Level 4 vs Level 5 Autonomy: A Founder-Grade Explanation
Cut through the marketing. Here is what Level 4 actually means for a Tokyo deployment — and why Level 5 is not a business question yet.
The SAE autonomy levels are the most-misquoted framework in mobility. Understanding them at a founder level is worth the fifteen minutes.
Level 4, in one sentence
The vehicle drives itself with no human intervention inside a defined operational design domain — a specific set of streets, weather conditions, and speeds. Outside that domain, it will not operate at all.
Level 5, in one sentence
The vehicle drives itself anywhere a human could. No commercial vehicle in the world operates at Level 5 today, and no credible timeline puts it inside this decade.
Why this matters for Tokyo
Every relevant Tokyo deployment is Level 4. That is a feature, not a limitation — it makes safety cases tractable, insurance underwritable, and permitting predictable.
Sources & references
Primary material, official filings, and operator publications referenced while researching this article.
- SAE J3016 — levels of driving automationwww.sae.org/standards/content/j3016_202104/
- NHTSA — Automated Vehicles Safetywww.nhtsa.gov/vehicle-safety/automated-vehicles-safety
- Japan Ministry of Land, Infrastructure, Transport and Tourism (MLIT)www.mlit.go.jp/en/
- Tier IV — open-source autonomous driving (Japan)tier4.jp/en/
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