I also assume that as long as the car is in range of a 5G tower, the NSA is able to remotely activate the mic and modem to capture recordings, regardless of a person's location in the world and regardless of whether they're paying for service.
Ditto (eventually) for several other spy agencies around the world.
Given Apple's and Google's emphasis on security, I'm doubtful the same is happening for phones... but with targeted use of zero-days (assuming the right ones exist) it's at least possible in theory.