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Speed signs not detected by Teslas?


Supporting Member
Jan 21, 2022
Local roads follow a neat pattern that i straight forward to train, a red circle with either 20, 30, 40 or 50 or national speed limit. Motorways have gantries with many different types of digital signs, roadworks signs, central reservations boards, sometimes different speeds for lanes, advisory limits etc. Tesla simply hasn't trained the cars AI to attenpt to recognise UK speed limits on motorways yet.
That’s fair. IMO We have far too many speed limits. On one section of road covering 4 miles near me it changes 10 times. 30/40/50/60/50/30/60/40/30/60. They could easily bounce between 30 and 50 safely.

I’ll give it a go locally again.
It's one of those wierd Tesla things that the speed limits are completely random and confusing. I've *never* had my car adjust for speed limits - always have to do it myself - on both TACC and AP, with or without FSD. But for some people it works.. almost like they have different software somehow, which wouldn't make sense (A/B testing is a thing but not for 3 years...).
The car doesn't adjust for speed limits, unless you are in a side road using Autopilot, where there's a restriction to 5mph over whatever limit that it detects.

So set the speed warning to some reasonable amount over the speed limit (say 2% for UK, and 15% here in the States) and it'll chime when you are going too fast, which is useful if you miss seeing a speed limit sign which the car sees.

IMHO The speed limit recognition isn't good enough to let the car take care of driving at the speed limit, though it is pretty good at keeping you out of trouble.

Fun story: There's a fun bug found driving on highways around Chicago, which has different speed limits for cars, for buses, and for trucks. But Tesla's speed limit sign detection doesn't read the text on the limit signs. Usually the signs are in the sequence above, so within a space of about 50 yds, the car decides the limit is 70 mph (right), 65, then 55. 😱

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