Sense we currently have smart phones that have maps gps etc.... As of right now the GPS is pretty useless except for the bearing which can also be found on compass....
It would be nice to be able to zoom in and out on the gps (seen it work in a mod) as well as show other team mates who also have gps on their person. This seems much more realistic and modern. Especially sense the setting of the game is in the future. We should also be able to set way points on map that show up on gps (similar to navigation) If possible even multiple way points in which you can connect for specific routes. Which on gps would end up looking like somewhat of a constellation if you zoom all the way out on gps. With that being said the lines connecting the way points could be colored accordingly(as they can be for markers) for team colors (red team, blue team, etc)
As for ground vehicles the route should work exactly like a normal navigation system where it follows the fastest route (on road) and will recalculate once another route closer is found (if you decide to drive off the designate route)
This will definitely help for drivers who don't want to keep opening the map to check which way to turn at each fork. This may also help for using AI to follow certain routes on a road you would like.
Perhaps using Yellow for vehicles would help as well as a paint marker you can use to fill road routes for vehicles you are sending out.