Daily missions ... something that should be added at the very beginning.
Missions should encourage spending time in the game. I invite you to provide suggestions on what type of mission should be.
The case also applies to Pixel Trucks.
build a car in class X and complete X (number) of races
spend X time in the game
Car equipped with X part (ride X races) - applies to all types of parts
ride X races
get X experience/money