The big question is always: if driving is made safer, will people rely on that and drive more riskily?

Will your system detect loose sand or gravel on the road ahead? If it relies on communication a lot, the first vehicle coming along after such a condition change is bound to be in for a surprise.

If you use a communicating system, the traction data stream is going to offer very fine-grained data about the position of every vehicle on the road. If you want to ambush a certain vehicle, you can do that automatically if you prepare a traction change (i.e. wet the road surface) where your ambush is.

You can also slow down cars by transmitting a fake report about ice on the road.

I am surprised that you care about ebay buyers revealing their bids in advance (in the sniping post) but don't mind revealing to everyone where you and your car are.