Blueprints are used to upgrade different parts of your car and improve your car's overall performance. 

There are 4 grades of blueprints: white, blue, yellow and black (the highest one). Higher-grade blueprints usually result in better performance.

Blueprints drop from winning different races (Underground, Toyo, Live Races, and so on).
You can also buy blueprints on the in-game market.
To use blueprints:
  • After receiving the blueprint, you can find it in your Storage (Garage -> Items). You will also see it when you enter the Upgrade section in your Garage. 
  • If you've got the cash and kits required to install the blueprint, go to the upgrade section of the car and parts. You should see the blueprint icon on the bottom - just tap it and click install!