Does it matter?
So long as the messages are informational, like "cars a half mile ahead are going 10 mph, prepare to slow down" so you don't top a hill and have to slam on your brakes because an accident caused a traffic jam, that's fine. Worst case, they make you slow down when you don't need to and a miscreant can cause a traffic jam by doing so.
I'd be more worried about the tracking aspects. At least with a cellular connection for something like OnStar, I can clip a wire and disable that. Something like this, it will probably be against federal law to disable it.