Rotate movieclip at center and move car simutaniously

1

Here is my code:

var m:Matrix = car.transform.matrix;
var point:Point = new Point(car.width/2, car.height/2);
point = m.transformPoint(point);


function spinOut(e:TimerEvent)
{
    m.translate( -point.x, -point.y);
    m.rotate(10 * (Math.PI / 180));  
    m.translate(point.x, point.y);  
    car.transform.matrix = m;
    car.x += 20;
    car.y -= 3;
}

the lines: **car.x += 20; **and car.y -= 3; show no affect, and the movieclip *jumps *back to its original position. (this timer is started after the movieclips x/y values exceed some number);

thanks in advance.