A 2022 Model 3 has been shown driving with Hardware 4 in place of the HW3 computer it left the factory with. The conversion was done privately and demonstrated on X, and the builder's summary is pointed: Tesla "could have done it ages ago".

Tesla has been promising roughly two million HW3 owners that exact upgrade since October 2024. It has not yet performed it on a single customer car.

What the conversion involved

By the builder's account, the work was narrower than Tesla's description of the same job. The FSD computer was replaced and a limited set of ECU changes were made. Rather than replacing every camera cable, the existing camera connections were adapted. Tesla's stated reason for the delay is that this cannot be done cheaply; the demonstration argues at least part of it can.

What it did not show

The caveats line up uncomfortably well with the parts Tesla says are hard:

  • No demonstration that Tesla's production AI4 software can be fully provisioned and operated in a converted 2022 car. A computer that boots and drives is not a car running the shipping stack for its hardware generation.
  • No evidence on long-term cooling. AI4 draws more power and rejects more heat than the unit it replaces, in a car whose cooling was designed around the older part.
  • Questions about fitment and the exact camera adapters remain unanswered.

Cooling is not a theoretical concern on this platform — TeslAnt has covered HW3 computers overheating under FSD v14 Lite, and that is the older, cooler chip.

So the hardware can be made to sit in the car and drive it. Whether a retrofitted car becomes a functional HW4 car is a separate question, and this does not answer it.

Why Tesla says it is hard

Tesla's position has been consistent: this is not a simple computer swap. The company says an HW3-to-AI4 upgrade needs the higher-resolution HW4 cameras, a new vehicle computer, and an extensive overhaul of the internal wiring harnesses to carry the additional bandwidth. AI4 also has different dimensions, power draw, cooling requirements and connectors from the unit it would replace. Tesla has discussed building dedicated mini-factories purely to perform the upgrades at volume.

The commitment has held while its shape kept moving. On the Q1 2026 earnings call Musk confirmed that HW3 will never achieve unsupervised FSD and repeated the free-upgrade promise for owners who bought FSD, without attaching a date. By the Q2 2026 call the plan had shifted again: rather than fitting AI4, Tesla may skip it and wait for its next-generation AI computer.

Why European owners in particular

This is the live legal question on the continent. The European HW3 claim against Tesla has passed 7,900 owners, built on the argument that FSD was sold against hardware that cannot deliver it. Every month without a performed retrofit strengthens that case, and a third party demonstrating a conversion in a garage does not help Tesla's account of why none have happened.

It cuts both ways. A private conversion carries none of Tesla's obligations: a retrofit that works across every HW3 build variant, survives a decade of thermal cycling, keeps type approval intact and can be performed thousands of times a week. One car on adapted connectors clears none of those bars.

What to do with this

Treat it as a demonstration, not a product. It cannot be bought, and attempting a conversion privately would risk both the warranty and the car's road-legal status.

What it usefully does is narrow the argument. The obstacle Tesla describes is cost, scale and validation across two million cars — not the raw impossibility of getting the part to work in the car.