I wasted a ton of time with the starter car stock set-up and then the level 5 car stock set-up wondering what I was doing wrong... barely being able to hit the bronze targets each run through.
From Garage hit "Mods / Swaps" and purchase the drift set-up. The Turbo & Racing set-up will reduce your ability to drift, "Drift" set-up is a game-changer.
I personally recommend running time trials until you have enough coins to purchase the drift setup as it's pretty easy to get gold on time trials and they give a lot of coins each time.