If you have the funds, head to the Shop to purchase a new car. You can purchase a car outright, or try your luck with the loot crates for a chance to win them. Cars are also available by winning Events.
For a list of available cars, please refer to the Shop in game.
You can also use your Keys to purchase crates. Please check the Crate Drop Rate FAQs for a complete list of what you can win from each crate.