What might indicate that a vehicle has been effectively engaged in combat?

A vehicle emitting smoke is a strong indicator that it has been effectively engaged in combat. Smoke can originate from various sources, such as engine damage, ammunition cook-off, or other battle-related impacts that compromise the vehicle's functionality. When a vehicle produces smoke, it can signal that it has sustained damage or is experiencing mechanical failure due to combat actions.

In contrast, the presence of a crew still operating the vehicle does not necessarily indicate engagement; they may be maneuvering for tactical reasons unrelated to combat effectiveness. Repositioning can occur for various strategic purposes, and maintaining speed might not reflect any combat engagement—it can occur regardless of whether the vehicle has encountered enemy action. Therefore, the emission of smoke serves as the most direct indicator of a vehicle's involvement in combat, highlighting its compromised state and the consequences of engagement.