An example of using a command object pattern.

CommandObject.java

import java.util.Scanner;

public class CommandObject {
    
    private static Scanner input = new Scanner(System.in);

    // a stubbed out example of how you can use OO to clean up 
    // how you take user input from the user.
    public static void main(String[] args) {
       Command c = getCommand();
       while(!c.isQuit()) {
           System.out.println(c);
           // .. some other code here ...
           c = getCommand();
       }
    }

    private static Command getCommand() {
        Command cmd = new Command();

        System.out.print("Which car would you like to use?\n");
        cmd.setCar(input.next().charAt(0));

        System.out.println("What would you like to do?");
        System.out.println("  1: Turn the ignition on/off.");
        System.out.println("  2: Change the position of car.");
        System.out.println("  3: Switch cars.");
        System.out.println("  Q: Quit this program.");
        cmd.setFunction(input.next().charAt(0));

        // etc..
        
        if(cmd.getFunction() == '2') {
            System.out.print("How far (negative value to move left)?\n");
            cmd.setLeftOrRight(input.next().charAt(0));
            System.out.print("How far (negative value to move up)?\n");
            cmd.setUpOrDown(input.next().charAt(0));
        } // else if..
        
        // etc..

        return cmd;
    }

    // 'static' in this case means 'as if it were a class defined in another file'
    // or more strictly speaking a 'top-level' class. Normal Java style is to not 
    // have more than one class in a file. I do it here for conciseness of the example.
    public static class Command {
        private char car;
        private char function;
        private char upOrDown;
        private char leftOrRight;

        public char getCar() {
            return car;
        }

        public void setCar(char car) {
            this.car = car;
        }

        public char getFunction() {
            return function;
        }

        public void setFunction(char function) {
            this.function = function;
        }

        public char getUpOrDown() {
            return upOrDown;
        }

        public void setUpOrDown(char upOrDown) {
            this.upOrDown = upOrDown;
        }

        public char getLeftOrRight() {
            return leftOrRight;
        }

        public void setLeftOrRight(char leftOrRight) {
            this.leftOrRight = leftOrRight;
        }

        public boolean isQuit() {
            return function == 'Q';
        }

        public String toString() {
            return "Command{" +
                    "car=" + car +
                    ", function=" + function +
                    ", upOrDown=" + upOrDown +
                    '}';
        }
    }
}