Choose the VW New Beetle Dune. Go to the large grassy area that has the pond. Near the bridge that is over the pond, there is a building that resembles a needle pointing towards the sky (it has small sloped sides). Go around the big pink building at full speed and face the needle building. Accelerate and hit the needle building from a side and you will start to flip rapidly. You will keep flipping until you land on your wheels.