Tesla owner beats the automaker: retrofits HW4 into an older Model 3 without waiting for promised upgrade

A Polish Tesla hacker, Mike Gapinski, has become the first person to successfully retrofit Hardware 4 (HW4) into a Hardware 3 (HW3)-equipped Tesla Model 3, completing a task that the automaker itself has been postponing for nearly two years. Tesla previously claimed that upgrading millions of cars sold between 2019 and 2023—which were marketed as "capable" of Full Self-Driving (FSD) but later admitted were not—would require a series of micro-factories.

Gapinski used a scavenged Autopilot computer from a Hardware 4 Tesla Model Y, along with new HW4 repeater cameras. He noted that the process was "not as bad as it seemed," requiring only the computer, the cameras, and some light ECU hacking. Crucially, he was able to reuse the existing coaxial wiring in the car by adapting it to the new HW4 cameras with adapters for the factory FAKRA connectors.

The hacker documented the entire process on X (formerly Twitter), showing that the retrofit required very few parts to complete. Tesla had sold millions of vehicles between 2019 and 2023 with HW3 computers, promising they would support full autonomy, but later backtracked on that claim. Instead of waiting for Tesla to build the promised upgrade infrastructure, Gapinski took matters into his own hands, creating a working "Frankenstein" car from a 2022 Model 3 and a Model Y's computer. His success demonstrates that the hardware swap is feasible for individual owners, despite Tesla's earlier assertions about the complexity and cost of such upgrades.