Maybe it uses both? My Honda can tell me the speed limit, and I'm sure it's not using the internet to do it.
How sure are you?
>Daniel Dunn was about to sign a lease for a Honda Fit last year when a detail buried in the lengthy agreement caught his eye. Honda wanted to track the location of his vehicle, the contract stated, according to Dunn — a stipulation that struck the 69-year-old Temecula, Calif., retiree as a bit odd. [...]
>There are 78 million cars on the road with an embedded cyber connection, a feature that makes monitoring customers easier, according to ABI Research. By 2021, according to the technology research firm Gartner, 98 percent of new cars sold in the United States and in Europe will be connected, a feature that is being highlighted this week here at the North American International Auto Show in Detroit.
>After being asked on multiple occasions what the company does with collected data, Natalie Kumaratne, a Honda spokeswoman, said that the company “cannot provide specifics at this time.” Kumaratne instead sent a copy of an owner’s manual for a Honda Clarity that notes that the vehicle is equipped with multiple monitoring systems that transmit data at a rate determined by Honda.
https://www.washingtonpost.com/news/innovations/wp/2018/01/1...
> How sure are you?
Pretty sure. The Honda Sensing display of the local speed limit changes on the dashboard at the instant you pass the sign, it's too exact to be using GPS. Nobody has geocoded the location of every sign in America, that would be too much work. Also, it's often wrong but in ways that you would be wrong if you were just reading the signs. For example, it will switch to 55 MPH speed limit in a 70 MPH zone on the interstate after it sees a sign that is intended for trucks only.
I think the clearest indication that Honda Sensing does not use location data for speed limits is that Honda Sensing is available on cars that don't have GPS at all.
EDIT: Here's info on it. https://www.dowhonda.com/2017/11/17/traffic-sign-recognition...