Modern cars have several microphones or directional microphones and can isolate a speaker.

I think well-done voice commands are a great addition to a car, especially for rentals. When figuring out how to do something in a new car, I have to choose between safety, interruption (stopping briefly) or not having my desires function change.

Most basic functions can be voice-controlled without Internet connectivity. You should only need that for conversational topics, not for controlling car functions.