Drive car with Pedals

I need to be able to drive a car like an electric vehicle with an automatic gearbox in Unity . I have a Pedal for acceleration and a Pedal for Brake, both have an output from -1 to 1.

The Pedal for acceleration works correctly. But when I press Brake, the car will Brake and then it drives backwards. I have tryed to code the Breake Pedal to "isBreaking = Input.GetKey(KeyCode.Space);" but i get a error because the Pedal ist not a Button, so the output is from -1 to 1.

So my question is, 1. How I have to code the Brake right, so the car apply only Breake, if Brake Pedal is pressed. 2. How can I code for driving Backwards like a gearshift logik. I want to go into reverse gear with the "r" button and then press the accelerator pedal, and the car should then go in reverse. If I then press the "f" button, the gear shift should be set back to forward and drive forward.

The code from Youtube (https://www.youtube.com/watch?v=Z4HA8zJhGEk)

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CarController : MonoBehaviour
 {
     private const string HORIZONTAL = "Horizontal";
     private const string VERTICAL = "Vertical";
 
     private float horizontalInput;
     private float verticalInput;
     private float currentSteerAngle;
     private float currentbreakForce;
     private bool isBreaking;
 
     [SerializeField] private float motorForce;
     [SerializeField] private float breakForce;
     [SerializeField] private float maxSteerAngle;
 
     [SerializeField] private WheelCollider frontLeftWheelCollider;
     [SerializeField] private WheelCollider frontRightWheelCollider;
     [SerializeField] private WheelCollider rearLeftWheelCollider;
     [SerializeField] private WheelCollider rearRightWheelCollider;
 
     [SerializeField] private Transform frontLeftWheelTransform;
     [SerializeField] private Transform frontRightWheeTransform;
     [SerializeField] private Transform rearLeftWheelTransform;
     [SerializeField] private Transform rearRightWheelTransform;
 
     private void FixedUpdate()
     {
         GetInput();
         HandleMotor();
         HandleSteering();
         UpdateWheels();
     }
 
 
     private void GetInput()
     {
         horizontalInput = Input.GetAxis(HORIZONTAL);
         verticalInput = Input.GetAxis(VERTICAL);
         isBreaking = Input.GetKey(KeyCode.Space);
     }
 
     private void HandleMotor()
     {
         frontLeftWheelCollider.motorTorque = verticalInput * motorForce;
         frontRightWheelCollider.motorTorque = verticalInput * motorForce;
         currentbreakForce = isBreaking ? breakForce : 0f;
         ApplyBreaking();       
     }
 
     private void ApplyBreaking()
     {
         frontRightWheelCollider.brakeTorque = currentbreakForce;
         frontLeftWheelCollider.brakeTorque = currentbreakForce;
         rearLeftWheelCollider.brakeTorque = currentbreakForce;
         rearRightWheelCollider.brakeTorque = currentbreakForce;
     }
 
     private void HandleSteering()
     {
         currentSteerAngle = maxSteerAngle * horizontalInput;
         frontLeftWheelCollider.steerAngle = currentSteerAngle;
         frontRightWheelCollider.steerAngle = currentSteerAngle;
     }
 
     private void UpdateWheels()
     {
         UpdateSingleWheel(frontLeftWheelCollider, frontLeftWheelTransform);
         UpdateSingleWheel(frontRightWheelCollider, frontRightWheeTransform);
         UpdateSingleWheel(rearRightWheelCollider, rearRightWheelTransform);
         UpdateSingleWheel(rearLeftWheelCollider, rearLeftWheelTransform);
     }
 
     private void UpdateSingleWheel(WheelCollider wheelCollider, Transform wheelTransform)
     {
         Vector3 pos;
         Quaternion rot;
         wheelCollider.GetWorldPose(out pos, out rot);
         wheelTransform.rotation = rot;
         wheelTransform.position = pos;
     }
 }