SAE autonomy levels

The SAE J3016 scale from Level 0 to 5 that classifies how much of the driving task an automated system performs.

• Levels 0–2 assist a human who remains responsible; Level 2 steers and brakes but needs constant supervision.
• Level 3 lets drivers look away in limited conditions but they must take over when prompted; Mercedes offers this on some highways.
• Level 4 needs no human inside its operating domain, which is where robotaxis sit; Level 5, anywhere at any time, does not exist.
• The key line is liability: any feature that needs supervision is Level 2, however it is marketed, including 'Full Self-Driving (Supervised)'.