I'm not an expert but my new car has a display on the dash and I cast Google Maps from my phone to it all the time.

So I think what it does is first picks the routes that best meet your search criteria. It almost always picks an alternate route or two. Then as your drive along the route, real-time traffic congestion, accidents, and even radar speed traps appear giving the driver the option of selecting a new route.

It's really really smart and takes into account your personal travel, eating, shopping, and other histories.