Hot Wheels Unleashed Secrets: How To Unlock Them?

How to unlock Hot Wheels Unleashed Secrets 1 (Unsolved Mystery)?

How To Unlock Hot Wheels Unleashed Secrets 3(Hidden To Most)?

How To Unlock Hot Wheels Unleashed Secrets 4(Covert)?

How To Unlock Hot Wheels Unleashed Secrets 5(Can You Keep A Secret?)