By videogame standards, The Crew features a fantastically massive open-world to drive around. As you can see in this video that was captured from the PC beta, getting from Miami to Los Angeles takes about forty minutes, and that doesn't account for all the northern regions that never get touched.
It might not take months and years to fulfill your Manifest Destiny in The Crew, but that doesn't mean you won't get lonely. The trip is probably better if you bring a few friends along. Ubisoft would like that, too. After all, it's one of the major premises of the game.