The Challenge Series consists of 68 challenges that the player can complete to unlock extra cars. Half of the challenges are Tollbooth Time Trials and the other half are Pursuit Challenges. The player drives a predetermined vehicle for each challenge and it cannot be changed. Challenges 41-50 allow the player to drive such things as a pizza delivery car, a pickup truck, a minivan, police cars, a dump truck, and a cement truck. There is a code for unlocking an extra challenge, the Burger King Challenge. To be fair, it is hard to figure out how this got it's name, but the start of the race is at a Burger King Restaurant. Even though the icon for this challenge is a tollbooth icon, it is a Sprint race. If you enter this code at the start of the game, then you can play it right away. However, the gift that shows up in a message after the race says you have unlocked every Junkman performance part. However, they will still be locked until you complete ALL the challenges. For the Xbox 360 version, the code for the Burger King Challenge is Up, Down, Up, Down, Left, Right, Left, Right. You need to do this at the title screen, and you press the directions with either the Left Stick or the D-Pad. A message will come up when you enter it correctly. Here, you drive the BMW M3 GTR in a Sprint against 3 others. Heat Level 1 cops show up, and the race is pretty self-explanatory.
The Black Edition Challenge is only available for the Black Edition version of Most Wanted for PC, PS2, and the Xbox, (not the xbox 360). It places you in the wheel of the Camaro SS and you need to evade Supercharged SUVS after getting 500,000 bounty. You can simply turn around and go to the Rosewood stadium, to your right after the intersection, and then hit the pursuit breakers and you are done.