Racebreaker is a nitrous refill gameplay mechanic featured in Need for Speed: Underground 2. It works in conjunction with a Nitrous Oxide upgraded vehicle. File:NitrousBarU2.jpg Unlike Need for Speed: Underground, nitrous is no longer limited and can be regained through the Racebreaker feature. It will restore a certain amount of used nitrous capacity upon the player performing driving stunts or giving themselves an competitive edge in a race. The player can fill up to two nitrous bars, with the second bar being highlighted by a brighter colour.