A free program for Android, by Game Tap.

Mega Ramps Ultimate Car Races is a car stunt game with a very intuitive interface. You just need to tap the screen to select a car and drive on an impossible track. As you drive, you will collect coins and the more daring you are, the more dangerous the track will be. If you get caught on a track, you will lose all the coins you have collected. 

In Mega Ramps Ultimate Car Races, you will have a huge variety of vehicles to choose from. Each vehicle has a different speed, defense, and strength. You will also have the freedom to drive on different impossible tracks. This game is a lot of fun and is easy to pick up and play.