Question Car control question (direction/movement/acceleration)

Greetings !

Currently I am working on a Unity top-down 2D simulator game with a car to drive in the city.
In order to move the car I use this code :

Code (CSharp):

1.  
2.  
3. public class car_move1 : MonoBehaviour
4.  
5. {
6.  
7. [SerializeField]
8.  
9. private float speed;
10.  
11. [SerializeField]
12.  
13. private float rotationSpeed;
14.  
15. void Update()
16.  
17. {
18.  
19. float horizontalInput = Input.GetAxis("Horizontal");
20.  
21. float verticalInput = Input.GetAxis("Vertical");
22.  
23. Vector2 movementDirection = new Vector2(horizontalInput, verticalInput);
24.  
25. float inputMagnitude = Mathf.Clamp01(movementDirection.magnitude);
26.  
27. movementDirection.Normalize();
28.  
29. transform.Translate(movementDirection * speed * inputMagnitude * Time.deltaTime, Space.World);
30.  
31. if (movementDirection != Vector2.zero)
32.  
33. {
34.  
35. Quaternion toRotation = Quaternion.LookRotation(Vector3.forward, movementDirection);
36.  
37. transform.rotation = Quaternion.RotateTowards(transform.rotation, toRotation, rotationSpeed * Time.deltaTime);
38.  
39. }
40.  
41. }
42.  
43. }
44.  

The question is, how to separate car rotation with its movement and add an acceleration, and all that by using separate keys. For example , arrow keys , ASDW and joystick on gamepad shall rotate, and 2 other keys will accelerate/move and break/stop the car (to be accurate let's take left and right triggers on gamepad).

By this post/message I'm not requesting/asking for a direct code, but if you please direct me, my thoughts to find out the solution.

Thank you

 

I think you overcomplicate the topic, below example is for 3D but should be easily adapted for 2D.
https://learn.unity.com/tutorial/lesson-1-4-use-user-input-to-control-the-vehicle

 

Thank you