OP you have a good point that I've thought about often. However, instead of digital communication, what cars lack is optical information about themselves projec

OP you have a good point that I've thought about often. However, instead of digital communication, what cars lack is optical information about themselves projected on the rear and front corners with speed, acceleration, and other metrics. This is easy to retrofit on 'dumb' cars with cheap LEDs, it will provide value to human drivers (as long as the format is standardized, intuitive and easy to read), and it's also valuable for camera-based AI driving, which all forms of driverless cars use. To me, this is something I wish every car would have, so I could tell at a glance if someone is accelerating/braking and their current speed.