SAE levels of driving automation

The SAE J3016 standard defines six levels of driving automation, from Level 0 (no automation) through Level 5 (full automation, anywhere, any condition). Each level specifies which driving tasks the automation handles AND the conditions under which the human must remain available to take over. Level 4 covers vehicles that drive themselves within a defined operational design domain; Level 5 removes the ODD constraint.

The distinction matters because cross-company comparison routinely treats SAE levels as a capability scoreboard, but the levels measure responsibility allocation, not safety or capability. Tesla FSD's "Level 2+" marketing implies a higher tier than the supervised-driver requirement actually permits. Waymo's Level 4 robotaxi service is structurally different from any Level 2 or Level 3 system — the human-as-backup assumption changes the entire safety architecture.