Computers assisting but not supplanting people's natural abilities is one of the utopian visions of how to use technology. GP's idea seems brilliant and the only downside is that 2020 has shown that lots of stupid people would proudly boast how they ignore the warnings or pump the statistics in the wrong direction. They would probably get a catchy name for themselves too.
Our brains are kinda specialised to process information at that speed, not at cars speeds.
Having an augmented reality is definitely useful, the same way it's useful for you to have access to maps with realtime location in your phone while walking in the city. Why don't you use your brain and navigate solely through memory? You could still do it, why use a smartphone for navigation? Because it helps.
The same is the case for augmenting information you have, in a car it can be quite useful if you end up missing a sign for the maximum speed (as I've done through Germany in some Autobahn stretches that change speed, most of the times due to construction). The same is the case of giving more spatial awareness through data, who is around you? That is the most basic skill you need as a driver, if there are systems to feed you this data in a quicker and more processable way rather than relying on other people's ability to maintain their attention to be checking their mirrors and keep awareness of their surroundings all the time, so be it. I do it all the time while driving, I don't trust others do the same.
So you know, you could also use that brain a bit more.
The idea suggested is interesting. Some of it I solve by a regular navigation app. But looking at this screen on my right may not be the ideal experience.