Nitro bar setup

Questions & Answers
1

Hello.
In my car game, I implemented nitro, when you apply it it multiplies the motortorque of the wheel colliders by two. But there’s somethings I whant to do but i can’t :
I want to give the nitro a duration (for exemple, it lasts 4 seconds) and then i want it to take a time to recharge.
I want to make a nitro bar associated with it (it shrinks as you use the nitro and grows as it recharges)

There is my nitro script :

*It is part of the car controller

void FixedUpdate()
    {
        NitroSystem();
    }

void NitroSystem()
    {
        if(inputManager.nitro)
        {
            nitroIsOn = true;
        }
        else
        {
            nitroIsOn = false;
        }

        if(nitroIsOn == true)
        {
            nitroValue = 5f;
            topSpeed = topSpeedValue * 2f;
        }
        else if (nitroIsOn == false)
        {
            nitroValue = 1f;
            topSpeed = topSpeedValue;
        }
    }
2

private float nitroAmount;
public float maxNitroAmount = 5;
public float nitroChargeSpeed;
public float nitroUseSpeed;

void Start()
     {
         NitroAmount = maxNitroAmount;
      }

void NitroSystem()
     {
         if(inputManager.nitro)
         {
             nitroIsOn = true;
         }
         else
         {
             nitroIsOn = false;
         }
 
         if(nitroIsOn == true && nitroAmount > 0)
         {
             nitroAmount = Mathf.Clamp(nitroAmount  - (Time.DeltaTime * nitroUseSpeed),0,nitroAmount); 
             topSpeed = topSpeedValue * 2f;
         }
         else if (nitroIsOn == false)
         {
             nitroAmount = Mathf.Clamp(nitroAmount + (Time.DeltaTime * nitroChargeSpeed),0,maxNitroAmount);
             topSpeed = topSpeedValue;
         }
     }