After spending too much time on this game i decided to stop playing entirely, and i can assure you it's my best decision this far. Quitting this game however is no easy task. It will take time and effort if you want to get rid of this addiction.

Step 1:
Stop spending money on the game. This will make it much easier to leave the game because you stop forcing value into the game.
No matte how much money you pay in this game, it will never increase the enjoyment "value". Basically what i mean is it wont be much more fun even if you buy the most unbalanced vehicle.

Step 2:
Uninstall the game. This will make it much easier as you can't play the game anymore.

Step 3:
Go outside. Seriously, go outside and go for a run. Training is much more valuable and will eventually be much more enjoyable than sitting inside playing games.