Can your car drive itself? The levels of autonomy, explained
Faced with the new technologies that vehicles incorporate and the constant messages from manufacturers and the media, many people are left wondering to what extent their car can drive itself. It is therefore important to clear up all the possible questions on the subject, because the level of attention a driver has to pay to the road depends a great deal on the features we are offered.
To measure the degree of automation of a vehicle, the Society of Automotive Engineers (SAE) has created a scale of six levels, from 0 to 5, which groups functions according to how much the vehicle does and how much the driver does. It is a reference classification (standard SAE J3016), not a law, and each country can adapt it to its legislation. As it is the reference commonly accepted by the whole ecosystem, it is the one we are going to look at.
In this article we will therefore try to explain in simple terms how this scale is built, in order to understand once and for all how these levels work and what each of them implies for the degree of attention and decision-making required of drivers.
Level 0: No driving automation
Level 0 is the starting point, the most basic level of all, and means the vehicle has no automation of any kind. The driver has to do all the work, from keeping control of speed and steering to detecting obstacles and making driving decisions.
Although this level is the most common in traditional vehicles, fewer and fewer vehicles on the market fall into it because of the growing popularity of automation in the car industry.
Level 1: Driver assistance
At Level 1, the vehicle has an automation system that can help the driver with a single function, such as maintaining speed (longitudinal movement) or keeping the vehicle in its lane (lateral movement). However, the driver is still driving and has to pay attention to what is happening on the road, because the system only handles one of the two tasks.
Although these systems can be useful, they still require a great deal of attention from the driver and are very far from being considered autonomous.
What does this level add compared with the previous one?
Only control of longitudinal or lateral movement. Just one of the two.
Note that the driver has to watch the road at all times, actively driving and making decisions continuously.
Level 2: Partial driving automation
Level 2 is a step forward from Level 1, as the vehicle can assist the driver with several functions at once. For example, the system can control speed and keep the vehicle in its lane. At this level the driver is still the one who monitors the road and responds to anything unexpected, and must be ready to step in at all times.
Although vehicles with these systems can be useful in smooth traffic, such as on a motorway, they still require the driver's continuous attention and are not fully autonomous
Most of the brands that incorporate the latest advances in autonomous driving today are at this level.
What does this level add compared with the previous one?
Driving that includes control of both longitudinal and lateral movement, both at the same time.
Note that the driver has to watch the road at all times, although driving is much more comfortable.
Level 3: Conditional driving automation
To put it more simply, we can also call it under certain conditions, with the driver available to take back control.
Level 3 is where we begin to see the real possibilities of vehicle autonomy. At this level the vehicle can drive itself in certain situations, such as motorway traffic, but the driver has to be available and ready to take back control when the system asks.
While the system is active, the vehicle monitors the road, but the driver has to be willing to take control in certain cases:
Whenever the vehicle requests it because of a system failure (a warning that must be given with enough time for the driver to get ready to step in),
Or when the system warns that it cannot continue, for example in an emergency or in adverse weather.
This level of autonomy is a big step forward from the previous levels; but there is still a great deal of work to do before vehicles are fully autonomous.
What does this level add compared with the previous one?
The vehicle takes care of monitoring the road while the system is active.
Note that the driver can stop watching the road while the system is active, knowing that they have to be ready to take back control when the system asks.
In early 2023, Mercedes, for example, offered this function on some German motorways, as long as the vehicle did not exceed 60 km/h.
Level 4: High driving automation
It means autonomous driving that works within certain conditions.
Level 4 is where the vehicle drives itself and does not expect anyone to take back control. However, it only does so within certain conditions and a certain zone, for example a specific area of a city or a fixed route. Outside them, the vehicle does not work as an .
The big leap from the previous level is that the vehicle responds by itself to possible system failures, which allows the people inside to stop paying attention to the road while the system operates within its conditions.
Although there is still a way to go before vehicles are fully autonomous, Level 4 is a big advance on the previous levels, and it is not yet widely available.
What does this level add compared with the previous one?
The vehicle is able to provide a fallback in case of a problem with the system, driving to a safe place if it cannot continue.
Note that the occupant does not have to watch the road: if the system cannot continue, the vehicle stops in a safe place.
Level 5: Full driving automation
And finally, full automation. Level 5 is the most advanced level of autonomy and means that the vehicle is fully autonomous and needs no intervention from the driver at any time. This means the vehicle can drive itself in any situation, from motorway traffic to city traffic, regardless of adverse weather.
To put it more graphically, in Level 5 autonomous vehicles, neither the steering wheel, the gear lever nor the pedals are needed any more.
Although there are still no cars on the market at this level of autonomy, many car makers and technology companies are working on technologies that will let them reach this goal, with prototypes that give us a glimpse of a future where mobility will be completely autonomous, smart, sustainable and inclusive.
Waymo's autonomous taxis or the pods from companies such as EasyMile operate today as Level 4: they run without a driver, but in defined zones such as airports, technology parks or specific areas of some cities. They are a step before Level 5.
What does this level add compared with the previous one?
The vehicle is able to react to any situation, regardless of weather conditions or emergencies.
Note that the presence of a driver is no longer necessary, and so the car can do without the steering wheel, the pedals and the gear lever.
Conclusion
The levels of autonomy in autonomous driving let us quickly understand how advanced the autonomy systems in a vehicle are, and clearly understand the role the machine will play and therefore the driver's responsibility in different situations.
As you can guess, the technologies in different vehicles mean that today we live with different levels of autonomy, so it is critical that we make sure drivers get suitable training in order to improve road safety, make the most of all these technologies and, as a result, reduce the number of accidents.
In this way we can easily answer the initial question: can my car drive itself?
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