Mario Kart Tour offers a number of characters and vehicles that you can control during the races. However, at the beginning of the game, you will have only one set. This page will tell you how to unlock more.
Before each race you have to choose a driver, vehicle and hang glider. Initially, you have access to only one such set. Over time, you will be able to unlock new elements. There are three ways to do this. First, the race awards. After collecting a certain number of stars, you will receive a gift. You can check a package's content before you open it.
The second option is a draw. The main menu has an option where for a certain amount of Rubies you can draw a specific bonus. With this option, you can also get items available periodically that are specific to a given city.
The last option to unlock new items is to simply buy them with real money. Packages are released periodically and you can purchase them in the main menu.