Worked for Ford for 15 yrs. The Ford pass app does deliver alot of info back to FMC for sure. Obviously some data for some for marketing back to you, and some data to be used to "make their vehicles better". Ford dealers can access newer Ford models remotely, due to a "telemetry" module that's in the vehicle network. With this hook up... your check engine light comes on, you can call the dealer. The dealer can remote into your car via his laptop with FMC software, and tell you what the code is. So yes, they can communicate with your vehicle, as long as it has a charged up battery. GM is the same.
I don't know federal guidelines well, but anything having to do with the computer controlled throttle (fly by wire, or TAC) being modified/accessed/controlled is highly regulated and engineered, to avoid situations like someone mentioning above about the throttle control being hacked. And, all manufacturers also build redundancies into the TAC circuits, to avoid any reason for the throttle to accelerate on its own. I've been in lawsuits/depositions, and worked with the NHTSC concerning sudden acceleration events. After all that, when I hear of sudden accell events, I'm already pretty damn sure the cause was not the computer controlled throttle.
Oh yeah, if your car has any type of "lane-keeping" feature, auto-parking or trailer backing feature, you have electric steering. No direct connection between the column and the front suspension. All done with electric motors, and that's how they can control the steering. It's all on a network, and there's multiple networks on each vehicle.