How to make Vehicle AI to change lanes

I am working on a project atm, and I need the vehicle AI to switch lanes. From lane 1 to lane 2 and vice versa. I made a script to make the vehicle stick to a lane, and in update i made it send a flag to the function (0 for first lane 1 for second lane) and make the car move towards that lane. but while moving towards the lane it starts to wobble when it reaches it..
NOTE: the lanes are 2 concentric ellipses-like (it's a race track)
I am using a waypoint in the middle of the track which moves along it's z axis as much as the vehicle. I calculate the distance from the waypoint to the vehicle and try too maintain it around a specified distance (band1, which is lane 1 and band2 which is lane2 and band1<band2)
.

I need to get rid of that wobble effect (it changes the steerAngle to make it keep the lane too much too fast)

here's the code of the function:

Code (csharp):

1. function AutoSteer(flag){
2.     var distance : float;
3.     distance = Vector3.Distance(reference.transform.position, transform.position);
4.     if(flag == 0){
5.         if(distance > band1 + maxDistance){
6.             colliderFL.steerAngle = MaxSteeringAngle * (band1 + maxDistance - distance) * 0.5;
7.         }
8.         else
9.             if(distance < band1 + minDistance){
10.                 colliderFL.steerAngle = MaxSteeringAngle * (band1 + minDistance - distance) * 0.5;
11.         }
12.         if(Mathf.Abs(colliderFL.steerAngle) > 10){
13.                 if(distance > (band1 + band2)/2)
14.                     colliderFL.steerAngle /= 8;//
15.                 else
16.                     colliderFL.steerAngle /= -10;
17.         }
18.     }
19.     if(flag == 1){
20.         if(distance > band2 + maxDistance){
21.             colliderFL.steerAngle = MaxSteeringAngle * (band2 + maxDistance - distance) * 0.5;
22.         }
23.         else
24.             if(distance < band2 + minDistance){
25.                 colliderFL.steerAngle = MaxSteeringAngle * (band2 + minDistance - distance) * 0.5;
26.         }
27.         if(Mathf.Abs(colliderFL.steerAngle) > 10){
28.                 if(distance < (band1 + band2)/2)
29.                     colliderFL.steerAngle /= 8;
30.                 else
31.                     colliderFL.steerAngle /= -10;
32.         }
33.     }

PS: I am kinda new to unity, and I tried to play around with the values.. with no luck. (all code was written by me, feel free to correct me, or offer a better solution)

 

Here is an image that I hope will explain better what I am trying to do.

 

i think using Ray from the reference object to the vehicle might do the trick, but i don't quite know how to use it, any help pls?

 

bump.