When you are in the Build menu, you will see a “+” symbol appear over your Merchandise Building, Garage, and R & D Center. Press “+” and purchase the building upgrade. These buildings can be leveled-up to Level 10. As you level them up, you will see them change in appearance, growing them from humble beginnings to the ultimate race team buildings!
Leveling up these buildings is also necessary to improve performance on the track. For example, to research higher level car parts, you will need to level-up your R&D Center. To increase your hourly revenue, you will need to level-up your Merchandise Building.
Note: You cannot upgrade the Race Building, Store, or Communications Tower buildings.