Tesla Manuals Shift FSD Hardware Names From AI4 to SI4

Tesla’s manuals have begun calling its driver assistance hardware the “SI Computer,” a quiet edit that could reach the names owners see in their cars. The wording appears in manuals for the Model 3, Model Y and Cybertruck, replacing “FSD Computer” in several places. Tesla hasn’t confirmed a full renaming, so the change signals a possible direction rather than a completed rollout.

The implications are clearest in the Model Y manual, where “SI Computer” now appears in both the driver assistance and climate control sections. The FSD section describes the computer as processing neural networks and making decisions to guide the vehicle to its destination. Separately, the climate control instructions say a feature isn’t supported on vehicles with SI Computer 2.0 or 2.5.

Owners may see the new label in software

The revised manual also directs owners to check their hardware version on the vehicle’s touchscreen: open Controls, then Software, and look for SI Computer. Earlier wording referred to an “AI Computer.” That detail makes the update more than a terminology change on a web page: Tesla’s own instructions now point to SI as the name drivers should expect to find in the car’s software interface.

There’s no confirmation that Tesla has already changed the touchscreen label. Still, matching the manual to the display would be a natural next step if the company adopts the new terminology across its vehicles. For owners, the immediate practical question is whether the label changes while the hardware itself stays the same. The manual edit alone doesn’t indicate a new computer, altered capability or software update.

The affected names could span several generations. Under the apparent scheme, HW2.0 would become SI2.0, HW2.5 would become SI2.5, HW3 would become SI3, and AI4 would become SI4. That would place older hardware and the newer AI4 generation under one naming family, while preserving distinctions between versions.

A naming change with hardware history

Tesla has changed the labels attached to its computing hardware before. The company renamed HW4 as AI4 to emphasize its intended focus, while HW3 retained its original designation because it wasn’t designed with AI in mind. Moving from AI to SI would therefore be another revision to the way Tesla describes the computers behind its driver assistance systems.

That distinction matters to customers because a hardware name can shape expectations about what a vehicle can do. But a new label doesn’t establish that older cars gain capability or that the systems’ performance has changed. Tesla has said HW3 won’t support unsupervised FSD and has outlined hardware upgrades for HW3 vehicles intended to make them compatible with unsupervised FSD. The naming edit doesn’t say whether those plans, or the upgrade path, have changed.

Timing is also part of the context. Tesla vice president Ashok Elluswamy recently said the company could begin rolling out unsupervised FSD by Q2 2027. That reported target places attention on the differences among computer generations, but the manual wording provides no new capability details or confirmation about which vehicles would qualify.

Future chips could follow the same pattern

The potential rename may extend to Tesla’s next computer generation. Its AI5 chip is in trial production at Samsung’s Texas factory; if the new naming convention carries forward, that chip could be called SI5, with later generations following as SI6 and beyond. Those names remain possibilities, not confirmed product labels.

The current evidence is narrow but specific: multiple vehicle manuals have replaced earlier terminology, and the revised Model Y instructions tell owners where to find the computer designation in the car. Tesla hasn’t formally confirmed a full hardware rename, and no performance or availability change is attached to the edit. Owners comparing vehicles should keep using the hardware version and capability information Tesla provides for each model; the next useful signal will be whether SI appears on vehicle screens or in further product materials.