A tank's engine determines the tank's ability to accelerate, climb hills, and generally maneuver over terrain.
A destroyed engine has a chance of starting a fire inside of your tank. This in turn can lead to the destruction of other modules, and eventually the entire tank. A damaged engine will cut the power in half, drastically reducing acceleration and maximum speed. An inoperable engine will reduce engine power to zero and disable the turning controls until it is repaired.
This is lesser-known among players, but the engine does affect traverse speed.
Power - The engine power affecting how quickly the tank accelerates. Measured in horsepower (hp).
Chance of Fire - The chance the engine will start a fire inside the tank if destroyed. Diesel engines usually have a higher chance to catch fire than gasoline engines.Type - The engine type. Can be diesel or gasoline. Some consumables are only available for specific engine types.