How does the car know what the speed limit is?

[David Gross]

By regional roads do you mean local/non-controlled access roads?

Because AP isn't intended for use on those in the first place.




From the owners manual-



Sounds like you have it set to "current driving speed"

To change it-

The speed limit sign in the display can be useful if the driver enters a road and the next speed limit sign is not for a while, but how does the car know what the speed limit is?

Is it through interpreting speed limit signs seen by the cameras? If so, then that has the same limitation as a driver would if entering a road where the speed limit signs are widely spaced.

Or is there some "crowdsourcing" mechanism where the cars report speed limit signs seen to some sort of central database that cars can look up when they enter the road?

Just got my new Y on Hawaii Island. I noticed the display picks up “minimum speed 40mph” as the speed limit, changing it from the actual speed limit of 55mpg that had just been posted. I assume that is a software glitch from the camera…..

 

[EdSt]

Its in the navigation data, just like it is in Waze and other navigation that know speed limits and one way streets.

 

[Flybyglass]

Originally, the cars data base had the speed limits and not always correct. About a year ago, an update had the vision read a speed limit sign in addition to data base if no sign present. Watch closely as approach a speed sign and observe the change as passing. GPS is not always that accurate to reply solely on database. You can also now enable a chime to alert when a speed limit changes. Useful on cross country trips with constant highway speed limit changes.

 

[David Gross]

Originally, the cars data base had the speed limits and not always correct. About a year ago, an update had the vision read a speed limit sign in addition to data base if no sign present. Watch closely as approach a speed sign and observe the change as passing. GPS is not always that accurate to reply solely on database. You can also now enable a chime to alert when a speed limit changes. Useful on cross country trips with constant highway speed limit changes.

Yes, got that - thanks. The problem is the AI that governs the info that the camera picks up, should be filtering out a sign that says "MINIMUM SPEED 40" as that is not the speed limit.

 

[Knightshade]

Yes, got that - thanks. The problem is the AI that governs the info that the camera picks up, should be filtering out a sign that says "MINIMUM SPEED 40" as that is not the speed limit.

Latest FSDBeta release notes specifically call out improved logic in this area

 

[RCAF 73]

The other day I got a speeding ticket. The issue I have is that when on Auto pilot or Cruise Control the car seems to read the speed limit signs and does not reset the cruise control setting automatically. Is this normal for those of us without FSD as I can only assume that in FSD the change in speed limits is recognized and implemented in the car. I know that when driving without aids the car reads the sign and indicates the max speed on the screen jsut as you pass it. I guess the question really is where does this data come from? The gripe I have is that the car does not always read the signs ( in construction zones when the signs are the same as on a normal highway without construction} but I assume uses positional data to indicate the maximum speed and I suppose this comes from Google maps. So does the car read speed limit signs at all or is it strictly positional data from Google maps? I often use cruise contro; in the city to avoid speeding but in the latest case the sign was not read and the Cruise speed was not lowered to the speed limit. This is a glitch that needs to be fixed in my opinion as the cameras need to read the signs and the car needs to comply with the reading. It does read the Green light for instance so what is going on and what is being read from the cameras and implemented in the car??

 

[rpiotro]

I can cruise on the freeway all day long at 90 MPH in a 70 zone. Can you imagine if the cruise control would limit you to the posted speed limit? Would you prefer that? The speed control is up to the person behind the wheel.