Street Parts can be bought with In-game Cash from the Performance Shop.
Race Improved and above parts can only be obtained from Lucky Draw, Card Packs and Treasure Hunt.
On May 1st, 2012, Cash rewards were increased by up to 100% across all game modes and all driver levels, allowing players to level up faster, and gain quicker access to new cars.
On September 5th, 2012, Cash rewards were increased again by 50% on all game modes and all driver levels. The reason for this increase is because of the Car Classes update on August 21st, 2012 which included the inflation of prices of most In-game Cash cars. The community was frustrated due to this because the cars were priced too high.
On December 14th, 2012, Cash rewards were increased yet again by 20% for Class-restricted events, and they were doubled until January 9th, 2013.