If you have around 40 chariots, there is no melee cavalry that make it to them to do damage but if they do, its fine because the Persian Calvary can have around 380 hp at fully upgraded. I don't find that these champion chariots are a problem. The Mauryans, Britons, and Selecuids chariots are actually weaker in health but cost metal. Persians are to overpowered because these chariots only costs food and wood. It is becoming a problem because in every game I play, everyone is wanting to use the Persian civ and nothing can counter these chariots.