Inadequate vehicle collisions

When I use handbrake, the car goes skid, and its OK.
But why does speed grow to thousands km\h after colliding frames and stuff?
Maybe parts shoud be less tough, but car should loose speed after collide, not to bounce to the nearest building
and explode.

Yeah there are quite a few problems with car collisions and it’s rather close to the top of the bug fixing list right now. Some fixes have already gone in (notably for the ping-pong ball car-on-car collisions) but there is still plenty more to be worked on.