Excess wounds inflicted against chariots are never carried through onto other chariots, not even where chariots are fighting in the same squadron.

In this respect chariots continue to fight as if they were single models, even when fighting in squadrons. However, they still take Break and psychology tests as one unit, will flee and pursue as one unit, and in other respects are treated as a unit. The reason excess wounds are ignored is that the models will not necessarily be touching (they can be up to 5" apart) and also because chariots are important parts of your army it seems appropriate that they should be treated individually.