Adapt self driving car logic to people-driven cars.
Could you mount a GPS like screen or maybe some audible things audible speakers or alerts or something in a car that a human is driving? And then use those to indicate to the human this is what the machines about to do this is what you can do etc.?
That way we could speed up stop signs and intersections and all that. All of these things could be mounted in existing cars, like XM radio's or any other kind of radio and they could transmit your position in your speed and where you're trying to go and it would be picked up by the network in the road or the network of cars around you and they would all communicate with each other and work out the logic of what needs to happen in the intersection.
Then you could even building logic that tow would tell everybody that a higher priority vehicle is coming and you need to pull over now. Or that you're being pulled over by police officer and you get an indication in the vehicle that you need to pull over the next parking lot for right now on the side of the road or whatever.
It could be like ADS-B in the airplanes or TCAS and we could all communicate with each other either driver or driver less and hopefully make things safer on the roads as well as make things or more clear a little more communicated out to the the rest of the world as to how busy roads are and what's happening and all that.