Tesla FSD v14.3.9 Adds Automatic Collision Evasion for Manual Driving

Tesla’s Full Self-Driving stack usually waits until you enable it. Automatic Collision Evasion (ACE) flips that assumption. Per Tesla Oracle’s September 12, 2026 report, Tesla started a limited rollout of FSD (Supervised) v14.3.9 on firmware 2026.27.6 for Hardware 4 cars, with FSD v14.2 Lite for Hardware 3 on the same firmware train.

What ACE is allowed to do

Tesla’s release notes, as quoted by Tesla Oracle, say ACE activates Full Self-Driving (Supervised) to try to keep the vehicle safe and then continue driving. It can engage while you are driving manually when: (1) a frontal collision is imminent and braking alone may not avoid it, or (2) the car detects you are not sufficiently attentive (example given: reaching toward the back seat) or that FSD may have been unintentionally disengaged. Owners are pointed to the Owner’s Manual for details.

Rollout reality check

The first 2026.27.5 wave was quickly superseded by 2026.27.6. As of the September 12 write-up, distribution was still limited—Early Access influencers and experienced owners—with wider release gated on safety confirmation and fleet telemetry. That is normal Tesla caution language; it also means most owners should not assume ACE is already on their car.

Other v14.3.9 notes that matter

Beyond ACE, the notes cite an upgraded reinforcement-learning stage, a stronger vision encoder for rare/low-visibility scenes, a rewritten AI compiler/runtime claiming ~20% faster reaction time, better emergency-vehicle and school-bus handling, Actually Smart Summon max speed raised to 8 mph (13 km/h), and a unified model path across Summon, FSD, and Robotaxi. Upcoming items listed include broader reasoning and pothole avoidance—promises, not shipped features.

Rocks take

ACE is the headline because it intervenes during manual driving, which is a bigger product and liability conversation than another supervised-city-streets polish. Treat Early Access notes as directional; wait for wide-release changelogs and independent near-miss videos before calling it a solved AEB replacement. Source: Tesla Oracle.

Manual-drive intervention is a product boundary shift

Traditional AEB brakes in a straight line. ACE, as described in Tesla’s notes, can hand control to the supervised FSD stack to evade and then keep going. That is a larger behavioral change than another “improved unprotected left.” It also raises the bar for explainability: owners will want cabin recordings and clear UI cues whenever ACE fires, especially in the inattention scenario where the system decides you were not watching the road.

Teslarati’s parallel September coverage on FSD v15 safety ambitions (earlier hazard prediction, faster reaction) shows Tesla is messaging a multi-version safety ladder—ACE on today’s 14.3.9 train, bigger architectural claims on v15. Until wide release, treat influencer Early Access clips as anecdotes, not a substitute for Tesla’s own safety report tables.

FAQ

Does ACE replace Autopilot/FSD subscriptions? Coverage describes it as part of the FSD Supervised v14.3.9 package on HW4—confirm entitlement in your car’s Software UI.

Is HW3 included? HW3 gets v14.2 Lite on the same firmware; ACE is called out for HW4 in the report.