Planet 51

You unlock vehicles by completing tasks, and by progressing through story missions. There are also 2 unlockable vehicles that are shown on the collectable map bellow. For those two cars simply enter the vehicle and drive it to the indicated destination, and the vehicle will be yours. If you complete all of the tasks in the game prior to doing the missions in the “Desert” you will unlock your last two in these missions. In fact the very last vehicle unlocks after finishing the final mission in the game. If you have done everything mentioned above, the achievement will unlock right after the “Complete all the Desert missions” achievement unlocks.