This is not necessarily "the man is taking over your car!" stuff. It could be locational, to let you know if a vehicle is in your blind spot. Or emergency, to let you know the car in front of you is violently decelerating or that the Mack truck behind you just lost his brakes.
If it's extremely short ranged, I'm not overly concerned. Cars already have built in networks, and yes, they can be hacked. Overtime security will generally tighten up. If you essentially make a read only wifi access point with a 100m transmission radius that exposes only some variables, it's not that bad.