DD6E-440D + D96E-446D Start with $128,000
5D6E-440D + D76E-446D Start with $88,000
6D6E-440D Start with $12,800
C224-CF8F Repair 10% of car for $100
3324-C45F Repair 10% of car for free
C22A-377D Free turbos
D169-443B Start with 6-speed transmission
8B81-34D7 Don't take damage in races

For the last two codes, you must have enough money to buy it.
DC28-348D + DD28-34ED Turbos for $1000
F028-348D + DD28-34ED Turbos for $2000