[MX04]PowerSlides/Handbrake Turn/Spinning out/Decay?

Hey guys,
Just wondering how would i manipulate this code here to have it so that the player can spinout do powerslide etc;


onClipEvent (load) {
this.smoke2._visible = false;
this.smoke._visible = false;
_root.land.car.vehicle._rotation = _root.land.car1._rotation;
}
onClipEvent (enterFrame) {
if (Key.isDown(Key.SPACE) && (Key.isDown(Key.UP))) {
this.smoke2._visible = true;
this.smoke._visible = true;
} else if ((Key.isDown(Key.DOWN) && _root.speed>0)) {
this.smoke2._visible = true;
this.smoke._visible = true;
} else if ((Key.isDown(Key.UP) && _root.speed<-0)) {
this.smoke2._visible = true;
this.smoke._visible = true;
} else {
this.smoke2._visible = false;
this.smoke._visible = false;
}
if (Key.isDown(Key.SPACE) && _root.speed<1 && _root.speed>-1) {
_root.speed = 0;
}
if (Key.isDown(Key.UP)) {
_root.speed += 1;
}
if (Key.isDown(Key.DOWN)) {
_root.speed -= .5;
}
if (Math.abs(_root.speed)>25) {
_root.speed *= .95;
}
if (Key.isDown(Key.LEFT)) {
_rotation -= _root.speed/2;
}
if (Key.isDown(Key.RIGHT)) {
_rotation += _root.speed/2;
}
if (Key.isDown(Key.LEFT) && (Key.isDown(Key.SPACE))) {
_rotation -= _root.speed;
}
if (Key.isDown(Key.RIGHT) && (Key.isDown(Key.SPACE))) {
_rotation += _root.speed;
}
if (Key.isDown(Key.SPACE) && _root.speed>0) {
_root.speed -= 1;
} else if (Key.isDown(Key.SPACE) && _root.speed<0) {
_root.speed += 1;
}
if (Key.isDown(Key.SHIFT)) {
if (_root.incar1 == true) {
_root.land.car1._visible = true;
_root.land.car1._rotation = this._rotation;
_root.land.car.dude._rotation = this._rotation;
_root.land.car1._y = this._y+(_root.land._y*-1)+299.5;
_root.land.car1._x = this._x+(_root.land._x*-1)+299.5;
_root.land.car.gotoAndStop(1);
}
}
}

i have attached a FLA of another example of mine which i want to merge in but cant figure it out; Please Help!