If this game's gameplay wasn't so cash shop oriented, maybe I would have kept playing it right now.
The first twenty levels are pretty fine, most of the time you'll be playing with other people who, like you, are simply trying out this game because they're curious...
...Then, if you didn't buy anything from the cash shop, unless you're Takumi from Initial D, I highly doubt you will win any race for a while.
This said, time to give you a few advices :
1) Don't miss a single Treasure Hunt. NOT. A. SINGLE. ONE. (unless there again you have money to spend) This is basically how you will get some of your best gears for your cars.
2) It's not because a car is jzihfugugrhugqly expensive it's a GOOD car. Also, it's not because their stats look better that you will have the best car. Honestly, if you're new to this game, you should ask a piece of advice from experienced players. There are a few... let's call them "hidden mechanics" in this game, that absolutely nobody could guess. Moreover, I've heard they are changing cars quite often now, probably to make people spend their money as soon as possible. how vicious~
3) Going past level 20 without buying anything ? good boy Then just be patient. After 2 months of hunting treasures (probably less if you're lucky. I wasn't.), you should have earned a lot of great items for your Tier C / Tier B cars. At this point, you will finally enjoy this game's races, with a car that can compete against these cash shop "monsters".