Speed limits

[vitesse]

I'm mainly interested in AP1 experience of this topic but it would be good to know how AP2 differs. In any case, on Facebook I'm getting a confusing response to the question:

* If a speed limit sign is recognised and it's incorrect (I find this happens, for example, with side street speed limit signs or when the subsequent change in speed limit is not sign-posted) is it possible to cancel the speed limit perceived by the car?

I asked this question because we've been trying the speed audible limit warning (bongs) but the speed limit registered by the car is wrong much of the time.

And there seems to a split opinion on whether Cruise or full AP actually adjusts the car's speed according to the recognised speed limit. I have not experienced this happen - should it/can it?

 

[12Pack]

One of my initial regrets going on to an AP2 car was the speed limit display. My perception was that the AP1 had been very reliable at least around my neck of the woods. Are you saying that is not the case for you?

AFAIK, no way to manually reset or correct the speed limit the cars sees.

 

[DJP31]

That’s pretty easy from an AP2 POV. It never gets it wrong because it doesn’t read the signs.

 

[vitesse]

One of my initial regrets going on to an AP2 car was the speed limit display. My perception was that the AP1 had been very reliable at least around my neck of the woods. Are you saying that is not the case for you?

AFAIK, no way to manually reset or correct the speed limit the cars sees.

It's very good at reading the speed limit signs which is great on smart motorways and when encountering temporary road work speed limits. However, if there is no sign when the limit changes up or down, then the car's knowledge of the current speed limit is incorrect. It can also read the limit signs on side roads you're passing, rather than turning into.

And some AP1 users reckon their cars will change speed according to the limit changes while others (me included) are very puzzled by that!

 

[WannabeOwner]

hether Cruise or full AP actually adjusts the car's speed according to the recognised speed limit.

I don't do it enough to know the foibles, but I think there are some. So all this subject to some experimentation to verify.

On country A-road here (Limit = 60 MPH) I set it to 60 (plus my 3 MPH offset). On SOME A-Roads it will not tolerate that, and will (after a bit) drop back to [can't remember exactly] 45 MPH maybe? (and I get a "Speed limited on this road for safety" type dashboard message)

But assuming it doesn't do that when I come into the 40 MPH limit SIGN for the village the car will slow to 40+3 MPH, and then speed up when it comes out of the limit (which, actually, is a bit alarming and isn't safe in this particular instance)

If I start my journey inside a 30 MPH zone then the car will NOT speed up when I come out of it.

If I am on motorway at 70 MPH and come to a reduced speed sign the dashboard will change to show it, but I do NOT think?? that the car slows. I can long-pull the AP stalk to adopt that speed; then the car will NOT speed up when it comes out of the limit (but, again, once the Dashboard has changed back to show 70 MPH I can long-pull stalk to change back to that).

It's very good at reading the speed limit signs

not the one near me which has a nice 50 MPH Roundel and then under that "In 1/2 mile" ... Car slams on the brakes and of course no one behind me is expecting that !!

 

[vitesse]

...when I come into the 40 MPH limit SIGN for the village the car will slow to 40+3 MPH, and then speed up when it comes out of the limit (which, actually, is a bit alarming and isn't safe in this particular instance)

That surprises me - so maybe there is some auto speed changing in some limited circumstances? I'll have to look out for that scenario...

...not the one near me which has a nice 50 MPH Roundel and then under that "In 1/2 mile" ... Car slams on the brakes and of course no one behind me is expecting that !!

Again - I don't recognise this; apart from when a car in front slows, I don't recall the car slowing unless adjusting the cruise speed down using the stalk. I'm not saying you are wrong - I just don't recall this ever happening, so I will be looking to reproduce that as well.

As I often say - I'm still learning!

 

[cezdoc]

Another AP1 anecdote to add to the mix. I use TACC and occasionally AP on urban roads (I'd prefer a speed limiter but TACC can approximate that). TACC doesn't seem to be affected by what the car *thinks* the speed limit is. AP apparently does reduce the cruising speed if it thinks the limit is lower than the set speed (and a warning message comes up); there is one specific section where the car reads a 20 mph limit on a side street about half the time, and if AP is on it will reduce the speed accordingly.

AP1 can be a bit flakey in this respect, I certainly drive with my left hand ready to cancel/reset the cruise speed if I'm using AP on a stretch where it might pick up incorrect speed limits. TACC is simpler but arguably safer to use for controlling the car speed.

I haven't tried putting the audible limit on, I just get a bulging speed limit sign which is much easier to ignore/miss.

AP1 used to pick up crazy limits like kmh labels on trucks, or speed limits on parallel railway lines, but that was back in the day when Tesla was still updating it and I think they ironed out obvious limit detection errors.

 

[WannabeOwner]

maybe there is some auto speed changing in some limited circumstances?

My best-guess is that on a non-70MPH-motorway the car will slow for speed limits (and speed up again) but on 70MPH motorway it only changes speed using the stalk

It definitely has different behaviour based on whether it is a high-speed road ... or not ... so the two go together, so-to-speak, I'm just not sure of what the deciding factor is that causes it to be doning A or B mode.

I will be looking to reproduce that as well

Just to be clear: its a regular speed limit sign, but with the text "In 1./2 mile", and of course the car does not read the text ... and assumes it is a speed limit sign.

Actually, thinking about it ... that IS on a 70 MPH road, so I wonder if just the Dash changes, and no actual braking. I can't remember ...

apart from when a car in front slows, I don't recall the car slowing unless adjusting the cruise speed down using the stalk

I think that may be right for 70 MPH road (but all of them? in all circumstances? Not sure about that ...)

And maybe something different for national speed limit 60 MPH rural single-carriageway roads (when you come into a 30 MPH / 40 MHPH village / town speed limit)

I don't use AP except on Dual Carriageway, so haven't really paid much attention - except that for my Mates Demo I put it on AP on the A-Road near the house, car then slows down for the 40 MPH limit coming into the village, takes the very tight double-bend in the village, and then comes out of the speed limit and speeds up - I know it does that 'coz that's the "Car just drives itself, you ought to get one" pitch that I make each time - with my tongue firmly in my cheek

 

[WannabeOwner]

AP1 used to pick up crazy limits like kmh labels on trucks, or speed limits on parallel railway lines, but that was back in the day when Tesla was still updating it and I think they ironed out obvious limit detection errors.

I can see how that would happen but I don't remember ever having that happen to me, so i guess that was fixed a while back