Various articles link to the section on SAE classification to explain references to Levels. There is also another description of these in Advanced driver-assistance system#ADAS levels and in Vehicular_automation#SAE_autonomy_levels. The former is rather elliptical, but the crucial point is in the sentence, "Cars may switch levels in accord with the driving mode". This could do with some exapansion with examples to aid undertanding, as I think sometimes the classification is misundertood as applying to cars without regard to the ODD.
I propose this text to explain the table along the following lines. I believe it's all supported by the main sources,[1][2][3] (with inline citations to follow) but it's very much my own description. So I'd welcome input on that point in case I'm guilty of original research.
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The SAE classification of Levels is based on the role of the driver, rather than the vehicle's capabilities, although these are related in the form of a "driving mode" (aka driving scenario). The mode is determined by both an operational design domain (ODD) and a "dyanmic driving requirement." The ODD is the circumstance in which the car is driving, and the driving requirement is what the system must do while remaining safe within the boundaries of that ODD. These two things define the SAE Level.
Cars may therefore switch levels according to the driving mode. A human analogy might be a mode in which you can stand unassisted on one leg (the requirement) if you are on the ground (the ODD), but would need support when standing on a tightrope.
Above Level 1, level differences are related to how responsibility for safe movement is divided/shared between the advanced driver-assistance system (ADAS) and driver, rather than specific driving features (see Concepts). A car might therefore have Level 3 capability for lane management (the driving requirement) up to 100km/h (the ODD), but Level 2 at speeds faster than that. Or it might have Level 4 for driverless navigation on designated highways, but Level 2 on urban side roads.
ADAS that are considered Level 1 are adaptive cruise control, emergency brake assist, automatic emergency brake assist, lane-keeping, and lane centering. ADAS that are considered Level 2 are: highway assist, autonomous obstacle avoidance, and autonomous parking. At Level 3 and above, if a car is driving and the ODD changes - for instance, a clear highway becomes a construction zone with hand-signals from a worker - the system must recognize that it is exiting its ODD and fall back accordingly, including asking for driver intervention if necessary.
A fully self-driving car would therefore stay at Level 5 for all dynamic driving requirements in all circumstances (speeds, roads, terrains, visibilities, obstacle types, jursidictions, etc.), while a car with no ADAS controlling the driving requirements would rely on the human driver for that, and stay at Level 0 regardless of the domain.
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I also propose that in other articles which refer to this definition, the first paragraph above should be excerpted there, together with the table (although I note the the level numbers are visible anchors, which won't transclude...)
Note also some text copied in the above from the ADAS article would need attribution.
-- gilgongo (talk) 16:38, 27 December 2025 (UTC)
- Looks good to me. Stepho talk 22:15, 2 January 2026 (UTC)
- OK I've now done that, and will see if I can excerpt to the relvant pages. gilgongo (talk) 12:39, 4 January 2026 (UTC)
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