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Car adjusting speed for Speed Limits ?
- Thread starter MrBadger
- Start date
Moderator comment - recent thread merged with an earlier thread on same topic containing a poll that has subsequently been deleted.
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Cardo
Active Member
Unfortunately, the available options don’t differentiate between TACC and AP, which in my experience behave completely differently in response to traffic signs.
True. The different behaviour between TACC and AP only came to light after the poll was originally posted. Its quite an old poll and probably lost some of its initial relevance so I have deleted it. The rest of the thread is still relevant.
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It looks like it's still as inconsistent as ever.. AP changes speed for some people and not others.
Suspect it's mapping related - esp. where limits have changed since 2019 - and you'd only get consistent results from different people on the same road. It's been going on too long to be some kind of minor version difference or a/b test.
Suspect it's mapping related - esp. where limits have changed since 2019 - and you'd only get consistent results from different people on the same road. It's been going on too long to be some kind of minor version difference or a/b test.
SpareHeadOne
Member
I agree that's it's inconsistent, I've definitely had the car slow going into lower limits, but not all of the time.
On top of that it's still having trouble with 50 signs, only recognising them about 20% of the time and not recognising temporary limits in roadworks at all for me.
A little bit off topic, but a 30 road near me has had all of the side roads reduced to 20 and when I pass the first one it thinks the main road has been reduced to 20 - incorrectly reading the limit signs on the side streets as being for the main carriageway. Another nail in the EAP/FSD coffin!
On top of that it's still having trouble with 50 signs, only recognising them about 20% of the time and not recognising temporary limits in roadworks at all for me.
A little bit off topic, but a 30 road near me has had all of the side roads reduced to 20 and when I pass the first one it thinks the main road has been reduced to 20 - incorrectly reading the limit signs on the side streets as being for the main carriageway. Another nail in the EAP/FSD coffin!
Cardo
Active Member
I find it odd that there is such an apparent variation in behaviour. Could it be a difference in hardware? Different FSD computers? As long as I’m on AP, I’ve found the speed lowering to be quite consistent. Though it only happens after going through the limit, which is not ideal.
inimic
Member
Is the basic autopilot supposed to automatically adjust the speed once it detects a new speed sign?
If you have it set to "Speed Limit" rather than "Current Speed". Also note this in the manual:
It's supposed to, but I've never seen that actually happen. Just as well given how inaccurate its sign detection is..
It works for some, so I conclude it's something to do with the mapping - some roads have been marked as adjusting.. just none around here.
Well, yes. But not if TACC was engaged separately first and only if set for speed limit. If it does change, it won’t go faster than the first set speed but will slow albeit too late. if first set speed is 70, it will slow and speed up to any limit including 70.
Some owners report auto speed change on TACC. Mine doesn’t and never has.
inimic
Member
Thank you. I am a new owner and I tried it a couple of times but it did not work. Will check again...
kelvin 660
White SR+ with LFP battery
It works for me, about 70% of the time but you need to set it when travelling at 70mph, for it to be able to down shift to lower speed limits. Then it will up shift back up to a maximum of 70mph (+ whatever offset you have set).
Note: It doesn't always work for overhead gantry speed limits so you have to keep an eye on it...
Note: It doesn't always work for overhead gantry speed limits so you have to keep an eye on it...
Watchout for it detecting speed limits incorrectly. The gantry detection is pretty new (possible that on some new cars it may not even have that version installed yet) and when I recently closely monitored its behaviour on M25 variable speed section, which it detected the gantry speed limit (which it never did until recently), the speed limit detected (so presumably the one that TACC etc will use) would change back to 70 even though the variable speed limit was 70. Weirdly, on quite a few gantries for this to be coincidence, this happened a few yards before the gantry so it briefly incorrectly displayed 70 before almost immediately going to back to the variable speed limit. Speed control wise, it was probably too brief to make too much of a difference to physical speed, but on a few occasions, it changed back to 70 where it would have time to potentially get you into a spot of bother if no other vehicles in front to control your speed.
tl;dr - don't bet your driving license on the car maintaining a legal speed limit.
MY LR AP only, is very unreliable on speed limits change. I developed the habit to hold the gear stalk down when approaching a speed sign and releasing it once passed the sign. This forces the car to change the speed up and down every time. Shame the car doesn’t do this automatically so well
It looks like you've quoted an old post, but mine will do that on some roads, but not others. We have 2 way roads with a 60 limit and it works fine, if you go up a class of road to a divided carriageway (each direction has its own road with a physical barrier between), it stops working for me.
Or you can hold down the right stalk for about 1 second. I find it easier than reaching and tapping the sign on screen.
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