When people hear self driving cars, they often picture very different things. For some, it’s a Tesla using Autopilot on the motorway. For others, it’s a Waymo robotaxi picking up passengers without a steering wheel in sight. This confusion is exactly why SAE International created its levels of driving automation, a six-step scale that defines how much control the car has versus how much the driver must retain.
These levels, set out in the SAE J3016 standard, are now used worldwide by automakers, regulators, and insurers. They matter because they don’t just describe technology, they set expectations for safety, responsibility, and liability. Understanding them is key if you want to know how close we are to a truly driverless future.
What Are the SAE Levels of Automation?
SAE levels describe the degree to which a car can perform the driving task. At one end of the spectrum, Level 0 means the driver does everything, while Level 5 means the car drives itself under all conditions. Each step up represents more tasks handled by the vehicle’s system and less responsibility on the driver.
Governments, safety agencies, and insurers have adopted this framework because it makes discussions about autonomy consistent. For example, when the UK introduced the Automated Vehicles Act 2024, which sets safety standards for autonomous cars, the SAE levels were the benchmark behind the legal definitions (gov.uk).
Level 0: No Automation
Level 0 means there’s no automation in the driving task. The driver controls everything, though the car may provide warnings like lane departure alerts or blind spot detection. Importantly, these alerts never act on the vehicle’s controls.
This is the level most drivers were used to until the 2010s, before advanced driver assistance systems (ADAS) became widespread.
Level 1: Driver Assistance
Level 1 marks the first step toward automation. Here, the car can control either steering or speed, but never both at the same time. Adaptive cruise control is a common feature, adjusting your speed to maintain distance from the car ahead while you continue to steer.
While helpful on long journeys, Level 1 systems are still firmly under the driver’s supervision. Research shows ADAS features like adaptive cruise already reduce crash rates by lowering the risk of rear-end collisions (IIHS).
Level 2: Partial Automation
At Level 2, the vehicle can handle both steering and speed simultaneously under certain conditions. However, the driver must stay fully engaged and ready to intervene at any moment.
This is the most advanced automation available in consumer cars today. Tesla’s Autopilot, Ford’s BlueCruise, and GM’s Super Cruise all fall into this category. They can keep a car centred in its lane, change lanes on command, and adjust speed. But if the system encounters poor weather, unexpected roadworks, or an unclear situation, the driver must instantly take over.
Surveys show this is where confusion often arises—drivers sometimes assume Level 2 systems are “self-driving,” leading to overconfidence. Regulators stress that at this stage the driver is still legally responsible.
Level 3: Conditional Automation
Level 3 is the first stage where a car can truly drive itself, but only in specific, pre-defined conditions. The system monitors the environment, makes driving decisions, and does not require the driver to constantly watch the road. However, it may request that the driver retake control with little warning if conditions change.
Mercedes-Benz has pioneered this technology with its Drive Pilot system, approved for use in Germany and certain U.S. states. In slow-moving motorway traffic, drivers can legally take their eyes off the road, checking emails, for instance, until the system alerts them to resume control.
The challenge here is liability. If a crash occurs while the vehicle is driving itself, does the fault lie with the driver, the automaker, or the software provider? This grey area is why insurers are already adapting policies for autonomous vehicle insurance, bridging gaps between human drivers and the technology controlling the car.
Level 4: High Automation
Level 4 vehicles are capable of driving themselves without any human input, but only in specific areas or under certain conditions. This is known as “geofenced autonomy.”
Waymo, for instance, operates Level 4 robotaxis in cities such as Phoenix and San Francisco. Passengers can hail a ride without touching the controls, and no safety driver is required. However, these cars are restricted to mapped urban zones and favourable weather conditions.
Level 4 is where automation begins to reshape transport at scale, particularly for commercial fleets and shared mobility. Analysts predict the global autonomous vehicle market could reach $400 billion by 2035, driven largely by fleet services and robotaxis (McKinsey).
Level 5: Full Automation
Level 5 is the ultimate goal, full autonomy in all conditions, everywhere. At this stage, cars wouldn’t need a steering wheel, pedals, or human involvement at all.
Despite years of hype, no Level 5 vehicles exist today. Even the most advanced systems are still constrained by weather, road complexity, or geography. Experts believe it could be decades before true Level 5 autonomy is achieved, if it ever is.
Why These Levels Matter
The SAE levels are more than a technical curiosity. They provide a shared framework for how society approaches the rise of autonomous vehicles.
- For drivers, they explain what technology can and cannot do.
- For manufacturers, they help market features responsibly without overstating autonomy.
- For regulators, they form the backbone of laws like the UK’s AV Act 2024.
- For insurers, they clarify where liability sits as cars take on more of the driving task.
Trust and accountability are as important as technology when it comes to adoption. The SAE levels are the roadmap that makes this journey transparent, and they sit at the heart of wider conversations about self driving cars.
Where We Stand Today
The vast majority of cars on the road are still Level 1 or Level 2. A handful of Level 3 systems are being trialled, Level 4 robotaxis are live in a few cities, and Level 5 remains theoretical.
Progress will be gradual. Studies show consumer demand is strong—many drivers say they would pay extra for advanced automation features—but widespread adoption depends on proving safety, lowering costs, and resolving liability challenges.
The SAE levels of automation explain, step by step, how we get from human-driven cars to a future where vehicles truly drive themselves. They set the rules for safety, shape public trust, and define how insurers, automakers, and governments share responsibility.
Right now, we’re in the middle of the journey, where automation is advanced enough to excite but not advanced enough to replace human drivers. Understanding these levels helps drivers and businesses alike prepare for what’s next, and ensures that when autonomous cars arrive in force, we’ll all know exactly what they can and cannot do.
What’s the difference between Level 4 and Level 5 autonomy?
Level 4 cars can operate without human input, but only in specific areas or conditions. For example, robotaxis from Waymo and Cruise are considered Level 4 because they work in mapped city zones but cannot drive everywhere. Level 5, on the other hand, represents full autonomy in all conditions — no steering wheel, pedals, or human backup. Today, no vehicles have reached Level 5.
Are self driving cars already on the road?
Self driving cars are on the road today but only at limited levels. Most consumer vehicles available today are Level 2, with partial automation like lane keeping and adaptive cruise control. Level 3 is just beginning to appear in select models and markets. Level 4 robotaxis are being tested and used in some cities, but widespread adoption is still years away.
Who is responsible if a self driving car crashes?
Responsibility depends on the level of automation. At Level 2, the driver is always accountable because the car is only assisting. At Level 3 and above, liability becomes less clear — is it the driver, the manufacturer, or the software provider? This legal uncertainty is why insurers are adapting products to cover autonomous vehicle insurance, helping bridge the gap as regulations catch up.
When will we see fully autonomous cars?
Industry experts predict gradual progress rather than a sudden leap. McKinsey estimates that by 2035, up to 17% of new cars could have Level 3+ features, with Level 4 fleets scaling first in cities. Level 5, where cars can drive anywhere without human input, may still be decades away, and some argue it may never be practical for every road condition.
Why do the SAE levels matter to drivers?
The SAE levels help set clear expectations. A car with Level 2 features is not a “self-driving car,” even if it looks advanced. Knowing the difference helps drivers stay safe, prevents misuse, and informs buying decisions. It also shapes how insurers and governments regulate technology, so understanding the levels means understanding your own responsibilities behind the wheel.
References
FutureIoT (Berg Insight)
https://futureiot.tech/autonomous-vehicle-adoption-expected-to-rise-sharply
S&P Global Mobility
https://www.spglobal.com/mobility/en/research-analysis/autonomous-vehicle-reality-check-widespread-adoption.html
MarketsandMarkets
https://www.marketsandmarkets.com/PressReleases/level-3-autonomous-vehicle.asp