Giving autonomous vehicles the ability to communicate has a lot of potential benefits: the entire network of cars will be able to operate with more information, making everything more efficient.
That said, I'm struggling to see any form of (useful) communication that doesn't have potential for abuse:
Communicating traffic levels can direct cars to take different routes. This could give a malicious car the ability to create traffic jams and slowdowns.
Communicating your position/velocity/route can cause cars to try and avoid your path. This has potential for causing swerving/accidents.
Fundamentally, if communication is used to improve navigation, then that influence can be abused to influence other car's navigation.
EDIT: To be clear, I'm not imagining a world where cars solely rely on other cars for navigation. Regardless, placing any trust in other cars is trust that can be abused.
What progress has been made in this area? How can cars trust one another in matters of navigation?