Asobo Studios' FUEL is a toy chest in the middle of a vast playground. It's packed with all manner of cars, trucks, bikes and buggies which you can pull out and play with over the remarkable 5000 square miles of game.
It works like this: in free-roam mode you can jump in any vehicle you've found/bought/unlocked and go exploring. As you zoom around you'll spot things to do - perhaps a race, perhaps a Vista Spot to soak in the 40km-long views, maybe a new vehicle or a whole province full of new challenges.
Stumble upon a career race or challenge, hit Start, select it and the event instances. Races are limited to a certain type of vehicle, specifically those you own within that section. It might be motorbikes, roadsters or trucks, depending on the terrain involved. Pick one and you're dropped at the start line amongst a collection of NPC racers.
It's all about winning fuel, which is the currency in this post-apocalyptic America. And only first place is good enough to get any. Being in pole position isn't just about learning the course - for the most part it's about ignoring the course altogether.
Checkpoints must be passed through, and in between them a floating stream of chevrons flows above your head indicating the designated route. You're under no obligation to take any notice of these, and if you believe there's a better way of reaching the next checkpoint you can go for it. You may discover you plunge straight into a deep stream, or you might find yourself immediately in the lead.