How about this:
For decades, highways have connected large cities and you couldn’t get off them into open wastelands. You were destined to live inside cities and move from one city to another without ever getting in touch with nature. But one day, you and your buddies run into an old guy in a super-junk ride and you see it’s covered with mud. Where did the mud come from? Cities are squeaky clean these days, and there hasn’t been rain in ages under the city dome (did I mention cities are enclosed in a huge-ass dome?
You stop at an intersection and the guy stops next to you. You catch a glimpse of the old man. Long hair, totally hippie looking (not that you’d have any clue as to what a hippie is or anything), very weird. You hear sirens, and the old man blasts though red lights, narrowly avoiding a dog and a lady with a cart (yeah, too corny), and drives away. You see 3 cops vehicles blast by you, as one of you buddies revs up to join the chase. You look at your 3 other buddies, and they nod.
You blast on to rescue the old guy…
Level 1: rescue the old man.
This is a simple obstacle course, and you have to learn how to handle your vehicle around sharp corners, jump over stuff, etc. Kinda like a tutorial course. Cops eventually hit some obstacles, and you shake them off… if you’re good enough.
Once level 1 is complete, you end up at a bar and the old man tells you he is part of a group that has found a crack in one of the tunnels, and a way out into the wasteland. If you’re interested, you can join them.
Level 2: into wasteland
You tail the man as he leads the way towards the exit point. Suddenly, you notice one of your buddies is missing. Where did he go? Turns out he’s a traitor, and he called the cops and bailed. Chase is on. A whole squad is on your tails. You navigate a complex maze of tunnels to shake off the cops. Old man calls you up into the intercomm and tells you about a device that jams the chip cops use to track you. You have to drive through a complicated loop to catch the device that old man throws out of his vehicle. You’ve only got one chance to get it. 
Once you’ve got the device, you have to drive like mad to shake the cops off (so they can’t make visual contact) before you reach the exit. If cops figure out where the exit is, they’ll seal it and it’s game over. You reach the exit, and the old man and 3 of your buddies jump out of a small hole in a wall… into the wide wasteland. Scene is beautiful.
The old guy leads into a nearby forest where he and 12 other men and women have set up a camp.
… And so on.
It’s a bit extravagant, I guess, but I was inspired. 
