Important: You won't be able to reset your character while inside a car. Just exit your car to reset.
Your next car will depend on your favorite way to grind, and your skill as a driver. The three cars you should choose from are the Chevron Cruiser, the Bull Striker, or the Mazama RTX.
How do I spawn a car? There's a "Spawn" Button on the right of your screen. Click that and it should show a list of your cars. Click the one you want to spawn. If there's not enough space, you won't be able to spawn a car. Move to a more open location.