As Mike has noted, the Assyrian Chariot is now strength three. However, the crew are armed with thrusting spears which ups its strength to 4 in close combat when it charges. Most players will upgrade to a four-man crew and gain plus one attack, giving them 3 S4 attacks plus D3 additional S4 impact hits on the turn that they charge (gulp!).
Nigel's notes in the chariot entry of the Assyrian list describes the hiostory of the chariot in the Assyrian army and explains why he didn't want to include any other types. They are too long to repeat here, but I will quote his finishing point:
"During the climax of the Assyrian empire, from Tiglath-Pileser III to the fall of Assyria, four-horse chariots were the rule, so this is the type described here. If you want to do omething else I leave it up to you to adapt the list."
Hope that helps,
Jervis