create a 'purer' performance car.

Example: Noble M600. No assistance systems is fitted so the driver is in full control of the car at all times.

Level 1

Level 1 is the first of the ‘assisted driving’ levels, where the car can ‘support’ driving functions. Most modern cars can be considered to be of this level because the car controls certain elements of travel when systems such as adaptive-speed steering, speed limiters, traction control and ABS are used. Very little control is given to the car, though, and that means it is often unnoticed by the driver.

Example: Skoda Fabia. Traction control: when the car loses traction under acceleration, the car reduces the amount of power delivered to the wheels to stop them from spinning.

Level 2

The second level of ‘assisted driving’ involves the car being able to ‘control lateral or longitudinal movement’. Examples of this are adaptive cruise control, which changes the speed of the car based upon the speed of the car in front, and lane-keeping assistance, which adjusts the steering if the car senses danger caused by you drifting out of your lane accidentally. At no point is the driver not paying attention to the road, nor are they taking their hands off the steering wheel. And in the case of adaptive cruise control, the driver still needs to keep the pedals covered in case of an emergency.

Example: Lexus NX. Adaptive cruise control: the car controls the speed at which it is travelling, but the driver controls everything else and must maintain focus on the road.

Level 3

Level 3 driving involves near-equal input from the driver and the car. An example of this type of car is a traffic jam assistance system, such as ALKS, which will operate the accelerator, brakes and steering in slow-moving traffic. Despite the car’s control in these situations, the driver must still concentrate on the road and take control when necessary, making it a theoretical ‘hands-off’ system but not an ‘eyes-off’ one.

Example: Seat Ateca. Traffic Jam Assist: controls all the driving functions of the car, but you must keep your hands on the wheel and your eyes on the road.

Level 4

The first of the ‘automated driving’ categories is also the first ‘eyes-off’ and ‘hands-off’ category. There are models with some form of Level 4 technology, but they can't be used until they become legal in spring 2022. Safety organisations dispute whether or not cars such as the C-Class have Level 4 technology, or if they are simply sophisticated Level 3 assisted driving systems. The Government describes Level 4 driving as “the driver is only responsible and exercises control when the system is not in use”. The car can be in charge of all driving functions without the driver’s intervention, attention or input. The systems can be turned off when the driver chooses and then normal driving resumes.

Example: None is available yet, but some of the latest car models have some of this functionality. 

Level 5

Level 5 is the highest point of automated driving, allowing the car to control its speed and direction fully without any need for driver intervention. Although the Government's guide does not specify it, this type of autonomous driving would allow the car to drive on its own without an occupant – similar to the feature on current Teslas that allows the driver to summon the car to them remotely. Level 5 vehicles are often referred to as ‘fully autonomous’.

Example: None is available yet, but the first fully autonomous cars are expected to appear in around 2025.

Self-driving car glossary

Autonomous Cars on the upper three levels are often described as ‘autonomous’ because the term can be applied to any car that can drive itself. This is why the word is interchangeable with the terms ‘driverless’, ‘self-driving’, ‘piloted driving’ and others.

Semi-autonomous Cars with autonomous systems that aren't active when the driver chooses them not to be, such as lane-keeping assistance, are widely regarded and often referred to as ‘semi-autonomous’.

Connected car Connected car technology is another widely used term in modern motoring. It applies to technologies that allow cars to communicate with each other and a central information database. The communication allows cars to update each other with changes in road terrain, safety hazards and other information that will allow them to become fully autonomous safely.

Eyes-off When a car can drive itself proficiently enough that the driver no longer needs to pay attention to the road, the term ‘eyes-off’ is used.

Hands-off When a car can take over functions of driving proficiently enough that the driver doesn’t have to have their hands on the wheel or their feet on the pedals, the term ‘hands-off’ is used.

Internet of Things This is a term that applies to the use of the internet to connect more everyday objects, such as cars, traffic lights and even household appliances, to the internet, allowing them to communicate with one another. In the context of cars, it allows the remote summoning of cars, as well as access to functions such as the climate control and security features from afar.

Next: the best electric cars and the one to avoid >>

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