The Cars Micro Drifters are sold in a set of 3. I believe there are 6 different box sets that you can currently buy for Micro Drifters. There are also Micro Drifter Playsets including:
Disney Pixar's Cars Micro Drifters Super Speedway
Dinsey Planes Micro Drifters Take-Off Launcher Dusty Crophopper
Disney Pixar's Cars Micro Drifters Mack Case
Disney CARS MICRO DRIFTERS Colossus XXL Car-Chomping Dump Truck
Disney Pixar's Cars Micro Drifters Vehicles - McQueen/Raoul/Mater
Disney Pixar's Cars Micro Drifters Vehicles - McQueen/LPM/Max Schnell
Disney Pixar's Cars Micro Drifters Vehicles - Grem/Professor/Finn
Disney Pixar's Cars Micro Drifters Vehicles - Nigel Gearsley/Jeff Gorvette/Francesco
Disney Pixar's Cars Micro Drifters Rapid-Fire Dispenser
Disney Pixar's Cars Micro Drifters Vehicles - Red McQueen/Octane Gain/Spare O Mint
Disney Pixar's Cars Micro Drifters Vehicles - Gold McQueen/Holley/Acer
Disney Pixar's Cars Micro Drifters Vehicles - Chick Hicks/Clutch Aid/Red McQueen
Cars 2 Micro Drifters Transforming Speedway Fast Flip with Lightning McQueen
Cars 2 Design and Drift Speedway Micro Drifters Hexbug War

Cars MICRO DRIFTERSTM Colussus XXL Car-Chomping Dump Truck*: In DisneyoPixar's Cars 2, kids meet Colossus XXL, a memorable large-scale character most famous for being tractor-tipped. Now, this true-to-scale Colossus XXL can tip others as he scoops up Micro Drifters vehicles with his loader and stores them in back. Dump to release and watch the characters (which feature ball-bearing technology) race, drift and swarm-just like they do in Disney/Pixar Cars! Includes 1 Micro Drifters vehicle. less