In fact, there's a goal for some people in this game. Actually, you control a vehicule you chose, and then you explore the map and drive as fast as they can.
Some people just visit the map, and they enjoy it. Other ones try to get to the end in the fastest time.
But there's the spirit of the game, you do what you want in this game =)
to move the vehicule in the world
To brake, because you may want to go fast, but sometimes you will need to brake ! (Remember, this is just a game, please drive carefully)