Unity Car Accelerometer

Hello everyone!!! I'm new to Unity. I have a problem, why when I launch a game on android the car isn't work with accelerometer(I mean when I tap on screen and rotate car isn't drive) ? The car spins along the axis z. Please help me, what's the problem? I have the following code in C #:

 using System.Collections;

using System.Collections.Generic; using UnityEngine;

public class CarController : MonoBehaviour {

 public float speed = 1500f;
 public float rotationSpeed = 15f;

 public WheelJoint2D backWheel;
 public WheelJoint2D frontWheel;

 public Rigidbody2D rb;

 private float movement = 0f;
 private float rotation = 0f;

 //private Vectro3 move;

 public Vector2 touchPosition;
 public double halfScreen;

 void Update()
 {
     //movement = -Input.GetAxisRaw("Vertical") * speed;
     //rotation = Input.GetAxisRaw("Horizontal");

     movement = -Input.acceleration.x * speed;
     rotation = Input.acceleration.z;

     if (Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Stationary)
     {
         touchPosition = Input.GetTouch(0).position;
         halfScreen = Screen.width / 2.0;
     }
 }

 void FixedUpdate()
 {

     if (movement == 0f)
     {
         backWheel.useMotor = false;
         frontWheel.useMotor = false;
     }
     else
     {

         if (touchPosition.x > halfScreen)
         {

             backWheel.useMotor = true;
             frontWheel.useMotor = true;

             JointMotor2D motor = new JointMotor2D { motorSpeed = movement, maxMotorTorque = 10000 };
             backWheel.motor = motor;
             frontWheel.motor = motor;

         }

         // move = new Vector3(Input.acceleration.x, 0.0f, Input.acceleration.y);
         

     }

     //transform.Rotate(0, 0, -movement * speed);
     rb.AddTorque(-rotation * rotationSpeed * Time.fixedDeltaTime);

 }

}

Thanks for your help in advance!