Yesterday, Elon Musk confirmed that FSD V12.5 is being tested on Chuck’s Unprotected Left Turn. This is a big step – as we usually see Chuck’s UPL getting tested a few weeks or months before the release of another set of software.

Chuck’s Left Turn

Chuck’s Unprotected Left Turn, or UPL, has regularly been seen as a challenge for FSD. Chuck’s UPL is a complex, 2-stage unprotected left turn into high-speed traffic. Ever since 2022, Tesla has been testing on Chuck’s UPL, which is in Jacksonville, Florida.

Vehicles are intersecting from different sides at different portions of the turn, making it one that is truly difficult for both humans and for FSD to get right. It can be a difficult challenge for regular drivers, and ensuring FSD gets it right every time Tesla releases a new build seems to have become a bit of a tradition for Tesla.

As such, we generally see Chuck’s UPL getting tested by Tesla’s ADAS testers prior to a new build being prepared for release to employees. These ADAS testers are pretty obvious – they’ve got manufacturer plates on, and the telltale 2-second halt at stop signs.

FSD V12.5 Around the Corner?

Although Tesla is already testing FSD 12.5, it doesn’t necessarily mean that v12.5 is around the corner just yet – there are still plenty of users that still need to receive FSD v12.4.3 before Tesla jumps to v12.5. About 20-25% of FSD users now have FSD 12.4.3, but most are still on update 2024.14.9 with FSD 12.3.6.

FSD v12.5 is expected to begin features such as fleet communication and the merger of city and highway software stacks, to FSD.

What we’re seeing in Florida on Chuck’s turn (Tesla refers to Chuck Cook in release notes) is likely just the ADAS testers working on the early builds of v12.5. As such, don’t get too wrapped up around v12.5 – most are still waiting for nag-free FSD for the most part.