Face Lara exactly north. Go to the inventory screen. Press and hold W, E, A, P, O, N, S for a moment, then release. Lara'll will scream if you got it right. This will gives you access to the secret level.
Life is good.
While in Lara's home, press R2, L2, L2, R2, L2, L2, L2, L2, L2, L2, R2, L2, L2, L2, L2, L2, R2, L2, L2. You can now enter the Racetrack. Walk one step forward , then take one step backward, turn around 3 full times, and lastly make Lara do a Forward jump. This causes Lara to explode up into many little chunks. L2 - again, you'll know when it has worked.