The loss of cellular connectivity of older Tesla Model S vehicles will disable certain remotely controlled functions, which can be prevented by scheduling the affected electric car for a relatively fairly-priced US$200 LTE modem upgrade.
https://www.notebookcheck.net/Older-Tesla-Model-S-vehicles-lose-their-cellular-connectivity-as-AT-T-s-3G-network-shuts-down.603805.0.html
Are there any other car manufacturers that will let you continue to have these functions if the vehicle can connect to the internet thru Wi-Fi of your phone?