Corrected entry: When Dom and Brian are running fast with the large vault behind them you can see how the vault is dragged into a tree, which is not moving and they drive on with the vault. Later you see a police car going into a similar tree, which then split in half. The vault is way too big and heavy to have left the tree untouched at that speed.
Mamasaur
25th May 2011
Correction: Three factors are in play here: 1) the species of the tree (it could be a much stronger tree); 2) where they crash the vault into it; and 3) how alive the tree was. Maybe the one the police car crashes into was nearly dead, and the vault is much bigger, which means that it spreads the load much more. The difference between hitting a plank with a hammer, and hitting a nail with a hammer.
Friso94