Win Streaks allow you to get Crowns for your Supply Boxes. 1 Crown is rewarded for a Win Streak of 5 battles. The crown automatically appears on a random supply box in the garage (only if the box is not unlocked yet).
Each box can have up to 3 crowns. Each crown increases the quality of a random part when the player opens the box (gives +1 star).
Quick fights allow you to win supply boxes: regular ones and superboxes. Superboxes drop randomly. You gain a new box each time you win 3 fights, not necessarily consecutive fights. You won't be able to get more boxes when all the slots are full.