Earlier quoted context omitted.
> Also, these cars know the speed limits for the road Does it always get this correct, or does it sometimes read a 30mph sign on a side road and then slow the car on the motorway down to that speed?
I'm not sure how the cars know the speed limit. Maybe someone else knows? My guess is combo of GPS/camera to position correctly on road and the lookup of known speed limit data. Perhaps it reads signs though?
It’s hard to imagine how speed limit systems would work without some sort of vision capabilities — a database of speed limits would never be up to date with roadworks and so on.