I would like to see that demonstration with the door at a 45 degree and at a 60 degree angle to the path of the bullets.
The film said "Don't ever use a car door" but as Maximumbob54 said, something is better than nothing.
I suspect a car door at a 60 degree angle would not be penetrated, but rather would deform at the point of impact and deflect the bullet. Multiple hits on the exact same spot would probably penetrate, I'll guess.
Anyone ever tried a car door at a sharp angle to the line of fire?