Hot Wheels: Velocity X

Unlock all cars and tracks:
Hold R1 + L1 and press Circle, Square(2), Triangle, X at the main menu. The sound of an engine revving will confirm correct code entry.
shane rowbotham.

All worlds:
Find the Hidden Key while completing Challenge 18. The yellow key is in the Mines, across a trestle at the end of a tunnel.
Kevin Lewallen.

All cars:
Collect 11 Bonus Stunt items while completing Challenge 8. Note: The Bonus Stunt Items are the purple balls with silver rings rotating around them.
Kevin Lewallen.

All gadgets:
Intentionally hit 25 Barrels while completing Challenge 7.
Kevin Lewallen and LOGONick200.

Laser upgrade:
Note: You must get an "A+" rank when doing the following. Complete all challenges, then unlock the "Timer Speed" cheat. Set it to 10% speed. Change the difficulty level to very hard then complete Challenge 18. Get the "A+" rank to unlock the "Laser Upgrade" cheat.
Kevin Lewallen.

Unlimited ammunition:
Intentionally hit 50 Barrels while completing Challenge 18.
Kevin Lewallen.

Unlimited health:
Intentionally hit 179 Barrels while completing Challenge 17.
Kevin Lewallen.

Unlimited turbo:
Collect 8 Zappers while completing Challenge 4.
Kevin Lewallen.

Timer speed:
Intentionally hit 13 Detour Signs while completing Challenge 15.
Kevin Lewallen.

Gadgets for completing challenges:
sallyr.

Challenge 1: Laser Cannon
Challenge 3: Sonic Boom
Challenge 4: Atom Blaster
Challenge 7: Freon Bomb
Challenge 9: Energy Shield
Challenge 10: Jet Booster
Challenge 13: Super Zapper
Challenge 15: Magnet Mine
Challenge 16: Doom Disks

Underworld Track:
Successfully complete Challenge 2.

Glacier Track:
Successfully complete Challenge 11.

Sewer Pipe Arena:
Successfully complete Challenge 5.

Crankshaft Docks:
Successfully complete Challenge 8.

Treadwell Plaza:
Successfully complete Challenge 14.

Underworld Arena:
Successfully complete Challenge 17.

Sho-Stopper vehicle:
Successfully complete Challenge 6.

Surf Crate vehicle:
Successfully complete Challenge 12.

Krazy 8s vehicle:
Successfully complete Challenge 18.

HW Prototype vehicle:
Successfully complete all missions in adventure mode.