This is exactly why Rockstar limits most ground vehicle speed in GTA to ~100mph (even jets travel slower than most cars are capable of in FH4). The higher speeds shrink the world. For reference, the Horizon 4 map and the GTA V map are almost exactly the same size (50mi^2) but, to me, the GTA Map feels larger (and more like a real place) because its far more detailed and the vehicles are much slower. Now obviously constraining speed to arbitrary limits doesn't work for a racing game with licensed vehicles, so the map in an ideal world should be around twice as big to compensate. Maybe next gen with some creative applications of procedural generation. I worry a bit that the Horizon games will never escape feeling like theme-parks rather than real places though.