Car acceleration sound ,Car accelerating engine sound script

I'm trying to find a script for car sounds and nothing worked.

I tried this last one... I put it in CarController script.

public float topSpeed = 100; private float currentSpeed = 0; private float pitch = 0;

void Update () { currentSpeed = transform.GetComponent().velocity.magnitude * 3.6f; pitch = currentSpeed / topSpeed;

  transform.GetComponent <AudioSource> ().Pitch = pitch;

}

and unity says:

'AudioSource' does not contain a definition for 'Pitch' and no accessible extension method 'Pitch' accepting a first argument of type 'AudioSource' could be found (are you missing a using directive or an assembly reference?)

if any other scripts are better please help,

thanks...