The starter gear disengages from the car's flywheel to avoid?

The starter gear disengages from the car's flywheel to avoid damage to the starter. When the car's engine starts, the starter motor engages with the flywheel to enable the engine to turn over. Once the engine is running, the starter gear must disengage from the flywheel to prevent the starter motor from continuing to drive against the spinning engine. If the starter gear remained engaged while the engine is running, it could lead to excessive wear and potential damage to the starter motor itself, which is not designed to operate under those conditions continuously.

In the context of the other options, while fuel consumption, wear on the engine, and battery drain are all relevant automotive concerns, they do not directly pertain to the function of the starter gear disengagement. The primary purpose of this mechanism is to protect the starter from damage after the engine has successfully started.