Laggy and feather car physics.

Unity Engine
1

Hi, me and my friend have been assigned to make a game for school and we decided to make a car game.
I chose to do the scripting and it havent turned out so well.
Instead i got a script from a friend and modifyed it a little.
As you see in the video the car starts to fly almost as soon as it touches a wall from about a 45° angle
(also very laggy colissions).
According to him it has something to do that the car has a rigid body,
but the scipt is not meant to work with rigid bodies. He said that i should use some code that make
the ridgid body get a push forward instead of the car (if i remember right).

I dont know what you need for info so im just gonna put some here.

video: http://www.youtube.com/watch?v=DgZed6AeRmU&feature=youtube_gdata

The car setup:
Car (with rigid body and car script)
–colission mesh (with mesh collider(smooth sphere collisions, convex)
–visual body
–tires
----all tires here(with wheel collider)

All the boxes(houses) have a unedited mesh collider attatched to them.

Code:

private var speed = 0.0;
private var turning = 0.0;
var acceleration = 0.2;
var autobreak = 0.99;
var max_turn = 65.0;
var turning_speed = 2.5;
var turn_friction = 0.96;
private var drift = 0.0;
var drift_amount = 12.5;
var min_drift_speed = 15.0;
var max_speed = 50;

function Update () {
  
   // Debug.DrawRay(transform.position, -up * 5, Color.green); 
   //if(Physics.Raycast(transform.position, -up, 5)){
   //}
   var up = transform.TransformDirection(Vector3.up);
 
/*MOVING FORWARD*/
	if (Input.GetButton("Vertical")  speed < max_speed) {
		if(Physics.Raycast(transform.position, -up, 8)){
			speed += acceleration*Input.GetAxis("Vertical");
			}}
		else {
			if(speed != 0) {
				speed *= autobreak;
			}
		}
	gameObject.transform.Translate(drift,0,speed * Time.deltaTime);
	
/*TURNING*/

	if (Input.GetButton("Horizontal")  turning < max_turn  turning > -max_turn) {
		turning += turning_speed*Input.GetAxis("Horizontal");
		}
	else {
		if(turning != 0) {
			turning*= turn_friction;
		}
	}
	gameObject.transform.Rotate(0,drift*drift_amount+turning*speed/8*Time.deltaTime,0);

/*Drifting*/

	if(speed > min_drift_speed) {
		drift = -0.1*(speed-min_drift_speed)*turning/500;
	}
	else {
		drift = 0;
	}


	if(speed > -0.01  speed < 0.01)  {
			speed = 0;
	}
}

Any help would be usefull.

2

You’re missing something important - Gravity.

3

nope, i have it on and it even if i have mass on 1000000000 theres no difference from 1.