There are two types of currency in the game:
Credits ( Cr)
Credits are the basic currency, being given as reward for races and license tests.
Premium Currency ( 
)
Premium Currency
Premium currency is worth 100 times more than credits. Vehicles can be bought with PC, which is 100 times less than credits. However, tuning upgrades are significantly cheaper when bought with PC.
Garage Space can only be bought with PC.