The easiest way to do a Barrel Roll is off the Barrel Roll ramps or Split ramps as they are called in the game. These ramps can be found throughout Paradise City. If you hit the left (or right) bit that is sticking up on these ramps with the left (or right) set of wheels it will make your car spin into a barrel roll. You can use your left stick to straighten out the roll. If your car has enough speed when you hit the ramp you can perform double, triple and even quad barrel rolls.
