ECUs are one of the most important parts in the game. The ECU determines how much gasoline your car uses per race. The higher the grade and level, the less gasoline you use. This means you can battle more often, increasing your chances in events like boss battles. Low gasoline consumption can also be used to lower the stamina of event bosses that are too powerful for you to win; by lowering their stamina you lower their overall battle power which make them easier to defeat.
ECUs can be acquired from the Daily ECU Event; you can only acquire up to Grade 11 from the Extreme category.
Parts are obtained from Story rewards, CP Orders, Gold Orders and Order Tickets. It is also possible to obtain these parts from the 24 Hour Part Races.