Coin (Diddy Kong Racing DS)
From the Super Mario Wiki
Replacing bananas from Diddy Kong Racing, they appear in every course and lie on the road. The player can drive through the coins to pick them up, increasing the amount of money the player has. This allows the player to buy a variety of different things such as unlock new features from Taj on the Wishes Menu. The player can unlock new courses. These courses are Thunder Cove, Meandering Mount, Splashdown Pass, and Strangled Shrine. The player can also upgrade their vehicles, unlock Battle Courses, Coin Challenge, and the Billboard Editor feature.
If a player picks up a green balloon, and uses a Power up token on it, the item turns into 5 Fake Coins.