Gold Coins
When you have passed level 6 you will start to be rewarded gold coins. Gold coins are earned only by finishing each quarter of a series, advancing to a higher driver level, completing Game Center/Google Play Games Achievements, or by watching 15-30 second advertisements that are available in-game.
Real Dollars (R$)
You will earn R$ when you complete races, advance in a series, complete laps without leaving the track or bumping into other cars, hiring the Manager and racing on consecutive days in a month via online check in method. There is also the option of buying it using real world money.