HW3 vs HW4 FSD in 2026

Same product name, two branches

By mid-August 2026, “which FSD do I have?” is a hardware question before it is a subscription question. Hardware 4 vehicles across Model S, 3, X, Y, and Cybertruck run FSD (Supervised) 14.3.7 on firmware 2026.21.5 and 2026.21.6. Hardware 3 Model 3 and Model Y run FSD 14.1 Lite on 2026.21.6. Both are supervised. Neither is autonomous. Tesla’s own notes say FSD does not make the vehicle autonomous; the driver must stay attentive.

This page is the hardware/software split. It is not a rewrite of Is FSD Supervised worth it in 2026?. For live cards, use fsdupdate.com. FSD Update is independent and not affiliated with Tesla, Inc.

What HW4 is running

The HW4 line’s major stack claims landed with FSD 14.3 on firmware 2026.2.9.6 (April 7, 2026): upgraded RL training stage, upgraded vision encoder, and Tesla’s MLIR compiler/runtime rewrite with Tesla’s claimed ~20% faster reaction time. That 20% figure is Tesla’s published claim, not an independent lab result.

Through spring and early summer, HW4 then picked up mid-cycle product work documented in 14.3.2 through 14.3.4: unified Actually Smart Summon / FSD / Robotaxi model language, intervention-reason feedback, ASS max speed at 8 mph on supported non-Cybertruck vehicles, streak stats, then Cybertruck ASS and destination-parking UI changes. August’s 14.3.7 kept the v14.3 note stack while the rollout and the HW3 Lite branch became the story.

What HW3 Lite is running

Tesla’s Lite notes on 2026.21.6 describe distilling intelligence from HW4 V14 into HW3, unlocking RL and offline-model improvements for HW3 in Tesla’s wording, plus responsiveness and comfort claims, parking/unparking/reversing, Arrival Options, and always-available Speed Profiles. Full detail: FSD 14.1 Lite for HW3, explained.

Lite notes do not claim the April MLIR rewrite or the ~20% reaction-time figure. They do not list the unified ASS/FSD/Robotaxi model, ASS at 8 mph, Cybertruck summon, or the mid-cycle streak/intervention surfaces as Lite features. Distillation is Tesla’s bridge language. It is not a promise that HW3 behavior matches every HW4 14.3.x clip.

Decision table in prose

If your computer is HW4, your August software identity is 14.3.7 on the 14.3 stack, including the spring training/runtime claims and the mid-cycle summon/parking arc unless a specific vehicle (for example Cybertruck timing on ASS) lagged a given point release. If your computer is HW3 Model 3 or Y, your August software identity is 14.1 Lite: distilled HW4 v14 guidance per Tesla, with parking and Speed Profile surfaces called out in Lite notes, without treating Lite as 14.3.7.

Owners shopping a subscription because a HW4 video looked smooth should confirm hardware first. Owners comparing clips should label HW3 vs HW4 in the filename before arguing about “the update.”

What both share

Both branches are FSD (Supervised). Both require attention. Both can improve or frustrate on the same commute for reasons that never appear in release notes. Community praise or complaints about brake feel, lane choice, or summon confidence are owner reports unless Tesla publishes them. We do not invent Tesla bullets to fill the gap.

Where to go next

• Tracker: fsdupdate.com
• HW4 flagship: What changed in FSD 14.3
• HW3 branch: FSD 14.1 Lite for HW3, explained
• August HW4 rollout context: What changed in FSD 14.3.7
• Subscription framing: Is FSD Supervised worth it in 2026?

FSD Update is independent and not affiliated with Tesla, Inc.