Be sure to drive under all exit ramps. The exit ramps them selves don't like to register on the edges so you actually have to drive on the edge of the exit ramp for it to register and most importantly drive all the way to the end of all dead end roads, and pull all the way into all horizon outposts (As I just spent the last 2 hours looking for my last 2 roads and just so happen there was 2 outposts that I Hadn't pulled into but the road was white on the map like it would be if I did drive on it).