The Slot Machine is a way to obtain different rewards throughout the 3 Smashy Road games. The rewards available change between the games. In Smashy Road: Wanted, only Vehicles are available. In Smashy Road Arena, Vehicles, Weapons and Colors are available. In Smashy Road: Wanted 2 Vehicles, Characters and Upgrades are available.
The rarities of all these rewards are similar to all other objects in-game: Common, Rare, Epic and Legendary. The Slot Machine normally costs 100 Cash to spin, but with a special purchase of real-life currency, it can cost 50 or even 25 Cash. It can also be 'upgraded' by purchasing new slot machines in Smashy Road: Wanted 2.