Discuss: How Your Tesla Really Knows the Speed Limit: It's Not Just Reading Signs

[Not a Tesla App]

Ever wonder how your Tesla knows the speed limit? It's a complex fusion of reading signs with its cameras and relying on detailed map data as a backup.… Read More

How Your Tesla Really Knows the Speed Limit: It's Not Just Reading Signs

Ever wonder how your Tesla knows the speed limit? It's a complex fusion of reading signs with its cameras and relying on detailed map data as a backup.

www.notateslaapp.com

 

[LenF]

I have a 2024 Y, running FSD 14.2.2, and have a real problem with speed. I have my FSD set up to exceed the speed limit by 7 mph. Most of the time, on city streets, I have no problem, and the car stays at reasonable speeds. On the highway, though, I cannot control the speed limit at all. On a 55 mph highway I often travel, it is not unusual for the car, in FSD standard, to drift up to 70 mph, way above what I want. If I move the mode to 'Chill,' the car won't go higher than 57 mph. I have tried a long press on the speed limit sign, but this works for a minute, then speeds up again. I would think that I could control the speed I want the car to drive at, as I was able to do with my 2020 Y. In the meantime, I have to either drive too slowly, risk a serious ticket or don't use FSD on highways.

 

[Procal]

Honestly, I don't know what this article is talking about, getting the speed limit right "most of the time". At least in my case, the speed is right maybe 70% to 80% of the time, even when it had a clear and perfect view of the signs with no glare or anything. Even my 2021 Acura RDX was able to manage getting the speed limit correct 99% of the time, and the only times it didn't were when it was blocked by a car or truck. And let's not even mention how FSD itself recently seems all over the place with speed profiles. I really don't know how they will solve this, or how long it will take, but they honestly need to do something because it is currently FSD's weakest point.

 

[SoMEtesla]

In Maine the state route signs are undecorated, simple white with black band around the outer edge. These are interpreted as speed limits sometimes. There seems to be some filtering for illogical values. There is a stretch of road where the limit is 45mph. The car reads a route 35 sign as the speed limit. Depending on the FSD profile that is selected it either ignores or honors the "35." Sloth and Chill slow down, hurry, and mad max ignore it. I don't recall how standard reacts.