Algodoo

nice idia

Hell that's still not realistic, if you brake and then accelerate the car will not move but it will still heat the brake disc. Try adding angVel instead of some number like:
scene.my.Y = scene.my.Y - (scene.my.angvel / x)
You don't need to use e.this when you're using postStep, update, onClick, onDie, onKey or whatever else that doesn't involve two things, for example in onCollide you have the object that is collided and the one that collides (you use e.other but not e.this), in onHitByLaser you have the laser and the geometry (you use e.laser but not e.this), onLaserHit you also have the laser and geometry (you use e.geom but not e.laser), and so on.
I may do my version, but as far as i know brakes don't lock when they overheat...