You haven't told us your current level of experience. If you are new to programming, to control systems as well as to the Arduino system then a control system for a "real" car is some way off. That would be a tough challenge for an experienced Arduino user.
Without working through a significant number of the examples that come with the Arduino IDE and studying several of the vaguely relevant Threads on the Forum your first big problem will be your lack of familiarity with the jargon. That will make it hard for you to ask for help and to understand the replies.
The Arduino system is easy to get to grips with and it is a great opportunity to learn by doing - trying out the examples and learning how to modify them.
An important thing to understand is that nothing complicated (and certainly nothing like a car control system) is designed as a single entity. The project must be seen as a series of small separate tasks (such as reading data from a sensor, or controlling a valve) which are tested and proved on their own before being integrated into the larger project.
And even the simplest program will have bugs in it. Skill at identifying and correcting bugs is an essential part of programming and doubly important where the computer (Arduino) interfaces with the real world.