Hello everyone,
I’m an environmental perception systems engineer who frequently tests various intelligent driving and robotic systems. I’d like to share a significant reproducible safety concern I’ve encountered with Tesla’s FSD (Full Self-Driving) version 13. I’m posting this on multiple forums in the hope of raising awareness among FSD users.
The Scenario
I’ve attached a schematic diagram depicting either a T-shaped or four-way intersection with an unprotected left turn. The critical factor is oncoming traffic traveling well above the posted speed limit—for instance, the posted limit is 45 mph, but the opposing traffic is moving at 55–60 mph.
When attempting an unprotected left turn under these conditions, FSD v13 does the following (always):
Root Cause Analysis
From my observations, the core issue is not the gap selection (i.e., when FSD decides to turn) but rather the acceleration profile after the turn begins. FSD seems committed to accelerating to the speed limit rather than adapting to the higher actual speed of oncoming vehicles. When those vehicles exceed the speed limit, reaching only 45 mph is insufficient.
Interestingly, with FSD v12, I found that the same scenario rarely posed a problem. It either delayed the turn or accelerated sufficiently to avoid forcing oncoming traffic to brake.
For everyone using or testing FSD v13, please be mindful of this possible hazard, especially when making unprotected left turns where cross traffic frequently exceeds the speed limit.
Testing FSD Ver. 13.2.8
Testing Vehicle: 2024 Model X
I’m an environmental perception systems engineer who frequently tests various intelligent driving and robotic systems. I’d like to share a significant reproducible safety concern I’ve encountered with Tesla’s FSD (Full Self-Driving) version 13. I’m posting this on multiple forums in the hope of raising awareness among FSD users.
The Scenario
I’ve attached a schematic diagram depicting either a T-shaped or four-way intersection with an unprotected left turn. The critical factor is oncoming traffic traveling well above the posted speed limit—for instance, the posted limit is 45 mph, but the opposing traffic is moving at 55–60 mph.
When attempting an unprotected left turn under these conditions, FSD v13 does the following (always):
- It initiates the left turn.
- It then accelerates only up to the posted speed limit (e.g., 45 mph).
Root Cause Analysis
From my observations, the core issue is not the gap selection (i.e., when FSD decides to turn) but rather the acceleration profile after the turn begins. FSD seems committed to accelerating to the speed limit rather than adapting to the higher actual speed of oncoming vehicles. When those vehicles exceed the speed limit, reaching only 45 mph is insufficient.
Interestingly, with FSD v12, I found that the same scenario rarely posed a problem. It either delayed the turn or accelerated sufficiently to avoid forcing oncoming traffic to brake.
For everyone using or testing FSD v13, please be mindful of this possible hazard, especially when making unprotected left turns where cross traffic frequently exceeds the speed limit.
Testing FSD Ver. 13.2.8
Testing Vehicle: 2024 Model X
