You can participate in 3v3 fights if you're in a gang. Each day you get a set of 10 opponents that you need to defeat in order to maximize your trophy count.
 
With each opponent, you fight with all your cars against all of your opponent's cars. You can also arrange the order in which your cars appear in the battle.
 
 
This is how it works:
 
  • You fight against the first enemy car.
  • If you win, you can change the car or leave it.
  • The HP of the damaged car WON'T be restored.
  • If you lose, you have to choose one of the remaining cars.
  • You win the fight if all enemy cars are destroyed.
  • You lose the fight if all your cars are destroyed.
 
 
When you win the fight, you earn trophies, which are added to the trophies of your gang mates to fill the bar of the gang Box. The more trophies you earn, the better gang box you'll get at the end of the Gang Battle round (which lasts for three days).
 
When all 10 opponents are defeated, you can refresh the daily set of opponents for gems and continue fighting for even more trophies, or simply wait for a new round.