Credits: Start with 5,000CR which can buy any starting Derby class car. Minimum CR needed for a starting Race class car is 13,000, the max is 18,000. Minimum CR needed for a starting Street class car is 36,000, the max is 45,000.

The amount of CR you earn in the Derby class is 22,500 + 32500 for completing level 1 and 2. The amount of CR you earn in the Race class is 43,500. The amount of CR you earn in the Street class is 102,000. The amount of CR you earn in the Grand Final is 86,000.

(NOTE: this is just doing the cups, not including the amount you get for going from Level 1 to Level 2, Level 2 to Level 3, or beating all the cups in the certain class. So you will get a lot more, I haven't done testing on Race or Street classes yet)

For upgrades, it is cheaper to buy the highest level of upgrade for your car in the Race and Street class, you don't get additional speed, handling etc. if you buy a level 1 upgrade and then a level 2 upgrade.