Gordon Johnson, an analyst at GLJ Research, is waving a big red flag over the latest data on Tesla Inc. (TSLA)'s Full Self-Driving (FSD) software. He's not using Tesla's own numbers, but data from a third-party FSD Community Tracker that measures something called "city miles to critical disengagement." Think of it as a key safety benchmark: how far can the car drive itself in complex city environments before the human driver has to urgently take over to avoid a problem?

According to Johnson's analysis posted on X, this metric has cratered. It peaked at a respectable 4,109 city miles per critical disengagement back in October 2025 when FSD version 14.1 was at its best. But after the rollout of version 14.2, that figure plunged to just 809 miles. That's a sharp deterioration by any measure. Notably, CEO Elon Musk has personally interacted with this same community tracker data that Johnson is citing, adding another layer of intrigue to the numbers.

Putting Tesla's Numbers in Context: The Waymo Comparison

Johnson didn't just stop at the alarming drop. He put Tesla's new, lower number in a context that makes it look even more concerning. He points out that Alphabet Inc. (GOOGL)-backed autonomous vehicle company Waymo did not remove safety drivers from behind the wheel in its vehicles until its system could reliably go 30,000 city miles between critical disengagements.

That creates a gap of more than 37 times between the two platforms on this specific metric. It's a comparison that raises hard questions about the relative maturity and safety readiness of the two different approaches to self-driving technology.

The Regulatory Question: Where's NHTSA in All This?

Perhaps the most pointed part of Johnson's analysis is the direct question he raises about oversight. He's essentially asking why the National Highway Traffic Safety Administration (NHTSA) is allowing a system with these reported performance characteristics to operate on public roads.

For its part, Tesla has published its own safety data. In February, the company said its Supervised FSD has driven over 8.2 billion miles, with 3 billion of those in city driving. Tesla claims this system causes "7X" fewer major collisions versus human drivers. It's a compelling statistic, but Johnson's analysis focuses on a different, more granular metric of system performance and reliability that appears to be moving in the wrong direction.

Tesla shares were down 1.94% at $389.03 at the time of the original report on Monday, according to market data.