Why this is a bad idea....
1) A federally-mandated standard, that will be unduly influenced by the Departments of Justice, Homeland Security and Defense. I'd expect that by the time it is really done there will at least be required firmware upgrades that enable vehicle tracking and deactivation by the government.
2) When was the last time you saw a federally-mandated standard that was truly secure or that was elegantly designed instead of being a hash?
3) The new electronics and probable requirements to upgrade older cars going to markedly increase the cost of cars for the many poor Americans who rely on used cars and already suffer from the high cost/unavailability of transportation.
4) I can think of much cheaper ways to save 1000 traffic deaths annually. Examples: Clearing trees and parked cars from blind intersections. Traffic light-synchronized gates on actual problem intersections. More responsive public transportation and better zoning laws to improve commutes. the last one will also help reduce pollution.
5) Hackers using this to shut down roadways or spoof messages from car to car or insert ransomware.
6) Fix-it tickets because your car-to-car electronics are not working. Oh wait, they are--its the cops' RF detector that wasn't working or being used correctly.