Self-Driving Cars: Technology, Levels, and Challenges

Self-driving car definitions

Self-driving cars are vehicles capable of operating with reduced or no human input, also known as autonomous, driverless, robotic, or robo-cars. However, "self-driving" has no universally agreed definition, and manufacturers may use terms such as "Autopilot" or "Full Self-Driving" for systems that still require driver supervision. As of 2026, no vehicle has achieved complete Level 5 autonomy in every environment; fully driverless operation is generally limited to specific operational design domains, such as designated urban areas used by robotaxi services. Definitions are commonly organized using SAE International's six automation levels, which range from Level 0, where the human performs all driving, to Level 5, where the system drives under all conditions. The levels depend primarily on the driver's responsibility for controlling the vehicle, monitoring the environment, and responding to failures. Important distinctions include advanced driver-assistance systems, which automate specific functions but require a human driver, and automated driving systems, which can perform broader driving tasks. Other frameworks, such as Mobileye's terminology, describe automation through driver engagement categories including hands-on/eyes-on, hands-off, eyes-off, and no driver.

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Operational design domains

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