How do I rotate an object based on the terrain?

I am making a kart game like MarioKart and I am shooting 4 rays down from the kart. I have 2 problems.

1: When I shoot the raycasts down with Vector3.down, it shoots downward, but not downward from the kart's rotation, which is what I need.

2: I want to rotate the kart based on the average of the hitInfos normals, but when I try this it says it can't convert a Vector3 to a float.

Basically I want the kart to rotate based on the terrain. If anyone could help me with my problems it would be great!

Thanks!

This is my code:

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

public class KartDriving : MonoBehaviour { public Transform kart; public Vector3 hitInfoAverageNormal;

 public Vector3 rayFrontStart;
 public Vector3 rayLeftStart;
 public Vector3 rayBackStart;
 public Vector3 rayRightStart;

 // Start is called before the first frame update
 void Start()
 {

 }

 // Update is called once per frame
 void Update()
 {
     rayFrontStart.Set(transform.position.x, transform.position.y - transform.localScale.y / 2, transform.position.z + transform.localScale.z / 2);
     rayLeftStart.Set(transform.position.x - transform.localScale.x / 2, transform.position.y - transform.localScale.y / 2, transform.position.z);
     rayBackStart.Set(transform.position.x, transform.position.y - transform.localScale.y / 2, transform.position.z - transform.localScale.z / 2);
     rayRightStart.Set(transform.position.x + transform.localScale.x / 2, transform.position.y - transform.localScale.y / 2, transform.position.z);
     StabalizeKart();
 }


 void StabalizeKart()
 {
     //Here we shoot the raycasts underneath the kart
     //------------------------------------------------------------------------------------------------

     RaycastHit hitInfoFront;
     RaycastHit hitInfoLeft;
     RaycastHit hitInfoBack;
     RaycastHit hitInfoRight;

     //Here we shoot the raycasts
     Physics.Raycast(rayFrontStart, Vector3.down, out hitInfoFront, 100);
     Physics.Raycast(rayLeftStart, Vector3.down, out hitInfoLeft, 100);
     Physics.Raycast(rayBackStart, Vector3.down, out hitInfoBack, 100);
     Physics.Raycast(rayRightStart, Vector3.down, out hitInfoRight, 100);

     //Here we debug the data stored from the raycasts
     if (Input.GetKey(KeyCode.Space))
     {
         Debug.DrawRay(rayFrontStart, Vector3.down);
         Debug.Log(hitInfoFront.distance);

         Debug.DrawRay(rayLeftStart, Vector3.down);
         Debug.Log(hitInfoLeft.distance);

         Debug.DrawRay(rayBackStart, Vector3.down);
         Debug.Log(hitInfoBack.distance);

         Debug.DrawRay(rayRightStart, Vector3.down);
         Debug.Log(hitInfoRight.distance);
     }

     //Here we use the data from the raycasts to rotate the kart
     //------------------------------------------------------------------------------------------------
     hitInfoAverageNormal.Set(hitInfoFront.normal + hitInfoBack.normal / 2, transform.position.y, hitInfoLeft.normal + hitInfoRight.normal / 2);
     kart.rotation = Quaternion.FromToRotation(Vector3.up, hitInfoFront.normal);