Tesla started pushing firmware 2026.21.6 on 9 August 2026, and it is an unusual release: one build carrying two different Full Self-Driving branches at once. Hardware 3 cars get FSD (Supervised) v14.1 Lite — the first version bump the cut-down branch has had since it appeared — while Hardware 4 cars get v14.3.7. Both halves are North America only.
HW3 inherits from HW4 on purpose
The most interesting line in the release notes describes method rather than a feature. Tesla says it distilled the intelligence from the HW4 v14 stack into HW3, letting the older computer learn how to handle scenarios using HW4 v14 as a guide.
That teacher-and-student arrangement is the whole point. AI3 does not have the camera resolution or the compute to train the reinforcement-learning and offline models that produced v14 on AI4, but it can be taught to imitate their output. It is the same principle that produced the original Lite branch when v14 Lite first reached HW3 cars in 2026.20.5.1 — this build extends it with the newer HW4 work.
What changes on HW3
| Area | Change |
|---|---|
| Traffic lights | Better handling at complex intersections — compound lights, curved approaches and yellow-light stopping, trained on hard examples sourced from the fleet |
| Responsiveness | Improved proactive and reactive behaviour in navigation handling, merges and forks, pedestrian interactions, traffic lights and vehicle cut-ins |
| Comfort | Fewer false slowdowns, smoother steering, more consistent lane centring |
| Manoeuvring | Parking, unparking and reversing under FSD |
| Arrival Options | Choose Parking Lot, Street or Driveway as the destination behaviour |
| Speed Profiles | Now always available rather than surfacing conditionally |
The comfort items are worth reading as the headline rather than the footnote. False slowdowns and hesitant steering were the complaints that defined the Lite branch's first weeks on the older computer, and they are exactly what a distillation pass is good at smoothing out.
HW4 gets v14.3.7 in the same package
For AI4 cars the FSD payload is v14.3.7, the build TeslAnt covered when it shipped to HW4 in firmware 2026.21.5 to fix the v14.3.6 braking regressions. Nothing about that branch changes here; 2026.21.6 simply folds it into a build that also serves HW3, alongside the wider release items — Actually Smart Summon reaching Cybertruck, starting self-driving from Park, and the new speed-profile options.
Rollout status
Early. NotATeslaApp tracked the build at three cars and effectively 0% of the fleet on release day. Expect the usual pattern of daily waves widening over the following week if the telemetry holds, with HW3 cars likely to move more slowly than HW4 given how recently the Lite branch reached wide release.
Europe is still not on this branch
The caveat matters more here than for most builds. FSD v14 Lite has never been released in Europe. Its only market outside North America is South Korea, which received it days earlier in firmware 2026.20.7.5, restricted to US-built cars. European HW3 owners remain on the older branch entirely, and v14.1 Lite does not change that.
It is still the most consequential build for them to watch. The roughly 7,900 European owners pressing Tesla over what HW3 was sold as capable of are arguing about whether the older computer can deliver what was promised, and the distillation approach is Tesla's answer to that question in software form. Whether it holds up is a separate matter — HW3 cars running the Lite branch have already produced reports of Autopilot computers running hot enough to fault, and asking AI3 to imitate a heavier stack is unlikely to reduce that load.