As Tesla prepares to deploy its most advanced Full Self-Driving (FSD) software yet—FSD V13—key differences between the company’s HW4 and older HW3 hardware are becoming increasingly clear. With FSD V13’s massive neural networks exceeding HW3’s computing capacity, Tesla is beginning to signal the end of the road for vehicles equipped with the legacy hardware.
FSD V13, currently exclusive to HW4-equipped vehicles, features a dramatic increase in neural network complexity. Tesla hacker Greentheonly revealed that Node B, which handles the core end-to-end driving logic, expanded from 2.3 GB in FSD V12 to 7.5 GB in V13. This major leap explains why HW3 vehicles—now limited to FSD V12.6—can’t run the latest software due to memory and processing constraints.
Although Tesla previously claimed HW3 still had room to grow, the scale of V13 has changed the equation. Tesla has acknowledged that HW3 updates will now take a backseat as developers prioritize HW4 and future-proofing their AI models. While some neural networks remain shared between V12.6 and V13.2, each build has now effectively split into its own path—V12.6 for HW3 and V13+ for HW4 and beyond.
Tesla has promised HW3 owners who purchased FSD a free hardware upgrade, but only if Tesla can no longer push updates to HW3. For now, Tesla continues to maintain a lighter, optimized FSD model for HW3 to try and deliver comparable performance within its limited hardware envelope.
Looking ahead, FSD V13 may already be pressing against HW4’s technical limits. Tesla has hinted that AI5—the next-gen hardware expected in late 2025—will offer even more computational power. It’s unclear whether AI5 will launch with the Robotaxi network or follow afterward, but Tesla is confident enough to plan the rollout of Unsupervised FSD in Austin this June, likely using HW4.
With HW3 nearing its cap and HW4 showing signs of strain, Tesla’s future in autonomy may hinge on AI5. Until then, owners with HW4 hardware remain on the leading edge, while HW3 vehicles may soon require upgrades to stay in the race toward full autonomy.
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