You often see scenes in films where people hide behind cars and even something as flimsy as a settee during a shoot out, but what would be the penetrative power of an uzi 9mm or weaponry of a similar type and calibre?
Even a low-power handgun or rifle would go straight through a car door. Something heftier would have no trouble going through both sides. Have you not seen the pics of cars ambushed by terrorists on the news? They look like colenders - and the people inside were killed.
The engine would probably stop a bullet, yes.
As for a sofa, probably even an air rifle would go through one.
I agree with Catso, but one reason to hide behind something if being shot at, is not as a protective barrier, but to hide your body and make it harder for the shooter to aim at you. There's more chance than can miss you if they shoot at a sofa, even if the bullet goes straight through.
The uzi does not have much penetrative power, it just shoots a lot of small bullets very quickly, others of the same type do the same. They only have a small amount of propellant in the small cartridges.
It would go through a car door easily though.
Five well aimed shots from a 7.65mm Belgian FN rifle, used by the british forces a few years ago would blow a hole through a double brick wall as the cartridges were much bigger.