Doing some stunts with your car is something that many would shy away from because it is far too dangerous. Even the brave would fear doing it. Those people doing it are called stunt devils. They are fearless and doesn't care about their lives.
Fortunately, this is just a game so you can try a lot of stunts while you are at the air. Actually, the game requires you to do some flips to activate the booster. This makes you go further in the game. The further you have gone, the more money it is for you. In other words, you earn more money based on how far you are able to go. Use the money to buy some upgrades or a better vehicle.