Is it a persistent world game, though?
Actually, I think the meaning of that term got kind of muddled recently. Yes, in most MMOs we have avatars that we return to and level up and keep playing to unlock more things. But the world itself doesn't change much in most games. Sure, you can get some phasing like in WoW, but that's a personal thing. It's like having a slice of single player on your MMO experience.
Uh, I digress. I'm guessing The Crew lets you go around an open world and see other people also driving around and exploring the world? Kind of like a beefed-up Fuel in multiplayer mode, maybe?