Align Rigidbody on Rail?

hello! i just wanted to create a small carrera rc slotcar kinda game. but i stuck at the part where the car should drive in a curve. the code looks simple as this:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. public class Carrera : MonoBehaviour {
4.      public float accerleration;
5.      void Update () {
6.          if (Input.GetKeyUp(KeyCode.DownArrow)) {
7.              this.gameObject.GetComponent<Rigidbody>().AddForce(this.gameObject.transform.forward * accerleration, ForceMode.Acceleration);
8.    
9.          }
10.          if (Input.GetKey(KeyCode.DownArrow)) {
11.              this.gameObject.GetComponent<Rigidbody>().AddForce(this.gameObject.transform.forward * -accerleration, ForceMode.Acceleration);
12.          }
13.    
14.      }
15. }
16.  

but the problem with this is that:



i somehow have to tell the rigidbody that he should rotate to the left in the curve or something like that. but how?

 

Rotate RB in direction of moment
transform.rotation = Quaternion.LookRotation(rigidbody.velocity);
i think above will work.
.