Once Coine has built a house in My City, you can bring him the Choro Q coins you've found throughout your adventure for gifts. The gifts are as follows:

Unlockable - How to Unlock
Big Tires - 50 Coins
Hyper Chassis - 80 Coins
Hyper Engine - 100 Coins
Hyper Gear - 70 Coins
Ladybug /Body #84 - 40 Coins
Metal Pad 90 Coins
Pumpkinhead /Body #80 - 20 Coins
Rocking Horse /Body #86 - 10 Coins
Snail /Body #81 - 30 Coins
X3 Steering Wheel - 60 Coins