Here's a more technical discussion from NHTSA. At page 74-75, the data elements of the Basic Safety Message I and II are listed. The BSM Part I message doesn't contain the vehicle ID, but it does contain latitude and longitude. The BSM Part II message has the vehicle's VIN. So this is explicitly not anonymous.
Back in the 1980s, when Caltrans was working on something similar, they used a random ID which was generated each time the ignition was switched on. That's all that's needed for safety purposes. This system has a totally unnecessary tracking feature.
Most of this stuff only works if all vehicles are equipped. It also relies heavily on very accurate GPS positions. However, there's no new sensing - no vehicle radar or LIDAR. The head of Google's autonomous car program is on record as being against V2V systems, because they don't provide reliable data for automatic driving and have the wrong sensors.
If something is going to be required, it should be "smart cruise" anti-collision radar. That's already on many high-end cars and has a good track record. It's really good at eliminating rear-end collisions, and starts braking earlier in other situations such as a car coming out of a cross street. Mercedes did a study once that showed that about half of all collisions are eliminated if braking starts 500ms earlier.
V2V communications should be an extension of vehicle radar. It's possible to send data from one radar to another. Identify-Friend-Foe systems do that, as does TCAS for aircraft. The useful data would be something like "Vehicle N to vehicle M. I see you at range 120m, closing rate 5m/sec, bearing 110 relative. No collision predicted". A reply would be "Vehicle M to vehicle N. I see you at range 120m, closing rate 5m/sec, bearing 205 relative. No collision predicted". That sort of info doesn't involve tracking; it's just what's needed to know what the other cars are doing. It's also independent of GPS. Useful additional info would be "This vehicle is a bus/delivery truck, is stopped, and will probably be moving in 5 seconds.", telling you that the big vehicle ahead is about to move and you don't need to change lanes to go around it.