Having problems with inputs.

I am having problems make my care move i have setup the inputs in project settings and have done it in code and i do not know why it is not working,

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Car : MonoBehaviour {
private Rigidbody carRigid;
public int speed;
public int rotatespeed;

// Use this for initialization
void Start () {

	carRigid = GetComponent<Rigidbody> ();
}

// Update is called once per frame
void Update () {
	
}

void FixedUpdate (){

	if (Input.GetButton ("Drive")) {
		carRigid.AddForce (transform.forward * speed * Time.deltaTime);
	}

	if (Input.GetButton ("Reverse")) {
		carRigid.AddForce (transform.forward * -speed * Time.deltaTime);
	}

	if (Input.GetButton ("Left")) {
		transform.Rotate (0, -rotatespeed, 0);
	}

	if (Input.GetButton ("Right")) {
		transform.Rotate (0, rotatespeed, 0);
	}
}

}

All code works fine for me, but maybe your speed float is to low.
I needed set speed to 1000 to get an aceptable velocity, if speed is lower than 500, the force is not enought and you cant see diference,