Sorry Sprout ...
The radar bit has already been worked on, by Mercedes-Benz I believe, in conjunction with 'cruise control' and braking. So to speak, an intelligent cruise control. It works fine ... in very limited situations. It's something like what was tried years back with automatic headlight dimming - let the electronics do the job.
Only problem was, even when it came to the relatively simple task of deciding whether or not to dim the headlights, there wasn't sufficient discrimination. So, even now, about some twenty years later and with a lot more computing power, you don't see cars with automatic headlight dimmers (at least, not that I'm aware of).
The ability to be situationally aware of all the traffic around your vehicle and properly anticipate what has to be done when things change quickly is something that most drivers have difficulty with. The most common response is to 'stand on the brake' - which usually leads to complete loss of control, thus the development of ABS. An improvement that permits the driver to maintain steering control, but is still not up to all situations.
To develop a computer system, based on radar, that would be situationally aware to the degree required is, at least for now, rather impractical. Now if you're talking about putting cars on 'electronic rails', that has been done. And it works, but again under limited circumstances, like on limited access 'super' highways, but not on general access roads - too many variables.
'fraid you're going to have to come up with a better idea.
)