There are six tiers of autonomous driving as set by the Society of Automotive Engineers (SAEⓇ). The spectrum begins at zero with vehicles lacking any autonomous driving technology and ends at five, which describes fully autonomous vehicles.
The majority of cars on the road are Level 0. These cars have no autonomous driving tech and a human driver is entirely in charge of operating them. A person must steer, accelerate, brake, navigate and park the car.
Some vehicles in this level have intervening technology types like blind spot warning systems, automatic emergency braking and forward-collision warnings. However, none of these technology types drive or help to drive the vehicle.
Level 1 vehicles have at least one form of automated driving assistance that either helps to steer or accelerate and brake — but not both at the same time. A common Level 1 technology is adaptive cruise control, which adjusts speed when the vehicle is in cruise control mode in order to maintain a safe distance from other vehicles.
Steering assistance is another Level 1 technology. It helps to keep the vehicle centered in its travel lane, preventing unintentional drifting that could cause a collision.
It’s important to note that Level 1 vehicles only use one of these options at a time. Combining steering assistance with braking and acceleration automation would place the vehicle in Level 2.
Vehicles categorized as Level 2 have what’s called advanced driver assistance systems (ADAS). ADAS can take over steering, acceleration and braking simultaneously in certain circumstances, but drivers must remain alert and ready to retake control of the vehicle if necessary.
Many automakers are equipping newer models with ADAS technology. Examples include Toyota Safety Sense™ and the Honda SensingⓇ suite, which have collision predictive technology, steering assistance, lane tracing assistance, automatic high beams and radar cruise control.
Level 3, also referred to as conditional driving automation, uses driver assistance technology along with artificial intelligence to react to changing conditions and make instant decisions. Drivers don’t need to monitor the tech but must remain alert and ready to take control if the system can’t operate safely or fails. This means that napping still isn’t allowed in Level 3 cars.
The gap between Level 2 and Level 3 is wide, and as of this writing, Level 3 vehicles aren’t available nationwide. Mercedes-Benz will soon be the first automaker to offer Level 3 cars to consumers, but only in California and Nevada.
Also known as high-driving automation, Level 4 technology doesn’t require human interaction during travel. If the system fails for any reason, the car is programmed to stop on its own. These cars use geofencing technology, which means they’re restricted to certain geographical areas. Level 4 vehicles currently act as rideshare services, shuttles and other forms of public transportation.
Level 5 vehicles are fully autonomous and require no human interaction beyond the input of a destination. These cars won’t be subject to geofencing, meaning they’ll be able to travel anywhere that a human-driven car can go. Weather and road conditions won’t affect these vehicles, which wouldn’t need steering wheels or acceleration and brake pedals.
Most experts believe that we’re at least a decade away from having Level 5 cars on the road, though the technology is under development.